Geosphere - St. Lawrence University Chimney Mtn Shawinigan.pdf · geosphere.gsapubs.org on February 1, 2011 . Timing of deformation in the Central Adirondacks . PSD C AB HH . F T

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Geosphere

Differentiating Shawinigan and Ottawan orogenesis in the Central Adirondacks

J Chiarenzelli D Valentino M Lupulescu E Thern and S Johnston

Geosphere 201172-22 doi 101130GES005831

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Notes

copy 2011 Geological Society of America



J Chiarenzelli1 D Valentino2 M Lupulescu3 E Thern4 and S Johnston5 1Department of Geology St Lawrence University Canton New York 13617 USA 2Department of Earth Sciences SUNY Oswego Oswego New York 13216 USA 3New York State Museum Research and Collections Albany New York 12230 USA 4Department of Imaging and Applied Physics Curtin University of Technology GPO Box U1987 Perth WA 6001 Australia 5Physics Department California Polytechnic State University San Luis Obispo California 93407-0404 USA

ABSTRACT

The rocks at Chimney Mountain proshyvide a rare glimpse into primary intrusive relations and exceptionally well-preserved pre-Shawinigan metasedimentary rocks in the Adirondack Highlands despite a strong Ottawan thermal overprint A near vertishycal contact between granite (ca 1172 Ma) and a shallowly dipping and structurally intact sequence of quartzose to calc-silicate metasedimentary rocks is exposed on the southern flank of Chimney Mountain in the Central Adirondacks The contact is marked by foliation truncation and a meta-somatic aureole with randomly orientated porphyro blasts of enstatite rimmed by anthophyllite (max 5 cm) and phlogopite (max 2 cm) and a zone of granular quartz-rich rock The granite is non- to weakly foliated and has a shallow north-plunging mineral lineation as do the metasedimentary rocks Zircons separated from a diopsideshybearing quartzite (82 SiO

2 075 m thick) are of variable size (up to 400 microm) equant and contain on average gt1000 ppm urashynium Scanning electron microscope investishygation indicates that there is little variation in a uniformly dark cathodoluminescence response no discernible cores or rims few inclusions and partially faceted to round morphologies Zircon U-Pb sensitive high-resolution ion microprobe (SHRIMP II) ages of 1042 plusmn 4 Ma and 1073 plusmn 15 Ma are coincishydent with Ottawan metamorphic ages from the Adirondack Highlands Zircons from the intrusive granite yield large cores with

E-mails Chiarenzelli jchiarenstlawuedu Valenshytino dvalentioswegoedu Lupulescu mlupules mailnysedgov Thern ericthernorg Johnston scjohnstcalpolyedu

typical anorthosite-mangerite-charnockiteshygranite (AMCG) ages (ca 11716 plusmn 63 Ma) and sparse thin younger rims (ca 1060ndash 1090 Ma) readily distinguishable by cathshyodoluminescence Despite the younger zirshycon ages the metasedimentary rocks and their fabric must predate the crosscutting granite The thermal effect of the Ottawan event was likely enhanced by volatile fl uxshying and resulted in recrystallization and resetting of zircons in the metasedimentary rocks However it had limited effects on zirshycons in the granite and produced only thin metamorphic rims emphasizing the imporshytance of local geochemical conditions to the response of zircon to metamorphism Elzeshyvirian or Shawinigan fabrics are preserved as the dominant foliation the lineation and folding is likely late (post-1170 Ma) Shawinshyigan or Ottawan (ca 1050 Ma) Titanites from the same metasedimentary sequence yield a range of 238U 206Pb ages from 969 to 1077 Ma with a maximum probability age of 1035 Ma similar to other titanites in the Adirondack Highlands Ottawan paleotemshyperatures estimated by zirconium in titanite thermometry range from 787 to 818 degC

INTRODUCTION

One of the most intriguing problems in the Adirondacks is the timing and origin of fabric forming events Recently work by Heumann et al (2006) and Rivers (2008) has pointed out the significance of the Shawinigan orogenic event (ca 1200ndash1140 Ma) in the Adirondack segment (Fig 1) of the Grenville Province (Davidson 1986 Wynne-Edwards 1972) In addition the overprint of the Ottawan Pulse (ca 1090ndash1020 Ma) of the Grenvillian Orogeny (Rivers 2008) is now known to be less pervashysive than once thought with signifi cant areas

of the Adirondacks including the Lowlands and parts of the Highlands lacking anatexis and metamorphic zircon of Ottawan age (Heushymann et al 2006 Bickford et al 2008) While these findings are based on the identifi cation of metamorphic zircon in pelitic gneisses that have undergone anatectic melting and are not directly linked to fabric formation they raise intriguing questions as to the four-dimensional evolution of the Adirondack region preliminarily addressed on an orogen scale by Rivers (2008)

The recognition of the Shawinigan event in Quebec (Corrigan 1995) and in the Adironshydacks (Heumann et al 2006 Mezger et al 1992) has some profound implications for the region and the Ottawan Pulse of the Grenvillian Orogeny (Rivers 2008) in particular (Fig 1) For example it has forced the reevaluation of many of the long-held assumptions about Adirondack and Grenville geology including the tectonic setting and origin of massif anorthoshysite and related rocks (intruded just after or pershyhaps during the waning phases of the Shawinshyigan Orogeny) the extent of the Elzevirian Orogeny (McLelland and Chiaren zelli 1989) the nature and disposition of metasedimentary rocks of the Trans-Adirondack Basin (Chiarenshyzelli et al 2010) and the age and origin of major structural features in the Adirondacks that were in the past generally assumed to be Ottawan or severely overprinted andor oblitershyated during the Ottawan tec tonism (McLelland and Isachsen 1980 McLelland et al 1996 Wiener et al 1984)

Most rocks in the Adirondacks show evidence of considerable deformation and display a wide variety of planar and linear fabrics (McLelland 1984 McLelland and Isachsen 1980 Wiener et al 1984) In most cases even metaplutonic rocks form continuous linear belts (Fig 2) with fabrics that are generally parallel to their overshyall shape and elongation (Isachsen et al 1990)

Geosphere February 2011 v 7 no 1 p 2ndash22 doi 101130GES005831 17 figures 6 tables

For permission to copy contact editinggeosocietyorg copy 2011 Geological Society of America

2

A H

N


Timing of deformation in the Central Adirondacks

PSD

C AB

GM

HH

GFTZ

S u p e r i o r P r o v i n c e

Orogenic Lid (no Ottawan overprint)

gt13 Ga Laurentian crust-Grenvillian Orogeny

Frontenac-Adirondack Belt-Shawinigan Orogeny

Composite Arc Belt-Elzivirian Orogeny

Grenville Outliers (GMmdashGreen Mtns HHmdashHudson and Housatonic Highlands)

(1090ndash980 Ma)

(1200ndash1140 Ma)

(1245ndash1225 Ma)

G r e n v i l l e P r o v i n c e

B L F C C M Z

47deg

46deg

45deg

44deg

43deg

42deg

80deg 78deg 76deg 74deg

100 km

N

SUPERIOR

NAIN

CHURCHILLGFTZ

AH

BCS

EGP

PT

CMB

CGB

500 km

40degN

84degW

55degW

56degN

CGT GRENVILLE

AL

A L


47deg

46deg

45deg

44deg

43deg

42deg

F-AB

Figure 1 Location diagram showing the Grenville Province extent of rocks known to be affected by the Shawinigan Orogeny and Central Adirondack study area Boundaries drawn after Rivers (2008) Upper diagram shows the major subdivisions of the Grenville Province after McLelland et al (1996) Abbreviations used AHmdashAdirondack Highlands ALmdashAdirondack Lowlands BCSmdashBaie Comeau segment BLFmdashBlack Lake fault CABmdash Composite Arc Belt CCMZmdashCarthage Colton Mylonite Zone CGBmdashCentral Gneiss Belt CGTmdashCentral Granulite terrane CMBmdashCentral Metasedimentary Belt EGPmdashEastern Grenville Province F-ABmdashFrontenac Adirondack Belt GFTZmdashGrenville Front Tectonic Zone GMmdashGreen Mountains HHmdashHudson and Housatonic Highlands PSDmdashParry Sound Domain PTmdashPinware terrane

In some areas (eg Southern Adirondacks) major folds are defined by the refolding of lithoshylogic units about fold axes of different orientashytions and perhaps related to temporally distinct events Supracrustal rocks are typically found in narrow attenuated linear belts and are often highly disrupted intruded and interleaved with metaigneous rocks A number of large strucshytural domes are also apparent and are defi ned by upward arching foliation trends (DeWaard and Romey 1969 Chiarenzelli et al 2000 Gates et al 2004) The overall picture is one of intense deformation and translation such that primary geologic relationships are rarely preshyserved However which event is responsible for any given individual structure or fabric is curshyrently unresolved

Nonetheless there are also some excellent examples of primary relationships particularly in and around the Marcy anorthosite massif At Lake Clear (NW of Saranac Lake) igneous rocks of anorthositic to gabbroic composition with primary fabrics display intrusive relations (McLelland and Chiarenzelli 1991) Roaring Brook on the side of Giant Mountain exposes a classic intrusion breccia (McLelland et al 2004) The preservation of these features is likely related to the competent nature of anorshythosite which would have been several hundred degrees below its melting temperature during peak metamorphism and deformation Smaller coronitic gabbro bodies have likely survived deformation in the same way In some instances coronitic gabbro bodies external to the Marcy Massif can be traced from their structurally intact core (with well-preserved ophitic texture) into strongly foliated garnetiferous amphiboshylites at their margins Interestingly these rocks record a two-stage metamorphic history with an initial granulite-facies corona forming event (McLelland and Whitney 1980) followed by the influx of fluids garnet and hornblende growth and textural modification In all of these examples relatively strong competent mafi c to intermediate rocks are involved primary relashytionships and textures in more ductile granitic rocks are rarely preserved intact

An ~10-m-wide near vertical contact zone is exposed on the southern flank of Chimney Mountain in the Central Adirondacks (Figs 2 and 3) external to anorthosite massifs where it can be traced for nearly a kilometer There hornblende granite intrudes a particularly well-preserved and compositionally layered supracrustal sequence exposed on the western summit Our goals for this contribution are to (1) document this contact zone (2) describe the layered metasedimentary sequence (3) use U-Pb zircon geochronology to constrain the age and origin of the contact zone and the fabric it

Geosphere February 2011 3

Indian LOld Forge

Station

Oregon Snowy Mtn

Gore Mtn


Canton

Malone

Gouverneur Tupper L

Canton

Boonville

LClear

Plattsburgh

Dresden

Saratoga Springs

Johnstown

Saranac L

LPlacid

Marcy

Chimney Mtn

CANADA US

Lowlands Highlands

0 25 50 kilometers

N

CCMZ

Anorthosite Massifs

Figure 2 Simplified geologic map of the Adirondack region showing locations of the areas mentioned in the text and place names for reference The small red squares show the locashytion of Chimney and Gore mountains

cuts (4) discuss the implications of our fi ndings on the regional tectonics in the Central Adironshydack Highlands particularly the preservation of early fabrics and nature of pre-Shawinigan metasedimentary rocks and (5) document the Ottawan thermal overprint

GEOLOGICAL SETTING AND FIELD RELATIONS

The Adirondack Mountains are part of the Grenville Province whose current domal topographic expression is a function of much younger uplift (Isachsen 1975 1981 Roden-Tice et al 2000) A fundamental boundary between the Adirondack Highlands and Lowshylands the Carthage Colton Mylonite Zone has been recognized (Geraghty et al 1981

Chiarenzelli et al

Streepey et al 2001) and refl ects differences in metamorphic timing (Mezger et al 1992) predominant rock types and topographic expression The zone likely has broader signifi shycance and represents the bounding fault of the upper carapace of the orogen down-dropped during orogenic collapse (Selleck et al 2005 Rivers 2008) The Chimney Mountain region is located within the Highlands ~30 km south of the Marcy anorthosite massif which forms the bedrock core to the High Peaks region (Figs 2 and 3) Just north of the study area there is an east-west arching belt of highly deformed marshybles and charnockitic gneisses Some of these rocks may be traced around the northern fl ank of Snowy Mountain Dome (deWaard and Romey 1969 Gates et al 2004 Valentino and Chiarenshyzelli 2008) into the Chimney Mountain area

across a large brittle fault within Indian Lake whose offset is unknown (Isachsen et al 1990)

The Chimney Mountain area is located within the Thirteenth Lake 15 min Quadrangle (Krieger 1937) about 10 km east of Indian Lake and 13 km due west of the Barton (Gore Mountain) garnet mine (Fig 2) It is part of a NNE-trending belt of interlayered supracrustal and metaigneous rock ~7 km wide between anorthositic to charnockitic rocks of Snowy Mountain Dome (to the west) and the Oregon Dome-Thirteenth Lake area (to the south and east) Lithologies include granitic charnockitic syenitic and gabbroic metaigneshyous rocks that intrude dismember and occasionshyally engulf a sequence of calc-silicates marbles quartzites and amphibolites (Krieger 1937) Anorthosite makes up more than half of the quadrangle occurring primarily east and south of Chimney Mountain (Fig 2)

Detailed mapping in the Thirteenth Lake quadrangle and those adjacent to it (Krieger 1937) indicate that the Grenville metasedimenshytary rocks are the oldest recognized rocks in the region and are intruded by a variety of igneous rocks thought to be nearly contemporaneous with one another and by all accounts similar to the anorthosite-mangerite-charnockite-granite (AMCG) rocks found throughout the Adironshydack Highlands Both granite-syenite and gabbro-anorthosite suites have been identifi ed during mapping as well as hybrid rocks known as the Keene Gneiss (Miller 1918) The metasedshyimentary rocks underlying Chimney Mountain are part of a 5-km-long and 1-km-wide belt that trends northwest and is surrounded and engulfed by metaplutonic rocks ranging in composition from syenitic to granitic (Fig 2)

Along the western summit of Chimney Mountain and within the ldquoGreatrdquo rift (Miller 1915) that marks the projection of a fault accommodating a post-Pleistocene landslide a sequence of shallowly dipping (lt30deg to the NNW) metasedimentary rocks are exposed (Fig 3) The sequence is noteworthy because of its apparent state of preservation the ability to trace sedimentary layers of distinct composition for tens of meters (Fig 4) and the relative lack of injected igneous material The well-layered (10ndash100 cm thick) metasedimentary rocks include individual layers of diopsidic quartzshyite diopsidite and rusty weathering micaceous quartzo feldspathic gneisses The sequence is markedly different than the thick sequence of calc-silicate gneisses exposed on the trail to the summit from Kings Landing where orthopyroxene-bearing leucosomes and pegmashytites intrude highly foliated and folded diopsidic gneisses with thin quartz veins (Fig 5) On the approach to the western summit diopside-rich rocks become subordinate and quartz-rich


4

86

8

0

1214

10

12

10

88

14



7232

24

28

14

7824

42

28

24 32

56

36

888

Grenville Series

Syenitic Gneiss

Syenitic Gneiss

40

36

Foliation andor compositional layering

Mineral lineation

Regional foliation trend Krieger (1937)

Observed contact

Sgr - Granite Gv - Grenville Series

05 miles

N

10 kilometers

Granite

Inferred contact

1 mile

W 7

4deg15

prime W 74deg10prime

Kings Landing

Below

Warren CountyHamilton County

N

N 43deg40prime

N 43deg40prime Geology by M H Krieger 1930ndash1931

Quaternary

Gabbro

Anorthosite

Anorthosite border facies

Granite gneiss

Syenitic gneiss

Grenville Series

Fault Trace

Figure 3 Upper diagram Geology of part of the northwest corner of Thirteenth Lake Quadrangle after Krieger (1937) Black recshytangular outline shows area of lower figure Lower diagram Simplified geologic and structural map of the summit and southern and western flanks of Chimney Mountain showing foliation and lineation trends Regional foliation trends taken from Krieger (1937)



Chiarenzelli et al

Chimney Mtn

Look direction of photograph above

Quartzite Geochron Sample Granite Geochron Sample

Hamilton County

Warren C

ounty

Infrared Imagery from httpwww1nygisstatenyusMainMapcf

meters

0 500 1000

Figure 4 Field photograph (upper position) of continuous layers of metasedimentary rock exposed on west summit of Chimney Mountain looking east across the Great ldquoriftrdquo of Miller (1915) Note people for scale (red circle) White layers are diopsidic quartzite rusty layers contain phlogopite and pyrite Infrared aerial photograph (lower position) shows the look direction of the photograph above and the location of samples selected for geochronology

lithologies predominate Folding in the upper sequence at Chimney Mountain is relatively rare however a moderately strong rodding lineation plunging from 0 to 14degN is readily observed (Fig 6)

In the saddle on the summit of Chimney Mountain a number of ledges of metasedishymentary rock and interlayered sheets (sills) of intrusive granite gneiss and pegmatite occur (Valentino and Chiarenzelli 2008) Some of the intrusive sheets contain garnet andor graphite On the eastern summit of Chimney Mountain hornblende granite with a strong north-dipping lineation similar in orientation to that in the metasedimentary rocks and weak sporadically developed foliation occurs Along the western margin of the eastern summit the contact between the metasedimentary rocks and the granite is exposed in several areas and can be traced south down the mountain for several kilometers along the course of an intermittent stream

The contact ranges from near vertical to steeply inclined to the west with the granite beneath the metasedimentary rocks (Fig 7) In some areas the contact is nearly conformable but in others the granite clearly truncates a preexistshying foliation developed in the metasedimentary rocks and demarked by elongate quartz grains and oriented micas In several areas a very coarse-grained rock contains large (up to 5 cm) blocky yellow-green sometimes twinned enstatite porphyroblasts The enstatite crystals have thin (1ndash2 mm) dark green outer rims of anthophyllite and grow in random orientations crosscutting foliation in the host rock (Fig 8) Phlogopite porphyoblasts (up to 3 cm) are also abundant and in some areas dominate the conshytact zone forming a ldquospottyrdquo schistose rock Other minerals include acicular tremolite develshyoped at or near the contact Metasedimentary rocks within meters of the contact are quartz-rich and coarse-grained but retain their foliation despite any changes in their bulk chemistry and mineralogy that may have occurred during intrusion or afterward Some quartzite samples appear to be brecciated with metamorphic minshyerals infilling veins between otherwise intact and angular fragments

ANALYTICAL METHODS AND RESULTS

See Appendix for complete analytical proceshydures and associated references

PETROGRAPHY AND GEOCHEMISTRY

Nine rocks from the metasedimentary sequence at Chimney Mountain representashytive of the lithological variation observed




Pegmatitic Leucosome


Diopsidite

Diopsidite

Diopsidite

Diopsidite


Figure 5 Field photograph of typical exposures of calc-silicate gneisses and pegmatite on trail to the western flank of Chimney Mountain The upper photograph displays pegmatitic leucosome that contains orthopyroxene and cuts nearly massive diopsidite Note GPS for scale Lower photograph displays diopside-rich calc-silicate gneiss with folded quartz veins (example outlined by dashed white line) Note penny for scale

were prepared for petrographic and geochemishycal analysis including the diopside-bearing quartzite used for geochronology (KS-4) Their mineral assemblage includes quartz diopshyside perthite plagioclase orthopyroxene and phlogopite Occasionally abundant accessory minerals occur including titanite pyrite and zircon Typical assemblages observed include diopside-quartz-perthite-titanite perthite-quartzshydiopside-phlogopite-titanite-pyrite and quartz-diopside-plagioclase-orthopyroxene (Fig 9) An additional sample of diopside-garnet calcshysilicate skarn was collected for comparison from Rt 28 between Indian Lake and Speculator Two samples of rock were collected for geochemical analysis near the contact The first has enstatite porphyroblasts (Contact A) and is shown in Figshyure 8 and the second is from a coarse-grained granular quartzite (Contact B) within 10 m of the contact A sample of granite (Granite on Table 1) from the eastern summit of Chimney Mountain was collected for geochronology and analyzed for major- and trace-element geochemistry

Quartzose and diopside-rich rocks are granoshyblastic and equigranular with polygonal grain boundaries Quartz is typically strain free some has slight undulatory extinction Titanite occurs as rounded inclusions in pyroxene and quartz and as polygonally bounded linked clusters Foliashytion when present is defined by the orientation of phlogopite and quartzofeldspathic lenses or quartz ribbons Some quartz occurs as thin elonshygate domains of uncertain origin parallel to comshypositional layering and foliation (Fig 8)

The major- and trace-element composition of samples from Chimney Mountain were anashylyzed by inductively coupled plasma-optical emissions spectra (ICP-OESmdashmajor elements) and inductively coupled plasma-mass specshytrometry (ICP-MSmdashtrace elements) at ACME Analytical Laboratories in Vancouver British Columbia (Table 1) The silica content of the Chimney Mountain metasedimentary rocks varies from 43 to 82 with the majority of the rocks containing 57ndash62 SiO

2 While

magnesium and calcium contents are generally elevated aluminum potassium and sodium are fairly low The loss on ignition (LOI) is also fairly low (02ndash14) Rare earth eleshyment (REE) concentrations range from ~25 to 200 of that of the post-Archean Australian Shale composite (Taylor and McLennan 1985) and are relatively flat when normalized to it (Fig 10) Three samples with low silica conshytents are depleted in light rare earth elements (LREE) but are enriched in the heavy rare earth elements (HREE) The sample with the greatest amount of silica (82) has the second least amount of REEs The skarn and granite samples have the highest REE concentrations



Chiarenzelli et al

L

L

Figure 6 Field photograph of a shallowly north-plunging rodding lineation developed in the quartzose metasedimentary rocks on the western summit of Chimney Mountain Lineation (L) is developed on a surface defined by foliation and compositional layering Note hammer for scale Inset shows near shallow north-plunging hornshyblende lineation (L) in granite from the eastern summit of Chimney

Figure 7 Contact of hornblende granite and supracrustal rocks near the eastern summit of Chimney Mountain Here the contact is near vertical and approximately parallel to foliation in the metasedimenshytary rock Note splitting along foliation in metasedimentary rocks and massive nature of the granite Hammer spanning contact for scale

Mountain Hammer head for scale

Compared to upper crustal estimates Cr and Ni are low while Ba and Sr are generally elevated Zirconium varies from 401 to 2183 ppm

Samples of the metasedimentary rock (coarse-grained quartzite and enstatite-bearing rock) from within 10 m of the contact conshytain 7083 and 7402 SiO

2 respectively In

nearly all regards their major-element composhysition matches that of the sample of diopsidic quartzite (KS-4) utilized for geochronology which has 8158 SiO

2 Among the samples

analyzed these three have the lowest concenshytrations of Al O Fe TiO Na O and MnO

2 3 T 2 2

However the contact zone samples have conshysiderably more MgO (988 and 1168) than the geochronology sample (465) In trace-element abundance the geochronology sample and the coarse-grained quartzite have

very similar trace-element abundances with most elements 4ndash5times less abundant than in the enstatite-bearing contact rock

U-Pb Zircon Geochronology

Diopsidic quartzitendashzircons were separated from a 075-m-thick diopsidic quartzite layer on the western summit of Chimney Mountain hundreds of meters from the contact (Fig 4) The rock had a granular texture and contains an assemblage of quartz-diopside-orthopyroxene Several zircons and titanites were seen as inclusions within larger pyroxene and quartz grains One kilogram of rock yielded several hundred round to equant zircon crystals some with one or more crystal faces visible (Fig 11) The zircons ranged from clear to dark and varshy

ied in size from 01 to 04 mm Investigation by scanning electron microscope and in cathodoshyluminescence mode failed to show internal complexity including zoning cores rims or inclusions Cathodoluminescence response was consistently dark with relatively little varishyation (Fig 12)

Zircons were analyzed by sensitive high-resolution ion microprobe (SHRIMP II) U-Th-Pb methods at the geochronological laboratory at Curtin Technical University in Perth Aus tralia (Table 2 Fig 13) Zircons had an average urashynium content of 1093 plusmn 483 ppm and UTh ratio of 53 plusmn 15 Two populations of zircons were evident from the analyses conducted A group of 31 mostly concordant analyses yielded an upper intercept age of 1042 plusmn 4 Ma (2σ) and a group of 3 concordant to slightly discordant




3 cm

qtz

antenst

antenst

phg

ant

qtz

Figure 8 Scanned slab containing large randomly oriented enstatite (enst) rimmed by anthophyllite (ant) porphyroblasts phlogopite (phg) and quartz (qtz) lenses in a quartz-rich metasedimentary rock within a few meters of the contact with the hornshyblende granite Note the thin dark green anthophyllite rims on otherwise pale green to yellow enstatite crystals Upper right hand crystal is ~3 cm long

analyses gave an age of 1073 plusmn 15 Ma (2σ) Six other analyses were highly discordant and their ages likely meaningless because of the magnishytude of Pb loss

Granitendashzircons were separated from a kiloshygram of lineated granite collected on the eastshyern summit of Chimney Mountain The modal mineralogy of the rock consists of k-feldspar quartz plagioclase hornblende and magneshytite A yield of nearly a thousand zircons was compatible with a zirconium concentration of 6456 ppm The zircons were large (01ndash 03 mm) pinkish and prismatic to equant Investigation by scanning electron microscope in cathodoluminescence mode revealed fi ne zoning inclusions and thin homogenous rims (Fig 14) Rims were best developed on the tips of euhedral crystals however they make up only a small percentage of the volume of zircon present

Zircons from the granite were analyzed by LA-MC-ICP-MS at the Arizona Laserchron Center at the University of Arizona in Tucson (Table 3 Fig 15) Individual analytical spots (~20ndash30 microm) contained from 79 to 1454 ppm uranium While variable UTh ratios typishycally ranged between 2 and 5 however values as high as 17 were found in some rims Two distinct age populations were identifi ed despite the apparent overlap on the Concordia diagram Seven zircon analyses of outer rims yielded an

qtz

qtz

plg

opx cpx

cpx

phg

cpx

qtz

tia

tia qtz

qtz

qtz cpx

opx tia

cpx tia

zrc

μm50

μm100

Figure 9 Photomicrographs of the equigranular texture and metamorphic minerals typically found in the Chimney Mountain metasedimentary rocks The upper photomicrograph is shown with crossed nichols and the lower in plane polarized light Minshyeral abbreviations include cpxmdashclinopyroxene (diopside) phgmdash phlogopite plgmdashplagioclase opxmdashorthopyroxene qtzmdashquartz tiamdashtitanite and zrcmdashzircon

age of 10848 plusmn 109 Ma while the remainder brown Their chemical composition is given in (n = 31) yielded a weighted mean average age Table 5 of 11716 plusmn 63 Ma Individual analytical spots (~35 microm) yield a

Titanitendashtitanites were separated from the variety of titanite compositions with U concenshysame diopsidic quartzite from which zircons tration ranging from 311 to 759 ppm and UTh were separated and analyzed by LA-MC-ICP- ratios of 034ndash066 (Table 4) Although the data MS at the Arizona Laserchron Center at the do not define a single age population iso topic University of Arizona (Table 4 Fig 16) Titanite data on individual spots yield concordant ages made up the majority of the heavy mineral frac- with 206Pb238U ages that range from 969 to tion of the rock and the grains were approxi- 1077 Ma and have a probability distribution mately the same size and shape as many of the with a peak at 1035 Ma that is skewed toward zircons They ranged in color from clear to dark younger ages (Fig 16)



Chiarenzelli et al

TABLE 1 MAJOR-ELEMENT ICP-OES ANALYSES OF SELECT SAMPLES FROM CHIMNEY MOUNTAIN

ICP-OES KS-1 KS-2 KS-3 KS-4 KS-5 KS-6 KS-7 KS-8 KS-9 KS-10 Diopsidic quartzite Contact Granite SiO2 6232 598 5568 8158 6136 4337 625 5712 5313 4393 7083 7402 6998 Al2O3 555 621 804 284 759 1171 1261 1115 488 57 176 157 1331 Fe2O3 358 371 584 157 187 1724 531 623 702 1423 226 199 474 MgO 898 93 852 465 902 618 414 662 1106 731 988 1168 011 CaO 1747 1844 1725 758 1348 1201 581 833 2079 2632 1357 838 123 Na2O 107 114 296 108 169 294 426 171 164 017 074 029 355 K2O 024 027 027 015 361 123 288 578 012 006 008 051 527 TiO2 041 051 06 015 051 353 077 065 047 049 011 011 044 P2O5 008 008 008 008 008 085 015 021 006 001 002 002 005 MnO 013 014 023 004 004 019 009 011 029 041 006 005 007 Cr2O3 0003 0005 0006 0002 0005 0009 0006 0006 0005 0005 lt0002 lt0002 lt0002 Ni ppm 21 20 16 7 43 22 25 23 20 5 lt20 lt20 lt20 Sc ppm 7 7 9 3 7 38 12 12 9 9 3 3 5 LOI 02 04 05 03 07 06 14 21 05 14 04 11 09 TOTC 017 019 004 001 005 004 002 013 002 052 006 003 011 TOTS 001 001 005 001 001 005 001 003 001 054 002 lt002 lt002 SUM 10003 10001 9997 10003 9997 9987 9993 10002 9997 10003 9972 9972 9962

ICP-MS Ag ppm lt01 lt01 lt01 lt01 lt01 lt01 lt01 lt01 lt01 02 02 lt01 lt01 As ppm 11 13 lt05 lt05 lt05 05 05 24 lt05 06 lt05 lt05 05 Au ppb 09 lt05 06 lt05 1 13 lt05 lt05 12 14 09 13 19 Ba ppm 312 595 382 342 9429 2604 5638 7135 214 136 19 61 893 Be ppm 2 2 3 1 2 2 3 3 3 7 lt1 1 3 Bi ppm lt01 lt01 lt01 lt01 lt01 01 01 01 lt01 03 lt01 lt01 lt01 Cd ppm lt01 lt01 lt01 lt01 lt01 01 01 lt01 lt01 lt01 lt01 lt01 lt01 Co ppm 73 82 97 38 145 45 141 133 198 79 49 241 1062 Cs ppm 03 03 lt01 lt01 08 01 04 97 lt01 01 lt01 13 02 Cu ppm 18 18 1 23 67 174 26 21 27 143 1 04 16 Ga ppm 69 75 109 44 84 231 163 159 89 131 28 38 262 Hf ppm 16 17 29 1 24 55 59 58 29 31 06 11 181 Hg ppm lt001 lt001 lt001 lt001 lt001 001 lt001 lt001 lt001 lt001 007 lt001 lt001 Mo ppm 07 04 02 1 03 13 05 15 02 02 21 07 22 Nb ppm 49 61 76 2 7 66 119 10 44 51 178 92 311 Ni ppm 38 4 14 4 332 189 122 105 17 47 2 18 2 Pb ppm 1 11 15 07 09 38 2 13 59 32 04 07 26 Rb ppm 41 5 23 12 715 25 768 1371 09 18 08 283 1547 Sb ppm lt01 01 01 lt01 lt01 01 01 03 01 08 lt01 lt01 lt01 Se ppm lt05 lt05 lt05 lt05 lt05 lt05 lt05 lt05 lt05 05 lt05 lt05 09 Sn ppm lt1 lt1 1 lt1 lt1 2 3 2 lt1 56 lt1 2 10 Sr ppm 1814 2159 3734 1362 4499 5132 4901 5135 1923 622 854 75 1119 Ta ppm 03 04 06 01 05 05 09 08 04 04 152 6 126 Th ppm 1 17 26 14 59 95 122 106 29 08 13 14 57 Tl ppm lt01 lt01 lt01 lt01 lt01 01 lt01 lt01 lt01 lt01 lt01 02 lt01 U ppm 05 06 08 05 15 31 35 42 12 1 04 05 18 V ppm 47 57 62 27 52 364 83 80 64 149 40 21 lt8 W ppm 01 02 03 01 05 25 08 09 02 182 Zn ppm 7 7 5 4 14 119 56 45 10 3 3 20 57 Zr ppm 484 636 919 401 897 1866 2183 1923 1049 102 233 318 6456 Y ppm 97 124 149 67 229 817 435 424 114 399 53 339 824 La ppm 54 71 9 5 26 944 32 294 62 13 51 11 324 Ce ppm 163 193 251 131 511 1788 807 705 195 39 78 324 1123 Pr ppm 199 244 343 159 571 1739 954 876 283 064 109 511 1512 Nd ppm 76 109 137 7 206 679 394 368 126 39 46 241 724 Sm ppm 19 23 33 14 44 134 86 75 28 2 098 554 1538 Eu ppm 033 043 048 02 066 426 161 13 041 096 014 031 308 Gd ppm 175 197 253 12 366 1359 708 616 245 302 095 584 1642 Tb ppm 037 039 041 022 068 224 119 127 044 076 016 100 268 Dy ppm 185 212 259 109 364 127 718 646 215 582 094 583 1605 Ho ppm 035 041 053 022 07 261 143 143 046 134 02 117 311 Er ppm 102 124 155 064 225 768 47 421 13 425 056 33 891 Tm ppm 016 02 023 01 032 113 071 065 018 068 008 05 132 Yb ppm 098 125 146 057 198 634 432 4 137 396 053 302 803 Lu ppm 014 017 024 009 031 101 07 068 025 06 009 042 12

Contamination from ball mill


KS-1

KS-9



50

Figure 10 Rare earth element 40 plot of the Chimney Mounshytain metasedimentary rocks

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

57

62 80

28

76

117

126 112

56

57

18

16

133

Al2 O

3

Contact Rock

Quartzite

KS-6

KS-2

KS-3

KS-4

KS-5

KS-7 KS-8

KS-10

Granite

normalized to post-Archean Australian Shale (Taylor and McLennan 1985) The two most enriched samples are not part of the Chimney Suite KS-6 is a sample of calc-silicate diopsideshygarnet skarn from south of

Nor

mal

ized

to P

AA

S30

20Indian Lake The granite sample is from the eastern summit of Chimney Mountain KS-4 is the sample of diopside-bearing quartzite used for detrital zirshycon U-Pb analysis

10

00

Zirconium in Titanite Geothermometry

The titanites described above were analyzed for zirconium by electron microprobe analysis at Rensselaer Polytechnic Institute and used for Zr in titanite geothermometry (Hayden et al 2008) Ten titanite grains yield Zr concentrashytions between 356 and 858 ppm With a TiO

2

activity of 10 a temperature of 787 plusmn 19 degC was calculated (used when rutile is also present) and with a TiO

2 activity of 06 a temperature of

818 plusmn 20 degC was calculated (Table 6)

DISCUSSION

Age and Origin of the Chimney Mountain Metasedimentary Sequence (CMMS)

The rocks exposed on the western summit of Chimney Mountain differ from metasedimenshytary rocks in the surrounding area primarily in their state of preservation and excellent exposhysure along the scarp of a landslide Lithologic units are layered on the decimeter to meter scale and individual units can be followed for tens of meters on the face of and across the Great ldquoriftrdquo of Miller (1915) Particularly strikshying are the continuity of quartz-rich units up to ~1 dcm to 1 m thick that weather in positive relief (Fig 4) In this area foliation is paralshylel to lithologic boundaries and a moderately strong rodding lineation approximately paralshy

lel to the shallow northward dip is developed in quartz-rich lithologies (Fig 6) These rocks despite minor folding appear to be part of a continuous sequence without structural disrupshytion duplication or significant granite intrusion so prevalent in Adirondack metasedimentary rocks throughout the Highlands (Krieger 1937 Summer hays 2006) Nonetheless their granushylite facies metamorphism is clearly demonshystrated by two pyroxene mineral assemblages and orthopyroxene-bearing leucosomes in metasedimentary rocks that are exposed on the western approach to the summit

While it may be speculative to suggest that the current chemical composition of the rocks reflects their original composition this sequence has experienced relatively little bulk composition change compared with highly intruded metasedimentary rocks elsewhere in the Highlands As noted by Krieger (1937) metasedimentary sequences in the Highlands are pervasively intruded by granitoids on all scales however intrusion is relatively minor or absent here The quartz-rich nature of much of the upper part of the sequence suggests an origin as relatively mature sand-dominated lithologies however rocks of similar composishytion have been interpreted as chert-dominated in the metasedimentary sequence at the Balshymat Zn-Pb mine (Whelan et al 1990) Despite the lack of marble in the Chimney Mountain metasedimentary sequence (CMMS) the abunshy

dance of diopside is consistent with a carbonate influence as well The production of diopside likely as a consequence of the prograde reacshytion between tremolite calcite and quartz libershyates CO

2 and H

2O However the LOI of these

samples is 02ndash14 indicating the loss of most volatiles liberated during metamorphism Nonetheless hydrous minerals remain includshying phlogopite and tremolite When plotted on a diagram showing Al

2O

3 versus (CaO+MgO)

[(CaO+MgO+SiO2)100] most samples fall

below 10 Al2O

3 indicative of relatively

small amounts of clay and feldspar originally (Fig 17) The majority of the samples also have relatively small amounts of both Na

2O and

K2O They plot parallel to the more aluminous

calcite-cemented basal arkoses of the unmetashymorphosed Potsdam sandstone from the northshyern fringe of the Adirondacks (Blumberg et al 2008) and at a distance from the relatively pure quartz arenites of the Potsdam Group

As might be expected in a sedimentary sequence about half of the samples have fl at post-Archean Australia Shale (PAAS) normalshyized rare earth element patterns and the remainshyder show enrichment in the HREEs Four of these samples have REE concentrations that are less than half those of PAAS generally an indication of dilution by quartz andor carbonshyate Three of the samples with low SiO

2 conshy

tents show variable enrichment in the HREEs and total concentrations greater than PAAS



0 200microns

Geochron Sample

1 m

1 mm

diopside

Figure 11 The photograph on the upper left shows the location of the diopside-bearing quartzite processed for heavy minerals On the upper right a photograph shows a heavy mineral mount containing numerous zircon crystals from the sample Note the variety in color size shape etc The lower photomicrograph is taken with crossed nicols and shows the quartz-rich nature of the sample used for geochronology Note the brightly colored and smaller diopside grains and relatively unstrained quartz grains

Rare earth element concentrations generally increase with increasing Al

2O

3 content One

sample with 61 SiO2 has a pattern and conshy

centrations nearly identical to PAAS (Fig 10) These trends are consistent with the differshyences in REE concentrations typically seen in sand and mud-dominated sedimentary litholoshygies diluted by a variable carbonate component and the enrichment in HREEs noted in some metamorphic minerals (Taylor and McLennan 1985) The granite sample used for geo chronoshylogical investigation and calc-silcate skarn (KS-6) samples have significantly more REEs and different patterns and are shown for comshyparison purposes

Chiarenzelli et al

The age of the sequence depends on the interpretation of the zircon ages obtained from the diopsidic quartzite investigated during this study and its field relations The maximum age of the zircon is given by three analyses that yield a concordant age of 1073 plusmn 15 Ma The bulk of the concordant zircon analyses yield an age of 1042 plusmn 4 Ma At least three interpretashytions could be if taken alone drawn from this data and they include (1) the zircons are detrital in origin and thus represent a maximum age of 1042 Ma for the CMMS (2) the zircons are metamorphic in origin and the ages obtained constrain the timing of high-grade metamorshyphism accompanying the Ottawan Orogeny or

(3) the zircons were originally detrital but have been completely recrystallized and isotopically reset during Ottawan high-grade metamorphism (Chrapowitzky et al 2007) The last two sceshynarios lead to the unusual circumstance where the zircons in a metasedimentary rock yield an age younger than the time of deposition

If the zircons analyzed are detrital then the CMMS must be younger than other Grenville metasedimentary rocks in the area and was deposited sometime after the Ottawan Orogshyeny (ca 1040ndash1080 Ma) If so the deformashytion and metamorphism they record must be related to a high-grade event not currently recognized in the Adirondack Region In addishytion this event would require unreasonably rapid post-Ottawan exhumation of the region and then burial and metamorphism as titanites in the same rocks yield cooling ages from 969 to 1077 Ma that are clearly Ottawan precludshying a younger high-grade metamorphic event Finally the CMMS was clearly intruded by the Chimney Mountain granite which has a U-Pb zircon age of 11716 plusmn 63 Ma and therefore must be older than it

Zircons in the CMMS sample may be metashymorphic in origin in concert with fi eld relations that indicate a deposition before granite intrushysion (ca 1172 Ma) The ages obtained (1042 and 1073 Ma) are within the known age range (1040ndash1080 Ma) of high-grade metamorphism associated with the Ottawan event in the Adironshydack Highlands Numerous discrete metamorshyphic grains and overgrowths have been well documented in a wide variety of Adirondack igneous rocks (Chiarenzelli and McLelland 1992 McLelland et al 1988 McLelland et al 2001) However this interpretation requires that the diopsidic quartzite (82 SiO

2) investigated

originally had few if any detrital zircons (no older ages were found out of 35 concordant spots analyzed) and that suffi cient zirconium and uranium were available from other phases in the rock to form the zircon during metamorshyphism In addition the metamorphic zircons formed would be quite variable in shape size color crystal face development and magnetic susceptibility and high in U-content as disshyplayed in Figure 11

The third option favored here is that zircons recovered from the CMMS were originally detrital in origin but have undergone nearly complete recrystallization and resetting Few studies have investigated zircons in carbonshyates however greenschist-grade Paleo proteroshyzoic dolostones (Aspler and Chiarenzelli 2002) of the Hurwitz Group in northern Canada have yielded silt-sized detrital zircon grains despite their fine grain size and carbonate-dominated composition (Aspler et al 2010)




BSE CL

100 μm

Figure 12 The upper diagram shows a cathodoluminscence (CL) scanning electron microscope image of zircons separated from diopshysidic quartzite collected on the western summit of Chimney Mountain Note featureless dark appearance of most grains Belowmdashcloseshyup images of one such zircon taken in both backscattered electron and CL mode showing the detailed features of a typical zircon Inset shows zircon crystal with possible reaction front Note size and euhedral face development of the zircons


TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020

Chimney Mtn GraniteSHRIMP II analyses

1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U

Figure 13 SHRIMP II U-Pb concordant diagram of zircons separated from diopsidic quartzite collected on the western summit of Chimshyney Mountain Zircon analyses with significant Pb loss have been excluded (n = 6) Shading separates zircons into two age groupings

Figure 14 Cathodoluminescence scanning electron microscope image of zircons separated from granite collected on the eastern summit of Chimney Mountain Note zoned cores and thin rims and ~30 μm ablation pits from the LA-MC-ICP-MS

16 17 18 19 20

TABLE 3 U-PB LA-MC-ICP-MS ANALYSES OF ZIRCONS SEPARATED FROM HORNBLENDE GRANITE ON THE EASTERN SUMMIT OF CHIMNEY MOUNTAIN

Isotope ratios Apparent ages (Ma)

U 206Pb UTh 206Pb plusmn 207Pb plusmn 206Pb plusmn Error 206Pb plusmn 207Pb plusmn 206Pb plusmn Analysis (ppm) 204Pb 207Pb () 235U () 238U () corr 238U (Ma) 235U (Ma) 207Pb (Ma)

CHM-1 90 5998 36 129123 23 20414 36 01912 28 078 11277 287 11294 244 11327 449 CHM-2 147 3834 21 127818 18 20465 25 01897 17 069 11198 178 11311 171 11529 360 CHM-3B 604 23274 39 125782 16 20163 26 01839 21 078 10884 207 11210 179 11847 324 CHM-4 562 45990 40 128896 15 20481 30 01915 26 087 11293 269 11317 203 11362 291 CHM-5 868 43532 48 132349 14 17984 31 01726 28 089 10266 264 10449 204 10834 289 CHM-6 103 6740 26 128948 13 20352 19 01903 13 070 11232 137 11274 129 11354 267 CHM-7 299 16330 45 132043 12 18568 23 01778 19 086 10551 188 10659 149 10880 234 CHM-8B 255 13662 24 128172 25 20865 35 01940 24 070 11428 254 11444 238 11474 490 CHM-9 420 19538 62 127771 34 18707 42 01734 24 057 10306 227 10708 276 11536 681 CHM-10 565 36184 64 128882 37 20277 39 01895 11 028 11189 111 11248 264 11364 743 CHM-11 103 7062 35 124962 33 22526 36 02042 13 037 11976 145 11976 250 11976 650 CHM-12 79 5488 35 128579 27 20193 31 01883 14 046 11122 145 11220 209 11411 545 CHM-13 707 41882 50 127061 20 21268 30 01960 22 074 11538 230 11576 205 11646 398 CHM-14 761 48492 125 131495 14 19285 21 01839 16 076 10883 158 10910 139 10963 272 CHM-15B 659 41986 42 125896 31 20178 45 01842 32 072 10901 323 11215 303 11829 611 CHM-16 172 12040 47 130869 30 20238 33 01921 15 045 11327 156 11235 225 11059 591 CHM-17 829 55326 22 125739 21 22632 34 02064 27 080 12096 299 12009 239 11853 405 CHM-18 504 28998 20 125821 22 22245 35 02030 27 077 11914 297 11888 247 11840 443 CHM-19 486 30504 37 127560 26 21585 28 01997 11 038 11737 115 11678 197 11569 522 CHM-20 466 28606 35 126268 21 21934 30 02009 21 070 11800 225 11790 209 11770 423 CHM-21 491 13500 31 126447 42 20604 51 01890 30 058 11157 304 11358 351 11742 828 CHM-22 503 30482 24 125017 19 21936 38 01989 32 086 11694 345 11790 262 11967 377 CHM-23 1005 55308 16 125929 18 21398 62 01954 60 096 11507 629 11618 432 11824 358 CHM-24 719 39322 21 125667 26 21748 46 01982 38 082 11657 401 11730 318 11865 516 CHM-25 771 46172 172 131487 24 18392 39 01754 31 080 10418 302 10596 258 10964 472 CHM-26 155 11166 27 125728 17 21731 26 01982 20 077 11654 213 11725 182 11855 332 CHM-27 568 33668 39 128792 21 19479 25 01819 14 056 10776 139 10977 168 11378 414 CHM-28 426 24024 26 129112 21 20769 24 01945 13 053 11456 135 11412 167 11328 410 CHM-29 931 50052 150 131685 17 18445 32 01762 27 084 10460 258 10615 209 10934 343 CHM-30 1454 33386 25 127064 31 18417 52 01697 42 080 10106 394 10605 345 11646 621 CHM-31 550 23948 42 129502 11 19271 27 01810 25 092 10725 245 10906 181 11268 218 CHM-32 605 36858 40 128525 12 19902 25 01855 23 089 10971 227 11122 171 11419 229 CHM-33 1061 39638 20 128648 10 19305 39 01801 37 097 10677 366 10917 258 11400 199 CHM-34 935 48604 17 126390 18 22104 51 02026 48 094 11894 524 11843 360 11751 354 CHM-35 436 15738 78 129207 16 17679 52 01657 50 095 9882 454 10337 338 11314 325 CHM-36 374 25900 94 133035 16 18250 31 01761 27 086 10455 258 10545 204 10730 318 CHM-37 357 23386 51 134070 13 17254 23 01678 19 084 9998 178 10181 147 10574 252 CHM-38 497 29190 66 133946 10 17204 23 01671 21 089 9963 190 10162 148 10593 207 CHM-39 386 17470 27 123742 17 21142 22 01897 14 065 11200 144 11534 149 12169 325 CHM-40 90 6150 28 126629 36 20086 43 01845 24 055 10913 238 11184 294 11714 718


bull e ___ _

021


Chiarenzelli et al 20

6 Pb

238 U

data-point error ellipses are 683 conf

023 Chimney Mtn GraniteRims excluded

1250 1250

1150 1150

019

1050 1050

017

950 Weighted Mean Average 950

015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U

1400 Weighted Mean = 11716 +ndash 63 Ma Weighted Mean = 10848 +ndash 109 Ma

Quartz-rich units at Chimney Mountain contain as much as 82 SiO

2 and must have contained

significant amounts of detrital quartz sand grains However if the zircons recovered were indeed detrital they have become completely reset during high-grade metamorphism Further the process of resetting apparently resulted in the retention of many of the original physical characteristics of the zircons as noted above including their variable size and shape and color (Fig 11) Curiously all but a few zircon grains have the same limited cathodoluminesshycence response (dark with few internal features) despite their range in physical properties and uranium content However several seem to have irregular recrystallization fronts preserved (Fig 12 inset) This recrystallization likely led to isotopic resetting and the obtained Ottawan metamorphic ages

If these zircons were truly once detrital and have been recrystallized and isotopically reset what was the mechanism Contrary to broad claims of the permanence of zircon systematics numerous examples of partial to complete transshyformation of preexisting zircon in situ during metamorphism have been documented (Ashshywal et al 1999 Chiarenzelli and McLelland 1992 Hoskin and Black 2000 Pidgeon 1992) Numerous microscale processes have been proposed including the coupled dissolutionshyreprecipitation of zircon in response to fl uids and melts In addition reaction fronts (Carson et al 2002 Geisler et al 2007 Vavra et al 1999)

MSWD = 16 1 sigma core MSWD = 08 1 sigma rim1300

1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600

Uranium Content of Zircons (ppm)

and CO2 inclusions have been photographed

(Chiarenzelli and McLelland 1992) The lack of cathodoluminescence response suggests a common state of crystallinity and chemical (and isotopic) makeup of the zircons despite the range in their physical characteristics

Interestingly work by Peck et al (2003) on the O isotopes in zircons from quartzites

Figure 15 LA-MC-ICP-MS U-Pb Concordia diagram of zircons separated from horn- showed that all Adirondack quartzites had detrital zircons that were out-of-equilibrium with host quartz suggesting they were indeed detrital The one exception a calc-silicate rock

blende granite collected on the eastern summit of Chimney Mountain Note that data from ablation pits located on rims have been excluded from the weighted mean average The lower diagram plots the 207Pb206Pb age of each zircon analyzed versus its uranium content (diopside+calcite+quartz) from Mount Pisgah

contained very little zircon and the O isotope fractionation between zircon and quartz was

TABLE 4 U-PB LA-MC-ICP-MS ANALYSES OF TITANITE SEPARATED FROM consistent with metamorphic equilibrium ItDIOPSIDIC QUARTZITE ON THE WESTERN SUMMIT OF CHIMNEY MOUNTAIN may be that zircon in calc-silicate rock is vul-

Data set point SiO2 ZrO2 F Al2O3 TiO2 CaO Total nerable to recrystallization due to fl uid fl uxing 12 1 3202 005 193 493 3353 2757 10002 13 1 3281 010 198 472 3312 2763 10036 during metamorphism 14 1 3115 012 166 408 3373 2727 9801 15 1 3052 012 169 486 3449 2841 10009 16 1 3007 010 087 269 3730 2810 9914 17 1 3084 009 175 511 3409 2815 10004 18 1 3098 007 179 536 3407 2835 10062 19 1 3071 011 175 481 3417 2809 9964 20 1 3085 005 174 522 3418 2809 10012 21 1 3036 007 177 509 3416 2823 9968 Mean 3103 009 169 469 3428 2799 9977 Standard deviation 081 003 030 078 113 037 074

The age of the grains analyzed tells us that the zircons were reset during peak metamorphic conditions associated with the Ottawan Orogshyeny when granulite facies mineral assemblages formed in rocks of the Central Adirondack Highlands Curiously zircons in nearby granitic rocks have survived nearly intact with metamorshyphic effects limited primarily to thin rims and




thickened tips on euhedral crystals and little if 1σ error ellipses any effects on the U-Pb ages of zircon interiors 1180 (11716 plusmn 63 Ma) One possible explanation 0078

1140 is that mineral phases in the metasedimentary sequence are more reactive than the typical

1100

1060

granitic assemblage In particular the reactions leading to the formation of diopside generally involve the release of carbon dioxide and water Fluxing of volatiles within the metasedimentary sequence may facilitate the recrystallization and

0074

207 P

b20

6 Pb

1020 Max probability

mass transfer of elements to and from sites of1035 Ma8 980 zircon dissolutionreprecipitation something

7 that is unlikely to occur within a coherent

Num

ber

Rel

ativ

e Pr

obab

ility

0070 940 6 low porosity and permeability and largely 5 an hydrous and unreactive granite body

4 Despite their unusual state of preservation

3 lithologic continuity and the U-Pb zircon ages obtained the metasedimentary rocks exposed on

2 the western approach and summit of Chimney 1 Mountain are typical of those exposed throughshy0 out the Adirondacks Evidence for this comes 940 980 1020 1060 1100

238U206Pb Age (Ma) from their field relations (part of a large xenolith

0066

0062 within metaigneous rocks of the AMCG suitemdash 48 52 56 60 64 see Fig 2) their granulite facies mineral assemshy

238U206Pb blages linear fabric of the same orientation as in surrounding granitic rocks titanite cooling

Figure 16 LA-MC-ICP-MS Tera-Wasserburg U-Pb plot of titanites separated from diop- age (ca 1035 Ma) zirconium in titanite geoshysidic quartzite collected on the western summit of Chimney Mountain Inset shows relative thermometry (787ndash818 degC) and their physical probability histogram of the data continuity with underlying strongly deformed

TABLE 5 LA-MC-ICP-MS ANALYSES OF TITANITE GRAINS SEPARATED FROM CHIMNEY MOUNTAIN METASEDIMENTARY ROCKS

Isotope ratios

U Th 238U plusmn 207Pb plusmn 204Pb plusmn Analysis (ppm) (ppm) UTh 206Pb () 206Pb () 206Pb ()

CMS-1 391 751 05 56338 21 00855 25 00010 64 CMS-2 350 758 05 56137 12 00852 23 00010 62 CMS-3 392 828 05 57126 15 00844 24 00010 61 CMS-4 372 785 05 56019 16 00845 23 00009 72 CMS-5 370 983 04 54766 11 00860 26 00010 52 CMS-6 338 935 04 52987 17 00882 20 00011 52 CMS-7 352 1006 04 55607 16 00856 18 00010 63 CMS-8 352 977 04 56838 15 00839 16 00009 91 CMS-9 312 653 05 54808 17 00880 37 00012 15 CMS-10 338 653 05 54234 26 00865 21 00012 106 CMS-11 398 729 05 55026 21 00834 42 00010 44 CMS-12 373 674 06 56345 22 00827 33 00009 79 CMS-13 696 1229 06 58463 15 00789 24 00006 42 CMS-14 393 838 05 59027 17 00830 27 00009 79 CMS-15 A 434 878 05 59938 18 00816 26 00008 55 CMS-16 364 812 04 56034 19 00842 20 00010 45 CMS-17 449 1061 04 55973 13 00804 23 00008 71 CMS-18 496 951 05 58227 11 00786 23 00007 73 CMS-19 387 904 04 57893 11 00830 31 00009 52 CMS-20 511 878 06 58933 13 00786 21 00007 42 CMS-21 373 899 04 57537 12 00853 31 00010 36 CMS-22 400 894 04 56035 12 00823 29 00009 94 CMS-23 434 925 05 57100 13 00811 25 00008 70 CMS-24 404 958 04 57199 14 00814 24 00009 31 CMS-26 761 1136 07 56955 19 00768 27 00005 74 CMS-27 459 746 06 58786 15 00782 25 00007 82 CMS-28 441 750 06 58060 18 00792 27 00007 61 CMS-29 351 713 05 54833 32 00885 33 00012 55 CMS-30 351 650 05 55248 22 00837 28 00010 69 CMS-31 360 661 05 53790 31 00836 31 00009 56 CMS-32 432 701 06 56139 20 00809 41 00009 64



Chiarenzelli et al

partially melted and highly intruded metasedishymentary rocks

The quartz-rich nature of the upper part of the CMMS suggests an origin involving quartz-rich sand However both mud (rusty micaeous schists) and carbonate (diopsidite) dominated layers occur as interlayered lithologies near the top of the sequence at Chimney Mounshytain The bottom of the sequence is dominated by diopside-rich lithologies many of which are intensely folded and contain orthopyroxshyene and garnet-bearing leucosomes Thus the exceptional preservation of the upper part of the sequence may be a function of its quartzshyose composition Nevertheless the metasedishymentary lithologies encountered are typical of the Central Adirondacks and Adirondacks in general and suggest both siliclastic and carbonshyate sources and relatively shallow near-shore depositional environments

GEOLOGICAL HISTORY AND REGIONAL CONTEXT OF

TABLE 6 RESULTS OF ZIRCONIUM IN TITANITE GEOTHERMOMETRY OF TITANITE SEPARATED FROM DIOPSIDIC QUARTZITE ON

THE WESTERN SUMMIT OF CHIMNEY MOUNTAIN

ZrO2 Zr (074) Zr (ppm) T degC (aTiO2 = 10) T degC (aTiO2 = 06) 0055 0040 4046 762 791 0099 0073 7326 796 828 0116 0086 8584 806 839 0115 0085 8510 806 838 0105 0077 7748 800 832 0093 0069 6867 793 824 0071 0052 5244 777 807 0109 0080 8036 802 834 0048 0036 3567 754 784 0070 0051 5149 775 806

Mean 787 818 Standard deviation 19 20

16Upper Continental Crust

14 Chimney Mountain

U Continental Crust 12 Potsdam Arkoses

Potsdam Quartz Arenite

THE CHIMNEY MOUNTAIN METASEDIMENTARY SEQUENCE

The rocks in the Central Adirondacks record a geologic history that began with the deposhysition of a metasedimentary sequence that includes mixed siliclastic andor carbonate rocks quartzites marbles pelites and pershyhaps minor amphibolite The basement to this

Al 2

O3

wt

10

8

6

4sequence is unknown and it may well have been deposited on transitional or oceanic crust along the rifted remnants of older arc terranes (Dickin and McNutt 2007 Chiarenzelli et al 2010) including those represented by the 130ndash135 Ga tonalitic gneisses in the southern and eastern Adirondack Highlands and beyond (McLelland and Chiarenzelli 1990) Similar metasedimenshytary rocks have been noted throughout much of the southern Grenville Province within the Censhytral Metasedimentary Belt and Central Granulite Terrane (Dickin and McNutt 2007)

Chiarenzelli et al (2010) have proposed that the metasedimentary rocks in the Adironshydack Lowlands and Highlands were deposited in a back-arc basin (Trans-Adirondack Basin) whose closure culminated in the Shawinigan Orogeny Many of these rocks for example the Popple Hill Gneiss and Upper Marble exposed in the Adirondack Lowlands may have been deposited during the contractional history of the basin Correlation with supracrustal rocks in the Highlands has been suggested by several workers (Heumann et al 2006 Wiener et al 1984) however it is also possible that they were deposited on opposing flanks of the Trans-Adirondack Basin (Chiarenzelli et al 2010) Regardless available evidence suggests suprashy

Geochronology Sample 2

Quartz Arenites Carbonates

0 0 5 10 15 20 25 30 35 40 45 50

[(CaO+MgO)(CaO+MgO+SiO2)] 100

Figure 17 Al2O3 versus (CaO+MgO)[(CaO+MgO+SiO2)100] diagram showing the various Chimney Mountain metasedimentary rocks plotted against carbonate-cemented arkoses of the Middle Cambrian lower Potsdam Group (Blumberg et al 2008) Potsdam Group quartz arenites and upper continental crust estimate of Rudnick and Gao (2003)

crustal rocks in both the Lowlands and broad areas of the Highlands experienced Shawinigan orogenesis resulting in anatexis and the growth of new zircon from 1160 to 1180 Ma

The depositional age of this sequence or sequences is difficult to determine because of the lack of original field relations and overprinting by subsequent tectonism The widespread disshyruption of the sequence by rocks of the AMCG and younger suites constrains its age to preshy1170 Ma Recent U-Pb SHRIMP II analyses of pelitic members of the sequence throughout the

Adirondack Highlands and Lowlands suggests that a depositional age as young as 1220 Ma is possible for some of the pelitic gneisses (Heushymann et al 2006) In many areas such as at Dresden Station (near Whitehall New York) strong fabrics outlined by high-grade mineral assemblages (McLelland and Chiarenzelli 1989) pre-dating Ottawan events by at least 100 million years have been demonstrated and recently the effects and timing of the Shawinshyigan Orogeny have been recognized in the Adirondack Highlands and Lowlands (Bickford




et al 2008 Chiarenzelli et al 2010 Heumann et al 2006) Therefore an intense widespread and high-grade tectonic event responsible for the mineral assemblage and fabric in the CMMS predates the Ottawan Phase of the Grenvillian Orogeny

The overprinting of this earlier fabric can be seen in several areas Gates et al (2004) and Valentino and Chiarenzelli (2008) document the overprinting and folding of an earlier fabric along the flanks of the Snowy Mountain Dome 10 km to the west A similar relationship can be seen at Chimney Mountain where an early foliation defi ned by the alignment of micas and quartzofeldspathic lenses is folded about shalshylowly plunging folds These folds have the same orientation as a rodding lineation developed in the quartz-rich metasedimentary lithologies and the hornblende granite that intrudes them Thus the foliation in the metasedimentary rocks which is truncated by the granite must predate the development of the lineation In this case the dominant fabric (foliation) is likely of Shawinshyigan age (pre-AMCG suite) whereas Ottawan fabrics are limited to minor folding and the aforementioned shallow north-plunging lineashytion Alternatively the dominant fabric may be Elzevirian in age and the linear fabric and folding related to late Shawinigan deformation and little or no deformation associated with the Ottawan event

It is somewhat more difficult to determine the ultimate origin of metamorphic mineral assemblages Recent work has clearly indicated substantial differences in timing of anatexis of pelitic gneisses throughout the Adirondacks (Bickford et al 2008 Heumann et al 2006) High-grade metamorphic mineral assemblages and anatexis have occurred both during Shawinshyigan and Ottawan orogenesis in various parts of the Adirondacks For example high-grade meta morphic mineral assemblages anatexis and deformation of the Popple Hill Gneiss (Major Paragneiss) are found in the Adirondack Lowlands whereas evidence of both Ottawan deformation and metamorphic overprint are lacking (Heumann et al 2006)

Clearly the rocks exposed on Chimney Mountain were highly deformed foliated and contain high-grade minerals developed durshying oro genesis prior to intrusion of the Chimshyney Mountain granite However the growth or recrystallization of zircon at ca 1070ndash1040 Ma in diopsidic quartzites and as thin rims on zirshycons in granitic gneiss implies high-grade conshyditions during the Ottawan Orogen as well Orthopyroxene-bearing leucosomes enstatite porphyroblasts in rocks along the contact and undeformed pegmatites in calc-silicate litholoshygies exposed on Chimney Mountain confi rm

this in agreement with previous studies of metashymorphic conditions in the Adirondack Highshylands (McLelland et al 2004) A wide variety of geothermometers and metamorphic zircon titanite monazite garnet and rutile (Mezger et al 1991) ages have been used to constraint metamorphic and cooling histories

The titanite analyzed in this study yields a range of 206Pb238U ages from 969 to 1077 Ma Mezger et al (1991 1992) reported ages of 991ndash1033 Ma for titanites from Highlands calcshysilicates and marbles Titanite from a sample of calc-silicate gneiss from the southeastern margin of the Snowy Mountain Dome located within 20 km of Chimney Mountain yielded an age of 1035 Ma identical to the most probshyable age of 1035 Ma of the titanite analyzed in this study The reason for the 100 Ma range of titanite ages in a single sample is unclear and may be related to a complex Pb-loss history differences in closure temperature diffusion related to grain-size variation or simply the fact that multiple grains rather than a single large crystal were analyzed in this study

Zirconium in titanite geothermometry has been completed on the titanites analyzed in this study Depending on the activity of TiO

2 temshy

peratures of 787ndash818 degC have been calculated (Hayden et al 2008) This is in good agreement with estimates of paleotemperatures reported by Bohlen et al (1985) as the Snowy Mounshytain Dome lies about halfway between their 725ndash775 degC isograds More recent estimates by Spear and Markusen (1997) suggest Bohlen et alrsquos paleotemperatures record post-peak conshyditions and that peak metamorphic temperatures were closer to 850 degC in areas of the Adirondack Highlands near the Marcy Massif

ORIGIN OF THE CONTACT ROCKS

The rocks along the contact of the granite and metasedimentary sequence on Chimney Mountain contain porphyroblasts of enstatite rimmed by anthophyllite and porphyroblasts of phlogopite They are quartz-rich (70ndash75 SiO

2 or more) and have a chemical makeup with

relatively little Al2O

3 Na

2O or K

2O and large

amounts of CaO and MgO In some instances they appear to have been brecciated or veined with development of porphyroblastic minerals in the intervening space between what appears to be otherwise coherent quartzite Most of these rocks retain a strong foliation outlined by an elongated network of large composite quartz lenses and oriented micas however in some the foliation is strongly overprinted by porphyroshyblasts of random orientation

The origin and timing of this contact zone is uncertain It may represent a contact metamorshy

phic aureole that developed within the metasedishymentary rocks shortly after the intrusion of the Chimney Mountain granite However given the well-developed lineation developed in both the metasedimentary rocks and granite it is diffi shycult to explain the random orientation of the porshyphyroblasts (youngest preserved texture) It is possible that the contact developed during water infiltration along the contact during Ottawan orogenesis A similar origin has been proposed for the garnet amphibolite at Gore Mountain where the contrasting rheologies of syenite and gabbro led to pathways for H

2O infi ltration and

subsequent metasomatism (Goldblum and Hill 1992) In this scenario there would be no recshyognizable Ottawan deformation features and the lineation observed is also part of the Shawinigan Orogen

Volatile infiltration including substantial amounts of water along the contact seems likely as hydrous minerals including tremoshylite anthophyllite and phlogopite are found The introduction of water must have followed the initiation of the thermal pulse as enstatite formed first and was then rimmed by anthoshyphyllite Anthophyllite and the assemblage phlogopite+quartz are both at their limits of stashybility at around 790 degC (Chernosky et al 1985 Evans et al 2001 Bohlen et al 1983) in good agreement with estimates for titanite geothershymometry reported above (787ndash817 degC) Since enstatite forms the cores of the porphyoblasts it appears that water activity was initially low and with fl uid infiltration anthophyllite eventually formed Thus the mineral assemblage petroshygenesis texture and chemistry are compatible with development of the contact rocks during the Ottawan thermal pulse by the infi ltration of a water-rich volatile phase and metasomatism of Mg-rich quartzites

CONCLUSIONS

(1) The summit of Chimney Mountain exposes a remarkably well-preserved granuliteshyfacies metasedimentary sequence consisting of diopside-bearing lithologies that can be traced for tens of meters on the face of the Great Rift a post-Pleistocene landslide scarp

(2) The geochemistry and petrography of the sequence is consistent with mixed siliclastic andor carbonate deposition in a shallow-water setting While sandy and muddy protoliths occur most had a substantial carbonate composhynent represented by ubiquitous and abundant diopside

(3) Near the eastern summit of Chimney Mountain a well-preserved metasomatic aureole is exposed Porphyroblasts of enstatite rimmed by anthophyllite and phlogopite have developed



Chiarenzelli et al

in the metasedimentary rocks within several meters of the contact with hornblende granite The randomly oriented porphyroblasts suggest their growth occurred late and is associated with Ottawan metamorphic effects The hornshyblende granite exposed on Chimney Mountain has zircon cores and rims with respective ages of 1172 plusmn 6 Ma and 1085 plusmn 11 Ma indicating intrusion during AMCG plutonism and metashymorphic overprint during the Ottawan pulse of the Grenvillian Orogeny

(4) The strong foliation in the metasedimenshytary rocks is truncated by the hornblende granshyite and must predate it and therefore must be Shawinigan or older in age

(5) The granite has a shallow north-plunging mineral lineation but lacks a penetrative planar fabric The lineation in the granite is parallel to that in the metasedimentary rocks and the axis of folds defined by the folded foliation and must postdate intrusion of the granite (1172 plusmn 6 Ma) It is late Shawinigan in age Deformation of this age is limited to minor folding and development of a mineral lineation in this part of the Adironshydack Highlands

(6) The Ottawan event was accompanied by a thermal pulse shown by the formation of enstatite-anthophyllite porphyroblasts along the granitic contact metamorphic zircon rims in the granite (1085 plusmn 11 Ma) recrystallization of detrital zircons in the quartz-rich metasedishymentary lithologies (1040 plusmn 4 Ma and 1073 plusmn 15 Ma) and the 238U206Pb age of the titanite (1035 Ma) The age range of the titanites 969ndash 1077 Ma is consistent with Ottawan metamorshyphism and nearby titanite analyses from previshyous studies

(7) The peak temperatures of the Ottawan metamorphism were between 787 and 818 degC as determined by Zr in titanite paleothermometry and mineral assemblages

(8) The differential response of granitic zirshycons (growth of thin metamorphic rims) versus detrital zircons in the quartzose metasedimenshytary lithologies (recrystallization and resetting) is likely a function of metamorphic reactions involving dolomite and fluxing of volatiles in the diopside-rich metasedimentary sequence and the nonreactivity of minerals in the granite

(9) The geologic relationships exposed on Chimney Mountain indicate at least two dynamo thermal deformational events have affected the area and provide rare insight into the original character of the supracrustal sequence that displays deformation related to both events Similar relationships have been suggested elsewhere in the Adirondack Highshylands (Gates et al 2004) and are consistent with emerging models for the tectonic evolution of the Adirondacks (Chiarenzelli et al 2010)

APPENDIX ANALYTICAL TECHNIQUES

SHRIMP II

In situ U-Th-Pb data were acquired using the Perth Consortium SHRIMP II ion microprobe located at Curtin University of Technology using procedures similar to those described in Nelson (1997) and Nelson (2001) Each analysis was comprised of four cycles of measurements at each of nine masses 196Zr2O (2 s) 204Pb (10 s) 204045Background (10 s) 206Pb (10 s) 207Pb (20 s) 208Pb (10 s) 238U (5 s) 248ThO (5 s) and 254UO (2 s)

Curtin University standard zircon CZ3 (Nelson 1997) with a 206Pb238U age of 564 Ma was used for UPb calibration and calculation of U and Th concenshytrations During the analysis session 15 CZ3 standard analyses indicated a PbU calibration uncertainty of 1249 (1 sigma)

SHRIMP data have been reduced using CONCH software (Nelson 2006) Common Pb corrections have been applied to all data using the 204Pb correcshytion method as described in Compston et al (1984) Common Pb measured in standard analyses is conshysidered to be derived from the gold coating and assumed to have an isotopic composition equivalent to Broken Hill common Pb (204Pb206Pb = 00625 204Pb206Pb = 09618 204Pb206Pb = 22285 Cumming and Richards 1975)

References

Compston W Williams IS and Meyer C 1984 U-Pb geochronology of zircons from lunar breccia 73217 using a sensitive high mass-resolution ion microprobe Journal of Geophysical Research v 89 p B525ndashB534

Cumming GL and Richards JR 1975 Ore lead isoshytope ratios in a continuously changing earth Earth and Planetary Science Letters v 28 p 155ndash171 doi 1010160012-821X(75)90223-X

Gehrels G Rusmore M Woodsworth G Crawford M Andronicos C Hollister L Patchett PJ Ducea M Butler RF Klepeis K Davidson C Friedman RM Haggart J Mahoney B Crawford W Pearshyson D and Girardi J 2009 U-Th-Pb geochronology of the Coast Mountains batholith in north-coastal Britshyish Columbia Constraints on age and tectonic evolushytion Geological Society of America Bulletin v 121 no 910 p 1341ndash1361 doi 101130B264041

Gehrels G Valencia VA and Ruiz J 2008 Enhanced precision accuracy efficiency and spatial resolution of U-Pb ages by laser ablationndashmulticollectorndashinductively coupled plasmandashmass spectrometry Geochemistry Geophysics and Geosystems v 9 no 3 doi 101029 2007GC001805

Nelson DR 2006 CONCH A Visual Basic program for interactive processing of ion-microprobe analytical data Computers amp Geosciences v 32 p 1479ndash1498 doi 101016jcageo200602009

Nelson DR 2001 Compilation of geochronology data 2000 Western Australia Geological Survey v 2001 no 2 189 p

Nelson DR 1997 Compilation of SHRIMP U-Pb zircon geochronology data 1996 Western Australia Geologishycal Survey v 1997 no 2 251 p

LA-MC-ICP-MS (zircon and titanite)

U-Pb geochronology of titanite and zircon was conducted by laser ablation-multicollector-inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) at the Arizona LaserChron Center (Gehrels et al 2008 2009) The analyses involve ablation of titanite with a New WaveLambda Physik DUV193 excimer laser (operating at a wavelength of 193 nm) using a spot diameter of 35 μm The ablated material is carshyried with helium gas into the plasma source of a GV

Instruments Isoprobe which is equipped with a fl ight tube of sufficient width that U Th and Pb isotopes are measured simultaneously All measurements are made in static mode using Faraday detectors for 238U and 232Th an ion-counting channel for 204Pb and either fara day collectors or ion-counting channels for 208ndash206Pb Ion yields are ~1 mv per ppm Each analyshysis consists of one 12-s integration on peaks with the laser off (for backgrounds) 12 one-second integrashytions with the laser firing and a 30 s delay to purge the previous sample and prepare for the next analysis The ablation pit is ~12 μm in depth

Common Pb correction is accomplished by using the measured 204Pb and assuming an initial Pb composhysition from Stacey and Kramers (1975) (with uncershytainties of 10 for 206Pb204Pb and 03 for 207Pb204Pb) Our measurement of 204Pb is unaffected by the presshyence of 204Hg because backgrounds are measured on peaks (thereby subtracting any background 204Hg and 204Pb) and because very little Hg is present in the argon gas

Interelement fractionation of PbU is generally ~40 whereas apparent fractionation of Pb isoshytopes is generally lt5 In-run analysis of fragments of a large Bear Lake Road titanite crystal (generally every fifth measurement) with known age of 10548 plusmn 22 Ma (2-sigma error) and Sri Lankan zircon (zircon) is used to correct for this fractionation The uncershytainty resulting from the calibration correction is generally 1ndash2 (2-sigma) for both 206Pb207Pb and 206Pb238U ages Concordia plots and probability denshysity plots were generated using Ludwig (2003)

References

Ludwig KR 2003 Isoplot 300 Berkeley Geochronology Center Special Publication 4 70 p

Stacey JS and Kramers JD 1975 Approximation of tershyrestrial lead isotope evolution by a two-stage model Earth and Planetary Science Letters v 26 p 207ndash221 doi 1010160012-821X(75)90088-6

Zr in titanite geothermometry and microprobe analyses

The titanites described above were analyzed by electron microprobe at the Rensselaer Polytechshynic Institute Several titanite crystals were selected mounted in epoxy polished and coated with carbon under vacuum for wavelength-dispersion electron microprobe analysis using a CAMECA SX 100 The operating conditions were accelerating voltage 15 kV beam current 15 nA with a beam diameter of 10 μm Standards used were kyanite (Si Al) rutile (Ti) synshythetic diopside (Ca) topaz (F) and zircon (ZrO2) The titanite grains show F content between 087 wt and 198 wt and Al2O3 269 wt to 536 wt

The wt of ZrO2 from the electron microprobe analyses were used for Zr in titanite geothermomshyetry (Hayden et al 2008) Cherniak (2006) based on experiments of Zr diffusion in titanite showed that the use of Zr in titanite geothermometer (Hayden et al 2008) is robust because the Zr concentrations in titanite are less likely to be affected by later thermal disturbance Ten titanite grains yield Zr concentrations between 356 and 858 ppm With a TiO2 activity of 10 an average temperature of 787 plusmn 19 degC was calculated and with a TiO2 activity of 06 an average temperature of 818 plusmn 20 degC was calculated (Table 6)

Major- and trace-element analyses

Major- and trace-element analyses were conducted at ACME Analytical Laboratories in Vancouver Britshyish Columbia After crushing and lithium metaborate




tetrabortate fusion and dilute nitric digestion a 02 g sample of rock powder was analyzed by ICP-emission spectrometry for major oxides and several minor eleshyments including Ni and Sc Loss on ignition (LOI) is by weight difference after ignition at 1000 degC Rare earth and refractory elements are determined by ICP-mass spectrometry following the same digestion proshycedure In addition a separate 05 g split is digested in Aqua Regia and analyzed by ICP-mass spectrometry for precious and base metals Total carbon and sulfur concentrations were determined by Leco combustion analysis Duplicates and standards were run with the samples to assure quality control

ACKNOWLEDGMENTS

This study was supported by St Lawrence Univershysity and the State University of New York at Oswego The SHRIMP analysis was possible due to a grant from the Dr James S Street Fund at St Lawrence University The authors would like to thank Kate Sumshymerhays and Lauren Chrapowitsky for their help with various aspects of the project The authors bene fi ted from discussions with participants of the Fall 2008 Friends of Grenville field conference and from the reviews of Robert Darling Graham Baird William Peck and an unknown reviewer

REFERENCES CITED

Ashwal LD Tucker RD and Zinner EK 1999 Slow cooling of deep crustal granulites and Pb-loss in zircon Geochimica et Cosmochimica Acta v 63 p 2839ndash2851 doi 101016S0016-7037(99)00166-0

Aspler LB and Chiarenzelli JR 2002 Mixed siliciclasshytic-dominated ramp in a rejuvenated Paleoproterozoic intracratonic basin Upper Hurwitz Group Nunavut Canada in Altermann W and Corcoran PL eds Special Publication Number 33 Precambrian Sedishymentary Environments A modern approach to ancient depositional systems International Association of Sedimentologists p 293ndash322

Aspler L Chiarenzelli J Pullen A Ibanez-Mejia M Bratt A and Gardner M 2010 Paleoproterozoic eroshysion of mafic bodies as revealed by LA-MC-ICP-MS detrital zircon geochronology Hurwitz Basin Westshyern Churchill Province Nunavut Canada Geological Society of America Abstracts with Programs v 42 no 1 p 161

Bickford ME McLelland JM Selleck BW Hill BM and Heumann MJ 2008 Timing of anatexis in the eastern Adirondack Highlands Implications for tecshytonic evolution during ca 1050 Ma Ottawan orogenshyesis Geological Society of America Bulletin v 120 p 950ndash961

Blumberg E Chiarenzelli J Husinec A and Rygel M 2008 Insight from cores in the Potsdam Group Northern New York (abstract) 43rd annual meeting of the Northeastern Section of the Geological Society of America Buffalo March 27ndash29 p 82

Bohlen SR Valley JW and Essene EJ 1985 Metamorshyphism in the Adirondacks I Petrology Temperature and Pressure Journal of Petrology v 26 p 971ndash992

Bohlen SR Boettcher AL Wall VJ and Clemens JD 1983 Stability of phlogopite-quartz and sanidine-quartz A model for melting in the lower crust Contributions to Mineralogy and Petrology v 83 p 270ndash277 doi 101007BF00371195

Carson CJ Ague JJ Grove M Coath CD and Harrishyson TM 2002 U-Pb isotopic behavior of zircon durshying the upper amphibolite facies fl uid infilitration in the Napier Complex east Antarctica Earth and Planetary Science v 199 p 287ndash310 doi 101016S0012-821X (02)00565-4

Cherniak DJ 2006 Zr diffusion in titanite Contributions to Mineralogy and Petrology v 152 p 639ndash647 doi 101007s00410-006-0133-0

Chernosky JV Jr Day HW and Caruso LJ 1985 Equilibria in the system MgO-SiO2-H2O Experimenshy

tal determination of the stability of Mg-anthophyllite The American Mineralogist v 70 p 223ndash236

Chiarenzelli J and McLelland J 1992 Granulite facies metamorphism paleoisotherms and disturbance of the U-Pb systematics of zircon in anorogenic plutonic rocks from the Adirondack Highlands Journal of Metamorphic Geology v 11 p 59ndash70 doi 101111 j1525-13141993tb00131x

Chiarenzelli JR Regan SP Peck WH Selleck BW Cousens BL Baird GB and Shrady CH 2010 Shawinigan arc magmatism in the Adirondack Lowlands as a consequence of closure of the Trans-Adirondack Back-Arc Basin Geosphere v 6 doi 101130 GES005761

Chiarenzelli J Valentino D and Gates A 2000 Sinisshytral transpression in the Adirondack Highlands durshying the Ottawan Orogeny Strike-slip faulting in the deep Grenvillian crust Abstract presented at the Milshylenium Geoscience Summit GeoCanada 2000 Calshygary Alberta May 29ndashJune 1 Geological Association of Canada

Chrapowitzky L Thern E Valentino D Nelson D Gehrels G and Chiarenzelli J 2007 Zircon geoshychronology of the Chimney Mountain Metasedimenshytary Sequence Adirondack Highlands (abstract) Annual meeting of the Geological Society of America Denver October 28ndash31 v 39 p 320

Corrigan D 1995 Mesoproterozoic evolution of the south-central Grenville orogen Structural metamorphic and geochronological constraints from the Maurice transhysect [PhD thesis] Ottawa Carleton University 308 p

Davidson A 1986 New interpretations in the southwestern Grenville Province Ontario in Moore JM Davidson A and Baer AJ eds The Grenville Province Geoshylogical Survey of Canada Special Paper 31 p 61ndash74

DeWaard D and Romey WD 1969 Chemical and petroshylogical trends in the anorthosite-charnockite series of the Snowy Mountain massif Adirondack Highlands The American Mineralogist v 54 p 529ndash538

Dickin AP and McNutt RH 2007 The Central Metasedishymentary Belt (Grenville Province) a failed back-arc rift zone Nd isotope evidence Earth and Planetary Science Letters v 259 p 97ndash106 doi 101016 jepsl200704031

Evans BW Ghiorso MS Yang H and Medenbach O 2001 Thermodynamics of the amphiboles Anthophylliteshyferroanthophyllite and the ortho-clino phase loop The American Mineralogist v 86 p 640ndash651

Gates AE Valentino DW Chiarenzelli JR Solar GS and Hamilton MA 2004 Exhumed Himalayan-type syntaxis in the Grenville orogen northeastern Laurenshytia Journal of Geodynamics v 37 p 337ndash359 doi 101016jjog200402011

Geisler T Schaltegger U and Tomaschek F 2007 Re-equilibrium of zircon in aqueous fluids and melts Eleshyments v 3 p 43ndash50 doi 102113gselements3143

Geraghty EP Isachsen YW and Wright SF 1981 Extent and character of the Carthage-Colton Mylonite Zone Northwest Adirondacks New York New York State Geological Survey Report to the US Nuclear Regulatory Commission 83 p

Goldblum DR and Hill ML 1992 Enhanced fl uid flow resulting from competency contrasts within a shear zone The garnet zone at Gore Mountain NY The Journal of Geology v 100 p 776ndash782 doi 101086629628

Hayden LA Watson EB and Wark DA 2008 A thermo barometer for sphene (titanite) Contributions to Mineralogy and Petrology v 155 p 529ndash540 doi 101007s00410-007-0256-y

Heumann MJ Bickford ME Hill BM McLelland JM Selleck BW and Jercinovic MJ 2006 Timshying of anatexis in metapelites from the Adirondack lowlands and southern highlands A manifestation of the Shawinigan orogeny and subsequent anorthositeshymangerite-charnockite-granite magmatism Geological Society of America Bulletin v 118 p 1283ndash1298 doi 101130B259271

Hoskin PW and Black LP 2000 Metamorphic zircon formation by solid state recrystallization of protolith igneous zircon Journal of Metamorphic Geology v 18 p 423ndash439 doi 101046j1525-1314200000266x

Isachsen YW 1981 Contemporary doming of the Adironshydack mountains Further evidence from releveling Tectonophysics v 71 p 95ndash96 doi 1010160040shy1951(81)90051-2

Isachsen YW 1975 Possible evidence for contemporary doming of the Adirondack mountains New York and suggested implications for regional tectonics and seismicity Tectonophysics v 29 p 169ndash181 doi 1010160040-1951(75)90142-0

Isachsen YW Mock TD Nyahay RE and Rogers WB 1990 New York State Geological Highway Map Educational Leaflet No 33 New York State Museum Albany New York

Krieger MH 1937 Geology of the Thirteenth Lake Quadshyrangle New York New York State Museum Bulletin v 308 p 124

McLelland JM 1984 The origin of ribbon lineations within the Southern Adirondacks Journal of Structural Geology v 6 p 147ndash157 doi 1010160191-8141 (84)90092-0

McLelland JM and Chiarenzelli J 1991 Geology and geochronology of the Adirondacks and the nature and evolution of the anorthosite-mangerite-charnockiteshygranite (AMCG) suite Hamilton New York Colgate University Guidebook of the IGCP-290 Anorthosite conference 107 p

McLelland J and Chiarenzelli J 1990 Geochronology and geochemistry of 13 Ga tonalitic gneisses of the Adirondack Highlands and their implications for the tectonic evolution of the Grenville Province in Middle Proterozoic Crustal Evolution of the North American and Baltic Shields Geological Association of Canada Special Paper 38 p 175ndash196

McLelland JM and Chiarenzelli J 1989 Age of xenolithshybearing olivine metagabbro eastern Adirondacks New York The Journal of Geology v 97 p 373ndash376 doi 101086629311

McLelland JM and Isachsen YW 1980 Structural synshythesis of the Southern and Central Adirondacks A model for the Adirondacks as a whole and plate tecshytonics interpretations Geological Society of America Bulletin v 91 p 208ndash292 doi 1011300016-7606 (1980)91lt68SSOTSAgt20CO2

McLelland JM and Whitney PR 1980 Compositional controls on spinel clouding and garnet formation in plagioclase of olivine metagabbros Adirondack Mountains New York Contributions to Mineralshyogy and Petrology v 73 p 243ndash251 doi 101007 BF00381443

McLelland JM Bickford ME Hill BM Clechenko CC Valley JW and Hamilton MA 2004 Direct dating of Adirondack massif anorthosite by U-Pb SHRIMP analysis of igneous zircon Implications for AMCG complexes Geological Society of America Bulletin v 116 p 1299ndash1317 doi 101130B254821

McLelland JM Hamilton M Selleck BW McLelland J Walker D and Orrell S 2001 Zircon U-Pb geoshychronology of the Ottawan Orogeny Adirondack Highshylands New York Regional and tectonic implications Precambrian Research v 109 p 39ndash72 doi 101016 S0301-9268(01)00141-3

McLelland JM Daly JS and McLelland J 1996 The Grenville Orogenic Cycle (ca 1350ndash1000 Ma) An Adirondack perspective Tectonophysics v 265 p 1ndash28 doi 101016S0040-1951(96)00144-8

McLelland J Chiarenzelli J Whitney P and Isachsen Y 1988 U-Pb zircon geochronology of the Adironshydack Mountains and implications for their geoshylogic evolution Geology v 16 p 920ndash924 doi 1011300091-7613(1988)016lt0920UPZGOTgt 23CO2

Mezger K van der Pluijm BA and Halliday AN 1992 The Carthage Colton Mylonite Zone (Adirondack Mountains New York) The site of a cryptic suture in the Grenville Orogen The Journal of Geology v 100 p 630ndash638 doi 101086629613

Mezger K Rawnsley CM Bohlen SR and Hanson GN 1991 U-Pb garnet sphene monazite and rutile ages Implications for the duration of high-grade metashymorphism and cooling histories Adirondack Mts New York The Journal of Geology v 99 p 415ndash428 doi 101086629503



Chiarenzelli et al

Miller WJ 1918 Adirondack anorthosite Geological Society of America Bulletin v 29 p 399ndash462

Miller WJ 1915 The great rift on Chimney Mountain Adirondack Mountains NY New York State Museum Bulletin v 177 p 143ndash146

Peck WH Valley JW and Graham CM 2003 Slow oxygen diffusion rates in igneous zircons from metashymorphic rocks The American Mineralogist v 88 p 1003ndash1014

Pidgeon RT 1992 Recrystallization of oscillatory zoned zircon Some geochronological and petrological intershypretations Contributions to Mineralogy and Petrology v 110 p 463ndash472 doi 101007BF00344081

Rivers T 2008 Assembly and preservation of lower mid and upper orogenic crust in the Grenville Provincemdash Implications for the evolution of large hot long-duration orogens Precambrian Research v 167 p 237ndash259 doi 101016jprecamres200808005

Roden-Tice M Tice S and Schofield IS 2000 Evidence for differential unroofing in the Adirondack Mountains New York State determined by apatite fi ssion-track thermochronology The Journal of Geology v 108 p 155ndash169 doi 101086314395

Rudnick RL and Gao S 2003 The Composition of the Continental Crust in Rudnick RL ed The Crust Vol 3 in Holland HD and Turekian KK

eds Treatise on Geochemistry Oxford Elsevier-Pergamon p 1ndash64

Selleck B McLelland JM and Bickford ME 2005 Granite emplacement during tectonic exhumation The Adirondack example Geology v 33 p 781ndash784 doi 101130G216311

Spear FS and Markusen JC 1997 Mineral zoning P-T-X-M phase relations and metamorphic evolushytion of Adirondack anorthosite New York Journal of Petrology v 38 p 757ndash783 doi 101093petrology 386757

Streepey MM Johnson EL Mezger K and van der Pluijm BA 2001 Early history of the Carthage-Colton Shear Zone Grenville Province Northwest Adirondacks New York (USA) The Journal of Geolshyogy v 109 p 479ndash492 doi 101086320792

Summerhays K 2006 Stratigraphic and petrologic examishynation of metasedimentary rocks at Chimney Mounshytain New York (abstract) Geological Society of America Abstracts with Programs v 38 no 2 p 82

Taylor SR and McLennan SM 1985 The Continental Crust Its Composition and Evolution Oxford Blackshywell Scientifi c Publications

Valentino D and Chiarenzelli J 2008 Field guide for Friends of the Grenville (FOG) Field Trip 2008 Sepshytember 28 Indian Lake New York 50 p

Vavra G Schmid R and Gebauer D 1999 Internal morphology habit and U-Th-Pb microanalysis of amphibolite-to-granulite facies zircons Geochronology of the Ivrea Zone (Southern Alps) Contributions to Minshyeralogy and Petrology v 134 p 380ndash404 doi 101007 s004100050492

Whelan JF Rye RO deLorraine WD and Ohmoto H 1990 Isotope geochemistry of a Mid-Proterozoic evaporate basin Balmat New York American Jourshynal of Science v 290 p 396ndash424 doi 102475 ajs2904396

Wiener RW McLelland JM Isachsen YW and Hall LM 1984 Stratigraphy and structural geology of the Adirondack Mountains New York in Bartholomew M ed The Grenville Event in the Appalachians and Related Topics Review and Synthesis Geological Society of America Special Paper 194 p 1ndash55

Wynne-Edwards HR 1972 The Grenville Province in Price RA and Douglas RJW eds Variations in tectonic styles in Canada Geological Association of Canada Special Paper 11 p 263ndash334

MANUSCRIPT RECEIVED 27 JANUARY 2010 REVISED MANUSCRIPT RECEIVED 13 JUNE 2010 MANUSCRIPT ACCEPTED 22 JUNE 2010




J Chiarenzelli1 D Valentino2 M Lupulescu3 E Thern4 and S Johnston5 1Department of Geology St Lawrence University Canton New York 13617 USA 2Department of Earth Sciences SUNY Oswego Oswego New York 13216 USA 3New York State Museum Research and Collections Albany New York 12230 USA 4Department of Imaging and Applied Physics Curtin University of Technology GPO Box U1987 Perth WA 6001 Australia 5Physics Department California Polytechnic State University San Luis Obispo California 93407-0404 USA

ABSTRACT

The rocks at Chimney Mountain proshyvide a rare glimpse into primary intrusive relations and exceptionally well-preserved pre-Shawinigan metasedimentary rocks in the Adirondack Highlands despite a strong Ottawan thermal overprint A near vertishycal contact between granite (ca 1172 Ma) and a shallowly dipping and structurally intact sequence of quartzose to calc-silicate metasedimentary rocks is exposed on the southern flank of Chimney Mountain in the Central Adirondacks The contact is marked by foliation truncation and a meta-somatic aureole with randomly orientated porphyro blasts of enstatite rimmed by anthophyllite (max 5 cm) and phlogopite (max 2 cm) and a zone of granular quartz-rich rock The granite is non- to weakly foliated and has a shallow north-plunging mineral lineation as do the metasedimentary rocks Zircons separated from a diopsideshybearing quartzite (82 SiO

2 075 m thick) are of variable size (up to 400 microm) equant and contain on average gt1000 ppm urashynium Scanning electron microscope investishygation indicates that there is little variation in a uniformly dark cathodoluminescence response no discernible cores or rims few inclusions and partially faceted to round morphologies Zircon U-Pb sensitive high-resolution ion microprobe (SHRIMP II) ages of 1042 plusmn 4 Ma and 1073 plusmn 15 Ma are coincishydent with Ottawan metamorphic ages from the Adirondack Highlands Zircons from the intrusive granite yield large cores with

E-mails Chiarenzelli jchiarenstlawuedu Valenshytino dvalentioswegoedu Lupulescu mlupules mailnysedgov Thern ericthernorg Johnston scjohnstcalpolyedu

typical anorthosite-mangerite-charnockiteshygranite (AMCG) ages (ca 11716 plusmn 63 Ma) and sparse thin younger rims (ca 1060ndash 1090 Ma) readily distinguishable by cathshyodoluminescence Despite the younger zirshycon ages the metasedimentary rocks and their fabric must predate the crosscutting granite The thermal effect of the Ottawan event was likely enhanced by volatile fl uxshying and resulted in recrystallization and resetting of zircons in the metasedimentary rocks However it had limited effects on zirshycons in the granite and produced only thin metamorphic rims emphasizing the imporshytance of local geochemical conditions to the response of zircon to metamorphism Elzeshyvirian or Shawinigan fabrics are preserved as the dominant foliation the lineation and folding is likely late (post-1170 Ma) Shawinshyigan or Ottawan (ca 1050 Ma) Titanites from the same metasedimentary sequence yield a range of 238U 206Pb ages from 969 to 1077 Ma with a maximum probability age of 1035 Ma similar to other titanites in the Adirondack Highlands Ottawan paleotemshyperatures estimated by zirconium in titanite thermometry range from 787 to 818 degC

INTRODUCTION

One of the most intriguing problems in the Adirondacks is the timing and origin of fabric forming events Recently work by Heumann et al (2006) and Rivers (2008) has pointed out the significance of the Shawinigan orogenic event (ca 1200ndash1140 Ma) in the Adirondack segment (Fig 1) of the Grenville Province (Davidson 1986 Wynne-Edwards 1972) In addition the overprint of the Ottawan Pulse (ca 1090ndash1020 Ma) of the Grenvillian Orogeny (Rivers 2008) is now known to be less pervashysive than once thought with signifi cant areas

of the Adirondacks including the Lowlands and parts of the Highlands lacking anatexis and metamorphic zircon of Ottawan age (Heushymann et al 2006 Bickford et al 2008) While these findings are based on the identifi cation of metamorphic zircon in pelitic gneisses that have undergone anatectic melting and are not directly linked to fabric formation they raise intriguing questions as to the four-dimensional evolution of the Adirondack region preliminarily addressed on an orogen scale by Rivers (2008)

The recognition of the Shawinigan event in Quebec (Corrigan 1995) and in the Adironshydacks (Heumann et al 2006 Mezger et al 1992) has some profound implications for the region and the Ottawan Pulse of the Grenvillian Orogeny (Rivers 2008) in particular (Fig 1) For example it has forced the reevaluation of many of the long-held assumptions about Adirondack and Grenville geology including the tectonic setting and origin of massif anorthoshysite and related rocks (intruded just after or pershyhaps during the waning phases of the Shawinshyigan Orogeny) the extent of the Elzevirian Orogeny (McLelland and Chiaren zelli 1989) the nature and disposition of metasedimentary rocks of the Trans-Adirondack Basin (Chiarenshyzelli et al 2010) and the age and origin of major structural features in the Adirondacks that were in the past generally assumed to be Ottawan or severely overprinted andor oblitershyated during the Ottawan tec tonism (McLelland and Isachsen 1980 McLelland et al 1996 Wiener et al 1984)

Most rocks in the Adirondacks show evidence of considerable deformation and display a wide variety of planar and linear fabrics (McLelland 1984 McLelland and Isachsen 1980 Wiener et al 1984) In most cases even metaplutonic rocks form continuous linear belts (Fig 2) with fabrics that are generally parallel to their overshyall shape and elongation (Isachsen et al 1990)

Geosphere February 2011 v 7 no 1 p 2ndash22 doi 101130GES005831 17 figures 6 tables

For permission to copy contact editinggeosocietyorg copy 2011 Geological Society of America

2

A H

N



PSD

C AB

GM

HH

GFTZ







(1090ndash980 Ma)

(1200ndash1140 Ma)

(1245ndash1225 Ma)


B L F C C M Z

47deg

46deg

45deg

44deg

43deg

42deg


100 km

N

SUPERIOR

NAIN

CHURCHILLGFTZ

AH

BCS

EGP

PT

CMB

CGB

500 km

40degN

84degW

55degW

56degN

CGT GRENVILLE

AL

A L


47deg

46deg

45deg

44deg

43deg

42deg

F-AB






Indian LOld Forge

Station

Oregon Snowy Mtn

Gore Mtn


Canton

Malone

Gouverneur Tupper L

Canton

Boonville

LClear

Plattsburgh

Dresden

Saratoga Springs

Johnstown

Saranac L

LPlacid

Marcy

Chimney Mtn

CANADA US

Lowlands Highlands

0 25 50 kilometers

N

CCMZ

Anorthosite Massifs





Chiarenzelli et al







4

86

8

0

1214

10

12

10

88

14



7232

24

28

14

7824

42

28

24 32

56

36

888

Grenville Series

Syenitic Gneiss

Syenitic Gneiss

40

36


Mineral lineation


Observed contact


05 miles

N

10 kilometers

Granite

Inferred contact

1 mile

W 7

4deg15


Kings Landing

Below


N

N 43deg40prime


Quaternary

Gabbro

Anorthosite


Granite gneiss

Syenitic gneiss

Grenville Series

Fault Trace




Chiarenzelli et al

Chimney Mtn



Hamilton County

Warren C

ounty


meters

0 500 1000














Diopsidite

Diopsidite

Diopsidite

Diopsidite






2 While




Chiarenzelli et al

L

L






2 respectively In


2 Among the samples


2 3 T 2 2










3 cm

qtz

antenst

antenst

phg

ant

qtz





qtz

qtz

plg

opx cpx

cpx

phg

cpx

qtz

tia

tia qtz

qtz

qtz cpx

opx tia

cpx tia

zrc

μm50

μm100






Chiarenzelli et al






KS-1

KS-9



50



57

62 80

28

76

117

126 112

56

57

18

16

133

Al2 O

3

Contact Rock

Quartzite

KS-6

KS-2

KS-3

KS-4

KS-5

KS-7 KS-8

KS-10

Granite


Nor

mal

ized

to P

AA

S30


10

00



2




DISCUSSION






2 and H



2O

3 versus (CaO+MgO)


below 10 Al2O



2O and




2 conshy




0 200microns

Geochron Sample

1 m

1 mm

diopside



2O

3 content One



Chiarenzelli et al





2) investigated






BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

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000

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cm

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000

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000

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38

000

22

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3 0

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100

1030

13

cm

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11

20

183

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01

007

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000

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004

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000

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000

22

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9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

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0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

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550

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94

ndash00

11

007

396

000

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006

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000

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000

22

178

3 0

027

100

1040

13

cm

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1 12

91

332

221

ndash00

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007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

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003

332

000

038

014

88

000

19

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8 0

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91

987

9 cm

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100

1079

15

cm

-16

1 85

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000

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43

000

22

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4 0

026

100

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11

cm

-17

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30

214

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0746

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0004

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0613

8 0

0007

3 0

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0

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1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

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8 0

0002

9 0

0436

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0004

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0

0012

0

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001

3 70

87

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cm-1

91

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79

942

8 cm

-21

1 13

19

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000

045

005

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000

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017

18

000

22

175

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98

1044

12

cm

-22

1 10

69

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000

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43

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22

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6 0

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100

1039

9

cm-2

31

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000

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004

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000

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28

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098

9 0

014

68

923

9 cm

-24

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6 10

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412

000

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003

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000

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80

000

22

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9 0

028

101

1045

15

cm

-25

1 77

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000

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000

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44

000

22

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3 0

026

98

1056

11

cm

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001

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0687

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0022

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002

4 10

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35

9 cm

-27

1 10

86

211

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001

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0735

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0003

6 0

0572

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0

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1

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002

5 10

0 10

29

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cm-2

81

1253

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cm

-29

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100

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cm-3

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945

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48

000

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100

1043

11

cm

-31

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4 84

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0

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000

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000

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100

1066

13

cm

-31

2 11

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200

001

1 0

0738

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0003

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0421

8 0

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1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

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000

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0667

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0004

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0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

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000

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000

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8 0

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1056

10

cm

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001

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0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al





















A H

N



PSD

C AB

GM

HH

GFTZ







(1090ndash980 Ma)

(1200ndash1140 Ma)

(1245ndash1225 Ma)


B L F C C M Z

47deg

46deg

45deg

44deg

43deg

42deg


100 km

N

SUPERIOR

NAIN

CHURCHILLGFTZ

AH

BCS

EGP

PT

CMB

CGB

500 km

40degN

84degW

55degW

56degN

CGT GRENVILLE

AL

A L


47deg

46deg

45deg

44deg

43deg

42deg

F-AB






Indian LOld Forge

Station

Oregon Snowy Mtn

Gore Mtn


Canton

Malone

Gouverneur Tupper L

Canton

Boonville

LClear

Plattsburgh

Dresden

Saratoga Springs

Johnstown

Saranac L

LPlacid

Marcy

Chimney Mtn

CANADA US

Lowlands Highlands

0 25 50 kilometers

N

CCMZ

Anorthosite Massifs





Chiarenzelli et al







4

86

8

0

1214

10

12

10

88

14



7232

24

28

14

7824

42

28

24 32

56

36

888

Grenville Series

Syenitic Gneiss

Syenitic Gneiss

40

36


Mineral lineation


Observed contact


05 miles

N

10 kilometers

Granite

Inferred contact

1 mile

W 7

4deg15


Kings Landing

Below


N

N 43deg40prime


Quaternary

Gabbro

Anorthosite


Granite gneiss

Syenitic gneiss

Grenville Series

Fault Trace




Chiarenzelli et al

Chimney Mtn



Hamilton County

Warren C

ounty


meters

0 500 1000














Diopsidite

Diopsidite

Diopsidite

Diopsidite






2 While




Chiarenzelli et al

L

L






2 respectively In


2 Among the samples


2 3 T 2 2










3 cm

qtz

antenst

antenst

phg

ant

qtz





qtz

qtz

plg

opx cpx

cpx

phg

cpx

qtz

tia

tia qtz

qtz

qtz cpx

opx tia

cpx tia

zrc

μm50

μm100






Chiarenzelli et al






KS-1

KS-9



50



57

62 80

28

76

117

126 112

56

57

18

16

133

Al2 O

3

Contact Rock

Quartzite

KS-6

KS-2

KS-3

KS-4

KS-5

KS-7 KS-8

KS-10

Granite


Nor

mal

ized

to P

AA

S30


10

00



2




DISCUSSION






2 and H



2O

3 versus (CaO+MgO)


below 10 Al2O



2O and




2 conshy




0 200microns

Geochron Sample

1 m

1 mm

diopside



2O

3 content One



Chiarenzelli et al





2) investigated






BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al





















Indian LOld Forge

Station

Oregon Snowy Mtn

Gore Mtn


Canton

Malone

Gouverneur Tupper L

Canton

Boonville

LClear

Plattsburgh

Dresden

Saratoga Springs

Johnstown

Saranac L

LPlacid

Marcy

Chimney Mtn

CANADA US

Lowlands Highlands

0 25 50 kilometers

N

CCMZ

Anorthosite Massifs





Chiarenzelli et al







4

86

8

0

1214

10

12

10

88

14



7232

24

28

14

7824

42

28

24 32

56

36

888

Grenville Series

Syenitic Gneiss

Syenitic Gneiss

40

36


Mineral lineation


Observed contact


05 miles

N

10 kilometers

Granite

Inferred contact

1 mile

W 7

4deg15


Kings Landing

Below


N

N 43deg40prime


Quaternary

Gabbro

Anorthosite


Granite gneiss

Syenitic gneiss

Grenville Series

Fault Trace




Chiarenzelli et al

Chimney Mtn



Hamilton County

Warren C

ounty


meters

0 500 1000














Diopsidite

Diopsidite

Diopsidite

Diopsidite






2 While




Chiarenzelli et al

L

L






2 respectively In


2 Among the samples


2 3 T 2 2










3 cm

qtz

antenst

antenst

phg

ant

qtz





qtz

qtz

plg

opx cpx

cpx

phg

cpx

qtz

tia

tia qtz

qtz

qtz cpx

opx tia

cpx tia

zrc

μm50

μm100






Chiarenzelli et al






KS-1

KS-9



50



57

62 80

28

76

117

126 112

56

57

18

16

133

Al2 O

3

Contact Rock

Quartzite

KS-6

KS-2

KS-3

KS-4

KS-5

KS-7 KS-8

KS-10

Granite


Nor

mal

ized

to P

AA

S30


10

00



2




DISCUSSION






2 and H



2O

3 versus (CaO+MgO)


below 10 Al2O



2O and




2 conshy




0 200microns

Geochron Sample

1 m

1 mm

diopside



2O

3 content One



Chiarenzelli et al





2) investigated






BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al





















4

86

8

0

1214

10

12

10

88

14



7232

24

28

14

7824

42

28

24 32

56

36

888

Grenville Series

Syenitic Gneiss

Syenitic Gneiss

40

36


Mineral lineation


Observed contact


05 miles

N

10 kilometers

Granite

Inferred contact

1 mile

W 7

4deg15


Kings Landing

Below


N

N 43deg40prime


Quaternary

Gabbro

Anorthosite


Granite gneiss

Syenitic gneiss

Grenville Series

Fault Trace




Chiarenzelli et al

Chimney Mtn



Hamilton County

Warren C

ounty


meters

0 500 1000














Diopsidite

Diopsidite

Diopsidite

Diopsidite






2 While




Chiarenzelli et al

L

L






2 respectively In


2 Among the samples


2 3 T 2 2










3 cm

qtz

antenst

antenst

phg

ant

qtz





qtz

qtz

plg

opx cpx

cpx

phg

cpx

qtz

tia

tia qtz

qtz

qtz cpx

opx tia

cpx tia

zrc

μm50

μm100






Chiarenzelli et al






KS-1

KS-9



50



57

62 80

28

76

117

126 112

56

57

18

16

133

Al2 O

3

Contact Rock

Quartzite

KS-6

KS-2

KS-3

KS-4

KS-5

KS-7 KS-8

KS-10

Granite


Nor

mal

ized

to P

AA

S30


10

00



2




DISCUSSION






2 and H



2O

3 versus (CaO+MgO)


below 10 Al2O



2O and




2 conshy




0 200microns

Geochron Sample

1 m

1 mm

diopside



2O

3 content One



Chiarenzelli et al





2) investigated






BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al






















Chiarenzelli et al

Chimney Mtn



Hamilton County

Warren C

ounty


meters

0 500 1000














Diopsidite

Diopsidite

Diopsidite

Diopsidite






2 While




Chiarenzelli et al

L

L






2 respectively In


2 Among the samples


2 3 T 2 2










3 cm

qtz

antenst

antenst

phg

ant

qtz





qtz

qtz

plg

opx cpx

cpx

phg

cpx

qtz

tia

tia qtz

qtz

qtz cpx

opx tia

cpx tia

zrc

μm50

μm100






Chiarenzelli et al






KS-1

KS-9



50



57

62 80

28

76

117

126 112

56

57

18

16

133

Al2 O

3

Contact Rock

Quartzite

KS-6

KS-2

KS-3

KS-4

KS-5

KS-7 KS-8

KS-10

Granite


Nor

mal

ized

to P

AA

S30


10

00



2




DISCUSSION






2 and H



2O

3 versus (CaO+MgO)


below 10 Al2O



2O and




2 conshy




0 200microns

Geochron Sample

1 m

1 mm

diopside



2O

3 content One



Chiarenzelli et al





2) investigated






BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al

























Diopsidite

Diopsidite

Diopsidite

Diopsidite






2 While




Chiarenzelli et al

L

L






2 respectively In


2 Among the samples


2 3 T 2 2










3 cm

qtz

antenst

antenst

phg

ant

qtz





qtz

qtz

plg

opx cpx

cpx

phg

cpx

qtz

tia

tia qtz

qtz

qtz cpx

opx tia

cpx tia

zrc

μm50

μm100






Chiarenzelli et al






KS-1

KS-9



50



57

62 80

28

76

117

126 112

56

57

18

16

133

Al2 O

3

Contact Rock

Quartzite

KS-6

KS-2

KS-3

KS-4

KS-5

KS-7 KS-8

KS-10

Granite


Nor

mal

ized

to P

AA

S30


10

00



2




DISCUSSION






2 and H



2O

3 versus (CaO+MgO)


below 10 Al2O



2O and




2 conshy




0 200microns

Geochron Sample

1 m

1 mm

diopside



2O

3 content One



Chiarenzelli et al





2) investigated






BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al






















Chiarenzelli et al

L

L






2 respectively In


2 Among the samples


2 3 T 2 2










3 cm

qtz

antenst

antenst

phg

ant

qtz





qtz

qtz

plg

opx cpx

cpx

phg

cpx

qtz

tia

tia qtz

qtz

qtz cpx

opx tia

cpx tia

zrc

μm50

μm100






Chiarenzelli et al






KS-1

KS-9



50



57

62 80

28

76

117

126 112

56

57

18

16

133

Al2 O

3

Contact Rock

Quartzite

KS-6

KS-2

KS-3

KS-4

KS-5

KS-7 KS-8

KS-10

Granite


Nor

mal

ized

to P

AA

S30


10

00



2




DISCUSSION






2 and H



2O

3 versus (CaO+MgO)


below 10 Al2O



2O and




2 conshy




0 200microns

Geochron Sample

1 m

1 mm

diopside



2O

3 content One



Chiarenzelli et al





2) investigated






BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al























3 cm

qtz

antenst

antenst

phg

ant

qtz





qtz

qtz

plg

opx cpx

cpx

phg

cpx

qtz

tia

tia qtz

qtz

qtz cpx

opx tia

cpx tia

zrc

μm50

μm100






Chiarenzelli et al






KS-1

KS-9



50



57

62 80

28

76

117

126 112

56

57

18

16

133

Al2 O

3

Contact Rock

Quartzite

KS-6

KS-2

KS-3

KS-4

KS-5

KS-7 KS-8

KS-10

Granite


Nor

mal

ized

to P

AA

S30


10

00



2




DISCUSSION






2 and H



2O

3 versus (CaO+MgO)


below 10 Al2O



2O and




2 conshy




0 200microns

Geochron Sample

1 m

1 mm

diopside



2O

3 content One



Chiarenzelli et al





2) investigated






BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al






















Chiarenzelli et al






KS-1

KS-9



50



57

62 80

28

76

117

126 112

56

57

18

16

133

Al2 O

3

Contact Rock

Quartzite

KS-6

KS-2

KS-3

KS-4

KS-5

KS-7 KS-8

KS-10

Granite


Nor

mal

ized

to P

AA

S30


10

00



2




DISCUSSION






2 and H



2O

3 versus (CaO+MgO)


below 10 Al2O



2O and




2 conshy




0 200microns

Geochron Sample

1 m

1 mm

diopside



2O

3 content One



Chiarenzelli et al





2) investigated






BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al





















KS-1

KS-9



50



57

62 80

28

76

117

126 112

56

57

18

16

133

Al2 O

3

Contact Rock

Quartzite

KS-6

KS-2

KS-3

KS-4

KS-5

KS-7 KS-8

KS-10

Granite


Nor

mal

ized

to P

AA

S30


10

00



2




DISCUSSION






2 and H



2O

3 versus (CaO+MgO)


below 10 Al2O



2O and




2 conshy




0 200microns

Geochron Sample

1 m

1 mm

diopside



2O

3 content One



Chiarenzelli et al





2) investigated






BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al






















0 200microns

Geochron Sample

1 m

1 mm

diopside



2O

3 content One



Chiarenzelli et al





2) investigated






BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al























BSE CL

100 μm



TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

001

5 0

0737

4 0

0004

4 0

0648

9 0

0007

7 0

1747

0

0022

1

776

002

6 10

0 10

34

12

cm-2

1

1220

43

1 21

5 0

016

007

435

000

033

010

440

000

057

017

35

000

22

177

8 0

025

98

1051

9

cm-3

1

576

99

100

001

0 0

0745

6 0

0006

0 0

0508

4 0

0010

7 0

1794

0

0023

1

844

002

9 10

1 10

57

16

cm-4

1

813

207

142

ndash00

02

007

431

000

038

007

618

000

053

017

70

000

22

181

4 0

026

100

1050

10

cm

-51

74

8 19

3 12

8 ndash0

003

0

0737

8 0

0004

0 0

0771

8 0

0006

0 0

1734

0

0022

1

764

002

5 10

0 10

36

11

cm-6

1

875

162

151

ndash00

24

007

519

000

041

005

555

000

062

017

80

000

22

184

5 0

026

98

1074

11

cm

-71

64

9 14

2 11

1 0

036

007

359

000

046

006

467

000

071

017

38

000

22

176

3 0

026

100

1030

13

cm

-81

11

20

183

191

ndash00

01

007

521

000

032

004

848

000

036

017

64

000

22

182

9 0

025

97

1074

9

cm-9

1

958

220

163

001

7 0

0737

7 0

0003

8 0

0672

2 0

0005

9 0

1730

0

0022

1

760

002

5 99

10

35

10

cm-1

01

550

127

94

ndash00

11

007

396

000

048

006

863

000

070

017

49

000

22

178

3 0

027

100

1040

13

cm

-11

1 12

91

332

221

ndash00

20

007

527

000

035

007

650

000

058

017

32

000

22

179

7 0

025

96

1076

9

cm-1

21

1113

24

2 18

8 0

008

007

403

000

033

006

513

000

044

017

21

000

22

175

7 0

024

98

1042

9

cm-1

31

998

279

172

002

0 0

0738

6 0

0003

6 0

0822

6 0

0005

6 0

1736

0

0022

1

768

002

5 99

10

38

10

cm-1

41

1713

19

3 24

2 0

025

007

203

000

030

003

332

000

038

014

88

000

19

147

8 0

020

91

987

9 cm

-15

1 59

6 12

0 10

6 0

019

007

541

000

055

006

297

000

092

018

14

000

23

188

6 0

029

100

1079

15

cm

-16

1 85

6 18

7 14

6 0

012

007

383

000

042

006

544

000

065

017

43

000

22

177

4 0

026

100

1037

11

cm

-17

1 10

30

214

173

000

8 0

0746

1 0

0004

2 0

0613

8 0

0007

3 0

1723

0

0022

1

772

002

6 97

10

58

11

cm-1

81

2539

38

0 24

2 ndash0

003

0

0682

8 0

0002

9 0

0436

7 0

0004

0 0

0996

0

0012

0

937

001

3 70

87

7 9

cm-1

91

439

81

76

000

5 0

0738

0 0

0005

3 0

0563

9 0

0007

0 0

1785

0

0023

1

816

002

8 10

2 10

36

14

cm-2

01

2327

26

8 26

9 0

022

007

046

000

027

003

241

000

033

012

18

000

15

118

4 0

016

79

942

8 cm

-21

1 13

19

256

221

ndash00

10

007

408

000

045

005

914

000

086

017

18

000

22

175

5 0

026

98

1044

12

cm

-22

1 10

69

228

182

ndash00

02

007

391

000

034

006

324

000

046

017

43

000

22

177

6 0

025

100

1039

9

cm-2

31

2482

50

9 24

5 0

018

006

981

000

029

004

862

000

040

010

28

000

13

098

9 0

014

68

923

9 cm

-24

1 79

6 10

6 13

6 0

020

007

412

000

054

003

900

000

098

017

80

000

22

181

9 0

028

101

1045

15

cm

-25

1 77

1 19

5 13

3 0

014

007

453

000

040

007

453

000

058

017

44

000

22

179

3 0

026

98

1056

11

cm

-26

1 10

99

254

188

001

2 0

0737

8 0

0003

3 0

0687

4 0

0004

5 0

1742

0

0022

1

772

002

4 10

0 10

35

9 cm

-27

1 10

86

211

183

001

9 0

0735

3 0

0003

6 0

0572

4 0

0005

5 0

1735

0

0022

1

759

002

5 10

0 10

29

10

cm-2

81

1253

27

4 21

5 0

007

007

387

000

037

006

548

000

063

017

48

000

22

178

0 0

025

100

1038

10

cm

-29

1 17

30

180

289

ndash00

03

007

399

000

030

003

064

000

042

017

59

000

22

179

5 0

024

100

1041

8

cm-3

01

945

212

162

ndash00

21

007

406

000

040

006

755

000

065

017

48

000

22

178

5 0

025

100

1043

11

cm

-31

1 49

4 84

86

0

005

007

489

000

048

005

057

000

056

017

95

000

23

185

3 0

027

100

1066

13

cm

-31

2 11

95

171

200

001

1 0

0738

3 0

0003

4 0

0421

8 0

0004

1 0

1747

0

0022

1

778

002

5 10

0 10

37

9 cm

-32

1 13

92

309

238

000

4 0

0737

1 0

0003

2 0

0667

6 0

0004

9 0

1743

0

0022

1

771

002

4 10

0 10

33

9 cm

-33

1 99

8 19

8 17

1 0

027

007

453

000

036

005

855

000

051

017

60

000

22

180

8 0

025

99

1056

10

cm

-34

1 11

33

245

185

001

8 0

0733

4 0

0003

3 0

0640

3 0

0004

6 0

1665

0

0021

1

684

002

3 97

10

23

9 cm

-35

1 12

15

251

208

000

5 0

0741

3 0

0003

1 0

0612

7 0

0003

9 0

1752

0

0022

1

790

002

5 10

0 10

45

8 cm

-36

1 71

8 12

6 12

3 0

000

007

445

000

039

005

233

000

045

017

73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al





















TAB

LE 2

U-P

B S

HR

IMP

II IS

OT

OP

IC A

NA

LYS

ES

OF

ZIR

CO

NS

SE

PA

RA

TE

D F

RO

M D

IOP

SID

IC Q

UA

RT

ZIT

E O

N T

HE

WE

ST

ER

N S

UM

MIT

OF

CH

IMN

EY

MO

UN

TAIN

labe

l U

T

h P

b 20

7 Pb

206 P

b 20

8 Pb

206 P

b 20

6 Pb

238 U

20

7 Pb

235 U

20

7 Pb

206 P

b s

pot

ppm

pp

m

ppm

f 2

06

20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ 20

4 cor

r plusmn1

σ co

nc

date

plusmn1

σ cm

-11

10

11

222

173

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9 cm

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100

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10

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23

9 cm

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1 12

15

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1 0

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0

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1

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002

5 10

0 10

45

8 cm

-36

1 71

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6 12

3 0

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039

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000

045

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73

000

22

182

0 0

026

100

1054

11

cm

-18

2 22

28

260

246

ndash00

05

007

057

000

028

003

413

000

028

011

61

000

15

113

0 0

015

75

945

8 cm

-14

2 20

81

233

283

000

9 0

0711

8 0

0002

7 0

0328

4 0

0003

0 0

1432

0

0018

1

405

001

9 90

96

3 8

cm-3

71

1329

30

6 22

7 0

024

007

418

000

032

006

742

000

048

017

37

000

22

177

7 0

024

99

1046

9

cm-3

81

888

200

150

ndash00

14

007

475

000

043

006

724

000

070

017

26

000

22

177

9 0

026

97

1062

11

f 206

= 1

00 times

(co

mm

on 20

6 Pb

tota

l 206 P

b)

207 P

b20

6 Pb

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

7 Pb

206 P

b ra

tio20

6 Pb

238 U

204 c

orr

= 20

4 Pb-

corr

ecte

d 20

6 Pb

238 U

rat

io

207 P

b23

5 U 20

4 cor

r =

204 P

b-co

rrec

ted

207 P

b23

5 U r

atio

con

c =

C

onco

rdan

ce20

7 Pb

206 P

b da

te =

cal

cula

ted

204 P

b-co

rrec

ted

207 P

b20

6 Pb

date


Chiarenzelli et al




206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al























206Pb238U 020


1042 +ndash 4 Ma018 n = 31 95

1073 +ndash 15 Ma n = 4 95

016 15

207Pb235U



16 17 18 19 20






bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al





















bull e ___ _

021



6 Pb

238 U



1250 1250

1150 1150

019

1050 1050

017


015 11716 +ndash 63 Ma MSWD = 16

013

14 16 18 20 22 24 26

207Pb235U







1200

207 P

b20

6 Pb

Age

1100

1000

0 200 400 600 800 1000 1200 1400 1600
















1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al

























1100

1060


0074

207 P

b20

6 Pb




Num

ber

Rel

ativ

e Pr

obab

ility






0066





Isotope ratios





Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al






















Chiarenzelli et al









14 Chimney Mountain





Al 2

O3

wt

10

8

6





0 0 5 10 15 20 25 30 35 40 45 50
















2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al






























2 temshy






3 Na

2O or K

2O and large







CONCLUSIONS






Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al






















Chiarenzelli et al









SHRIMP II




References













References












ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al
























ACKNOWLEDGMENTS


REFERENCES CITED














































Chiarenzelli et al






















Chiarenzelli et al





















Documents

Geosphere - St. Lawrence University Chimney Mtn Shawinigan.pdf · geosphere.gsapubs.org on February 1, 2011 . Timing of deformation in the Central Adirondacks . PSD C AB HH . F T