Igneous rock n Field Relationships - Copy.ppt

7/25/2019 Igneous rock n Field Relationships - Copy.ppt

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Chapter 4: Igneous StructuresChapter 4: Igneous Structures

and Field Relationshipsand Field Relationships

Figure 4.1a.Calculated viscosities of anhydrous silicate liquids at one atmosphere pressure, calculated by the method of

ottinga and !eill "#$%&' by (ess "#$)$', *rigin of Igneous Roc+s. (arvard niversity -ress. b.ariation in the viscosity of

basalt as it crystalli/es "after 0urase and 0cirney, #$%1', 2eol. Soc. 3mer. ull., 84, 15161$&. c.ariation in the

viscosity of rhyolite at #777oC 8ith increasing (&* content "after Sha8, #$5, 3mer. 9. Sci., 263, #&76#1'.


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Structures and Field RelationshipsStructures and Field Relationships

Figure 4.2. olcanic landforms associated 8ith a central vent "all at same scale'.


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Figure 4.3a.Illustrative cross section of a stratovolcano. 3fter

0acdonald "#$%&', Volcanoes. -rentice6(all, Inc., ngle8ood

Cliffs, ;. 9., #6#7. b.


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Figure 4.4.Schematic cross section of the >assen -ea+ area. 3fter !illiams "#$1&', Univ. of Cal. Publ. Geol. Sci. Bull. , .


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Figure 4.5. Cross sectional structure and morphology of small

e?plosive volcanic landforms 8ith appro?imate scales. 3fter

!ohlet/ and Sheridan "#$)1',Amer. J. Sci, 283, 1)64#1.


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Figure 4.6a.Maar,(ole6in6the62round, *regon "upper courtesy of S2S,

lo8er my o8n'. b.Tuff ring,


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Figure 4.7.Schematic cross section through a lava dome.


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Figure 4.8. -ressure ridges on the surface of ig *bsidian Flo8, ;e8berry olcano, *R. Flo8 direction is to8ard the left. = 9ohn

!inter and -rentice (all.


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Figure 4.9.a+e caldera. 3fter acon

"#$))'. Crater >a+e ;ational -ar+ and icinity, *regon.

#:5&,776scale topographic map. . S. 2eol. Surv. ;atl. -ar+

Series.


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Figure 4.1.>ocation of the e?posed feeder di+es

"heavy lines' and vents "@s' of the southeastern

portion of the Columbia River asalts. nshaded area

covered by CR. 3fter Aolan et al. "#$)$', = Geol.

Soc. Amer. Special Paper, 239. pp. #6&7.


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Figure 4.11.3erial e?tent of the ;& 2rande Ronde flo8 unit "appro?imately flo8s'. 3fter Aolan et al."#$)$'. = Geol. Soc.Amer. Special Paper, 239. pp. #6&7.


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Figure 4.12. a.Ropy surface of a pahoehoe flo8, #$$5

flo8s, Balapana area, (a8aii. = 9ohn !inter and

-rentice (all.

a

b

Figure 4.12. b.!a"oe"oe"left' and aa"right' meet in the#$%4 flo8s from 0auna lu, (a8aii. = 9ohn !inter and

-rentice (all.


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Figure 4.12. c#e.Illustration of the development of an inflate$

flo%. In $, a thin flo8 spreads around a roc+ 8all. In "e', the

flo8 is inflated by the addition of more lava beneath the earlier

crust. 3 old stone 8all anchors the crust, +eeping it from lifting.

Ahe 8all can be seen in the lo8 area in part "c'. = 9ohn !interand -rentice (all.

cc


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Figure 4.13. a.Schematic dra8ing of colu&nar 'ointsin a basalt flo8, sho8ing the four common subdivisions of a typical flo8. Ahe column

8idths in "a' are e?aggerated about 4?. 3fter >ong and !ood "#$)5' = Geol. Soc. Amer. Bull., 97, ##446##.

b.(olonna$e#entablature#colonna$ein a basalt flo8, Croo+ed River 2orge, *R. = 9ohn !inter and -rentice (all.


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Figure 4.14.Subaqueous )illo% basalts, *lympic -eninsula,!ashington.

(ammer for scale


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Figure 4.15.3sh cloud and deposits of the #$)7

eruption of 0t. St. (elens. a.-hoto of 0t. St. (elens

vertical ash column, 0ay #), #$)7 "courtesy S2S'.b.ertical section of the ash cloud sho8ing temporal

development during first #1 minutes. c.0ap vie8 of

the ash deposit. Ahic+ness is in cm. 3fter Sarna6

!ocic+i et al." #$)#' in The 19! "ruptions of

#ount St. $elens% &ashin'ton. USGS Prof. Pap.,

125, %6577.


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Figure 4.16.3ppro?imate aerial e?tent and thic+ness of 0t. 0a/ama "Crater >a+e' ash fall, erupted 5$7 years ago. 3fter Doung "#$$7', npubl.

-h. ancaster. B.


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Figure 4.17.0a?imum aerial e?tent of the ishop ash fall deposit erupted at >ong alley

%77,777 years ago. 3fter 0iller et al. "#$)&' USGS (pen)*ile +eport)&6)1.


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Figure 4.18. Aypes of pyroclastic flo8 deposits. 3fter 0ac


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Figure 4.19.Section through a typical ignimbrite,

sho8ing basal surge deposit, middle flo8, and upper

ash fall cover. Aan bloc+s represent pumice, and purple

represents denser lithic fragments. 3fter Spar+s et al.

"#$%1' Geolo',, 1, ##6##). 2eol. Soc. 3merica

Structures and FieldStructures and Field

RelationshipsRelationships


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Figure 4.2. Schematic bloc+ diagram of some intrusive bodies.


Figure 4 21 Kangmiut dike swarm in the Sndre


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Figure 4.21. Kangmiut dike swarm in the Sndre

Strmfjord region of SE Greenland. From Escher et al.

(1!"#$ Geology of Greenland$ % &he Geological

Sur'e of )enmark and Greenland. !!*+.


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Figure 4.22.a.Radial di+e s8arm around Spanish -ea+s, Colorado. 3fter Bnopf "#$15', Geol. Soc. Amer. Bull., 47,

#%&%6#%)4. b.roded remnant of a volcanic nec+ 8ith radial di+es. Ship Roc+, ;e8 0e?ico. From 9ohn Shelton =

"#$55' Geolo', llustrate/. !. (. Freeman. San Francisco.


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Figure 4.23. Ahe formation

of ring di+es and cone

sheets.

a.Cross section of a rising

pluton causing fracture and

stoping of roof bloc+s.

b.Cylindrical bloc+s drop

into less dense magma

belo8, resulting in ring

di+es. c.(ypothetical map

vie8 of a ring di+e 8ith ;6

S stri+ing country roc+

strata as might result from

erosion to a level

appro?imating G6D in "b'.

$.p8ard pressure of a

pluton lifts the roof as

conical bloc+s in this cross

section. 0agma follo8s the

fractures, producing cone

sheets. *riginal hori/ontal

bedding plane sho8s offsets

in the conical bloc+s. "a',

"b', and "d' after illings"#$%&', Structural Geolo',.

-rentice6(all, Inc. "c' after

Compton "#$)', Geolo',

in the *iel/. 0 !iley. ;e8

Dor+.


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Figure 4.24.a. 0ap ofring $ies, Island

of 0ull, Scotland. 3fter ailey et al.

"#$&4', Tertiar, an/ post)tertiar,

'eolo', of #ull% och Aline an/ (ban.

2eol. Surv. Scot. 0ull 0emoir.

Copyright ritish 2eological Survey.


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Figure 4.24.b.(one s"eetsin the same area of 0ull, after Ritchey "#$5#',British +e'ional Geolo',. Scotlan/% the Tertiar, Volcanic 2istricts.;ote that the yello8 felsite ring di+e in part "a' is sho8n as the red ring in the ;! of part "b'. ritish 2eological Survey.


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Figure 4.25.Aypes of tabular igneous bodies in bedded strata based on method of emplacement.a.Simple $ilation"arro8s' associated

8ith in'ection. b.;o dilation associated 8ith re)lace&entor sto)ing. = 9ohn !inter and -rentice (all.



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Figure 4.26.Shapes of t8o concordant plutons. a.*accolit"8ith flat floor and arched roof. b.*o)olit"intruded into a structural

basin. Ahe scale is not the same for these t8o plutons, a lopolith is generally much larger. = 9ohn !inter and -rentice (all.



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Figure 4.27.ra$ational bor$er /onesbet8een homogeneous igneous roc+ "light' and country roc+ "dar+'. 3fter Compton "#$5&',

#anual of *iel/ Geolo',. = R. Compton.



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Figure 4.28.Marginal foliations developed 8ithin a pluton as a result of differential motion across the contact. From >ahee "#$5#',

*iel/ Geolo',. 0 0c2ra8 (ill. ;e8 Dor+.



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Figure 4.29. (ontinuit0 of foliationacross an igneous contact for a pre6 or syn6tectonic pluton.From Compton "#$5&',#anual of *iel/ Geolo',. = R. Compton.



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Figure 4.3.loc+ diagram several +ilometers across, illustrating some relationships 8ith the country roc+ near the top of a barely

e?posed pluton in the epi/one. Ahe original upper contact above the surface is appro?imated by the dashed line on the front plane.

From >ahee "#$5#',*iel/ Geolo',. 0 0c2ra8 (ill. ;e8 Dor+.



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Figure 4.31.a.2eneral characteristics of plutons in the e)i/one, &eso/one, and cata/one.

From uddington "#$$', Geol. Soc. Amer. Bull., 7, 5%#6%4%.



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Figure 4.32.


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Figure 4.33.loc+ diagram of subsurface salt $ia)irsin ;orthern 2ermany. 3fter

Arusheim "#$57',Bull. Amer. Assoc. Petrol. Geol., 44, ##$6#47 = 33-2.


S d Fi ld R l i hi


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Figure 4.34.


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Figure 4.35.S+etches of diapirs in soft putty models created in a centrifuge by Ramberg "#$%7', In ;e8ell, 2., and ;. Rast, "#$%7'

"eds.',#echanism of 'neous ntrusion. >iverpool 2eol. Soc., 2eol. 9. Spec. Issue no. 2.


S d i ld l i hiS d Fi ld R l i hi


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Figure 4.36.


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Figure 4.37.-ossible methods by 8hich a large batholith may gro8 by successive small increments over millions of years.

0agma rises initially as a series of di+es in an e?tensional terrane. ach di+e spreads laterally as a thic+ sill upon reaching a

level at 8hich it is no longer significantly buoyant. Room may be created by: a.lifting the roof roc+s if the overburden is small,

b.depressing the chamber floor as magma is displaced up8ard and 8ithdra8n from belo8 "Cruden and 0cCaffrey, &77#H

Cruden, &77', or c.some more irregular and sporadic process. Image courtesy of 9ohn artley.



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Figure 4.38.Schematic section through a hydrothermal system developed above a magma chamber in a silicic volcanic terrane. 3fter

(enley and llis "#$)1',"arth Sci. +ev., 19, #67. *?ygen isotopic studies have sho8n that most of the 8ater flo8 "dar+ arro8s' is

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Igneous rock n Field Relationships - Copy.ppt