Iron Deposits

8/2/2019 Iron Deposits

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THE LOW Ti - Fe OXIDEFLUORAPATITE DEPOSITS - CASE

STUDY: NEW YORK


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MAGNETITE - FLUORAPATITE (KIRUNA)-TYPE DEPOSITS

LOW-Ti MAGNETITE-FLUORAPATITE

GEOLOGICAL SETTING:

- RIFTED CONTINENTAL MARGINS (BACK ARCS)

- INTRACONTINENTAL RIFTS (ANOROGENIC)

- WITHIN A SUBAERIAL TO SHALLOW MARINE ENVIRONMENT

- ACCOMPANIED BY VOLCANO-PLUTONIC ACTIVITY

- LARGE SCALE FLUID OVERPRINT EXPRESSED BY SODIC ALTERATION

ORIGIN:

-LIQUID IMMISCIBILITY (Frietsch 1978; Nystrom & Henriquez 1994;Naslund et al. 2000);

- EXHALATIVE-SYNSEDIMENTARY (Parak 1975)

-HYDROTHERMAL (Hildebrand 1986; Bookstrom 1977; Gleason et al.2000; Sillitoe & Burrows 2002)

END-MEMBER OF THE HYDROTHERMAL IRON OXIDE-COPPER-GOLD (IOCG) CLAN (Hitzman et al. 1992; Hitzman

2000).


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Bafq deposit, Iran

Daliran, 2010


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http://www.scielo.cl


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Bedded hematite ash and lappilli. This deposit is composed of loose,

uncemented, material that can be dug out by hand. El Laco sur Credit: Dr. R. Naslund


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Magnetite spindle bombs collected in situ from loose, bedded hematite ash. Some ofthe spindle bombs had well developed bomb sags beneath them and bedded ashdrapped over their tops

Credit: Dr. R. Naslund


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Bedded hematite ash with in situ magnetite spindle bombs. El Laco sur

Credit: Dr. R. Naslund


8/47TAROM deposit, Iran


9/47http://www.qedata.se

KIRUNA


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http://upload.wikimedia.org/wikipedia/commons/c/c4/Grenville-Timeline.png


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Extent (orange regions) of the Grenvilleorogeny, after Tollo et al (2004) and

Darabi (2004).

Timeline of the Grenvilleorogeny, after Rivers

(2002)
http://upload.wikimedia.org/wikipedia/commons/c/c4/Grenville-Timeline.pnghttp://upload.wikimedia.org/wikipedia/commons/f/fe/Grenville-Extent.png


13/47McLelland & Selleck, 2011


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THREE HOLES RUTGERS MINE AUSABLE FORKS


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THREE HOLESMINE, PORT HENRY

RUTGERS MINE, AUSABLE FORKS

ICE CAVE MINE, PORT HENRY BARTON HILL MINE, MINEVILLE


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Fluorapatite1852

REE influorapatite

1940

Williams StrategicMinerals: 1983

Rhone-Poulenc, Inc.1986

Rhodia, Inc


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1

10

100

1000

10000

100000

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

Mineville

Mineville

Mineville

Kiruna

Durango

Mishdovan

Chahgaz

Avnik (massive)

Avnik(stock)

La2O3: 1.24 1.35 wt.%

Ce2O3: 2.66 2.84 wt.%

Nd2O3: 1.21 1.34 wt.%

Y2O3: 1.40 1.99 wt.%

Y: 10112 ppm

La: 8990 ppm

Ce: 17804 ppm

Pr: 2255 ppm

Nd: 10112 ppm

Sm: 1755 ppm

Eu: 174 ppm

Gd: 1825 ppm

Tb: 254 ppm

Dy: 1566 ppm

Er: 1016 ppm

Tm: 151 ppm

Yb: 857 ppm

Lu: 109 ppm


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Charge compensation mechanism:


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Charge compensation mechanism:

(REE + Y)3+ + Si4- = Ca2+ + P3-

Fluorapatite S.S. Britholite-(Ce,Y)

Ca

5

(PO

4

)

4

(F,OH) (Ce,Y,Ca)

5

(SiO

4

,PO

4

)

3

(OH,F)

R2

= 0.9354

y = -0.7152x + 11.043

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

13 13.5 14 14.5 15 15.5

Ca + P

Si+(REE+Y)

Additional coupled substitutions:

(REE + Y)3+ + Na+ = 2Ca2+

2(REE + Y)3+ + vacancy = 3Ca2+


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-large, wetting-like, mantle-like crystals

- no evidence of zoning

- one large crystal yielded 392 ppm Zr

- 789 C (P = 0.75 GPa)assuming coexistence withrutile and quartz

-760 C (P = 0.5 GPa)

(Hayden et al. 2008)


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- weakly molted appearance

-zoned with respect to BSE

-zones not resolvable for probesanalysis of Ti

- 10.1 6.3 ppm Ti

736 + 48/- 92 C

(Watson et al. 2006)


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0.150

0.154

0.158

0.162

0.166

0.170

0.174

0.178

0.182

1.45 1.55 1.65 1.75 1.85

206Pb/238U

207Pb/235U

940

980

1020

1060

Interceptsat

25050& 102213 [14]Ma

MSWD= 0.25forced interce t

data-point error ellipses are 68.3% conf.

ZIRCON GEOCHRONOLOGY

(LA-MC-ICPMS)

Old Bed, Mineville, Essex County


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0.144

0.148

0.152

0.156

0.160

0.164

0.168

0.172

1.2 1.4 1.6 1.8

2

06Pb/238U

207Pb/235U

900

940

980

1020

ConcordiaAge = 949 10 Ma

(2s,decay-const. errs included)

MSWD(of concordance) = 1.5,

Probability(of concordance) =


Barton

Hill

0.15

0.16

0.17

0.18

0.19

0.20

1.4 1.6 1.8 2.0 2.2

206Pb

/238U

07Pb/235U

1000

1100

ConcordiaAge = 1039 11 Ma

(2s,decay-const. errs included)

MSWD(of concordance) = 0.13,

Probability(of concordance) =


Barton Hill mines, Mineville, EssexCounty


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Distribution of the iron depositsin the Hudson Highlands

Location:

roughly 60 km

north of New York

City

Map courtesy of

Janet Manchester,

N.Y. State Museum


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The intrusive contact is knife-sharp; the amphibole-dominant rock seems to have formed from an iron-rich

ultramafic melt

Hogencamp mine


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A cumulate of Grt xenocrysts

Contact with

syenite, Dater mine


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An interesting discovery


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An unusual composition

A new species of calcic amphibole, fluoro-potassichastingsite, from the Greenwoodiron mine

Ideally, KCa2(Fe2+4Fe3+)Si6Al2O22F2 Empirically, A(K0.59Na0.25)0.84

B(Ca1.87Na0.13)2.00C

(Fe2+

2.60Mg1.56Fe3+

0.53Al0.26Mn0.03Ti0.01)4.99T(Si6.36Al1.64)8.00 022.68O3[F1.11(OH)0.73Cl0.16]2.00

Mg# = [100 Mg / (Mg + Fetotal

+ Mn] = 33


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The association

Fluoro-potassichastingsite in crystals up to 1cm across, associated with Mgt, Cpx, Opx,Po, Cp, Phl; the assemblage is not deformed

Magnetite mineralization exploited during theCivil War (18611865), last worked in 1880

Host rocks: gneiss, amphibolite, marble, peakmetamorphism 1010 1160 Ma (Grenville)

Part of the Reading Prong, uplifted Grenville-age basement


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The holotype specimen offluoro-potassichastingsite


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The Greenwood mine today


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0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

5.566.577.58

Si apfu

Mg/(Mg+Fe)

Cl>0.5 apfu

F>0.5 apfuCl>0.25 apfu

F>0.25 apfu

(Cl+F)>0.5 apfu

OH-dominant

Tremolite

Actinolite

Ferro -

actinolite

Edenite

Ferro - edenite

Pargasite (VIAl>Fe3+)

Magnesiohastingsite

(VIAlFe3+)

Hastingsite(VIAl


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Variability in F:Cl ratio in similar amphibolesin the nearby Dater and ONeil mines

A similar amphibole-dominant

rock is prominent at each mine

The composition of the coarse-

grained amphibole is iron-dominant,with a Mg# of 35 or so, and it

coexists with magnetite pyrrhotite

chalcopyrite

Its F:Cl ratio is very variable from

one mine to the other


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What do the textures indicate?

In the holotype specimen, the amphiboleforms a compact mass of subhedral crystalsassociated with Mgt, Cpx, Opx

Some blotchiness may occur, but no

evidence of a replacement relationship Some coarse euhedral crystals may be found

set in a carbonate matrix In cases, the amphibole itself seems to have

been a melt phase, as it is a matrix forcumulus pyroxene, and at some mines,olivine

Evidence of net-textured Po + Cp + Mgt


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Our amphibole as representative ofan iron-rich ultrabasic melt?

ONeil mine

HUDSONITE was proposed in 1885


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The American Naturalist19(10), October 1885, pages 991-994.

HUDSONITE was proposed in 1885by Prof. G.H. Williams!


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Summary of key observations

Evidence of an ultramafic magma

Efficient settling of cumulus phases (e.g., Mgt) andxenocrysts (Grt) from assimilated gneiss

Evidence of assimilation of marble and meta-evaporite horizons to account for high Cl, primarycarbonate

Evidence of a syenitic melt

Evidence of a carbonate melt Evidence of a sulfide oxide melt

Evolved derivative of a ferropicritic melt of ultimateasthenospheric origin?


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The juxtaposition of such multiple partialmelts

Has been found in other granulite terranesafter the cessation of contractional forces,

e.g., in the Oaxacan terrane in southernMexico (also of Grenville age)

These coexisting partial melts can be

expected to contain isotopic evidence amixture of crust and mantle components


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McLelland et al. (2010)

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Iron Deposits