the diversity of sodium metasomatic processes and their …. diversity of na... · 2015-05-20 ·...

The diversity of sodium metasomatic processes and their relations to

uranium deposits

inpl nancy

UNIVERSITE DE LORRAINE – GEORESSOURCES CREGU – CNRS

54 506, Vandoeuvre les NANCY France

Also named : albitite-type uranium deposits

This class of deposit is economically significant with very larges resources especially in Ukraine & Brazil in the Lagoa Real district

Some of these deposits are transitional with other deposit types: Related to magmatic fractionation: Bokan Mountain Vein type deposits with the episyenitization (dequartzification): Beaverlodge Volcanic related deposits, when volcanic rocks are albitized: Michelin Metamorphic deposits: Lagoa Real

In these district albitisation is always associated with U mineralization but the albitized zones extend on much arger volumes. There is a large diversity of albitite types & only some are mineralized

The diversity of sodium metasomatic processes and their relations to uranium deposits

TYPOLOGY OF ALBITITES This word has been used widely covering different meanings TYPE I : MAGMATIC ALBITITES Ia – Associated to peraluminous leucogranites Ib – Associated to peralkaline / calc-alkaline granites - Ib1 purely magmatic - Ib2 magmatic-hydrothermal Ic – Associated to ultrabasic complexes TYPE II : HYDROTHERMAL ALBITITES IIa – With dequartzification (episyenite type) IIb – Vein type IIc – Hydrothermal diagenetic in volcanic rocks

IIc – Hydrothermal diagenetic at unconformities IId – IOCG related

Albitite: definition A name proposed by Turner (1896) for granular igneous rocks consisting essentially of albite. Occur in dikes in the Sierra Nevada mountains, California http://www.wordnik.com/words/albitite A coarse-grained porphyritic dike rock composed almost wholly of albite McGraw-Hill Dictionary of Scientific & Technical Terms A granular dike rock consisting essentially of albite http://www.merriam-webster.com/dictionary/albitite

TYPOLOGY OF ALBITITES TYPE I : MAGMATIC ALBITITES Ia – Associated to peraluminous leucogranites Ib – Associated to peralkaline / calc-alkaline granites - Ib1 purely magmatic - Ib2 magmatic-hydrothermal Ic – Associated to ultrabasic complexes TYPE II : HYDROTHERMAL ALBITITES IIa – With dequartzification (episyenite type) IIb – Vein type IIc – Hydrothermal diagenetic in volcanic rocks

Eutectic

QUARTZ

ALBITE K-FELDSPAR

EFFECT of FLUORINE on the EUTECTIC of the GRANITE SYSTEM

Increasing F content : decrease Qz and K-Feld contents increases albite content convergence with true albitites

Manning, 1981 C.M.P., 76, 206-215

TYPE I : MAGMATIC ALBITITES Ia – Albitites associated to peraluminous leucogranites

Ultimate intrusions of peraluminous leucogranitic complexes Li-Muscovite, Lepidolite, Li-Be-phosphates, Rich in P, Ta, Nb, Sn, U, Li, Cs, F, Be, Rb … Very poor in REE, Th, Zr … During magma fractionation with increasing F content in melt: Decreasing SiO2 content K increasingly hosted in lepidolite Increasing Na2O content Increasing albite porportions But not real albitites because: still 15 to 20% quartz in the rock

GPF DRILLING LOUROUX DE B. SERVANT

BEAUVOIR GRANITE

COLETTES GRANITE

PRESUMED LA BOSSE GRANITE

PRESUMED DIORITIC BODY

POUZOL-SERVANT GRANITE

FERBERITE STOCKWORK

LA SIOULE MICASCHIST

GNEISS & MIGMATITES

X X X X

X X X X X

X X X X X X

X X X X X

X X X X

BEAUVOIR « ALBITITE » in the ECHASSIERES GRANITIC COMPLEX (FRENCH MASSIF CENTRAL)

TYPE I : MAGMATIC ALBITITES Ia – Albitites associated to peraluminous leucogranites

F-rich ALBITIC F-poor GRANITE GRANITE

SIO2 67.50 72.10

Al2O3 17.40 16.00

Fe2O3 0.18 0.72

Na2O 5.07 4.01

K2O 3.71 3.81 Be= 260 ppm; Cs= 612 ppm; Nb= 158 ppm; Ta= 425 ppm; Rb= 4000 ppm, Sn= 1400 ppm

Th = 1 ppm Zr = 20 ppm REE = 2 ppm

Late Neoproterozoic intrusive Taar

albitite Southern Sinai,

Azer et al., 2010 IGES, 99, 245-267

TYPE I : MAGMATIC ALBITITES Ib1 – Albitites associated to peralkaline/calcalkaline granites

TAAR ALBITITE

SIO2 69.13

Al2O3 18.69

Fe2O3 0.33

Na2O 10.55

K2O 0.15

Be= 1.8ppm; Li= 0.5ppm; Nb= 18ppm; Ta= 1.5ppm; Rb= 1.9ppm; U= 1ppm; Th= 6ppm Zr= 277 ppm; REE= 135 ppm

Azer et al., 2010 IGES, 99, 245-267

Magmatic textures : Porphyritic varieties, with tabular euhedral albite crystals in a fine-grained groundmass

Tarr albitites

In fact it is an albitic granite because there is up to 11% quartz Mantle origin : Low εNd = +4 to +6.5 ; Sri = 0.70356 very low Rb (1.9 ppm), Li (0.5 ppm)

Residual magma remaining after near-total crystallization of an A-type granite pluton at depth, emplaced into the roof above the cooling pluton

BOKAN MOUNTAIN ALASKA

MAGMATIC/HYDROTHERMAL U-DEPOSIT (ROSS ADAMS)

RELATED TO A PERALKALINE GRANITE

TYPE I : MAGMATIC ALBITITES Ib2 - Magmatic/hydrothermal

Associated to peralkaline/calc-alkaline granites

BOKAN MOUNTAIN INTRUSION

ALASKA

BOKAN MOUNTAIN, ALASKA

MAGMATIC/HYDROTHERMAL

U-DEPOSIT (Ross Adams mine) Production 1000 t U @ 1% U

U-Th deposit

REE veins

granites

-400 -300 -200 -100 0

P = K- (Na+Ca)

l/3-(N

K Na exchange

dequartzification and albitization

argillization silicification

quartz

K-feldspar albite

GAg GAgAr GAgArf

GAgArs GAgAra

n.m.abtz.Ag. m.abtz.Ag. m.abtz.dq.Ag

GAgArh syn-ore alteration

granites

post-ore alteration

BOKAN MOUNTAIN

ALASKA

QUARTZ / FELDSPAR

PROPORTIONS GRANITE ALBITITE

SIO2 74.90 61.90

Al2O3 10.30 12.40

Fe2O3 4.80 6.00

Na2O 4.50 9.50

K2O 4.20 0.40

GAgArf

n.m.abtz.Ag.

m.abtz.Ag. m.abtz.dq.Ag

GAgArh

syn-ore alteration

granites

BOKAN MOUNTAIN ALASKA

Th - U FRACTIONATION ?

Granites 10 < Th < 70 ppm 2 < U < 30 ppm

Mineralization 400 ppm < Th < 3 % 100 ppm < U < 1.8 %

granites

mineralization BOKAN MOUNTAIN

ALASKA

Th - Zr

FRACTIONATION

Granites 300< Zr <2000ppm

Mineralization 600 ppm < Zr < 1%

Bokan Mountain granite peralkaline magmas derive from low degree of partial melting of the mantle with subsequent fractionation

most fractionated and most apical part of a larger magmatic complex existing at a relatively shallow depth.

U mineralization derived nearly directly from mantle, extreme magma fractionation and magmatic fluids unmixing

Initial U-Th enrichment of the mantle through subduction of oceanic slab & sediments, enhance the U and Th concentrations in melts

Th/U ratios remain close to chondritic ratio of 3.5 during magma fractionation, even in the mineralized albitites.

GENETIC MODEL

Lherzolite massifs with albitite dikes in the north Pyrenean metamorphic zone (Azambre & Monchoux,1998)

FRANCE

Lherzolite (dark grey) intruded by albitic dykes (white)

Dikes of albitite cross-cutting serpentinized lherzolite in the Pyrénées, France

Paragenesis : Albite + muscovite + biotite + chlorite, epidote, zircon, titanite, thorite, pyrochlore, aeschynite-(Ce), Fe-columbite, allanite-(Ce), chevkinite-(Ce), apatite, monazite-(Ce), rutile, ilmenite, magnetite Textures: pegmatitic & reflect a rapid magmatic crystallization Large crystals of albite predate the fine-grained minerals of Ca, Sr, Fe, Mg, Zr, Ti, Y, REE, U, Th.

Urdach (with corundum: open circles; without corundum: asterisks), Garba Tula (solid square) and Finero (solid circles) albitites in the diagram of Cox et al. (1979).

Positive εNdi values (+1.9 to +3.4) derivation from a mantle source low rate of partial melting (0.5-0.7%) of a metasomatized peridotite

Dikes of albitite in lherzolite, Pyrénées, France

ALBITITE SIO2 63.50 Al2O3 20.60 Fe2O3 1.63 Na2O 10.20 K2O 0.39 Rb = 3.9ppm; Zr = 231ppm

Nb=239 ppm; Ta=17ppm; Th=82ppm U = 106ppm; REE = 1950ppm

Ultimate intrusion of ultrabasic complexes Rospigliani albitites (Corsica, France)

No dequartzification (albitic syenites of albitic granite) Albite + quartz ± Na amphibole or pyroxene Zr-rich (1640 ppm) Low U (0.2 – 0.5 ppm), Th (0.3 – 2 ppm), Rb (0,09 ppm), Li

ALBITITE SiO2 59.90 Al2O3 17.23 Fe2O3 6.32 Na2O 10.80 K2O 0.10

TYPE II : HYDROTHERMAL ALBITITES IIa – With dequartzification (episyenite type) Dequartzification may represent the unique alteration Followed or synchronous with albitization: - of plagioclase (removal of the anorthite component) - of K-feldspar - new formation of albite in the vugs Followed or not by Ca-metasomatic and/or uranium mineralization Rarely followed by K-metasomatism Most trace elements are stable except Rb, Ba, Sr Low saline aqueous fluids Common in granite plutons, but also occur in metasedimentary rocks Generally post-magmatic phenomena, variable extension

Albitisation of K-feldpar

K Na exchange

Albite-Microcline-Qz metasomatite

QUARTZ

K-FELDSPAR 200 100 0

K – (Na+Ca) -100 -200

MQ SQ DQ

GENERAL CHEMICAL-MINERALOGICAL EVOLUTION OF Na-METASOMATISM

granite field

Albitite

Na K exchange

Quartz dissolution

TYPE II : HYDROTHERMAL ALBITITES IIa – With dequartzification (episyenite type) Margeride, France

(i) Locally developped in granitic intrusion, can be mineralized

GRANITE EPISYENITE

SIO2 76.38 69.57

Al2O3 12.86 17.75 (increase due to volume loss)

Fe2O3 0.27 0.21

Na2O 3.8 9.16

K2O 4.23 1.21

EPISYENITE BERNARDAN

MARCHE OCCIDENTALE

Albite replacing K-feldspar with a chessboard microstructure

ALBITITE – EPIDOTE EPISYENITE

May 2001 The last U ton leaves the Bernardan mine in France = end of U mining in France, more than 200 mines operated from 1954 to 2001

Open pit mine BERNARDAN

3 D MODEL OF THE

BERNARDAN EPISYENITE U DEPOSIT

France, by GOCAD

J.J. ROYER, 1992

Up to 1 km

vertical extension

Ashton, 2010

Zone of episyenite alteration (Gunnar open pit), Ashton, 2010

Cross section throught the Gunnar episyenite (after Evoy, 1986)

TYPE II : HYDROTHERMAL ALBITITES IIa – With dequartzification (episyenite type)

(2) developped at the regional scale, with the largest U resources Developed along regional, transcrustal shear zones (>2.4 km depth)

High temperature processes (600 to >300°C)

May affect any type of rock (granite, banded iron formation, metased.

Surficial origin of the fluids most commonly,

Na-metasomatism generally followed by Ca ± K metasomatism,

Albitization extends over much larger zones than U mineralization

Mineralization U ± Zr, no Th, low REE

Michelin

Arjeplog-Arvidsjaur

Valhalla LAGOA REAL

CENTRAL UKRAINE

Timdrart

Kurupung

Small Medium LARGE

Coles Hill

Kitongo

Espinharas ITATAIA

1.8-1.5 Ga 0.5-0.2 Ga

Lianshanguan

North Rajasthan

WORLD DISTRIBUTION OF HYDROTHERMAL METASOMATIC DEPOSITS II-5a (HMtNa) associated with Na-metasomatism

Alio Ghelle

Gunnar Beaverlodge

ParanaBasin

BazilianoBelt

40°20°

Atlantic

SaoFrancisco

Craton

SouthernAmazonCraton

NorthernAmazonCraton

Amazon Basin

ParnaibaBasin

10°60°

0 500 1000

Andean foreland basinAndes

ean Apiacac-Xingu Platform

AndesBasins < 350 MaBraziliano 900-520 MaCratons > 1100 Ma

ItataiaEspinharas

LagoaReal

Poçosde Caldas

Salvador

ParanaBasin

BazilianoBelt

40°20°

Atlantic

SaoFrancisco

Craton

SouthernAmazonCraton

NorthernAmazonCraton

Amazon Basin

ParnaibaBasin

10°60°

0 500 1000

Andean foreland basinAndes

ean Apiacac-Xingu Platform

AndesBasins < 350 MaBraziliano 900-520 MaCratons > 1100 Ma

ItataiaEspinharas

LagoaReal

Poçosde Caldas

Salvador

Main U deposits in Brazil

Map of the uranium deposits of the

Lagoa Real District

Bahia, Brazil

Undeformed St Timoteo granite

Orthogneissified St Timoteo granite

Uranium deposits

QUARTZ –FELDSPAR PROPORTION VARIATIONS AT LAGOA REAL

1 10 100 1000 10000 100000

U (ppm)

amphibolites

Th-Nb G.

Granites

Albitized G.

Albit.dequart. G.

Barren A.D.G.

Th/U = 0.1Th/U=3.5

Th/U=10

Th/U = 1 Th/U = 0.01

Th – U VARIATIONS DURING Na-Ca METASOMATISM

100 1000 10000

Zr (ppm)

amphibolites

Th-Nb G.

Granites

Albitized G.

Albit.dequart. G.

Barren A.D.G.

Zr/Th = 10

Zr/Th = 100

Th – Zr VARIATIONS DURING Na-Ca METASOMATISM

Krivoi Rog

Kremenshug

Novounkrainska granite

Korsun-Novomirgorodsk granite

Monzo-gabbros-dioritesUranium deposits

100 km

Sevsk - Ingulets

Sumy - DnieprVoronezh

Krivoi Rog

Kremenshug

Novounkrainska granite

Korsun-Novomirgorodsk granite

Monzo-gabbros-dioritesUranium deposits

100 km

Sevsk - Ingulets

Sumy - DnieprVoronezh

CENTRAL UKRAINE DISTRICT

U districts: Kirovograd-Novoukrainka (I), Krivy Rig (II). Major faults : Kirovograd (1), Novokonstantinovka (2), Zvenigorod-Annivka (3), Subotsk-Moshorynsk (4), Central (5)

Cratons

Mobile belts

Evolution of quartz content relative to K-feldspar & Na-Ca mineral contents in the granitoids and altered zones associated with U mineralization

Uranium versus thorium concentration variations in the granitoids and altered zones of Central Ukraine

Metallogenic model for the genesis of the uranium mineralization associated with Na-metasomatism of Central Ukraine

TYPE II : HYDROTHERMAL ALBITITES IIb – Vein type

Wall rocks are generally metamorphic rocks

Albitization is variably developed and confined to the wall roks

The uranium mineralization fill veins or breccias

At Beaverlodge the U mineralization is emplaces in the red mylonite which consists of fine grained albitite or quartz albitite

Some pitcheblende veins has albite as a gangue mineral partial overlap between albitization and U deposition

E.A.G. Trueman, 2009

The Rožná U deposit

Czeck Republic

The Rožná U deposit In plagioclase-biotite paragneisses Hydrothermal U ores related to mylonite, fault breccia Cement = graphite + pyrite, cut by carbonate veinlets. Metasomatic alteration : muscovitization, albitization, chloritization or carbonatization Ores bodies with disseminated U mineralization. U minerals : uraninite + coffinite (rare brannerite & montroseite) with calcite and chlorite. Hexavalent U minerals (liebigite, metaautunite …) Grade : 0.01-0.5% U (0.3 % in average), up to 5% locally

The Rožná U deposit

Czeck Republic

TYPE II : HYDROTHERMAL ALBITITES IIc – Diagenetic in volcanic rocks

Keratophyres and spillites

Association of basic and acidic volcanic rocks

Abundant carbonates, chlorite, epidote

U ± Zr, if peralkaline tuffs

Ex. Permian from Switzerland Alps

Tokoro Shirmeck (Japan) (Vosges) SIO2 66.10 71.50 Al2O3 16.55 12.97 Fe2O3 5.50 5.12 CaO 3.01 0.46 Na2O 6.19 4.72 K2O 0.01 1.35

Spillites &

keratophyres in the Quartz/

Feldspar diagram

Trends with decreasing

quartz & increasing

albite contents

K-feldspathisation

silicification

K-FELDSPAR K-(Na+Ca)

Si/3-(Na+K+2Ca/3)

PLAGIOCLASE

Ultrabasic trend

ALKALINE

QUARTZ

TYPE II : HYDROTHERMAL ALBITITES IIc – Diagenetic at unconformities

Tendancy to dequartzification

Diagenetic saline aqueous fluids (100 – 150°C)

Small intracontinental basins

K-feldspathization also occur

U deposits from Rouergue (Bertholène, )

ALBITITE SIO2 56.11 Al2O3 17.46 Fe2O3 6.00 CaO 4.42 Na2O 6.95 K2O 0.24 Yerle, 1978

TYPE II : HYDROTHERMAL ALBITITES IIe – IOCG deposit related

3 main types are associated with IOCG deposits: Ca-Na, Fe, K alterations The Na-Ca alteration zones: regional in scale (>1 km wide) range from a strong albitization (± Cpx, titanite), such as in the Cloncurry district, to the CAM assemblage of Skirrow et al. (2002) with calc-silicate (Cpx, amphibole, garnet) - K-feldspar - albite ± Fe-Cu sulphides, ± albite, actinolite, magnetite, apatite, late epidote (Pollard et al, 1998; Wyborn, 1998) In extreme cases it can also result in the formation of albitites Early alterations prepare the ground for subsequent alterations In the Cloncurry district, albitites are extensive, and a spatial & temporal association exists between albitite & U but also between albitite & Cu-Au of IOCG type. But, most albitites in the region are devoid of U, Cu, Au.

Detailed distribution of two of the major phases of

alteration and mineralization around the

Ernest Henry Cu-Au deposit (Mark et al., 2000)

Titanite ages for the Cloncurry district suggest a temporal relationship between granite

intrusion & albitization (Mark & Foster, 2000; Pollard, 2001)

C and O isotope data typical for fluids derived from, or equilibrated with, felsic igneous rocks. S isotope values for sulfides from the deposits and albitite-related pyrite at Ernest Henry, point toward an igneous fluid source The regional albitization was most likely

produced by fluids derived at least partly from crystallizing plutons (Mark et al., 2000)

TYPE II : HYDROTHERMAL ALBITITES IIe –IOCG deposit related (Conclurry district) ALBITIC ABITIC PELITE PELITE Qz Monzonite Qz-Monzonite

SIO2 56.10 65.30 66.50 68.41

Al2O3 21.70 19.50 14.96 15.69

Fe2O3 8.29 0.47 3.81 1.99

CaO 0.35 0.65 2.02 2.47 Na2O 0.53 10.69 4.83 8.94

K2O 6.52 0.38 4.79 0.17

Zr= 130 ppm; Nb= 18 ppm; Rb= 13 ppm Oliver, 2004, Econ. Geol.

Mark G, Foster DRW 2000 Magmatic hydrothermal albite-actinolite- apatite-rich rocks from the Cloncurry district, NW Queensland, Australia: Lithos, 51, 223-245.

Fluid inclusions in the albitites from the Conclurry district

NaCl-KCl-CaCl2-H2OCO2 ± hematite-gypsum fluids with 2 or more daughter minerals, salinity >50 wt %NaCl eq, NaCl-H2O-CO2 fluids with halite and 20 to 30 wt % NaCl eq. CO2-rich fluids

Pressure corrected entrapment temperatures of inclusions associated both with albitites and with the ores are 300° to 550°C

Albitization stage reached temperatures of 450° to 600°C, determined from calc-silicate mineral equilibria and calcite-dolomite geothermometry (Oliver et al., 1993; Oliver, 1995), & oxygen isotope geothermometry on quartz, magnetite, albite, and amphibole (Mark, 1998a; Mark and Foster, 2000)

CONCLUSIONS

Extreme diversity of the types of sodium metasomatism : Developped in a wide range of temperature and pressures

Related to a wide variety of fluid types from magmatic to surficial

Only some specific types can be associated with U mineralization processes

Albization envelops exceed largely the U mineralized zones

Dequartzification is generally necessary to create the space necessary for U mineralization precipitation

the diversity of sodium metasomatic processes and their …. diversity of na... · 2015-05-20 ·...

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