Strontium isotope systematics of hydrothermal minerals from epigenetic Archean gold deposits in the Yilgarn Block, Western Australia

Mueller, Andreas G.; Laeter, J. R. De; Groves, David

doi:10.2113/gsecongeo.86.4.780

Cited by 62 publications

(19 citation statements)

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“…2.63 Ga (Mueller et al 1991a). A contribution of Sr from anatectic granitoids or their old crustal source rocks is implicated, with the scheelites from higher metamorphic grade settings, commonly closer to the margins of these anatectic granitoids, having the higher initial Sr isotope ratios.…”

Section: Fluid and Solute Sourcementioning

confidence: 97%

The crustal continuum model for late-Archaean lode-gold deposits of the Yilgarn Block, Western Australia

1993

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Abstract. Most Archaean gold ores belong to a coherent genetic group of structurally controlled lode-deposits that are characteristically enriched in Au with variable enrichments in Ag, As, W, Sb, Bi, Te, B and Pb, but rarely Cu or Zn, and are surrounded by wallrock alteration haloes enriched in K, LILE and CO2, with variable Na and/or Ca addition. Evidence from the Yilgarn Block of Western Australia, combined with similar evidence from Canada and elsewhere, indicates that such deposits represent a crustal continuum that formed under a variety of crustal r6gimes over at least a 15 km crustal profile at PT conditions ranging from 180 ~ at < 1 kb to 700 ~ at 5 kb. Individual deposits, separated by tens to hundreds of kilometres, collectively show transitional variations in structural style of mineralisation, vein textures, and mineralogy of wallrock alteration that relate to the PT conditions of their formation at varying crustal depths. Specific transitions within the total spectrum may be shown also by deposits within gold camps, although nowhere is the entire continuum of deposits recorded from a single gold camp or even greenstone belt.Recognition of the crustal continuum of deposits implicates the existence of giant late-Archaean hydrothermal systems with a deep source for the primary ore fluid. A number of deep fluid and solute reservoirs are possible, including the basal segments of greenstone belts, deeplevel intrusive granitoids, mid-to lower-crustal granitoidgneisses, mantle lithosphere, or even subducted oceanic lithosphere, given the probable convergent-margin setting of the host greenstone terranes. Individual stable and radiogenic isotope ratios of fluid and solute components implicate fluid evolution from, or equilibrium with, a number of these reservoirs, stressing the potential complexity of pathways for fluid advection to depositional sites. Lead and strontium isotope ratios of ore-associated minerals provide the most persuasive evidence for fluid advection through deep-level intrusive granitoids or granitoid-gneiss crust, whereas preliminary oxygen isotope data show that mixing of deeply sourced fluid and surface waters only occurred at the highest crustal levels recorded by the lode gold deposits.The papers in this volume are devoted to the nature and genesis of Archaean lode-gold deposits of the Western Australian Shield, with emphasis on the late-Archaean deposits of the Yilgarn Block. Such lode-gold deposits are widespread in other Archaean granitoid-greenstone terranes (see, for example, reviews by Colvine 1989 and Foster 1989), and similar deposits occur in the Phanerozoic Cordilleran terranes of North America (e.g. Nesbitt et al. 1986) and other more recent terranes. Following early controversy over syngenetic vs. epigenetic models for these deposits, there has been general acceptance of an epigenetic origin, even for BIF-hosted deposits, with dominant structural and host-rock controls, and major controversy has shifted to their geodynamic setting (e.g. Wyman and Kerrich 1988;Barley et al....

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Section: Fluid and Solute Sourcementioning

confidence: 97%

The crustal continuum model for late-Archaean lode-gold deposits of the Yilgarn Block, Western Australia

1993

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“…Suite I monzogranite-granodiorite suite 0.7044 (Arriens 1971;Muhling and de Laeter 1971;de Laeter and Baxter 1987;Watkins et al 1991;Mueller et al 1991).…”

Section: Granitoid Intrusions In the Murchison Provincementioning

confidence: 99%

“…The Sr isotope compositions of scheelites from Yilgarn gold deposits are summarised and discussed in relation to the nature of source rocks by Mueller et al (1990Mueller et al ( , 1991. At the time of mineralisation, gold deposits in the Yilgarn Block vary in initial Sr isotope ratios from 0.7014 to 0.7035 (n = 23).…”

Section: Isotope Composition Of Lead In Ore Fluidsmentioning

confidence: 99%

“…Two gold-related scheelites from the Cue and Golden Crown deposits in the Murchison Province, have initial Sr isotope ratios of 0.7019 and 0.7032, respectively. Mueller et al (1990Mueller et al ( , 1991 concluded that the initial Sr isotope compositions of most gold deposits, particularly those deposits hosted in high grade terranes, are generally more radiogenic than those for the ultramafic and marie volcanic rocks and the intrusive Suite II TTG granitoids (0.7007 to 0.7018), but are broadly comparable to those for the Suite I monzogranite batholiths and plutons (0.7023 to 0.7044). The available Sr isotope data for the two gold deposits from the Murchison Province appear to be consistent with this conclusion, although more data are clearly required and models for mixed Sr from different sources cannot be ruled out.…”

Section: Isotope Composition Of Lead In Ore Fluidsmentioning

confidence: 99%

“…Groves et al 1988;Kerrich 1989). However, recent Sr isotope studies of scheelite from gold deposits in the Yilgarn Block show that the granitegranodiorite batholiths probably contributed radiogenic Sr to the ore fluids (Mueller et al , 1991, although it is not clear whether ore fluid solutes were directly derived from these batholiths, or indirectly via ore fluids infiltrating through their source region, during mineralisation.…”

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An overview of the relationship between granitoid intrusions and gold mineralisation in the Archaean Murchison Province, Western Australia

1993

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Abstract. In the Archaean Murchison Province of Western Australia, granitoid batholiths and plutons that intruded into the ca. 2.7-2.8 Ga and ca. 3.0 Ga greenstone belts can be divided into three major suites. Suite I is a ca. 2.69 Ga monzogranite-granodiorite suite, which was derived from anatexis of old continental crust and occurs as syn-tectonic composite batholiths over the entire province. Suite II is a trondhjemite-tonalite suite (termed Itype) derived from partial melting of subducted basaltic crust, which intruded as syn-to late-tectonic plutons into the greenstone belts in the northeastern part of the province where most of the major gold deposits are situated. One of the Suite II trondhjemite plutons has a Pb-Pb isochron age of 2641 ___ 36 Ma, and one of the structurally youngest tonalite plutons has a minimum Pb-Pb isochron age of 2630.1 _ 4.3 Ma. Suite III is a ca. 2.65-2.62 Ga A-type monzogranite-syenogranite suite which is most abundant in the largely unmineralised southwestern part of the province. Gold deposits in the province are mostly hosted in brittle-ductile shear zones, and were formed at a late stage in the history of metamorphism, deformation and granitoid emplacement. At one locality, mineralisation has been dated at 2636.8 _ 4.2 Ma through a pyritetitanite Pb-Pb isochron. Lead and Sr isotope studies of granitoids and gold deposits indicate that, although most gold deposits have initial Pb isotope compositions most closely similar to those of Suite II intrusions, both Suite I and Suite II intrusions or their source regions could have contributed solutes to the ore fluids. These preliminary data suggest that gold mineralisation in the Murchison Province was temporally and spatially associated with Suite II 1-type granitoids in the northeastern part of the province. This association is consistent with the concept that Archaean gold mineralisation was related to convergent-style tectonic settings, as generation of both Suite II I-type granitoids and hydrothermal ore fluids could have been linked to the dehydration and partial fusion of subducted oceanic crust, and old sialic crust or its anatectic products may also contribute solutes to the ore fluids. Integration of data from this study with other geological and radiogenic isotope constraints in the Yilgarn Block argue against direct derivation of gold ore fluids from specific I-type granitoid plutons, but favour a broad association with convergent tectonics and granitoid magmatism in the late Archaean.

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Effects of Metasomatism on Mineral Systems and Their Host Rocks: Alkali Metasomatism, Skarns, Greisens, Tourmalinites, Rodingites, Black-Wall Alteration and Listvenites

Pirajno

2012

Lecture Notes in Earth System Sciences

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Strontium isotope systematics of hydrothermal minerals from epigenetic Archean gold deposits in the Yilgarn Block, Western Australia

Cited by 62 publications

References 0 publications

The crustal continuum model for late-Archaean lode-gold deposits of the Yilgarn Block, Western Australia

The crustal continuum model for late-Archaean lode-gold deposits of the Yilgarn Block, Western Australia

An overview of the relationship between granitoid intrusions and gold mineralisation in the Archaean Murchison Province, Western Australia

Effects of Metasomatism on Mineral Systems and Their Host Rocks: Alkali Metasomatism, Skarns, Greisens, Tourmalinites, Rodingites, Black-Wall Alteration and Listvenites

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