Anomalous sulfur isotope compositions in the Golden Mile, Kalgoorlie

Phillips, Neil; Groves, David; Neall, F. B.; Donnelly, T. H.; Lambert, I. B.

doi:10.2113/gsecongeo.81.8.2008

Cited by 48 publications

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“…Those with δ 34 S values more negative than -3 ‰ are variably accompanied by hypogene sulfate minerals (Sasaki et al, 1984;Goldfarb et al, 1991). Phillips et al (1986) found that the highly negative δ 34 S values for pyrites in gold-bearing quartz veins may occur under relatively oxidizing conditions of ore formation. However, no hypogene sulfate minerals have been identified in the veins or their igneous wall rocks in the Dongping deposit.…”

Section: Sulfur Isotopesmentioning

confidence: 99%

Geology and Origin of the Dongping Alkalic‐Type Gold Deposit, Northern Hebei Province, People's Republic of China

Fengjun

1998

Resource Geology

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: The Dongping deposit, located near the center of the northern margin of the north China craton, is one of the largest gold deposits in China. It is spatially, temporally, and genetically associated with the shallowly‐emplaced Hercynian Shuiquan‐gou alkaline intrusive complex. The complex intrudes high‐grade metamorphic rocks of the Archean Sanggan Group along a deep‐seated fault zone within the north China craton. Four major ore bodies (Nos. 1, 2, 22, and 70), consisting mainly of a set of en echelon lenses and veins, have been delineated at the Dongping deposit. Hypogene hydrothermal activities can be divided into four periods from early to late including: (1) gold‐bearing K–feldspar–quartz stockworks and veins; (2) disseminated sulfide and gold zones; (3) gold‐bearing quartz veins, and (4) barren calcite‐quartz veins. Individual veins and stockwork systems can be traced along strike for 125 to 600 m and downdip for 100 to 600 m; they range from 0. 5 to 3 m in thickness. The mineralogical composition of the ore in the first three hypogene periods is relatively simple. It is composed of pyrite, galena, sphalerite, magnetite, specularite, chalcopyrite, native gold, electrum, calaverite, and altaite. Gangue minerals include K–feldspar, quartz, sericite, chlorite, epidote, albite, and calcite. Ore grade averages 6 g/t Au, but varies between 4. 14 and 22. 66 g/t Au. Gold is generally fine‐grained and not visible in hand specimen. Fluid inclusions in ore‐bearing quartz of periods 1, 2, and 3 are CO2–rich, variable salinity (2. 5–21 wt% equiv. NaCl), and have variable homogenization temperatures of 195° to 340°C. Quartz in the gold‐bearing K–feldspar–quartz stockworks (period 1), disseminated sulfide and gold zones (period 2), and the gold‐bearing quartz veins (period 3) has calculated δ18OH2O values between –1. 7 and 6. 9%, and δ values of fluid inclusion waters between –101 and –66%. All these isotope data of the ore‐forming fluids plot between the magmatic fluid field and the meteoric water line. Sulfide minerals disseminated in host rocks show positive δ34S values of 1. 9 to 3. 5%. Pyrite separates from he gold‐bearing K–feldspar–quartz stockworks and veins (period 1) have a δ34S range of –4. 3 to 0. 5%, whereas δ34S values of pyrite, chalcopyrite, galena, and sphalerite from the disseminated sul‐fide and gold zones (period 2) and the gold‐bearing quartz veins (period 3) vary from –5. 3 to –13. 4%. Gold ores are also characterized by relatively radiogenic lead isotope compositions compared to those of the alkaline syenite host rock. The data are interpreted as indicative of a mixing of lead from the alkaline intrusive complex with lead from Archean metamorphic rocks. The combined fluid inclusion measurements, sulfur, oxygen, hydrogen, and lead isotope data, and petrological observations indicate that the Dongping deposit was formed from the mixing of these magmatic fluids with meteoric waters. The deposit is, therefore, believed to be a product of Hercynian alkaline igneous processes within the north Chi...

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Section: Sulfur Isotopesmentioning

confidence: 99%

Geology and Origin of the Dongping Alkalic‐Type Gold Deposit, Northern Hebei Province, People's Republic of China

Fengjun

1998

Resource Geology

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“…Golden Mile mineralization is hosted by a differentiated basic igneous intrusion (the Golden Mile Dolerite), and has two well-documented features which are found in only a small number of Archean gold deposits. One is the presence of pyrite with moderately negative δ 34 S isotope values (-10 to -2‰; Lambert et al, 1984;Phillips et al, 1986;Cameron and Hattori, 1987;Bateman and Hagemann, 2004). Such negative values differ from the 0 ± 4 per mil values for pyrite in the Paringa basalt adjacent to the Golden Mile Dolerite, the Mount Charlotte deposit, which is also in the Golden Mile Dolerite within the Kalgoorlie gold field, and most other Archean greenstone gold deposits (Lambert et al, 1984).…”

Section: Introductionmentioning

confidence: 99%

“…The negative sulfur isotopes have been interpreted as a record of the presence of aqueous sulfate during ore deposition (Golding and Wilson, 1983;Phillips et al, 1986). The sulfate is thought to have been a product of oxidization that also produced hematite from preexisting magnetite; however, the cause of the oxidation and the role that it played in ore deposition is not well known (compare Phillips et al, 1986, andCameron, 1988).…”

Section: Introductionmentioning

confidence: 99%

“…The sulfate is thought to have been a product of oxidization that also produced hematite from preexisting magnetite; however, the cause of the oxidation and the role that it played in ore deposition is not well known (compare Phillips et al, 1986, andCameron, 1988). Explanations for the oxidation are divided into those that require infiltration of an externally derived oxidizing fluid prior to or during ore deposition (e.g., Clout, 1989) and those in which the original bulk composition of the host rocks was sufficiently oxidizing that reaction with the mineralizing fluids caused aqueous sulfate and hematite to form (e.g., Phillips et al, 1986). Assessment of these hypotheses requires detailed petrological documentation and quantification of possible pressure-, temperature-, and fluiddriven changes in the mineral assemblages.…”

Section: Introductionmentioning

confidence: 99%

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Rock-Buffering of Auriferous Fluids in Altered Rocks Associated with the Golden Mile-Style Mineralization, Kalgoorlie Gold Field, Western Australia

Evans¹,

Phillips²,

Powell³

2006

Economic Geology

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The Kalgoorlie gold field contains structurally controlled, epigenetic gold deposits hosted by mafic rocks in the Archean Yilgarn craton of Western Australia. Its giant size has prompted much interest in the processes that led to its formation, particularly of the Golden Mile mineralization, which hosts over 70 percent of the gold in the Kalgoorlie gold field. It is generally agreed that the widespread presence of hematite and the moderately negative sulfur isotope composition of some of the pyrite (δ 34 S of -10 to -2‰) in the Golden Mile lodes and associated alteration indicate the presence of a relatively oxidizing ([SO 4 2-

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“…7), because sulphides in oxidised systems can display substantial negative fractionation from the ~34S value of the fluid. However, such systems commonly also show a wide isotopic range (Large 1975, Scott et al 1985, Phillips et al 1986. In this instance the narrow negative range may therefore favour a thermally-degraded organic sulphur source, or dissolution of "open system" biogenic pyrite.…”

Section: "mentioning

confidence: 99%

Two sulphur isotope provinces deduced from ores in the Mount Isa Eastern Succession, Australia

Davidson

Dixon²

1992

Mineral. Deposita

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Anomalous sulfur isotope compositions in the Golden Mile, Kalgoorlie

Cited by 48 publications

References 0 publications

Geology and Origin of the Dongping Alkalic‐Type Gold Deposit, Northern Hebei Province, People's Republic of China

Geology and Origin of the Dongping Alkalic‐Type Gold Deposit, Northern Hebei Province, People's Republic of China

Rock-Buffering of Auriferous Fluids in Altered Rocks Associated with the Golden Mile-Style Mineralization, Kalgoorlie Gold Field, Western Australia

Two sulphur isotope provinces deduced from ores in the Mount Isa Eastern Succession, Australia

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