Studies of the base metal sulfide deposits at McArthur River, Northern Territory, Australia; III, The stable isotope geochemistry of the H.Y.C., Ridge, and Cooley deposits

Rye, Danny M.; Williams, N.

doi:10.2113/gsecongeo.76.1.1

Cited by 65 publications

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“…Data represent pyrite and the full range of base metal sulfi des present, as well as disseminated sulfi des within the host sediments. References and location information are as follows: Aberfeldy, Scotland (Willan and Coleman, 1983); Balmat-Edwards, United States (Whelan et al, 1984); Jianshengpan, Dongshengmiao, and Tanyaokou, China (Ding and Jiang, 2000); Sullivan, Canada (Campbell et al, 1978(Campbell et al, , 1980; Belt Supergroup, United States (Lyons et al, 2000;Luepke and Lyons, 2001); Amjhore, India (Guha, 1971;Pandalai et al, 1991); McArthur River, Australia (Smith and Croxford, 1975;Rye and Williams, 1981;Eldridge et al, 1993;Shen et al, 2002); Mount Isa, Australia (Solomon, 1965;Smith et al, 1978;Andrew et al, 1989;Davidson and Dixon, 1992;Painter et al, 1999;McShane, 1996); Dugald River, Australia (Dixon and Davidson, 1996;Davidson and Dixon, 1992); Lady Loretta, Australia, (Carr and Smith, 1977;Scott et al, 1985). With the exception of the Chinese deposits, the histograms are stacked in a generally correct stratigraphic order.…”

Section: Implications Stratigraphic Isotope Trendsmentioning

confidence: 99%

Proterozoic sedimentary exhalative (SEDEX) deposits and links to evolving global ocean chemistry

Lyons¹,

Gellatly²,

McGoldrick³

et al. 2006

Evolution of Early Earth's Atmosphere, Hydrosphere, and Biosphere - Constraints From Ore Deposits

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Sedimentary exhalative (SEDEX) Zn-Pb-sulfi de mineralization fi rst occurred on a large scale during the late Paleoproterozoic. Metal sulfi des in most Proterozoic deposits have yielded broad ranges of predominantly positive δ 34 S values traditionally attributed to bacterial sulfate reduction. Heavy isotopic signatures are often ascribed to fractionation within closed or partly closed local reservoirs isolated from the global ocean by rifting before, during, and after the formation of Rodinia. Although such conditions likely played a central role, we argue here that the fi rst appearance of signifi cant SEDEX mineralization during the Proterozoic and the isotopic properties of those deposits are also strongly coupled to temporal evolution of the amount of sulfate in seawater.The ubiquity of 34 S-enriched sulfi de in ore bodies and shales and the widespread stratigraphic patterns of rapid δ 34 S variability expressed in both sulfate and sulfi de data are among the principal evidence for global seawater sulfate that was increasing during the Proterozoic but remained substantially lower than today. Because sulfate is produced mostly through weathering of the continents in the presence of oxygen, low Proterozoic concentrations imply that levels of atmospheric oxygen fell between the abundances of the Phanerozoic and the defi ciencies of the Archean, which are also indicated by the Precambrian sulfur isotope record. Given the limited availability of atmospheric oxygen, deep-water anoxia may have persisted well into the Proterozoic in the presence of a growing sulfate reservoir, which promoted prevalent euxinia. Collectively, these observations suggest that the mid-Proterozoic maximum in SEDEX mineralization and the absence of Archean deposits refl ect a critical threshold in the accumulation of oceanic sulfate and thus sulfi de within anoxic bottom waters and pore fl uids-conditions that favored both the production and preservation of sulfi de mineralization at or just below the seafl oor. Consistent with these evolving global conditions, the appearance of voluminous SEDEX mineralization ca. 1800 Ma coincides generally with the disappearance of banded iron formations-marking the transition from an early iron-dominated ocean to one more strongly infl uenced by sulfi de availability. 170 T.W. Lyons et al.

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Section: Implications Stratigraphic Isotope Trendsmentioning

confidence: 99%

Proterozoic sedimentary exhalative (SEDEX) deposits and links to evolving global ocean chemistry

Lyons¹,

Gellatly²,

McGoldrick³

et al. 2006

Evolution of Early Earth's Atmosphere, Hydrosphere, and Biosphere - Constraints From Ore Deposits

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“…Weber et al 1976;Land et al 1977) and the removal of acid-volatile sulfur compounds by a silver phosphate pretreatment (e.g. Smith and Croxford 1975;Rye and Williams 1981). We have used the pretreatment procedure proposed by Charef and Sheppard (1984) to minimize the effects of organosulfur species.…”

Section: Sodium Hypoehlorite and Silver Phosphate Pretreatmentmentioning

confidence: 99%

“…Sulfides and organic matter, which are abundant in most carbonate-hosted base metal deposits, can strongly affect the carbon and oxygen isotope analyses (e.g. Smith and Croxford 1975;Weber et al 1976;Rye and Williams 1981;Charef and Sheppard 1984), and may account for the large isotopic variations at a small scale. We want to emphasize the need for controlling the influence of organic, organosulfur, and sulfur species of the measured 6t3C and 6180 values of carbonates.…”

mentioning

confidence: 99%

Apparent stable isotope heterogeneities in gangue carbonates of the Mississippi Valley-type Zn-Pb deposit of San Vicente, central Peru

1995

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Abstract. The aim of the present communication is to emphasize that some variations of the measured 613C and 6180 values are apparent, and due to analytical interferences caused by the presence of sulfur and organosulfur compounds in the analyzed carbonates. This is particularly relevant for isotopic studies on carbonate-hosted mineral deposits, where the nearly ubiquitous association of the host carbonates with organic matter and sulfides can certainly affect the metallogenetic interpretations. In this work two methods were used to overcome the disturbing effects of sulfides and organic matter: (1) sample pretreatment following the method proposed by Charef and Sheppard (1984), combining the oxidation of organic matter with sodium hypochlorite and trapping of the sulfur species with silver phosphate; and (2) laser-based microprobe extraction. Apparent isotopic variations in sparry dolomite from a single hand sample of zebra ore from the MVT Zn-Pb deposit, San Vicente, central Peru, are as large as 6%0 613C and 4%0 6180. These variations are reduced to several tenths of a per rail when the samples are pretreated. A careful examination of the effects of treatment with NaOC1 and/or AgaPO4 in relation to the concentration of sulfide inclusions indicates that the main disturbing effects for 613 C values are the presence of sulfur species and organic matter, whereas the 6180 values are mainly affected by the presence of sulfides. Fine-and medium-grained replacement carbonates from MVT and other sediment-hosted base metal deposits are potentially the most affected during isotope analysis, due to the common presence of organic matter and sulfides. Using in situ laser microprobe techniques, it is possible to determine isotopic variations at a sub-millimeter scale. Our results show that laser extraction analysis allows a more precise sampling of the carbonate minerals, and minimizes contamination of the sample with sulfides and to some extent with intergrown organic matter. However, there is an isotopic shift associated with the laser extraction technique, of the order of 0.5-1%o for 613C and 6180 values.Changes in the stable isotope composition of host and gangue carbonates of Mississippi Valley-type (MVT)

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“…Using these models, researchers worldwide have elucidated the formation mechanisms of numerous deposits (e.g., Zheng 1990;Zheng and Hoefs 1993;Peng and Hu 2001;Choi et al 2003;Zhou et al 2013a, b, c). Carbon and oxygen isotopic covariation in carbonates associated with hydrothermal mineralization can supply useful mineralization information, such as temperature and isotopic composition of hydrothermal fluid, and the nature of dissolved carbon species (e.g., Rye and Williams 1981;Matsuhisa et al 1985;Zheng 1990). In this paper, we present the first analysis of the isotopic compositions of carbon and oxygen in limestone, marble, silicate-bearing limestone, and calcite formed at different stages in the Langdu skarn copper deposit, Yunnan Province, China.…”

Section: Introductionmentioning

confidence: 99%

Carbon–oxygen isotopic covariations of calcite from Langdu skarn copper deposit, China: implications for sulfide precipitation

et al. 2014

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The Langdu skarn copper deposit in the Zhongdian area, Yunnan Province, China, has an average Cu grade of 6.49 %. The deposit is related to a porphyry intrusion (*216 Ma), which was emplaced in the Upper Triassic sedimentary rocks of the Tumugou and Qugasi Formations. At the Langdu skarn copper deposit, carbon and oxygen isotope ratios of fresh limestones (d 18 O = 3.0-5.6 % relative to V-SMOW; d 13 C = 24.5-25.7 % relative to PDB) and partly altered limestones (d 18 O = 27-7.2 to -1.9 %; d 13 C = 11.8-15.2 %) indicated that the deposit was a typical marine carbonate source. Oxygen and carbon isotope values for calcites formed at different hydrothermal stages are -9.1 to 0.2 and 10.1-16.3 %, respectively. Moreover, the carbon-oxygen isotopic composition of an ore-forming fluid (d 18 O = 5.0-9.5 %, d 13 C = -7.3 to -5.3 %) suggested the presence of magmatic water, which most likely came from the differentiation or melting of a homologous magma chamber. The deposition of Calcite I may arise from metasomatism in an open system with a progressively decreasing temperature. Later, the minerals chalcopyrite, pyrrhotite, quartz and Calcite II were precipitated due to immiscibility. Water-rock interaction could potentially be responsible for Calcite III precipitation in the post-ore stage.

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Studies of the base metal sulfide deposits at McArthur River, Northern Territory, Australia; III, The stable isotope geochemistry of the H.Y.C., Ridge, and Cooley deposits

Cited by 65 publications

References 0 publications

Proterozoic sedimentary exhalative (SEDEX) deposits and links to evolving global ocean chemistry

Proterozoic sedimentary exhalative (SEDEX) deposits and links to evolving global ocean chemistry

Apparent stable isotope heterogeneities in gangue carbonates of the Mississippi Valley-type Zn-Pb deposit of San Vicente, central Peru

Carbon–oxygen isotopic covariations of calcite from Langdu skarn copper deposit, China: implications for sulfide precipitation

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