Fluid volatile composition associated with orogenic gold mineralization, Otago Schist, New Zealand: Implications of H2 and C2H6 for fluid evolution and gold source

Gaboury, Damien; MacKenzie, Doug; Craw, Dave

doi:10.1016/j.oregeorev.2021.104086

Cited by 11 publications

(2 citation statements)

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“…While N 2 is present in the Harlech “methanoic” fluid inclusions, H 2 is absent. This contrasts with orogenic gold mineralisation in the Otago Schist, New Zealand where H 2 and N 2 often coexist, with H 2 > N 2 , the greenschist/amphibolite transition is present and the hydrocarbon gases (e.g., CH 4 , C 2 H 6 ) created during maturation of carbonaceous OM in earlier basin history will degrade at much higher temperatures after basin inversion to yield H 2 (Gaboury et al, 2021). But the greenschist/amphibolite transition is not reached in Harlech, with the Kübler Index values (Table 5) including some low anchizone levels, post mature from a hydrocarbon gas generation perspective, but some distance from conditions which would generate H 2 from their breakdown.…”

Section: Discussionmentioning

confidence: 99%

“…But the greenschist/amphibolite transition is not reached in Harlech, with the Kübler Index values (Table 5) including some low anchizone levels, post mature from a hydrocarbon gas generation perspective, but some distance from conditions which would generate H 2 from their breakdown. A range of 315–700°C at 1 atmosphere was determined experimentally for CH 4 > C + 2H 2 (Gaboury et al, 2021). The bonanzas such as those at Clogau and Gwynfynydd may simply reflect the local presence of exceptional levels of C, and also NH 4 in the “ammonium” minerals in the host wall‐rocks.…”

Section: Discussionmentioning

confidence: 99%

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Black shales and mesozonal quartz vein‐hosted Au: The Truchas Syncline, Spain and the Harlech Dome, Wales, a comparative study

et al. 2022

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A comparative study of quartz vein‐hosted gold occurrences associated with Palaeozoic metapelites in two areas of Wales and Spain combines new, previously unpublished and published data. Metamorphic grade is greenschist in both areas, but very low‐grade indicators in the host metapelites distance the environment from the greenschist/amphibolite transition zone required for some orogenic gold occurrences. Basin fertility for Au is indicated by the presence of auriferous pyrites in the protolith black shales in Spain. Only minor igneous activity has taken place in both study areas. Mineral parageneses are similar, with early sulphide phases characterized by As/Co and later auriferous phases by Cu/Pb/Zn sulphides. Mesozonal P–T conditions apply at deposition in both terranes. In Spain, mineralisation typically occurs in quartzites near to the metapelites, but not where the veins are in contact with them, and extensional faulting appears to be a stronger control over mineralisation than geochemical interaction with metapelite wall‐rocks. In Wales, both structural and geochemical factors (C content of the wall‐rocks and coupled oxidation of NH4 ions substituted in wall‐rock phyllosilicates to produce CH4 and N2) could have a role in Au deposition. In both areas, minor cross‐fault systems between larger faults are typical hosts of the mineralisation. Assignment is made to different subtypes of the orogenic gold model but these subtypes share the characteristic of a local source. This has implications for exploration methodology in epizonal/anchizonal metapelite‐dominated terranes, where indicators of basin fertility for Au within the protolith itself assume importance.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Black shales and mesozonal quartz vein‐hosted Au: The Truchas Syncline, Spain and the Harlech Dome, Wales, a comparative study

et al. 2022

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Metallogenic models as the key to successful exploration — a review and trends

Pohl

2022

Miner Econ

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Metallogeny is the science of ore and mineral deposit formation in geological space and time. Metallogeny is interdisciplinary by nature, comprising elements of natural science disciplines such as planetology to solid state physics and chemistry, and volcanology. It is the experimental forefront of research and bold thinking, based on an ever-growing foundation of solid knowledge. Therefore, metallogeny is not a closed system of knowledge but a fast-growing assemblage of structured and unstructured information in perpetual flux. This paper intends to review its current state and trends. The latter may introduce speculation and fuzziness. Metallogeny has existed for over 100 years as a branch of Earth Science. From the discovery of plate tectonics (ca. 1950) to the end of the last century, metallogeny passed through a worldwide phase of formally published ‘metallogenetic’ maps. In the last decades, a rapidly growing number of scientists, digitization and splendid new tools fundamentally boosted research. More innovations may be expected by the growing use of an evolving systematic ‘Geodata Science’ for metallogenic research by an increasingly global human talent pool. Future requirements for metallic and mineral raw materials, especially the critical natural elements and compounds that are needed for the nascent carbon-free economy, already drive activities on stock markets and in the resource industry. State geological surveys, academia and private companies embrace the challenges. The new age requires intensified metallogenic backing. In this paper, principles of metallogeny are recalled concerning concepts and terms. A metallogenic classification of ore and mineral deposits is proposed, and the intimate relations of metallogenesis with geodynamics are sketched (ancient lid tectonics and modern plate tectonics). Metallogenic models assemble a great diversity of data that allow an ever better understanding of ore formation, foremost by illuminating the geological source-to-trap migration of ore metals, the petrogenetic and geodynamic–tectonic setting, the spatial architecture of ore deposits and the nature and precise timing of involved processes. Applied metallogeny allows companies to choose strategy and tactics for exploration investment and for planning the work. Based on comprehensive metallogenic knowledge, mineral system analysis (MSA) selects those elements of complex metallogenic models, which are detectable and can guide exploration in order to support applications such as mineral prospectivity mapping, mineral potential evaluation and targeting of detailed investigations. MSA founded on metallogenic models can be applied across whole continents, or at the scale of regional greenfield search, or in brownfields at district to camp scale. By delivering the fundamental keys for MSA, supported by unceasing innovative research, the stream of new metallogenic insights is essential for improving endowment estimates and for successful exploration.

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Prograde metamorphism provides gold and base metals to orogenic gold deposits in southern Tibet: Insights from thermodynamic modeling

Ding

Sun

Zhong

et al. 2023

Journal of Asian Earth Sciences

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Fluid volatile composition associated with orogenic gold mineralization, Otago Schist, New Zealand: Implications of H2 and C2H6 for fluid evolution and gold source

Cited by 11 publications

References 73 publications

Black shales and mesozonal quartz vein‐hosted Au: The Truchas Syncline, Spain and the Harlech Dome, Wales, a comparative study

Black shales and mesozonal quartz vein‐hosted Au: The Truchas Syncline, Spain and the Harlech Dome, Wales, a comparative study

Metallogenic models as the key to successful exploration — a review and trends

Prograde metamorphism provides gold and base metals to orogenic gold deposits in southern Tibet: Insights from thermodynamic modeling

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