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The Paleoproterozoic McArthur River (HYC) Pb/Zn/Ag deposit of northern Australia: Organic geochemistry and ore genesis

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Created 20/01/2025

Updated 20/01/2025

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Polycyclic aromatic hydrocarbons (PAH) in ore and mudstone within the McArthur River ore deposit show compound distributions similar to those of hydrothermally-generated petroleum in the Guaymas Basin and significantly different from those found in conventional oil (Chen et al., submitted). PAH abundances and isomer distribution also reflect a temperature gradient between the source of mineralising fluids and the sediments fringing the ore system during ore formation. Along with other geochemical, geological and mineralogical lines of evidence, these data provide strong evidence that the ore formed in a ?diagenetic? environment under marine conditions. Given that the McArthur River orebody is an exquisitely preserved example of a sediment-hosted base metal deposit, these results may be widely applicable. Organic geochemistry can make significant contributions to understanding processes of ore deposition. The distribution of PAHs suggests that they were generated at temperatures between 250-400?C (Simoneit, pers. comm 2001), in contrast to previous estimates of 150-250?C. This has new and significant implications for ore formation and exploration models. The higher temperature estimates for ore forming brines require a deeper metal source within the basin, and fluid volumes may have been lower because metal carrying capacity increases with temperature. Importantly, at higher temperatures hydrogen sulfide can be transported with the metal ions, indicating that evaporites are not required as a source of sulfur. The McArthur deposit is also a rich repository of paleobiological information, allowing studies of the microbiology of ore formation and the paleobiology of an ancient hydrothermal system (Logan et al., 2001).

Chen J., Walter M.R., Logan G.A., Hinman M.C. and Summons R.E. (submitted) Geology

Logan G.A., Hinman M.C., Walter M.R. and Summons R.E. (2001) Geochim.Cosmochim. Acta 65, 2317-2336.

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Title The Paleoproterozoic McArthur River (HYC) Pb/Zn/Ag deposit of northern Australia: Organic geochemistry and ore genesis
Language eng
Licence notspecified
Landing Page https://devweb.dga.links.com.au/data/dataset/b698ade6-c690-498b-ae82-9d734459694f
Contact Point
Geoscience Australia
clientservices@ga.gov.au
Reference Period 10/04/2018
Geospatial Coverage http://www.ga.gov.au/place-names/PlaceDetails.jsp?submit1=GA1
Data Portal data.gov.au