Authors / CoAuthors
Huston, D.L. | Eglington, B.M. | Pehrsson, S. | Doublier, M.P.
Abstract
The distribution of volcanic-hosted massive sulphide deposits through time is episodic, involving relatively short time intervals of apparent high productivity and long intervals of low productivity. This distribution is principally related to the geodynamic evolution of the Earth. The vast majority of these deposits is associated with the assembly of supercontinents and form along convergent margins, generally in back-arc basins or rifted arcs. This contrasts with the distribution of black smoker deposits, which presently form along both convergent margins, particularly in the western Pacific, and divergent margins at mid-ocean ridges. However, the latter environment is rarely preserved deep into the geological past. There also appear to be systematic patterns in a number of other features of volcanic-hosted massive deposits through time. Deposits hosted by mafic-dominated successions are dominant in Archean to Proterozoic rocks, whereas deposits hosted by felsic-dominated successions are most common in Phanerozoic rocks. Geochemical characteristics of felsic rocks within the host successions and ore lead and sulphur isotope data of the ores have also changed with time. This suggests changes in the process of subduction and/or changes in the characteristics of the over-riding plate with time, consistent with isotopic and geologic evidence for greater reworking of pre-existing crust during the Phanerozoic. Other secular changes that are reflected in characteristics of volcanic-hosted massive sulphide deposits include the redox state and salinity of coeval oceans. As an example, both the abundance of sulphate minerals and sulphur isotope patterns reflect the development of periods of anoxic conditions over time, with major intervals of anoxia, reflected by a virtual lack or low abundance of sulphate minerals in volcanic-hosted massive sulphide deposits in the Mesoarchean to the Paleoproterozoic, and shorter intervals since.
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nonGeographicDataset
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82585
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- External Publication
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2015-01-01T00:00:00
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