Authors / CoAuthors
Taylor, G.F. | Scott, K.M.
Abstract
Structural, textural, mineralogical, and geochemical properties of gossans associated with lead-zinc mineralisation in the Carpentarian Mount Isa Inlier of northwest Queensland have been studied. Mineralisation at Mount Isa, Hilton, and Lady Loretta is associated with abundant stratiform pyrite, which, upon oxidation, has formed prominent gossanous ridges at each deposit. The gossans, which have a laminated structure and occasional boxworks and casts after pyrite, generally carry only minor to trace levels of target and pathfinder elements. Where orebodies were close to the surface, cerussite and other secondary lead minerals are abundant, but Zn and Ag have been substantially leached from surface gossans. Immature gossans are found on the Dugald River and Pegmont dposits, both of which have low iron sulphide contents and a partially truncated profile. At Dugald River, the normally mobile elements (e.g. K , S, Zn, Cu, Cd, Tl) have been retained because of reaction between acid solutions and carbonate-rich wall rocks. The Pegmont mineralisation occurs in a quartz-magnetite-garnet-apatite banded iron formation, which, on oxidation, has given rise to a Mn-, Pb-, and Zn-rich gossan with abundant plumbogummite, pyromorphite, and coronadite. Gossans and ironstones from elsewhere within the Paradise Creek Formation, Soldiers Cap Group, Mount Isa Group, and Answer Slate often have similar laminated structures and mineralogy, but their variable geochemical signatures make direct comparison with other deposits difficult. Various statistical techniques have been used to evaluate these geochemical data in relation to gossans and ironstones of known association from throughout the Mount Isa Inlier. Although reflecting some known mineralogical and elemental associations, neither correlation coefficients nor R-mode factor analysis are of use in assigning group membership, because of the diverse geochemical characteristics of the ferruginous outcrops. Stepwise discriminant analysis using Pb, P, Ba, As, Zn, Mn, Co, S, and Sb was found to classify all gossans and ironstones into six geologically distinct groups.
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document
eCat Id
81114
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Keywords
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- GA PublicationJournal
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- QLD
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_External
Publication Date
1982-01-01T00:00:00
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geoscientificInformation
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BMR Journal of Australian Geology and Geophysics 7:3:159-179
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Unknown
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[-22.0, -19.0, 139.0, 141.0]
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