Weathering and its effect upon geochemical dispersion at the polymetallic Wagga Tank deposit, N.S.W., Australia

Journal of Geochemical Exploration
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Abstract

The Wagga Tank Zn-Pb-Cu-Ag-Au deposit comprises multiple, steeply dipping and structurally controlled sulfide lodes within Early Devonian turbidites and volcaniclastics. Complete weathering at the prospect extends to 100 m below the current land surface. Detailed geochemical studies of drill-derived regolith material were supplemented by extensive mineralogical investigations and enable the major features of the weathered profile to be delineated.

The profile consists of soil with reworked portions of a ferruginous lateritic capping within a largely transported overburden. Below the soil, some residual ferruginous capping (characterized by maghemite) occurs above a kaolinite-rich zone which passes into goethitic saprolite containing alunitejarosite family minerals. This lateritic profile was developed during the Tertiary period prior to the Late Miocene onset of more arid conditions. Within the goethitic saprolite, Pb and some Au have remained in their Miocene positions. However, the distributions of Cu and Zn largely reflect the effect of post-Miocene aridity. Thus, these elements (and some Au) are concentrated as supergene minerals at the current water table, with isolated zones higher in the weathered profile reflecting former levels of the water table.

Publication type Article
Publication Subtype Journal Article
Title Weathering and its effect upon geochemical dispersion at the polymetallic Wagga Tank deposit, N.S.W., Australia
Series title Journal of Geochemical Exploration
DOI 10.1016/0375-6742(91)90050-5
Volume 40
Issue 1-3
Year Published 1991
Language English
Publisher Elsevier
Description 14 p.
First page 413
Last page 426
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