113-22 Investigations of Alteration, Elemental Mass Transfer and Pathfinders to Gold Mineralisation in the Esaase Deposit, Ghana

Session: Mineralogical Characterization of Economic Resources: From Critical Minerals to Gemstones (Posters)

Poster Booth No.: 267

Presenting Author:

Boateng Agyenim

Authors:

Agyenim, Boateng¹, Adomako-Ansah, Kofi²

(1) Department of Geological Engineering, University of Mines and Technology, Tarkwa, Ghana, (2) Department of Geological Engineering, University of Mines and Technology, Tarkwa, Ghana,

Abstract:

The Esaase turbidite-hosted gold deposit is located in the Asankrangwa Gold Belt, and within the Paleoproterozoic Birimian Supergroup of the Kumasi basin. The geology of the Esaase gold deposit include greywacke and sandstone, and both are interbedded with siltstone and shale. The hydrothermal gold mineralization at Esaase is related to epigenetic quartz veins. This study used mineralogical and whole-rock geochemical techniques to comprehend hydrothermal mineralization. Multivariate statistical analysis was used to establish the elemental pathfinders associated with the gold mineralization and isocon analysis was used to identify the mass changes during the hydrothermal alteration. The petrographic studies reveal two major stages of alteration: (I) metamorphic and (II) hydrothermal. Stage II is associated with gold mineralization. The metamorphic alteration is characterized by sericite, chlorite, paragonite and albite, while the hydrothermal alteration is characterised by coarse grained sericite, chlorite, carbonates, quartz, albite, paragonite, pyrite, arsenopyrite and traces of chalcopyrite and gold. The pathfinder elements for Au are As-Bi-Sb-Cr-Pb-Te-Cu and the mass transfer calculations indicate an enrichment of Au, As, Bi, Sb, Cr, Pb, and Ni in the host rocks during the hydrothermal alteration. The depletion of CaO did not modify K₂O or Na₂O concentrations during the hydrothermal mineralisation. Based on the Alkali-Alumina Molar Ratio (Na₂O/Al₃O₂ vs. K₂O/Al₃O₂), sericite-chlorite assemblage was the most dominant alteration type associated with gold mineralization as compared to sericite-albite alteration. All the above are useful indicators for mineral exploration in the region. The deposit geology, alteration mineralogy, and lithogeochemistry of the Esaase turbidite-hosted gold deposit are similar to other world-class turbidite-hosted gold deposits (e.g., Bendigo, Australia; Meguma, Canada; Reefton, New Zealand; Shangxu, China), providing key exploration indicators for the region.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-4536

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