Communication Dans Un Congrès Année : 2019

Trace element signature of pyrite from Bagassi gold deposit, western Burkina Faso

Résumé

The Bagassi gold deposit is situated on the Hounde greenstone belt. It is a high-grade (1.8 million tons @ 11.47 g/t) deposit in which mineralization is located at the contact between volcanic mafic rocks and granitoids. Two types of mineralization were observed. (i) gold disseminated within sulfides within host-rock and ankerite-rich veinlets and (ii) as free particles within quartz-rich tension gashes. Two types of pyrite associated to gold events were identified. Py-1 is generally overgrown by Py-2 which contain native gold inclusions. LA-ICP-MS data reveal that Py-1 is enriched in trace elements (Median Au = similar to 4 ppm, median As = similar to 9000 ppm) compared to Py2 which have median Au = 0.01 ppm and median As = similar to 320 ppm ppm. Py-1 and Py-2 show approximately the same range for Ni, Co, Zn, Te and Se and are both depleted in Cu, Sb, Ag, Bi and Pb (Median < 2 ppm). At 55 Zone gold mineralization refers to a single hydrothermal event associated to remobilized gold (gold fineness > 906). Earlier stage of this event consist of an As-Au rich fluid with incorporation of primary gold into As rich Py-1 lattice. The later stage implicates an Au-oversaturated fluids forming free gold nuggets in the quartz-rich veins related to second generation Py-2.

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Dates et versions

hal-04933096 , version 1 (06-02-2025)

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  • HAL Id : hal-04933096 , version 1

Citer

Hilaire Somtebda Dakoure, Aurélien Eglinger, Anne-Sylvie André-Mayer, Séta Naba, Wilfried Antoine Bassou Toé, et al.. Trace element signature of pyrite from Bagassi gold deposit, western Burkina Faso. 15th SGA Biennial Meeting on Life with Ore Deposits on Earth, Aug 2019, Glasgow, United Kingdom. pp.679-682. ⟨hal-04933096⟩
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