TITLE:
Alteration Typology and Geochemical Signatures of the Napélépéra Gold-Bearing Granodiorite in South-West Burkina Faso (West Africa)
AUTHORS:
Théophile Ouédraogo, Sâga Sawadogo, Hermann Ilboudo, Séta Naba
KEYWORDS:
Gold Mineralization, Alteration, Mass Balance Granodiorite
JOURNAL NAME:
Open Journal of Geology,
Vol.13 No.10,
October
31,
2023
ABSTRACT: The characterization of the relationships between
mineralization and hydrothermal alteration is an essential element in
understanding gold deposits. In south-west Burkina Faso, the Napélépéra
mineralisation, the mobility of chemical elements and alteration-mineralization
relationships were studied by means of selected core drilling and geochemical
analyses using ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and
ICP-AES (Inductively coupled plasma atomic emission spectroscopy). The
mineralised granodiorite is grey porphyroid with quartz, plagioclase, biotite and amphibole. It
is metaluminous and located in the tholeiitic series. The Na2O + CaO versus Fe2O3 + MgO
alteration diagram divides the samples according to alteration dominance.
Chloritisation and carbonation are the main alterations. There is a
relationship between gold mineralisation at Napélépéra and alteration, and the
paragenesis of gold + pyrite ± carbonate ± silica ± sericite is the main
characteristic. Carbonation is the result of fluid input in the shear corridor
of the mineralised zone. The mass balance of comparative metals in the proximal
and distal zones of the mineralisation shows the absence of metals, while As,
Hg, Ag and Bi are strongly enriched from the distal zone to the mineralised
zone. The oxides associated with the mineralisation are mainly NaO, SrO and CaO.