TITLE:
Hydrothermal Alteration in Diénéméra-Gongondy Paleoproterozoic Porphyry Copper Deposit, Burkina Faso, West African Craton
AUTHORS:
Aristide Belemsobgo, Wendkouni Passecdé Pauline Zongo, Bepowo Hien, Urbain Wenmenga, Séta Naba
KEYWORDS:
West African Craton, Birimian, Porphyry Copper, Hydrothermal Alteration
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.13 No.4,
July
4,
2025
ABSTRACT: Diénéméra-Gongondy copper-gold deposit is one of the rare Paleoproterozoic porphyry copper deposit of West African Craton. Like most of the Precambrian porphyry copper deposits, the mineralization of Diénéméra-Gongondy copper-gold deposit still remains controversial. In this study, we used thirteen drill cores of “Projet Minier Gaoua” to characterize the petrographic, geochemical signature and ore mineralogy. However, δ34S isotopic analyses has been also conducted on these samples in order to determine the source of fluids associated to the Diénéméra-Gongondy copper-gold deposit. Macroscopic and microscopic observations revealed a complex lithology encompassing a wide range of subvolcanic to volcano-plutonic rocks variable in mineralogy and texture, dominated by several facies of microdiorites which host the mineralization. This mineralization is affected by several phases of hydrothermal alteration dominated at Diénéméra by propylitization. However, at Gongondy, phyllitic-carbonate alteration type is dominant. The geochemical study of alteration minerals confirmed the presence of these alterations, but the potassic alteration is absent, probably destroy by late alteration events or retrograde metamorphism. The δ34S isotopic analyses on pyrite form four samples of pyrite and chalcopyrite of Diénéméra and Gongondy deposits showed that the δ34S values range from −4.1 to 4.7. These values are in accordance with a magmatic origin of the sulfide, with a probable little contribution of late hydrothermal or meteoritic fluids. The (Cs + Rb)/Th normalized diagram confirms the potential mineralization of Diénéméra and Gongondy deposits, whereas the excess Aluminum diagram is confident for a porphyry type of mineralization. In definitive, all the results show that the Diénéméra-Gongondy copper-gold deposit is a porphyry type of birimian age affected by late stage magmatic, structural and hydrothermal events.