TITLE:
Glacial Evidence of Neoproterozoic Carbonate Deposits from Firgoun Area, Southeastern Border of Gourma Basin (Western Niger)
AUTHORS:
Diafarou Alzouma Amadou, Hassan Ibrahim Maharou, Ibrahim Abdou Ali, Karimou Laouali Idi, Kamayé Tourba, Moussa Konaté
KEYWORDS:
Cap Carbonates, Neoproterozoic Glacial Deposits, Firgoun Area, West Africa, Sedimentology and Geochemistry
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.14 No.7,
July
8,
2026
ABSTRACT: The Firgoun area sedimentary deposits are located on the eastern edge of the West African Craton, precisely in the western part of Niger. They are related to the basal deposits of the Ydouban Group (Gourma basin) considered as Neoproterozoic in age. In the Firgoun area, the uppermost deposits include successively interbedded diamictites, carbonates and cherts (silexites), which are assimilated to the triad, a potential stratigraphic marker that characterized the Neoproterozoic glacial event in West Africa. So, the carbonate sediments associated with the Neoproterozoic glacial deposits are regarded as a useful tool to understand the stratigraphy of Neoproterozoic basins. Previous investigations on the deposits of the Firgoun region regarding the stratigraphy are fragmentary. The age of these deposits is still debated. In this paper sedimentological and preliminary geochemistry analyses were carried out in order: to characterize the uppermost deposits of the Firgoun area, identify the carbonate rocks and correlate them to the cap carbonates neoproterozoic deposits of the West Africa Craton. Two kinds of carbonate rocks lithofacies were identified in the Firgoun area: 1) unmetamorphosed brown dolomitic limestones exhibiting a cavernous appearance and 2) massive marbles with milky white to pinkish colors. These carbonate rocks are mainly composed of calcite, dolomite and accessory minerals such as quartz, oxides and clays. Geochemical analyses of major elements highlight the mixed (humid and arid climates) paleoclimatic characteristics for the Firgoun upper deposits. Isotopic data (negative values δ13C (−7.1‰) and δ18O (−15.6‰)) enable the correlation of the Firgoun carbonate rocks to the West African Craton Cap carbonates.