Mineralogical evolution and Cretaceous paleoclimate inferences in the central Koum Basin, North Cameroon.

The Koum Basin is a North Cameroonian intracontinental basin that is part of the upper Benue Trough, notably the Yola arm. The sediments of this basin were examined to determine paleoenvironmental and paleoclimatic interpretations, which were based mostly on sedimentology and mineralogical evolution in its central part. The examined materials are dominated by claystone and siltstones of varied colours, which are, for the most part, carbonated, and a few layers of fine to medium sandstone and conglomerate. The bulk organic geochemistry enabled the designation of type III kerogen, indicating a terrestrial origin of organic matter, which shows predominantly immature issues. The bulk mineralogy development exhibits no significant changes and is dominated by phyllosilicate (25.66%), calcite (24.5%), plagioclase (19.36%), and quartz (19.31%). Smectite, illite, and vermiculite dominate clay mineral fraction, with only low quantities of kaolinite and chlorite. The diagenesis influence is low to moderate, as shown by moderate illitization and chloritization as well as Tmax values. The deposition occurred in a globally semi-arid climate, as evidenced by the permanent occurrence of smectite, punctuated by short periods of drier and humid weather. [ABSTRACT FROM AUTHOR]