Diagenetic and Geochemical Study of Sediments from the Cretaceous Basin of Babouri-Figuil (North-Cameroon)

Abstract

The purpose of this work is to characterize the sediments of the Babouri-Figuil Basin from a diagenetic point of view, the protolith context and weathering conditions, using major element geochemistry and mineralogy of the sedimentary rocks. Microscopic observations of diagenetic phenomena (on and around detrital grains of the basin), and the study of precipitation of the cement show that these sediments have undergone phenomena of compaction, dissolution, recrystallization and cementation. Cementation of quartz by silica is controlled by the rate of precipitation of silica, which is closely related to temperature than pressure. Thus, the sediments of the basin could be influenced by hydrothermalism during diagenesis, which would have inhibited their reservoir quality by generalized cementation phenomena. Geochemical features of the sediments show high contents in SiO 2 (47.49 wt% -90.79 wt%), Al 2 O 3 (2.92 wt% -23.18 wt%), Fe 2 O 3 (0.2 wt% -6.22 wt%) and alkali and alkaline earth metals (>3%). The chemical alteration index varies between 30.92% and 95.08%. This variation in the CIA values reflects the variation in the proportion of feldspars and different clay minerals in these sediments. However, the ICV calculation and the ICV versus CIA show compositional immature to mature sediments, with low to intense weathering character of these sediments. Petrographic and geochemical characteristics of sediments of the basin are compatible with the composition of the granitic and gneissic surrounding bedrocks.