1. Thermal and hydrothermal effects of magmatic intrusions on cretaceous formations of the Babouri-Figuil basin (northern Cameroon): Perspectives on atypical petroleum system.
- Author
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Manga, William Gaspard Owona, Fonseca, Carolina, Meying, Arsène, Filho, João Graciano Mendonça, and Bessong, Moise
- Subjects
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PETROLEUM , *PETROLEUM prospecting , *CHLORITE minerals , *CLAY minerals , *ORGANIC compounds - Abstract
The Babouri-Figuil Basin (BFB) is a frontier basin for petroleum exploration in northern Cameroon that belongs to the series of Cretaceous rift basins of the West and Central Rift System (WCARS), and contiguous related WCARS rift basins in Niger, Chad, Sudan, and Nigeria have yielded commercial deposits. The recent discovery of Precambrian basement reservoirs in Chad (Bongor basin) highlights the existence of a new play for petroleum exploration in the region. A network of interconnected magmatic intrusions directly related to basement faults cross-cuts the BFB stratigraphy. This study aims to evaluate the interactions between magmatic intrusions and potential source rocks in the BFB and make comparisons with similar basins in the WCARS context. The results showed that magmatic intrusions are made up of dolerite and basalt, characterized by onion peel (ball-shape) or columnar joint structures, respectively, and a fine-grained microlithic-porphyritic texture. The analyzed samples are thermally immature except for the samples located close to magmatic intrusions, which are thermally mature. The SEM images revealed that organic matter was subrounded with a regular shape in the samples that are located away from magmatic intrusions, while it presented a characteristic pattern of thermally evolved organic matter in sample located closer to magmatic intrusions, characterized by a cloudy visual aspect that is filling small fractures and being disseminated over mineral grains. Contact metamorphism and hydrothermal processes led to the neoformation of mixed-layered illite/chlorite and illite/micas. This study shows that the interactions between sedimentary formations and magmatic intrusions are stronger when the distance toward magmatic intrusions decreases. The source rock maturation of outcrop samples was predominantly triggered by magmatic intrusions, so that the overall area would be immature without intrusions. The formation of secondary organic matter (solid bitumen) in source rocks provides a perspective into a working petroleum system in the BFB. The presence of magmatic intrusions in the Babouri-Figuil Basin may positively affect the thermal maturation history of source rocks and can activate petroleum generation at a shallow burial depth. Thus, the Babouri-Figuil Basin may host an atypical petroleum system. • The magmatic intrusions in the Babouri-Figuil Basin are made up of dolerite and basalt. • Contact metamorphism and hydrothermal processes led to the disappearance of detrital clay minerals and the neoformation of mixed-layered illite/chlorite and illite/micas. • The thermal maturity proxies of the analyzed samples revealed a systematic increase in thermal maturity indexes as the distance with magmatic intrusions decreases. • The formation of solid bitumen in source rocks provides a perspective on an atypical petroleum system in the Babouri-Figuil Basin. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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