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<p>Hamakoussou Sedimentary Basin (HSB) is one of the eastern structures of the Benue trough in North Cameroon, which needs more detailed geological and structural data to understand its development. This study describes the petrography and structural features to understand the HSB's development concerning its basement. The basement of HSB is made up of plutonic rocks (amphibole granite, amphibole and biotite granite, biotite granite, two micas granite, granodiorite, and syenite) and metamorphic rocks (amphibole and biotite gneiss, biotite gneiss, biotite migmatitic gneiss, and quartzite), which have been crosscut by volcanic (rhyolite) and subvolcanic (dolerite) rocks. The sedimentary series of the HSB is made up of claystone, siltstone, and sandstones (fine grained, medium grained, and coarse grained) interbedded with volcanic formations. Their mineralogy is dominated by quartz, plagioclase, and K-feldspar and is accompanied by diagenetic phases (Fe oxide, silica, and carbonate). From a structural point of view, the Hamakoussou area was affected by two episodes of deformation, D and D', respectively, in the basement and sedimentary formations. The D episode is characterized by three phases of deformation: D1 deformational phase, responsible for N–S-oriented S1 foliation; D2 deformational phase, which formed S2 schistosity, F2 fold, and B2 boudin; the D3 deformational phase is brittle with NNW–SSE fractures and the formation of N–S trending dolerite dykes. The D' episode started with the formation of stratification S'0 setup during the diagenetic process in the sedimentary basin; N–S to NNW–SSE shortening of sedimentary series resulted in the formation of F'1 syncline fold at the scale of the whole basin with an E–W axis (D'1deformational phase); dextral-shear movement of strike–slip fault in the basement resulted in the E–W shortening with undulation of the synclinal axis; reactivation of fractures in the basement induced fractures in the sedimentary formations (D'2 deformational phase). The evolution and the actual configuration of the HSB are dependent on the cretaceous to post-cretaceous activities of the Pan-African basement structures. Similarities with contemporaneous basins in central Africa and South America strengthen the assumption that they have shared the same tectonic–sedimentary history since the opening of the Atlantic Ocean.</p>

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Petrographic and structural studies of the Hamakoussou Cretaceous sedimentary basin and its Precambrian basement (Central Africa): implication on the geometry of the basin

  • 期刊论文

  • 发表日期：

    2025年1月4日

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  • Alpha Baster Kenfack Fokem,
  • Jacqueline Ntsama Atangana,
  • Alembert Alexandre Ganwa,
  • Benjamin Ngounou Ngatcha

摘要

Hamakoussou Sedimentary Basin (HSB) is one of the eastern structures of the Benue trough in North Cameroon, which needs more detailed geological and structural data to understand its development. This study describes the petrography and structural features to understand the HSB's development concerning its basement. The basement of HSB is made up of plutonic rocks (amphibole granite, amphibole and biotite granite, biotite granite, two micas granite, granodiorite, and syenite) and metamorphic rocks (amphibole and biotite gneiss, biotite gneiss, biotite migmatitic gneiss, and quartzite), which have been crosscut by volcanic (rhyolite) and subvolcanic (dolerite) rocks. The sedimentary series of the HSB is made up of claystone, siltstone, and sandstones (fine grained, medium grained, and coarse grained) interbedded with volcanic formations. Their mineralogy is dominated by quartz, plagioclase, and K-feldspar and is accompanied by diagenetic phases (Fe oxide, silica, and carbonate). From a structural point of view, the Hamakoussou area was affected by two episodes of deformation, D and D', respectively, in the basement and sedimentary formations. The D episode is characterized by three phases of deformation: D1 deformational phase, responsible for N–S-oriented S1 foliation; D2 deformational phase, which formed S2 schistosity, F2 fold, and B2 boudin; the D3 deformational phase is brittle with NNW–SSE fractures and the formation of N–S trending dolerite dykes. The D' episode started with the formation of stratification S'0 setup during the diagenetic process in the sedimentary basin; N–S to NNW–SSE shortening of sedimentary series resulted in the formation of F'1 syncline fold at the scale of the whole basin with an E–W axis (D'1deformational phase); dextral-shear movement of strike–slip fault in the basement resulted in the E–W shortening with undulation of the synclinal axis; reactivation of fractures in the basement induced fractures in the sedimentary formations (D'2 deformational phase). The evolution and the actual configuration of the HSB are dependent on the cretaceous to post-cretaceous activities of the Pan-African basement structures. Similarities with contemporaneous basins in central Africa and South America strengthen the assumption that they have shared the same tectonic–sedimentary history since the opening of the Atlantic Ocean.