Dolerite sills in the sandstone of Bangui, Central African Republic: geochemistry and petrology

Hubert François Mapoka; Jean Biandja; Konstantin A. Savko; Sylvain Marius N’gbatouka; Nikolay S. Bazikov

doi:10.17308/geology/1609-0691/2023/1/65-79

Authors

Hubert François Mapoka Geosciences Laboratory, Department of Earth Sciences, University of Bangui https://orcid.org/0009-0007-5538-3124 (unauthenticated)
Jean Biandja Georesources Laboratory, Department of the Mines and Geology, Higher Institute of Technology https://orcid.org/0009-0004-2911-2513 (unauthenticated)
Konstantin A. Savko Voronezh State University https://orcid.org/0000-0002-7291-7024 (unauthenticated)
Sylvain Marius N’gbatouka Georesources Laboratory, Department of the Mines and Geology, Higher Institute of Technology https://orcid.org/0009-0005-0592-8814 (unauthenticated)
Nikolay S. Bazikov Voronezh State University https://orcid.org/0000-0002-0847-6498 (unauthenticated)

DOI:

https://doi.org/10.17308/geology/1609-0691/2023/1/65-79

Keywords:

lithostratigraphic synthesis, dolerite sills, sandstone, tangential tectonics, lithological succession, mylonitisation, breccia, tholeiitic affinity

Abstract

The geology of the Bangui region is not very known, although sufficient data exist. However, the lithostratigraphic synthesis remains limited. The presence of certain rock types such as dolerite sills in sandstones can be observed as a consequence of extensional tectonics in the region. The dolerites of the Bangui-Mbaiki-Boali series correspond in composition to ferruginous subalkaline basalts of the tholeiite affinity. They are enriched in LILE, HFSE and LREE with low concentrations of Ni and Cr, and have experienced fractional crystallization with fractionation of olivine and pyroxene. Parental magmas were formed in shallow conditions of garnet instability. They are characterized by a high degree of oxidation and an increased content of fluid. The source for the dolerites could be enriched protoliths from the subcontinental lithospheric mantle. The Bangui dolerites were formed in an intraplate setting.

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Author Biographies

Hubert François Mapoka, Geosciences Laboratory, Department of Earth Sciences, University of Bangui

Assistant in Geology, Director of the Geosciences Laboratory, Department of Earth Sciences, University of Bangui, Central African Republic
Jean Biandja, Georesources Laboratory, Department of the Mines and Geology, Higher Institute of Technology

Professor, Director of the Georesources Laboratory, Department of the Mines and Geology, Higher Institute of Technology, Bangui, Central African Republic
Konstantin A. Savko, Voronezh State University

Dr.habil. in Geology and Mineralogy, Professor, Head of the Department of Mineral Resources and Mineral Management Studies, Voronezh State University, Voronezh, Russian Federation
Sylvain Marius N’gbatouka, Georesources Laboratory, Department of the Mines and Geology, Higher Institute of Technology

Assistant in Geology, Membre of the Georesources Laboratory, Department of the Mines and Geology, Higher Institute of Technology, Bangui, Central African Republic
Nikolay S. Bazikov, Voronezh State University

PhD in Geology and Mineralogy, associate professor, Department of Mineral Resources and Mineral Management Studies, Voronezh State University, Voronezh, Russian Federation