CHARACTERIZATION OF THE MAEVARANO FORMATION’S ANEMBALEMBA MEMBER (CAMPANIAN) IN BONGOMILITERA SITE

Earth sciences

Studies have been conducted in the Mahajanga Basin for the diversity of fossils it contains, both vertebrates and invertebrates. They have mainly been concentrated in the pilot site of Berivotra, in the central part of the basin, where fossils are abundant and well preserved. This study focuses on the characterization of the Maevarano Formation’s Anembalemba Member in the Bongomilitera sector, localized in the Commune of Masiakakoho, in the southwestern part of the basin, where expeditions are still rare. A comparison was made between the sedimentary deposits of the two sectors, and the morphoscopic, mineralogical, and geochemical studies of the sediments revealed that there is an obvious concordance between their lithology and their stratigraphic columns. However, the study area’s strata are more subject to weathering and natural conditions do not allow the burial, formation, and conservation of large vertebrate fossils there. The paleoenvironmental reconstruction, based on the study of grains transport and deposit conditions in the area, confirms the existence of a relatively calm period followed by a great flood towards the end of the Campanian. These deposits correspond to the Anembalemba Member, which abounds in dinosaur bones in the Berivotra sector but does not present any in the Bongomilitera sector.

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