Volcanism and tectonics unveiled in the Comoros Archipelago between Africa and Madagascar

Geophysical and geological data from the North Mozambique Channel acquired during the 2020-2021 SISMAORE oceanographic cruise reveal a corridor of recent volcanic and tectonic features 200 km wide and 600 km long within and north of Comoros Archipelago. Here we identify and describe two major submarine tectono-volcanic fields: the N'Drounde province oriented N160 degrees E north of Grande-Comore Island, and the Mwezi province oriented N130 degrees E north of Anjouan and Mayotte Islands. The presence of popping basaltic rocks sampled in the Mwezi province suggests post-Pleistocene volcanic activity. The geometry and distribution of recent structures observed on the seafloor are consistent with a current regional dextral transtensional context. Their orientations change progressively from west to east (similar to N160 degrees E, similar to N130 degrees E, similar to EW). The volcanismin the western part appears to be influenced by the pre-existing structural fabric of the Mesozoic crust. The 200 kmwide and 600 km-long tectono-volcanic corridor underlines the incipient Somalia-Lwandle dextral lithospheric plate boundary between the East-African Rift System andMadagascar.