First characterization of the volcanism in the southern Mozambique Channel: Geomorphological and structural analyses

Type Article
Date 2022-03
Language English
Author(s) Berthod C.1, Bachèlery P.1, Jorry StephanORCID2, Pitel-Roudaut MathildeORCID2, Ruffet G.3, 4, Revillon Sidonie5, Courgeon S.6, Doucelance R.1
Affiliation(s) 1 : Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, 6 avenue Blaise Pascal, 63178 Aubière, France
2 : Geo-Ocean, Ifremer, Université de Bretagne Occidentale, CNRS, 29280 Plouzané, France
3 : Université de Rennes 1, Géosciences Rennes, F-35042 Rennes Cedex, France
4 : CNRS (CNRS/INSU) UMR 6118, Géosciences Rennes, F-35042 Rennes Cedex, France
5 : SEDISOR, Univ. Brest UMR6538, IUEM, Plouzané, France
6 : Geneva Petroleum Consultants International, Chemin des Vergers 4, CH-1205, Switzerland
Source Marine Geology (0025-3227) (Elsevier BV), 2022-03 , Vol. 445 , P. 106755 (39p.)
DOI 10.1016/j.margeo.2022.106755
WOS© Times Cited 4
Keyword(s) Mozambique channel, Bassas da India, Europa, Volcanic ridges, Volcanic cones, Structural inheritance

The southern part of the Mozambique Channel is characterized by a cluster of isolated seamounts, including the Bassas da India atoll and Europa Island, ranging in latitude from 20°S to 22°S and from 38° to 40° in longitude, and located at the Rovuma-Lwandle plate boundary. Only Cenozoic carbonate platforms have previously been studied in this region, with very little work done on the volcanic history. We confirm here the volcanic nature of the basement of the Bassa da India/Europa complex by providing important constraints on the setting of this hitherto poorly understood volcanism.

Recent bathymetric surveys and dredging operations allowed us to map and date these seamounts, comprising, from west to east, the Hall Bank, the Jaguar Bank, Bassas da India, Ptolemee, and Europa. In addition, we discovered, to the south of Bassas da India, two large new polygenetic volcanic edifices, Pamela Seamount 1 (PS1) and Pamela Seamount 2 (PS2), showing heights and diameters of up to 900 m and 13 km, respectively. Mapping and statistical analysis carried out revealed that the volcanic structures of the Bassas da India/Europa complex are organized along two main alignments with different stages of development: (i) a NE-SW volcanic alignment characterized by volcanic ridges up to 700 m in height, comprising small individual volcanic cones; and (ii) a NW-SE volcanic alignment in which many large and well-developed individual volcanic cones can be found. From this distribution of the volcanism, we suggest that the large volcanic edifices of the Bassas da India/Europa complex were fed by long-lived magma systems, repeatedly supplied from deep magma reservoirs through a significant network of dykes and faults, with lateral injections of magma guided by a dense network of faults allowing magma to reach the surface along rift-zones. 40Ar/39Ar dating confirms that the volcanism covers a period from the Oligo-Miocene to the Pleistocene, and probably extends to the present day. The two volcanic alignments are also consistent with the tectonic features already recognized for the region and are spatially superimposed by active seismicity. Magma ascent is strongly controlled by large pre-existing crustal structures.

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Berthod C., Bachèlery P., Jorry Stephan, Pitel-Roudaut Mathilde, Ruffet G., Revillon Sidonie, Courgeon S., Doucelance R. (2022). First characterization of the volcanism in the southern Mozambique Channel: Geomorphological and structural analyses. Marine Geology, 445, 106755 (39p.). Publisher's official version : , Open Access version :