Rifting, volcanism, and neotectonic processes in Madagascar: understanding the mechanism of breakup of old, stable continental lithosphere

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Continental tearing or rifting is one of the most important plate tectonic processes on Earth, yet the cause and mechanism of rift are poorly understood. Understanding how continental rifting starts, propagates and eventually forms oceanic basins are fundamental to our understanding of the dynamics of the Earth, and how tectonic processes shape the Earth's surface. In addition, continental rift zones are often associated with earthquakes and volcanoes, as such understanding their cause and evolution are crucial for volcanic and earthquake hazards mitigation. Most rift systems within the North American continent (craton) are old, often buried by thick sediments and/or have been affected by numerous post-rifting deformation events, thus, preventing direct study of the rifting processes. Madagascar, on the other hand, provides an opportunity to investigate the birth and early development of continental rift zones, as it is undergoing active extension related to the possible propagation of the southern arm of the East African Rift System (EARS), also known as the Somalian-African diffuse plate boundary. The island is critically positioned to reveal important features of the EARS: (1) the nature and geometry of rift-related fault system; (2) the rift evolution through time and space, and (3) the relationships between tectonic structures and rift magmatism. The proposed research program will focus on the two most seismically, tectonically, and volcanically active regions of Madagascar, Itasy-Ankaratra (central) and Nosy Be-Anivorano (northern) to: (1) further investigate the nature, geometry, origin and evolution of the active rift system in the Island and its morphological expressions; (2) establish the geometric relationship between tectonic structures and volcano locations; and (3) further document and evaluate the prevalence of recent volcanism in these regions. This research will involve an integrated program of systematic geological mapping, structural field study, remote sensing analysis, age dating, as well as petrology and geochemistry. In addition, the study will integrate other geophysical data such as seismic, gravity and electromagnetic data when available. This research program will result in a new model of fault system and magmatic interactions during the rifting of continental lithosphere that can serve as benchmark to both old and younger rifts affecting small or large continents (e.g. North American Craton). It will also lead to a new understanding of geometry, kinematics, age and structural evolution of the southern branch of the EARS and the Quaternary volcanic fields in Madagascar where divergent views of its evolution and origin are emerging. The program will involve collaboration between professional colleagues in Canada and Madagascar, and allow for the participation and training of Canadian and Malagasy in field-and laboratory-based research.