Geophysical investigation of thermal structures beneath the Malawi rift
Most magmatic continental rifts are characterized by surficial expression of magma, which explains the role played by magma in softening the lithosphere in extensional environments, enhancing rifting. The Malawi Rift forms the southern limit of the Western Branch of the East African Rift System (EARS). The Malawi Rift, though showing geomorphic features of a rift, does not show any volcanism except at its northern tip where the rift is older. This has raised the question of the need for magma in rift initiation. Determining the thermal structure beneath the Malawi rift could provide an insight into the mechanism of strain localisation during the rift initiation. The purpose of this study is to determine the thermal structures beneath the Malawi rift through 2D power density spectral analysis of aeromagnetic data collected over Malawi, and how they are related to strain localisation during rift initiation. The thermal structure was determined from heat flow values derived from the Curie point depth (CPD) of the Malawi rift. CPD of the Malawi Rift range from 17.8 to 27.5 km. The estimated heat flow values range between 52 and 81 mW m -2. Elevated heat flow values (>75 mW m -2) occur in the north, center and south of the rift. Areas of elevated heat flow values are interpreted as due to the presents of partial melts and mantle fluids.
Geography, Geology, and Planning
Njinju*, Emmanuel A., Estella A. Atekwana, Kevin L. Mickus, Daniel A. Laó–Dávila, Mohamed G. Abdelsalam, and Eliot A. Atekwana. "Geophysical investigation of thermal structures beneath the Malawi rift." In SEG Technical Program Expanded Abstracts 2015, pp. 1578-1583. Society of Exploration Geophysicists, 2015.
SEG Technical Program Expanded Abstracts