An integrated analysis of lithospheric structure across the East African plateau based on gravity anomalies and recent seismic studies

摘要: Abstract Data from recent gravity surveys carried out by the University of Texas at El Paso (USA) and other institutions existing data were combined integrated with seismic results KRISP project geologic to analyze regional lithospheric structure beneath East African plateau. A series maps constructed, they show that plateau is associated a broad negative anomaly which about 1200 ± 100 km wide has an amplitude −150 20 mGal. Superimposed on this are narrower, steeper-sided anomalies 200 amplitudes −30 −60 These eastern western arms rift. also low gradients in Tanzanian craton, Kasai craton Congo basin areas while there high within rifts mobile belt-craton boundaries. With increased filter wavelength cutoff, rift-related lows broaden eventually merge into one whose apex centered Lake Victoria. Seismic refraction, teleseismic, mantle xenolith, petrochemical used as constraints during construction models represent across Three W-E profiles N-S profile along axis Eastern rift Kenya Tanzania modeled. together filtered demonstrate thinning suggest existence deep craton. The widely believed be plume our indicate diameter its head 600 km. Two diameters less than 250 extend penetrate lithosphere shallow levels under Western rifts. In southern part (Tanzania), these features deeper Kenya. This study provides additional evidence long Bouguer over can explained heating thinning. model suggests it propagating southwards central suggested age initiation volcanism.