The northern Angolan margin imaged by wide angle seismic data

Boavida, Joaquim, Geophysical Sector, University of Luanda A. Neto Luanda, Angola; Giancarlo Biella, C.S.G.A.Q., National Research Council, Milano, Italy; Roberto de Franco, C.S.G.A.Q., National Research Council, Milano, Italy; Dario Luzio, Geophysical Department, University of Palermo, Palermo, Italy; Alfredo Lozej, Earth Science Department, University of Milano, Milano, Italy; Zaiango Group (Ifremer, France) and "Terra-Mar Group" (University of Luanda and Endiama, Angola; Centro Geofisico da Universidade de Lisboa, Portugal;CNR-Milano, DISTER-Genova and INGV-Roma, Italy)

Abstract

Wide-angle seismic data collected on land in northern Angola during the March-April 2000 Zaiango seismic experiment provide the first detailed image to date of the whole crust up to the upper mantle on the northern Angolan margin.

Travel times of P refracted arrivals and prominent crustal and mantle reflectors observed to offset of over 200 km were used to model a crust/mantle boundary which beneath the continent rises in an oceanward direction, from 40 km to 25 km. In the center of the line, where the crust thins most rapidly, a high velocity body has been modelled at the base of the crust, reaching some 8 km in thickness. This higher velocity body is thought to represent an area of localized magmatic underplating related to the opening of the South Atlantic and to the Cenomanian volcanism in Angola, as well as the late uplift of the mainland, which may have deep rooted causes.