The Davie Fracture Zone: new insights into the crustal structure of the Mozambique Channel

Abstract

The Davie Ridge is the central morphological element of the Mozambique Channel between East Africa and Madagascar. It extends along the Davie Fracture Zone, which played an important part in the break-up of Gondwana 180 million years ago, were a part of East Gondwana moved southward along the East African coast (West Gondwana). About 120 Million years ago, the southward movement stopped and Madagascar reached its present position relative to Africa. The exact position of Madagascar and the Davie Ridge within Gondwana and their movement are not fully understood. In the beginning of 2014, an expedition to the Mozambique channel was conducted in the scope of the PAGE-FOUR and MOCOM projects to examine the crustal structure and its impacts for reconstructions of the plate tectonics of Gondwana. This thesis presents the four seismic refraction profiles modelled across the Davie Ridge between 11.5° S and 16.5° S. The presented models determine the continent-ocean-boundary along the northern coastline of Mozambique and reveal a continental origin for the southern Davie Ridge. The northern Mozambican margin shows a complex and varying continent ocean transition, which hints towards an oblique opening mechanism. The high velocity lower crustal body of central Mozambique can be followed northwards up to 15.5° S. A plate reconstruction includes for the first time the continental sliver of the Davie Ridge.