Gas Hydrate Indications on the Southwest African Continental Margin

A widespread occurrence of bottom-simulating reflectors has been detected in multichannel seismic profiles on the upper continental slope in the southern periphery of the Orange River delta, probably indicating the presence of large quantities of gas hydrates along the Atlantic margin of South Africa. A cluster of mud volcanos trending in a N-to-N/NW direction intersects the shallowest part of the BSR and associated gas hydrate zone. This article presents an overview of the spatial distribution between these two features and discusses their possible relationship to subsurface faulting. While gas from this area has not yet been sampled or analyzed, we suggest that gas hydrates in this region may consist of a mixture of microbial and thermogenic gas, as much of the gas flowing through the mud volcanoes has probably originated from deep-seated Aptian source shales.