Among their similarities are the half-graben as the fundamental structural unit, the dimensions of these units, and the types of facies (lacustrine and fluvial-deltaic) which infill these units.

Each system, however, is developed within a different crustal setting. Newark Supergroup basins are built within the thickened crust of the Appalachian orogen where dominant pre-existing structures in the form of thrust zones are present. These thrusts were reactivated to form the border faults of these basins. The Tanganyika-Malawi system is largely developed on Precambrian mobile belts lying between stable cratons. Karoo (Permian-Jurassic) extensional trends intersect the Cenozoic rift trends at oblique angles as well. Certainly other important features for comparison are the presence or absence of master detachments and the geometry of these elements, which, at present, remain poorly known. Several models which compare the role of pure and simple shear in the rifting process have recently been developed for both sets of basins. However, present data are insufficient to determine unequivocally the nature of crustal deformation at depth in either system. Differences in both crustal setting and deformation at depth must be responsible, in large part, for the dissimilarities in volcanic abundance and occurrence between the two systems.

Differences within the individual basins of each system include internal structural architecture such as accommodation zones and stratigraphic architecture. The latter is due to variations in climate and hydrology as well as differences in the structural evolution of separate basins.

Through such a comparative study, we hope to isolate themes which are fundamental to the rifting process, as well as identify important differences in the tectono-stratigraphic evolution of rift systems.

Go back to list of publications