STYLES OF POST-RIFT DEFORMATION ON THE ATLANTIC AND INDIAN OCEAN MARGINS

A variety of post-rift deformations are found on basins alonn the margins of the Atlantic and Indian Oceans. These deformations are most pronounced in deep water settings, but are also observed in shallow water. The resulting structures range in scale from local uplift and inversion to basin-wide exhumation.

Compression is observed on the margins of the North Atlantic Ocean, and on the Australian Northwest Shelf of the Indian Ocean. The effects range from minor inversion of normal faults to large-scale doming. These features occur near transform faults. The reorganization of sea floor spreading appears to be coeval with the development of these features.

Strike-slip deformation is observed on both margins of the Equatorial Atlantic. Long transform faults offset the ocean crust, and appear to be intermittently active in the Holocene. Both positive and negative flower structures occur on the African and South American margins.

Poly-phase deformation is observed on the East African margin. Normal faulting accompanied transform rifting between Tanzania and Madagascar. Subsequently the East African rift system has extended eastward into the eastern Indian Ocean, offshore Tanzania, reactivating older structures.