Structural segmentation, inversion, and salt tectonics on a passive margin: Evolution of the Inner Kwanza Basin, Angola

摘要

The Kwanza Basin, Angola, is divided into the Inner and Outer Kwanza salt basins, separated by a chain of synrift basement highs on which Aptian (112–122 Ma) salt is thin or absent. North- to northwest-trending basement structures in the Inner Kwanza Basin have repeatedly been reactivated since Neocomian (144–127 Ma) rifting. Reactivation formed three northwest-striking fold-and-thrust belts near basement uplifts. The thrust belts are bounded by northeast-striking rift-related transfer-fault zones that were apparently reactivated during subsequent shortening. Three episodes of postrift, basement-involved shortening are documented in the Inner Kwanza Basin: (1) Albian–early Cenomanian (112–96 Ma), (2) Senonian (89–65 Ma), and (3) Oligocene–Holocene (34–0 Ma). We relate the Albian–early Cenomanian event to ridge push, the Senonian event to global-plate reorganization, and Oligocene–Holocene shortening to uplift of the African superswell.