| Abstract: | Well over one hundred separate graben formed in association with ocean opening can be recognized around the shores of the Atlantic Ocean. The graben are linked forming an elaborate network of triple-rift systems. Some rifts developed to form ocean but many failed. The stratigraphie and structural history of these rift structures is varied and helps to illuminate the processes that operate at continental rupture. Rifting has been commonly accompanied by basaltic vulcanism and rapid accumulation of several kilometers of sediment. Horsts within the graben strongly influence early sediment distribution. Generally, rift faulting ceases about the time of onset of normal marine sedimentation but there are a few exceptions and some graben formed at ocean opening have influenced sediment distribution more than 100 m.y. later. Although tensional structures predominate strike-slip and compressional structures have developed locally in the graben. The rivers bringing the largest amounts of sediment into the Atlantic during the last 150 m.y. have prograded along failed rift arms formed at continental rupture. In some cases their deltas have come to lie on oceanic crust. |
