Sea-Floor Spreading and Structural Evolution of Southern Red Sea: ABSTRACT

Abstract

The Red Sea is in the early to intermediate stages of continental breakup, and its structural evolution has been fundamentally the rifting and breaching of continental lithosphere by normal faulting attendant to the process of sea-floor spreading. In Oligocene time, the continental lithosphere of the Red Sea area was bowed into a large regional arch with normal faults across the crest. Subsequently, rifting by normal faults that propagated upward from the base of the lithosphere caused strong subsidence on horst and graben and tilted blocks; this rifting led to an extensive marine incursion, and a thick evaporite sequence was deposited in the restricted, hot, arid, low-latitude setting of the Miocene Red Sea trough. A second rift westward of the earlier central or axial M ocene rift originated in the southern Red Sea area in Pliocene time, and the 2 features are now evolving concurrently over a distance of at least 400 km. An evaporite section of very shallow marine origin accumulated in the western rift during the Quaternary; it constitutes a modern example of salt accumulating in a narrow, restricted, rifted trough which is forming as a consequence of continental breakup. The present opposing coastlines of the Red Sea were never in contact, because the fragmentation of continental lithosphere was attained very largely by normal faulting. Only if a vertical fault surface cut the entire thickness of lithosphere could points on opposite coastlines ever have been contiguous. End_of_Article - Last_Page 349------------