University:
Massachusetts Institute of Technology
Course:
12.520 | Geodynamics
Academic year:

2023
Views:

436

Pages:

14
Author:

nomessuspension

Erosion and deposition as the swell rises Late Cret. and Paleocene outcrops near coast due to isostatic rebound of eroded area Benguela Current, a cold current, began to flow to the north when an ice-sheet first formed in Antarctica (ca.35 Ma). Namib desert formed and persists. Drainage changes as basins and swells began to form. Southwest is Mainly based on Mike de Wit in Econ. Geol. 1999 Du Toit discerned sub-swells in 1934 North and West Africa Swells are smaller, but it rained more until the Sahara first formed at 2.8 Ma. Sandstone Escarpments are a feature. Bauxites, formed on the low-lying equatorial surface 100 Ma- 30 Ma, are now Elevated to varied extents Before northern hemisphere ice sheets formed and related Sahara initiation( at 2.8 Ma) conditions year round were those of the two lower Figures. Rainfall on S. African swell Was mainly on S.E. coast where Great Escarpment is highest and offshore dip is higher Basins and Swells of the past 30 million years in the Northwest EAST AFRICAN RIFT SYSTEM Active extent from 30 Ma until Now: From Dead Sea transform (active since 15 Ma) through Suez and the Red Sea to the Ethiopian and East African swells, the Malawi rift and the offshore rift east of Mozambique on the site of the Davie FZ. (Definitions of the EAR vary greatly) EAR NOT YET FORMED Mwadui and Uweinat ages are Wrong. Possible Migration of 45-35 small Plume from S. Ethiopia to W of Lake Turkana Afar plume erupted at 31 Ma. Cracks that formed in an attempt to relieve stress modification in a newly formed ~ 1km high dome propagated to: 1.Rt-angled bend in Levant corner, 2.to volcanic area of S. Ethiopia 3. on Gulf of Aden site. Dikes emplaced in cracks accommodated initial extension in newly formed rifts that on the future Red Sea site had stabilized at 70 km wide by 25 Ma. Offshore rift segment of EAR on site of Davie FZ. Reflector ages are tied to a DSDP hole. Mougenot et al. Nature (1986)