Late Precambrian ensimatic volcanism in the Central Eastern Desert of Egypt

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1979

OSTI ID:5473392

Stern, R J

Early stages in the geologic evolution of the Central Eastern Desert of Egypt (CED) reflect ensimatic, ocean-floor and island-arc volcanic activity. This thesis studies the stratigraphy, distribution, geochronology, and petrology of these volcanic rocks, providing insights into Late Precambrian crustal evolution in NE Africa and Arabia. A three-fold stratigraphy is preserved in the basement of the CED. A section of oceanic crust is basal. These Older Metavolcanics (OMV) are conformably overlain by Immature Metasediments (IM). The IM are dominated by volcanogenic wackes and breccias, with subordinate hematitic Fe-formation and jasper, marls, and conglomerates derived from older sial. The IM are conformably succeeded by calc-alkaline Younger Metavolcanics (YMV). OMV, IM, and YMV are restricted to the Central Eastern Desert, but analogous terranes are found in N. Arabia. The YMV and associated plutons are dated by Rb/Sr techniques. The CED is the youngest crustal domain in the Egyptian basement, being flanked by older Proterozoic crust to the north and south and by the Archean Saharan Craton to the west. The data show that an intense episode of instability, convection, and widespread melting occurred in the mantle beneath Afro-Arabia at the end of the Precambrian. A model is presented whereby NE Gondwanaland was rifted, 650-620 mya, along a N-S trend to form a Late Proterozoic proto-Red Sea. This basin was closed by reconvergence of the Saharan and E. Arabian cratons at about 620-600 mya.

• Research Organization: California Univ., San Diego (USA)
• OSTI ID: 5473392
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100* -- Geology & Hydrology-- (-1989)
580202 -- Geophysics-- Volcanology-- (1980-1989)
AFRICA
AGE ESTIMATION
ARID LANDS
DESERTS
DEVELOPING COUNTRIES
EARTH CRUST
EARTH MANTLE
EGYPTIAN ARAB REPUBLIC
GEOLOGIC AGES
GEOLOGY
IGNEOUS ROCKS
OCEANIC CRUST
ORIGIN
PETROLOGY
PRECAMBRIAN ERA
ROCKS
STRATIGRAPHY
VOLCANIC ROCKS
VOLCANISM