--> Abstract: Tectonic Controls on Deposition of Mesozoic Source Rocks, Northern Margin of African Plate, by I. O. Norton and G. J. Grabowski, Jr.; #90987 (1993).

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NORTON, IAN O., and G. J. GRABOWSKI, Jr., Exxon Production Research Company and Exxon Exploration Company, Houston, TX

ABSTRACT: Tectonic Controls on Deposition of Mesozoic Source Rocks, Northern Margin of African Plate

Multiple pulses of rifting on the northern margin of the African Plate occurred from Triassic through Cretaceous time, separated by intervals of sag. Only parallic to shallow-marine sedimentation occurred along this margin. Oil-prone organic-rich rocks were deposited in the initial marine sediments of narrow rifts and in parts of the subsiding margin. Coaly sediments formed in a parallic environment along the entire northern margin of the African Plate during the sag phases.

Rifting in the latest Triassic was related to the breakup of Pangea and affected a wide expanse of southern Europe and northern Africa, including Apulia (Italy-Dinarides-Greece-Turkey). Organic-rich shales(Noto-Streppenosa Formation) formed in restricted, shallow-marine waters in some of these rifts, whereas evaporites formed in others. Marine waters spread out across the region during the Jurassic-early Cretaceous sag phase, with coal-bearing parallic deposits forming in Tunisia and Egypt.

Oceanic crust formed in the eastern Mediterranean as a product of the final rifting phase that was initiated during Aptian time. Horsts and grabens formed across the African margin, controlling subsequent depositional patterns. One of these grabens is the Sirte Basin, where Upper Cretaceous marine organic-rich rocks (Socna Formation) overlie initial nonmarine rift fill. During the Late Cretaceous and Early Tertiary sag phase, subsidence above these grabens localized the deposition of shallow-marine organic-rich rocks in the Western Desert of Egypt (Abu Roash-F Formation) and the Pelagian Basin of Tunisia (Mouelha, Bahloul and Bou Dabbous Formations).

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.