Journal of Petroleum Geology, Vol.10, No.3, pp. 335-350, 1987

©Copyright 2000 Scientific Press, Ltd.

SEDIMENTARY HISTORY AND PALEOGEOGRAPHY OF LOWER AND MIDDLE JURASSIC ROCKS, CENTRAL SAUDI ARABIA

Mohamed A. Moshrif*

* Geology Dept., College of Science, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia.

Abstract

Eight clastic and carbonate lithofacies of Lower and Middle Jurassic age (the Marrat and Dhruma Formations respectively) have been identified. These lithofacies are mainly shales, shales-and- siltstones, siltstones-and-shales, sandstones, argillaceous limestones, calcarenitic limestones, calcarenites and dolomites. Intraclasts, pellets, oolites, gypsum, algae, and coral reefs were also found to be dominant among these lithofacies. Furthermore, these beds contained either restricted or diversified biota, with a few sedimentary structures such as lamination, cross-bedding and common bioturbation. Thus, it is presumed that the Lower and Middle Jurassic rocks in Central Saudi Arabia were deposited in very shallow (i.e. tidal flat and lagoon), shallow-neritic, and deep-marine conditions of the Tethys Sea.