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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 3. (March)

First Page: 462

Last Page: 462

Title: Shallow-Water Carbonate and Evaporite Sedimentation Patterns in Lower and Middle Jurassic Rocks of Southern Tunisia: ABSTRACT

Author(s): Andrew G. Harding

Article Type: Meeting abstract


The Lower and Middle Jurassic rocks in southern Tunisia can be divided on the basis of lithology into two distinct regions, the central and northern provinces.

Outcrops in the central province extend in a continuous escarpment south from the Wadi Tatahouine and display a variety of carbonate and sulfate rock types representing very shallow-water deposition. The Lower Jurassic and lower Middle Jurassic Mestaoua Formation is a largely gypsiferous sequence representing deposition in lagoons and on hypersaline shotts. The overlying Bathonian Krachoua Formation displays a range of carbonate lithologies, representing shoreline and tidal-flat environments, and sulfate units, again indicative of gypsiferous lagoons and shotts.

These formations pass northwestward into massive and laminated carbonate strata indicative of deposition on extensive wind-tidal flats. This is the northern province. The lower part of the sequence, the Semoumenia Breccias, is composed of breccias believed to have resulted from evaporite-solution processes. This sequence passes into clastic facies, the Sidi Stout Sandstones (an accumulation of wind-blown sand dunes), toward the Permian outlier of Djebel Tebaga.

Paleogeographic reconstructions show that the area preserves part of the carbonate shoreline sequence which acted as the sill separating a true marine area on the northeast, Tethys, and the Algerian-Tunisian salt basin on the southwest. Periodic marine incursions into the margin of this salt basin are suggested by the presence of extensive storm deposits.

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