--> Depositional History of a Marine to Evaporite Succession: Triassic of Central Syria, by P. W. Choquette, D. H. Craig, D. M. Cooper, and J. C. Steinmetz; #90986 (1994).

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Abstract: Depositional History of a Marine to Evaporite Succession: Triassic of Central Syria

P. W. Choquette, D. H. Craig, D. M. Cooper, J. C. Steinmetz

A one-to-two thousand meter succession of mid-to-late Triassic carbonates, shales and evaporites underlies much of the Palmyrid trough, an elongate Mesozoic depocenter that extended west-southwest across Syria from Neotethys. Six wells drilled by Marathon Petroleum Syria sampled a 2500 sq km area along the trough axis in central Syria. Extensive coring of the 300 m mid-Triassic section provides new information about the basin's Triassic history.

The mid-Triassic encompasses three informal stratigraphic members of the Kurrachine Formation. The lowest member ("E") comprises dark-gray micrite-rich limestones and shales of marine middle shelf or ramp origin. Gradationally overlying this is the 25-30 m "D member" made up of 7-8 cycles of shoaling-upward, shallow shelf to peritidal carbonates with rare meter-scale anhydrites. The carbonates include petroleum reservoir-grade and non-reservoir dolomites of multiple origins from early diagenetic to hydrothermal. The "D member" is overlain at a regional drowning unconformity by the "C member", composed of a basal 15-19 m shale and lime mudstone overlain by 47+ shale-carbonate-anhydrite cycles 1-20 m thick. These cycles appear to represent repeated interludes of restricted-marine sedime tation in mud-dominated shallow offshore regimes that evolved to penesaline, sulfate-precipitating coastal lakes or lagoons.

Overall, the succession portrays a history of shoaling and filling of the axial part of a shallow-marine shelf/ramp carbonate basin, regional exposure and drowning, and cyclic marine to penesaline-lake sedimentation.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994