Soft-sediment deformation structures (slumps) triggered by tectonic activity in the Upper Triassic carbonate succession of Tataouin Basin (south-eastern Tunisia)

Abstract

Soft-sediment deformation structure crops out in the Upper Triassic carbonate succession of Messaoudi Formation in the north eastern of Tataouine basin (south eastern Tunisia). The deformed interval is about 10 m thick and tack place between shallow-water limestone and stromatolitic bed. Soft-sediment deformation structures (slump), supareted by undeformed beds include boudins, pinch-and-swell structure, and normal faults and folded structures. Observations and measurements of the deformed structure and bed thickness of hinges and limbs indicate that all the deformed structures are related to slump structure, which affects unconsolidated sediment in the local paleo-slope. The internal mechanisms are ruled out due to the absence of features (high sediment rate, traction feature, chemical process). The slump was triggered by external mechanisms; tectonic effects related to the reactivation of EW faults during the opening movements of the paleotethys. These tectonic events generat a moderat seismic activity wich affected unconsolidated sediment.