The Upper Cretaceous-Lower Eocene carbonate platforms of the Mateur-Beja area (NW of Tunisia): A pattern of isolated platform

Abstract

Paleogeographic reconstruction of ancient carbonate platforms contributes to better understanding carbonate facies distribution and their economic interests. Based on facies analyses, depositional environment interpretations and a comparison with modern platforms, the present study interprets the Upper Cretaceous and Lower Eocene carbonate deposits of the Mateur-Beja area, northwestern Tunisian domain, as deposited in an isolated platform. Facies belts of this platform are dominated by detrital and lithoclastic limestone mixed with pelagic carbonate and occasionally skeletal-rich and/or breccia deposits. Facies analysis shows that facies spectrum was deposited by diverse transport agents including storm currents, gravity-driven currents and bottom currents. Paleogeographic reconstruction of platform architecture shows that the platform is characterized by a flat-topped edge during the Late Cretaceous and a shoal-rimmed platform edge during the Early Eocene passing basinward through a depositional slope margin. Lateral arrangement of slope facies as well as the predominance of lime mud and sand led us to interpret slope deposits as wedge-shaped carbonate apron. Paleogeographic conclusions inferred from this study of suggest that the northwestern Tunisian isolated platform was developed in an offshore domain presumably detached from Maghrebian continental margin.