Faciological analysis of Triassic deposits in the Khemisset–Rommani Basin (Moroccan Meseta)

The Triassic basin of Khemisset–Rommani is located in northwestern Morocco, approximately 80 kilometers east of Rabat. It appears as a vast, gently undulating plateau.

This basin is a NE–SW oriented graben in the northern part of the Moroccan Meseta with Hercynian structuring. It is filled with a powerful volcano-sedimentary series and developed in an extensive tectonic context linked to the early stages of the breakup of Pangaea and the opening of the central Atlantic.

This basin is of particular interest due to the presence of significant salt reserves. The preliminary study conducted in the basin is based on a facies analysis, carried out using field surveys and detailed descriptions of representative stratigraphic sections exposed in different parts of the basin. The analysis includes lithological description, identification of sedimentary structures, and characterization of lithofacies. Facies classification is based on Miall’s nomenclature (1978, 1985, 2006).

Detailed facies analysis identified the following facies, from bottom to top, according to Miall’s classification: kh1 (Gmm, Sp, Sr, Sh) and kh2 (Ff, Fm). The fine-grained Ff and Fm facies are locally associated with gypsum levels.

The deposits studied lie directly on the Paleozoic bedrock and are topped by greenish basaltic flows.

This succession of facies shows that the depositional environment gradually changed from a high-energy continental environment at the base to a calmer, evaporitic lagoonal environment at the top, before being covered by volcanic flows.