Sedimentology, provenance, and paleoclimate of Jurassic–Cretaceous red beds: Example from the southern front of the Central High Atlas and Northern Preafrican Trough, Morocco

Abstract

Five stratigraphic sections from the Aghbalou N’Kerdouss–Tadighoust area were analyzed using integrated petrographic, granulometric, calcimetric, and mineralogical approaches applied to both bulk samples and clay fractions. The findings reveal a transitional depositional environment shaped by a dynamic interplay of continental and restricted marine influences, particularly within the Ifezouane Formation (Member 2), which reflects low-amplitude sea-level oscillations under confined paleoenvironmental conditions. Whole-rock mineralogy is dominated by quartz, K-feldspar, plagioclase, hematite, calcite, dolomite, siderite, and gypsum. The associated clay mineral assemblages comprise illite, kaolinite, smectite, and chlorite, with compositional variability across sections. Illite crystallinity and illite chemistry index data indicate a dual provenance, with sediment sources originating from both the Anti-Atlas and Sahara regions to the south, as well as the Jurassic uplands to the north. These interpretations are supported by petrographic evidence and mineralogical signatures. Furthermore, the mineralogical data suggest that arid to semi-arid climatic conditions and/or tectonic activity played a significant role during deposition. This study demonstrates how the integration of clay mineral signatures with petrography, grain-size distribution, and calcimetric data offers a reliable basis for reconstructing provenance, unraveling paleoenvironmental conditions, and refining palaeogeographic reconstructions of peri-Tethyan basins, while also providing a comparative framework applicable to analogous red bed systems worldwide. • Illite and kaolinite dominate the clay minerals assemblage of the studied Red Bed • Two geographically distinct sources of sediment provenance • The main sediment provenance linked to the erosion of the Anti-Atlas reliefs • A predominance of local arid climate throughout the studied interval