Provenance and source-to-sink of lower-middle Jurassic sediments from hinterland mounts to NW-Gondwana hyper-extended passive margin (Prerif sub-domain, External Rif, Morocco): First evidence from sedimentary petrology and detrital Zircon geochronology

Abstract

The present work deals with the provenance of lower-middle Jurassic successions belonging to the External Prerif Foreland basin, which remains till now misunderstood and requires a deep investigation dealing with sedimentary petrology and Zircon geochronology. Detrital modal signatures, mudrocks geochemistry combined with Zircon geochronology of lower middle Jurassic pre-orogenic successions of the External Prerif basin have been used to detect provenance relationships with potential Precambrian and Variscan orogenic belts of the Anti-Atlas, Western Meseta, and the exotic “Sehoul Block”. The analyzed sandstone suites, mudrocks, and marls have been collected from Jebel Outita, Jebel Zerhoune, and Dhar N'sour sections which were accumulated in different depositional paleoenvironments evolving down-slope from proximal delta to bathyal and deep-sea basin. These early-middle Jurassic deposits belonged to the NW-Gondwana hyper-extended margin during the earliest rifting-drifting stages of the western Tethyan Ocean edge. The analyzed terrigenous sandstone suites are siliciclastic hybrids characterized by lithic arkoses, feldspathic litharenites, and litharenites framework composition. Detrital sandstone modes reflect provenance from a continental block and recycled orogens with 90% of confidence. These results were corroborated by various provenance ratios (Th/Sc, Th/Co, Th/Cr, Cr/Th, and La/Sc) which indicate felsic source rocks close to the Post Archean Australian Shale (PAAS) and Upper Continental Crust (UCC) values, with probably minor mafic supply. Indeed, the provenance inferred from detrital Zircon geochronology points to different high-grade metamorphic, plutonic basements and overlying sedimentary source rocks aged from Paleoproterozoic to middle-Late Devonian, related to basement source rocks of the exotic “Sehoul Block”, the Western Meseta, and the Central and Occidental Anti Atlas belts.