Sedimentological, mineralogical and geochemical investigation of Chichaoua’s bassin depot system: potential origin and provenance

Abstract

High Atlas Rivers are common along the Atlas Mountains of Morocco and result from the combined effectof river flow, winds, vegetation and other meteorological conditions. In this paper, we study the texturaland compositional parameters of fluvial deposits, from the Chichaoua catchment across the Seksaoua riverbanks, and their provenance. Morphologically, they are in the form of current active river, Paleozoic deposits.To study the provenance of the grains, we opted for laboratory analyses including grain size, mineralogy,micro textures and micro morphology. Sands from active deposits showed very fine to medium averagegrain size and moderate sorting, while those from fluvial deposits showed fine to very fine average grainsize and very low sorting. The deposits studied showed the dominance of grain forms ranging from angularto freshly angular. As far as mineralogy is concerned, calcite is predominant in the sands on the right bankof the river, whilequartz is more abundant in the deposits on the left bank. In the active streams on the leftbank, other carbonates were also detected in the bioclasts such as aragonite, dolomite and magnesian calcite,suggesting a fluvial origin. The siliciclastic grains of the studied stream generations are likely to be ofTriassic, Jurassic and Quaternary units origin crossed by the Seksaoua River. Indeed, the results revealedthe presence of minerals such as albite, plagioclase, microcline and illite which could come from Triassic asalts which is often associated with Jurassic evaporates associated with Jurassic evaporite rocks. This studyhas suggested the probable origin of the sands that form these deposits based on the detailed study of theirgrains, which has not been studied in previous research in the area. Furthermore, this research is particularlyrelevant as it is part of the current research trend related to the understanding of the evolution of Plio-Quaternary atlasic fluvial systems in the world and may be applicable to other fluvial systems in the mountainranges of Morocco in the future.