Abstract—This paper presents the results of Sedimentary Facies and Depositional Environments of AL Musauwarat- Umm Ali Area, Shendi Formation, River Nile State, Sudan. Study area is dominated by Mesozoic sediments of continental origin from fluvial and lacustrine depositional environments which are widely spread in central Sudan. This study aims to the interpretation of depositional environment using lithofacies analysis, grain size analysis and petrographic description. During the field work trip, fourteen vertical and three lateral sedimentary profiles have been examined and discussed. The studied profiles exhibit eleven lithofacies identified at the outcrop section which are matrix supported massive conglomerate (Gmm) facies, stratified conglomerate (Gt), trough cross-bedded sandstone facies (St), Shallow scour pebbly sandstone (Ss), planar cross-bedded sandstone facies (Sp), horizontally–bedded sandstone facies (Sh), ripple cross-bedded sandstone facies (Sr), massive sandstone facies (Sm), massive mudstone (Fm), fine-laminated mudstone (Fl) and rootbed mudstone (Fr). On the basis of their sedimentological character theses facies are interpreted to be deposited in fluvial depositional environment, by multi braided river channels. Based on grain-size analysis, the upper cretaceous strata can be classified as fluvial-dominated units. According to the plot of skewness against sorting, all samples proved to show a river, fluvial-dominated environment origin. The formations may have been formed in meandering rivers or multi-braided channels. In relation to the revealed lithofacies, there is no doubt that these formations were formed mostly in channel environments, and also overbank environments due to channel-breaking or flooding. Thin section investigations of the outcrops samples that the sedimentary rocks in Shandi basins consist mainly of polycrystalline quartz occurs in higher percentages than monocrystalline quartz indicate a metamorphic source region, feldspar which found are usually altered, lithic fragments, detrital micas are present and also some fine-grained matrix. The cementing materials are quartz, carbonates, iron oxides and some matrix (kaolinite and chlorite), The most abundant kind of the sedimentary rocks is arenite which support the hypothesis that area is fluviatile.

Index Terms—Facies, depositional environments, Shendi Formation, representative, fluvial.

Cite:Mohamed M. M. Abujaball, Sadam H. M. A. Eltayib, and Omer A. Ali, "Sedimentary Facies and Depositional Environments of AL Musauwarat-Umm Ali Area, Shendi Formation, River Nile State, Sudan," International Journal of Geology and Earth Sciences, Vol. 7, No. 3, pp. 17-26, September 2021. doi: 10.18178/ijges.7.3.17-26