Lithostratigraphy and Petrography of Mesozoic Sedimentary Rocks of Lemi Area, North Shewa, Central Ethiopia

Abstract

The Mesozoic sedimentary basins in Ethiopia, particularly the Central Ethiopia, and Blue Nile Basin within the central main Ethiopian rift region are characterized by a diverse range of volcano-sedimentary rocks dominated by sedimentary sequences. The lithostratigraphy and petrology of Mesozoic sedimentary rocks of Lemi area, North Shewa, in Central Ethiopia within the Blue Nile basin, is described based on detailed field observations, lithostratigraphic analysis, petrographic examinations. The lithological units identified during fieldwork include Mudstone, Sandstone, and Basaltic rock formations. The sandstone unit in the study covers an estimated average thickness is 237 meters with intercalations of thinly bedded mudstone. The average thickness of each sandstone units (coarse (23 meters), medium (90 meters) and fine-grained (115 meters) sandstone unit) are varying from place to place within the study area. The stratigraphic section logs in four each block (Geza Washa, Dalota, Ruka, and Gosh Wiha) shows coarsening upward indicating the depositional environment transition from deep marine to the fluvial environment. The results of the study reveal the geological history and paleoenvironmental conditions of the Mesozoic sedimentary rocks in the Lemi area. This study contributes to our understanding of the geological processes that have influenced the formation of the Lemi area and provides valuable interpretations of regional geology.