111 Volume 4 • Issue 1 • 1000114 Int J Earth Sci Geol. ISSN: 2642-1569 International Journal of Earth Science and Geology ISSN: 2642-1569 Research Article Open Access A.T. Abdalrhman 1 *, T.G. Fagier 1 *, N.H. Abakar 1 *, E.M. Abdelrhman 2 , A. M. Khairy 1 , K.A.Ali 1 and I. Khalifa 1 1 Geological Research Authority of Sudan, Sudan 2 Alneelain University, Sudan Article Info *Corresponding author: A.T. Abdalrhman Geological Research Authority of Sudan Sudan E-mail: ahmedtarig559@gmail.com Received: January 05, 2022 Accepted: April 27, 2022 Published: May 16, 2022 Citation: Abdalrhman AT, Fagier TG, Abakar NH, Abdelrhman EM, Khairy AM, Ali KA, Khalifa I. The Paleodepositional Environments in the Shandi Sub-Basin as part of the Atbara Basin, North Sudan. Int J Earth Sci Geol. 2022; 4(1): 111-120. doi: 10.18689/ijeg-1000115 Copyright: © 2022 The Author(s). This work is licensed under a Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Published by Madridge Publishers Abstract This study describes the lithofacies diagnoses and the depositional environments of the Shendi sub-basin (a part of Atbara Basin) in North Sudan. Several full body fossils were observed in the study area such as trilobites, conulariids, Gyrophyllites and Archaeocyathids, in addition a number of trace fossils such as Rhizocorallium, and skolithos were reported. These fossils indicate deposition in a range of marine environments from intertidal to deep water. Furthermore, Herringbone cross- stratification is observed and it suggested a shallow water environment. Two formations can be identified in the Shendi sub-basin; the lower formation was deposited in a range of shallow to deep marine environments of probable Lower Cambrian age while the upper formation of the ‘Nubian Sandstone’ was most likely deposited in fluvial environments of the Upper Cretaceous age. The lower formation is composed of four facies form bottom to top as; shale facies, carbonate facies, siltstone, fine sandstone facies, and chert facies. This study reveals the presence of the Archaeocyathids of Cambrian age, the oldest formation of the Paleozoic marine sedimentary rock ever found in Sudan. Keywords: Shendi sub basin, Elbarda Abu telaih formation, Archaeocyatha, Lower Cambrian 1. Introduction The study area occupies 2475 km 2 land lies west of Shendi town on the western bank of the River Nile around Jebel Abu Telaih and Jebel Elbarda 150 km northeast of Khartoum (Fig 1), between latitudes (16º 40’ 00’’) (17º 10’ 00’’) and longitudes (33º 05’ 00’’) (33º 30’ 00’’). It is surrounded by the Pre-Cambrian units in Arab-Nubian Shield. Basins in this area were caused by rifting of the shield due to break up of Gondwanaland (Worrall, 1957, Whiteman, 1971). Paleozoic sediments are sometimes preserved in the deeper parts of the rifts basins. Previous studies divided the main geological units in the study area into basement complex (Precambrian age), Nubian sandstone (Upper Cretaceous), Hudi chert (Oligocene), and Quaternary superficial deposits (Awad, 1994; Mukhtar, 1999) Basement crops out in the north around Mukabrab village and in the south in Um Shadida village (Kheirallah,1966). Awad (1994) classified the Nubian sandstone into three sequences (lower, middle and upper), the lower is sandstone overlying the basement, and the middle part is ferruginous shale. The upper sequence is a sandstone that crops out in escarpments and in the inselbergs. The Paleodepositional Environments in the Shendi Sub-Basin as part of the Atbara Basin, North Sudan