Geology of the Sinda-Mohari Region, Haut-Zaire Province, Eastern Zaire

Abstract

The Sinda-Mohari region is topographically divided into the Mutimba plateau, hilly land and Semliki Plain. The hilly land is underlain by Precambrain basement rocks, Sinda Beds, Higher Terrace Deposits, Middle Terrace Deposits, Lower Terrace Deposits, and Alluvium (Recent river floor deposits). The Sinda Beds are subdivided into the lower, middle and upper members. The lower member consists of clayey white coarse sand and yields such mammal fossils as Bovidae, etc. from the upper part. The middle member is characterized by alternating sand and mud beds. The upper member is composed of alternating thicker beds pf sand and mud and contains such mammal fossils as Predeinotherium, etc. Generally, the Sinda Beds gently dip south to southeast. Folds parallel the northern boundary faults. An inferred fault is drawn parallel just north of these folds. The context of geological phenomena from the older to the younger in this region is as follows: 1) formation of an extensive sedimentary basin by downwarping, 2) deposition of the Sinda Beds, 3)long-term denudation and peneplanation, 4) intense activity of the northern boundary faults and formation of the Higher Terrace Deposits, 5) activity of the southeastern boundary fault, 6) formation of the present Semliki Plain as the floor of the rift valley, 7) completion of the present drainage system, and 8) formation of the Middle and Lower Terrace Deposits within the deep valleys.