Micromorphological Study of a Sediment Core from the Malha Crater Lake, Sudan

Abstract An eight meter long core of loose sediments from the Malha crater lake, NW Darfur, Sudan, was studied with the aid of thin sections. The high salt content of the material required special precautions during preparation. The microscopic study allowed the distinction between syngenetic, diagenetic and sedimentary salt minerals. Following salts were recognized: nahcolite, gaylussite, magadiite and the rare eitelite. Fabric studies, combined with the mineralogy, made it possible to distinguish several meromictic phases and subdivisions in an important holomictic phase in the history of the lake, which was even dry on two occasions.