Lithostratigraphic subdivision of the Karoo rocks of the Luwegu Basin (Tanzania) and their biostratigraphic classification based on microfloras, macrofloras, fossil woods and vertebrates

Abstract

For the first time a comprehensive stratigraphic classification of the Karoo deposits of the Luwegu Basin in southern Tanzania is presented. The Karoo strata attain a total thickness of almost 6000 metres and are composed of deltaic-lacustrine and fluvial deposits. The sedimentary sequence has been subdivided into nine major lithostratigraphic units. The results of biostratigraphic investigations (microfloras, macrofloras, fossil woods, vertebrates) indicate, that the Karoo Sequence ranges in age from Upper Permian to Lower Jurassic. The palynological sequence comprises microfloras of the Upper Permian, the Upper Triassic (Onslow and Ipswich type) and the Lower Jurassic. Their age is assessed from correlation with palynofloras of Malagasy, Australia and Zimbabwe. Resulting from this regional as well as intercontinental correlations with the Karoo strata of East and South Africa, the Karoo-type strata of North Africa and the Gondwana sequences of Australia and India can be proposed. Furthermore on the base of radiometric datings of hitherto unknown occurrences of volcanic rocks a Karoo volcanism and an Early Tertiary volcanism can be distinguished.