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RATCLIFFE, K. T., and R. T. J. MOODY, Kingston Geological Services, Kingston Upon Thames, Surrey, England

ABSTRACT: The Stratigraphy of the Taoudeni Basin, West Africa

The Taoudeni basin is one of the major structural units of the west African craton, with an areal extent in excess of 2,000,000 sq km. Sediment thicknesses can reach over 3000 m, but have an average thickness of 1250 m. The majority of the basin-fill sediments are Precambrian to Carboniferous, with Mesozoic rocks present in the eastern margin adjacent to the Adrar des Iforas. Due to the paucity of exploration in the Taoudoni basin, there are no detailed works on source potential, maturity, or reservoir quality. However, within the sediment pile, there are excellent potential reservoirs, in the form of poorly cemented sandstones, and apparently organic-rich sediments, which may have source potential.

Three major Paleozoic tectono-sedimentary units are recognized within the basin, all of which are found in the Adrar de Mauritania, which is taken as the "type section" for the Taoudeni basin. Unit 1 (Upper Riphean) is composed of alternating sandstones, limestones, and mudstones, which show rapid lateral thickness variations. Units 2 and 3 are far more uniform in thickness and distribution. Unit 2 (late Precambrian-Lower Ordovician) is composed of shales and sandstones with minor limestones. The base of this unit is composed of the Triad, or the Eocambrian glacial deposits that can be correlated across west Africa. Unit 3 (Upper Ordovician-Devonian) is composed of a variety of lithofacies varying from a basal glacial unit through basinal graptolitic shales into shallow marine/contine tal deposits. Each of these units will be discussed in detail and the petroleum potential of the constituent lithofacies considered.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.