An unusual Proterozoic petroleum play in Western Africa: the Atar Group carbonates (Taoudeni Basin, Mauritania)

Abstract The Taoudeni Basin is the largest sedimentary basin in Africa. This intracratonic basin, which forms the sedimentary cover of the West African Craton, records episodic sedimentation since the Proterozoic. It is a largely unexplored basin, with only eight exploration wells drilled to date, although its petroleum prospectivity was established in 1974 when gas and liquids were tested in the Abolag-1 well. This paper focuses on the identification and assessment of potential source rocks and reservoirs in the Taoudeni Basin in Mauritania and aims to establish a geochemical genetic link between the occurrence of petroleum and potential sources. Various disciplines and techniques were integrated to reach a better understanding of the petroleum systems potentially existing in this basin. We also define and describe the elements and processes of the Atar-Atar (!) petroleum system. This study is an example of the exploration of an unusual and high-risk play in some of the oldest sedimentary rocks on Earth, with a long, polyphase structural evolution, a complex thermal history (where burial might not be the only controlling factor), a massively diagenetized carbonate reservoir, and large uncertainties on the timing of generation, trap formation and preservation.