Depositional environments of Late Cretaceous Gongila and Fika formations,Chad (Bornu) Basin,Northeast Nigeria |
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| Institution: | 1. Geology Programme, Abubakar Tafawa Balewa University, Bauchi, PMB 0248 Bauchi, Nigeria;2. School of Geography, Earth and Environmental Sciences, Plymouth University, Drake Circus, Plymouth, Devon PL4 8AA, UK;1. National Taiwan Normal University, Department of Earth Science, 88 Tingzhou Road Section 4, Taipei 11677, Taiwan;2. Chinese Petroleum Corporation-Taiwan, Exploration and Development Research Institute, Wen Fa Road, Miaoli 36042, Taiwan;3. Academia Sinica, Institute of Earth Science, 128 Academia Road Section 2, Nankang, Taipei 11529, Taiwan;1. Department of Geosciences, College of Petroleum Engineering & Geosciences, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia;2. Sudapet Company, Exploration Department, P.O Box: 13188, Khartoum, Sudan;1. Institute of Geoscience, Kiel University, Kiel, Germany;2. Department of Geology, University of Benin, Benin City, Nigeria;3. Department of Geosciences and Geological and Petroleum Engineering, Missouri University of Science and Technology, Rolla, MO, USA;1. Department Geology University of Maiduguri, P.M.B. 1069, Maiduguri, Borno State, Nigeria;2. National Centre for Petroleum Research and Development (Energy Commission of Nigeria), A.T.B.U, Bauchi, Nigeria;3. Department of Applied Geology ATBU, Bauchi, Nigeria;1. Department of Applied Geology, Federal University of Technology, Akure, Ondo, Nigeria;2. IC2MP-HydrASA, UMR CNRS 7285, Université de Poitiers, Poitiers, France |
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| Abstract: | Organic geochemical and palynofacies studies of 172 ditch cuttings samples of possible source rock shales from the Late Cretaceous Gongila and Fika formations in the Chad Basin of NE Nigeria were carried out to determine their paleoenvironments of deposition. Although dominated by amorphous organic matter, C/S ratios and molecular parameters suggest the mostly organic lean shales (TOC contents typically below 1.5%) were deposited in a normal marine environment. Levels of oxygenation influenced by water depth in the depositional environment appear to control organic richness and quality of the dark grey shales.The organic rich (TOC > 2.0%) upper part of the Fika Formation was deposited under anoxic conditions during the Late Cretaceous and could represent an Oceanic Anoxic Event. Mature intervals where such conditions prevailed would have generated liquid hydrocarbon, although none were sampled here.A trend of increasing organic richness towards the central part of the larger Chad Basin observed in this and other studies supports the development of organic rich marine shales (average TOC contents of 2–3%) of equivalent age in the Termit Basin where water depth would have been deeper and oxygen conditions at levels that permitted preservation of marine organic matter. |
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| Keywords: | Gongila Fika Chad Basin Depositional environment Organic geochemical Palynofacies Normal marine Anoxic |
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