Hydrocarbon source rock potential of the Late Cretaceous sediments in the Asaga–Ohafia Axis, Afikpo Basin, Nigeria: Insights from facies and kerogen analyses
This study investigated the hydrocarbon source rock potential of the Late Cretaceous Mamu and Nkporo formations in the Asaga–Ohafia Axis, Afikpo Basin, southeastern Nigeria, using integrated facies analysis, organic geochemical and palynofacies data. Five lithofacies were identified: dark grey shale...
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KeAi Communications Co., Ltd.
2025-12-01
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S266675922500068X |
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| author | Samuel Okechukwu Onyekuru Timothy Chibuike Anyanwu Kenneth Okechukwu Nwosu Ifeyinwa Juliana Ofoh Francis Begianpuye Akiang Obinna Chigoziem Akakuru Onyema Uchenna Achukwu–Ononye Kalu Kalu Ibe Godwin Okumagbe Aigbadon |
| author_facet | Samuel Okechukwu Onyekuru Timothy Chibuike Anyanwu Kenneth Okechukwu Nwosu Ifeyinwa Juliana Ofoh Francis Begianpuye Akiang Obinna Chigoziem Akakuru Onyema Uchenna Achukwu–Ononye Kalu Kalu Ibe Godwin Okumagbe Aigbadon |
| author_sort | Samuel Okechukwu Onyekuru |
| collection | DOAJ |
| description | This study investigated the hydrocarbon source rock potential of the Late Cretaceous Mamu and Nkporo formations in the Asaga–Ohafia Axis, Afikpo Basin, southeastern Nigeria, using integrated facies analysis, organic geochemical and palynofacies data. Five lithofacies were identified: dark grey shale, oolitic limestone, heterolithic mudstone/sandstone, laminated bioturbated sandstone, and calcareous mudstone, indicating estuarine, deltaic, and shallow marine depositional environments. Total organic carbon (TOC) contents range from 1.47 to 2.40 wt%, which reflects moderate to good organic richness. For the Mamu Formation, kerogen composition is dominated by Type II/III, composed of 30 %–50 % amorphous organic matter (AOM), 5 %–10 % liptinite, 30 %–50 % vitrinite, and 10 %–20 % inertinite. Spore coloration and Thermal Alteration Index (TAI: 3–3+) suggest thermal maturity within the oil window (Ro: 0.80 %–1.50 %). In contrast, the Nkporo Formation shows comparable kerogen composition (20 %–45 % AOM, 0–20 % liptinite, and 40 %–65 % vitrinite) but lower maturity (TAI: 2–2+; Ro: 0.45 %–0.80 %). Rock–Eval pyrolysis further supports these findings. The Mamu Formation displays higher Hydrogen Index, favorable Tmax, and Production Index values, confirming its maturity and oil and gas–prone potential. Palynological assemblages, including marine dinoflagellate cysts (Mamu Formation) and freshwater algae/fungal spores (Nkporo Formation), align with the inferred depositional settings. Thus, the Mamu Formation is the more prolific source rock, characterized by superior organic quality and thermal maturity. |
| format | Article |
| id | doaj-art-d18bbd27a2d34cd59c1f34b99292647f |
| institution | Kabale University |
| issn | 2666-7592 |
| language | English |
| publishDate | 2025-12-01 |
| publisher | KeAi Communications Co., Ltd. |
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| series | Energy Geoscience |
| spelling | doaj-art-d18bbd27a2d34cd59c1f34b99292647f2025-08-20T03:36:42ZengKeAi Communications Co., Ltd.Energy Geoscience2666-75922025-12-016410044710.1016/j.engeos.2025.100447Hydrocarbon source rock potential of the Late Cretaceous sediments in the Asaga–Ohafia Axis, Afikpo Basin, Nigeria: Insights from facies and kerogen analysesSamuel Okechukwu Onyekuru0Timothy Chibuike Anyanwu1Kenneth Okechukwu Nwosu2Ifeyinwa Juliana Ofoh3Francis Begianpuye Akiang4Obinna Chigoziem Akakuru5Onyema Uchenna Achukwu–Ononye6Kalu Kalu Ibe7Godwin Okumagbe Aigbadon8Department of Geology, Federal University of Technology, P.M.B. 1526, Owerri, NigeriaDepartment of Geology, Federal University of Technology, P.M.B. 1526, Owerri, Nigeria; Corresponding author.Department of Geology, Federal University of Technology, P.M.B. 1526, Owerri, NigeriaDepartment of Geology, Federal University of Technology, P.M.B. 1526, Owerri, NigeriaDepartment of Geology, Federal University of Technology, P.M.B. 1526, Owerri, NigeriaDepartment of Geology, Federal University of Technology, P.M.B. 1526, Owerri, NigeriaDepartment of Geology, Federal University of Technology, P.M.B. 1526, Owerri, NigeriaDepartment of Geology, Federal University of Technology, P.M.B. 1526, Owerri, NigeriaDepartment of Geology, University of Benin, P.M.B. 1154, Benin City, NigeriaThis study investigated the hydrocarbon source rock potential of the Late Cretaceous Mamu and Nkporo formations in the Asaga–Ohafia Axis, Afikpo Basin, southeastern Nigeria, using integrated facies analysis, organic geochemical and palynofacies data. Five lithofacies were identified: dark grey shale, oolitic limestone, heterolithic mudstone/sandstone, laminated bioturbated sandstone, and calcareous mudstone, indicating estuarine, deltaic, and shallow marine depositional environments. Total organic carbon (TOC) contents range from 1.47 to 2.40 wt%, which reflects moderate to good organic richness. For the Mamu Formation, kerogen composition is dominated by Type II/III, composed of 30 %–50 % amorphous organic matter (AOM), 5 %–10 % liptinite, 30 %–50 % vitrinite, and 10 %–20 % inertinite. Spore coloration and Thermal Alteration Index (TAI: 3–3+) suggest thermal maturity within the oil window (Ro: 0.80 %–1.50 %). In contrast, the Nkporo Formation shows comparable kerogen composition (20 %–45 % AOM, 0–20 % liptinite, and 40 %–65 % vitrinite) but lower maturity (TAI: 2–2+; Ro: 0.45 %–0.80 %). Rock–Eval pyrolysis further supports these findings. The Mamu Formation displays higher Hydrogen Index, favorable Tmax, and Production Index values, confirming its maturity and oil and gas–prone potential. Palynological assemblages, including marine dinoflagellate cysts (Mamu Formation) and freshwater algae/fungal spores (Nkporo Formation), align with the inferred depositional settings. Thus, the Mamu Formation is the more prolific source rock, characterized by superior organic quality and thermal maturity.http://www.sciencedirect.com/science/article/pii/S266675922500068XDepositional faciesPalynomorphsKerogen typingTotal organic carbon (TOC)Hydrocarbon sourceAfikpo Basin |
| spellingShingle | Samuel Okechukwu Onyekuru Timothy Chibuike Anyanwu Kenneth Okechukwu Nwosu Ifeyinwa Juliana Ofoh Francis Begianpuye Akiang Obinna Chigoziem Akakuru Onyema Uchenna Achukwu–Ononye Kalu Kalu Ibe Godwin Okumagbe Aigbadon Hydrocarbon source rock potential of the Late Cretaceous sediments in the Asaga–Ohafia Axis, Afikpo Basin, Nigeria: Insights from facies and kerogen analyses Energy Geoscience Depositional facies Palynomorphs Kerogen typing Total organic carbon (TOC) Hydrocarbon source Afikpo Basin |
| title | Hydrocarbon source rock potential of the Late Cretaceous sediments in the Asaga–Ohafia Axis, Afikpo Basin, Nigeria: Insights from facies and kerogen analyses |
| title_full | Hydrocarbon source rock potential of the Late Cretaceous sediments in the Asaga–Ohafia Axis, Afikpo Basin, Nigeria: Insights from facies and kerogen analyses |
| title_fullStr | Hydrocarbon source rock potential of the Late Cretaceous sediments in the Asaga–Ohafia Axis, Afikpo Basin, Nigeria: Insights from facies and kerogen analyses |
| title_full_unstemmed | Hydrocarbon source rock potential of the Late Cretaceous sediments in the Asaga–Ohafia Axis, Afikpo Basin, Nigeria: Insights from facies and kerogen analyses |
| title_short | Hydrocarbon source rock potential of the Late Cretaceous sediments in the Asaga–Ohafia Axis, Afikpo Basin, Nigeria: Insights from facies and kerogen analyses |
| title_sort | hydrocarbon source rock potential of the late cretaceous sediments in the asaga ohafia axis afikpo basin nigeria insights from facies and kerogen analyses |
| topic | Depositional facies Palynomorphs Kerogen typing Total organic carbon (TOC) Hydrocarbon source Afikpo Basin |
| url | http://www.sciencedirect.com/science/article/pii/S266675922500068X |
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