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<p>This study investigates the Late Cretaceous–Paleogene stratigraphy, paleoclimate, paleoenvironment, and hydrocarbon potential of the offshore Eastern Dahomey Basin, Nigeria, utilizing data from the AB-1 and BG-1 wells by identifying the physical rock and fossil characteristics to subdivide the rock units and reconstruct the ancient environment. Lithological analysis identified five major rock types: shale, sandstone, mudstone, shaley sandstone, and siltstone, delineated into lithofacies units and corresponding lithostratigraphic formations (Afowo, Araromi, Ilaro, and Ogwashi-Asaba). Three (3) informal palynological biozones were recognized in the AB-1 well: B1, B-2 and B-3 palynozones that correlate with the <i>Droseridites senonicus, Longapertites sp. 3—Spinizonocolpites baculatus</i> palynological zones of (Lawal and Moullade, Rev Palaeobot Palynol 46:305–323, 1986), and <i>Proxapertites operculatus</i> zone of Salard-Cheboldaeff, J Afr Earth Sc 11:1–24, 1990a,Salard-Cheboldaeff, Rev Palaeobot Palynol 65:25–33, 1990b) respectively. They are considered Santonian (Late Cretaceous) at the base and Danian (Paleocene) at the top. On the other hand, three (3) informal palynological biozones were recognized in the BG-1well namely AI, AII, and AIII palynozones, that correlate with the <i>Droseridites senonicus</i>, <i>Auriculiidites reticulatus</i>—<i>Proteacidites dehaani</i> and <i>Spinizonocolpites echinatus and Younger</i> palynological zones of Muller et al., (1987). The palyzones from both wells reveal notable unconformities marking the Cretaceous-Paleogene boundary. Palynofacies analysis revealed significant paleoclimatic transitions, with humid, deltaic conditions during the Santonian-Campanian and fluctuating marine-terrestrial influences during the Maastrichtian-Danian. These transitions align with global eustatic sea-level changes and regional tectonic events. Hydrocarbon potential assessments favor the oil and gas-generative potential of the organic-rich shales of the Araromi Formation, promising sandstone reservoirs in the Afowo and Ogwashi-Asaba formations, and effective seals provided by interbedded shales. Comparisons with surrounding West African basins, such as the Niger Delta and Gabon basins, reveal stratigraphic and biozone similarities, underscoring shared depositional and tectonic histories across the region. The findings demonstrate the significance of the Eastern Dahomey Basin in understanding the Late Cretaceous–Paleogene depositional systems and its potential for hydrocarbon exploration, thereby advancing regional geological and energy research.</p>

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Palynostratigraphic and palynofacies framework of the cretaceous-paleogene offshore dahomey basin; implications for paleoclimate, paleoenvironment and hydrocarbon exploration

  • 期刊论文

  • 发表日期：

    2025年6月9日

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  • Tope Shade Alege,
  • Zachi Amos Shigiri,
  • Oluwafolakunmi Adedotun Bello,
  • Mujeeb Adio,
  • Muazu Tunde Abdulsalam

摘要

This study investigates the Late Cretaceous–Paleogene stratigraphy, paleoclimate, paleoenvironment, and hydrocarbon potential of the offshore Eastern Dahomey Basin, Nigeria, utilizing data from the AB-1 and BG-1 wells by identifying the physical rock and fossil characteristics to subdivide the rock units and reconstruct the ancient environment. Lithological analysis identified five major rock types: shale, sandstone, mudstone, shaley sandstone, and siltstone, delineated into lithofacies units and corresponding lithostratigraphic formations (Afowo, Araromi, Ilaro, and Ogwashi-Asaba). Three (3) informal palynological biozones were recognized in the AB-1 well: B1, B-2 and B-3 palynozones that correlate with the Droseridites senonicus, Longapertites sp. 3—Spinizonocolpites baculatus palynological zones of (Lawal and Moullade, Rev Palaeobot Palynol 46:305–323, 1986), and Proxapertites operculatus zone of Salard-Cheboldaeff, J Afr Earth Sc 11:1–24, 1990a,Salard-Cheboldaeff, Rev Palaeobot Palynol 65:25–33, 1990b) respectively. They are considered Santonian (Late Cretaceous) at the base and Danian (Paleocene) at the top. On the other hand, three (3) informal palynological biozones were recognized in the BG-1well namely AI, AII, and AIII palynozones, that correlate with the Droseridites senonicus, Auriculiidites reticulatus—Proteacidites dehaani and Spinizonocolpites echinatus and Younger palynological zones of Muller et al., (1987). The palyzones from both wells reveal notable unconformities marking the Cretaceous-Paleogene boundary. Palynofacies analysis revealed significant paleoclimatic transitions, with humid, deltaic conditions during the Santonian-Campanian and fluctuating marine-terrestrial influences during the Maastrichtian-Danian. These transitions align with global eustatic sea-level changes and regional tectonic events. Hydrocarbon potential assessments favor the oil and gas-generative potential of the organic-rich shales of the Araromi Formation, promising sandstone reservoirs in the Afowo and Ogwashi-Asaba formations, and effective seals provided by interbedded shales. Comparisons with surrounding West African basins, such as the Niger Delta and Gabon basins, reveal stratigraphic and biozone similarities, underscoring shared depositional and tectonic histories across the region. The findings demonstrate the significance of the Eastern Dahomey Basin in understanding the Late Cretaceous–Paleogene depositional systems and its potential for hydrocarbon exploration, thereby advancing regional geological and energy research.