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Palynological insights into the Eocene-Oligocene biostratigraphy , palaeoenvironment, and palaeoclimates of the Kwanza Basin, Angola
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ABSTRACT: New biostratigraphic and palaeoenvironmental data from Cabo de Sao Bras in the Kwanza Basin reveal over 40 m of marine sediments (Cunga and Quifangondo formations) spanning the Eocene-Oligocene transition. Wellpreserved dinoflagellate cysts within these sediments provide precise age determinations and palaeoenvironmental insights. The Cunga Formation, ranging from the late Eocene to the Oligocene, is characterized by sporadic occurrences of Diphyes colligerum, Glaphyrocysta semitecta, Schematophora cf. speciosa, Deflandrea heterophlycta, Rhombodinium draco, and Rhombodinium porosum. The overlying interval reveals a Rupelian assemblage, including Achomosphaera alcicornu and Hystrichokolpoma cf. Pseudooceanicum. The uppermost part of the Cunga Formation is marked by the lowest occurrence of Tuberculodinium vancampoae and the highest occurrence of Achomosphaera alcicornu during the Chattian. In contrast to existing geological maps, the transition to the Quifangondo Formation reveals a continuous sequence from the uppermost Chattian, based on the cooccurrence of Distatodinium paradoxum and Phelodinium africanum, along with a significant acme of Hystrichokolpoma spp. Palaeoenvironmental analysis suggests a marine setting with periods of both low and high productivity. Significant environmental transitions are observed, ranging from outer neritic to oceanic conditions at the base of the Cunga Formation (late Eocene-Oligocene, late Rupelian-early Chattian). In the late Oligocene, despite considerable terrigenous input, palynological data suggest predominantly inner to outer neritic conditions at the top of the Cunga Formation and the base of the Quifangondo Formation. Fluctuations in dinoflagellate cyst influxes reflect changes in water temperatures, providing insights into past climate shifts, during the EoceneOligocene transition, and offering a valuable framework for future palaeoclimatic investigations.
Descrição
Palavras-chave
Palynostratigraphy Palaeoenvironment Palynofacies Biostratigraphy Kwanza basin Angola
Contexto Educativo
Citação
Pereira, Z., Mendes, M., Rodrigues, C., & Nsungani, P.C. (2026). Palynological insights into the Eocene-Oligocene biostratigraphy, palaeoenvironment, and palaeoclimates of the Kwanza Basin, Angola. In: Journal of African Earth Sciences, 2026, vol. 237, article 106043. https://doi.org/10.1016/j.jafrearsci.2026.106043
Editora
Elsevier