Palynology of the Albian–Turonian sediments from the Sumbe region, Kwanza Basin (Angola): Implications for paleoenvironment, paleoclimate, and paleogeography

Abstract

Palynological investigations in the Sumbe region of the Kwanza Basin, Angola, have identified Albian to Turonian assemblages in four sections of the Quissonde Facies of the Mucanzo, Cabo Ledo, and Itombe formations. These studies aimed to determine their biostratigraphic ages and infer paleoenvironmental, paleoclimatic, and paleogeographic models. The presence of Odontochitina costata, Palaeohystrichophora infusorioides, and Xiphophoridium alatum cysts supports an upper Albian to lower Cenomanian age for the Mucanzo Formation. Litosphaeridium siphoniphorum cyst and the Elateroplicites africaensis pollen found In the Cabo Ledo Formation suggest a Cenomanian age, while Conosphaeridium striatoconum, Heterosphaeridium difficile, and Dinogymnium acuminatum supports a Turonian age for the lower part of the Itombe Formation. All samples predominantly contain fluorescent amorphous organic matter (AOM) derived from phytoplankton degradation, with increasing AOM in the uppermost units, indicating inner neritic marine deposition under dysoxic-anoxic conditions. During the Lower to mid-Cretaceous, the Gondwana breakup caused significant changes, with the palynological indicating a Tethyan affinity with some high-latitude taxa, suggesting a cosmopolitan distribution. The subtropical to tropical nature of the assemblages, along with high-latitude species, indicates a mid-Cretaceous water connection between the Central Atlantic and the South Atlantic oceans, extending to the Kwanza Basin.