New palynological data from Maniamba Basin, Mozambique (Karoo): Correlations and implications for Lopingian floristic ecosystem reconstruction

Abstract

Two borehole cores (JOG16N-5 and JOG16N-7) from the Maniamba Basin, northern Mozambique (central Gondwana) were studied for palynology. As a result, five palynoassemblages were identified from JOG16N-5 (T1, T2, T3, T4, T5) whereas only three were identified for the latter borehole (B1, B2 and B3). Palynoasssemblages T1, B1, B2, B3 were assigned to Wuchiapingian whereas the assemblages T2, T2, T3, T4 and T5 were are assigned to Changhsingian.

The age was assigned based on the common occurrence of Lopingian taxa (e.g., Guttulapollenites, Alisporites, Weylandites, Cycadopites, Marsupipollenites, Scheuringipollenites, Protohaploxypinus, and Striatopodocarpites) together with abundant occurrence of stratigraphically important taxa, Thymospora pseudothiessenii as well as Osmundacidites senectus. Typical Gondwana vegetation is observed in both cores and is characterised by dominance of pollen grains assigned to the Protohaploxypinus and Striatopodocarpites genera whereas the monosaccate pollen indicators of upland vegetation are rare. Palynomorph indicators of a lowland setting are common and include Ginkgoales, Filicopsida, sphenopsids, and lycopsids that can be interpreted as the existence of a vast lowland fluvial setting together with floodplains and wetlands in the Basin. Yet, variations in lithofacies indicate a change in the dynamic of the drainage system that prevailed during the Lopingian in the Maniamba Basin. Furthermore, similar palynoevents in Lopingian northern Karoo-aged basins of south-central Africa, and central Gondwana basins from Madagascar, India, and Antarctica are well correlated. However, in contrast, some distinct Lopingian palynoevents are observed with southern Karoo-aged basins which could suggest the existence of tectonic barriers that prevented floral exchange thus, confirming intra-Gondwanan floristic provincialism.