Dinoflagellate cyst biostratigraphy and palaeoecology of the early Paleogene Landana reference section, Cabinda Province, Angola
Forty-four rock samples from the Landana section, belonging to the historical Dartevelle collection of the Royal Museum for Central Africa (RMCA) at Tervuren, Belgium, were palynologically processed and analysed. Systematic analysis of the samples from the Landana sea cliff locality has revealed 90 dinoflagellate cyst taxa spanning an interval that ranges at least from the middle Paleocene to the late Eocene/early Oligocene. This locality represents the first extensive sub-equatorial African Paleogene dinoflagellate cyst record. Dinoflagellate cyst occurrences were calibrated and evaluated against newly revised foraminiferal ranges. This novel dinoflagellate cyst biostratigraphic record was compared and correlated with contemporaneous records relatively close by in the Gulf of Guinea, as well as with records from more distant locations such as Antarctica, Australia and New Zealand. A preliminary dinoflagellate cyst zonation is here proposed comprising three zones and five unzoned yet otherwise distinct intervals. The lower part of the Landana section records a large portion of the early to middle/late Selandian, which is made apparent by the presence of taxa such as Isabelidinium cingulatum, Isabelidinium? viborgense, and Spinidinium densispinatum. The Thanetian through Lutetian part of the section is more fragmentary and is devoid of any significant marker taxa normally typical for this time interval elsewhere. The upper part of the record is largely devoid of dinoflagellate cysts, with the few dinoflagellate cyst-bearing samples pointing to an Eocene to early Oligocene age. Dinoflagellate cyst assemblages are relatively variable and often largely dominated by a single particular taxon or complex. We record remarkably abundant peridinioid cysts signalling high palaeoproductivity for protracted periods of time, resulting from either heightened terrestrial influence or enhanced upwelling.