Sprecher
Beschreibung
Palynological analysis of the Falcão-1 well provides new insights into depositional environments and sediment sourcing offshore São Tomé from the Late Cretaceous to Oligocene. Quantitative palynodata are consistently well recovered from cuttings, despite moderate to poor preservation linked to transport-related abrasion.
The Palaeogene succession (Late Palaeocene–Late Oligocene) is characterised by predominantly open marine conditions, reflected by diverse dinocyst assemblages. However, recurrent high abundances of leiospheres indicate input from more proximal settings characterised by stressed surface water conditions. Terrestrial input is limited and dominated by low-diversity miospores derived from coastal swamp vegetation. A notable increase in fungal spores and epiphyllous fungi in the Oligocene suggests enhanced soil development and sustained input from adjacent coastal plains, coincident with phases of increased arenaceous deposition. Stratigraphic discontinuities, including probable hiatuses at the Bartonian-Rupelian and possibly Ypresian-Lutetian boundaries, are interpreted to reflect intensified bottom-water circulation inhibiting sediment accumulation.
In contrast, the Late Cretaceous succession records stronger terrigenous influence under offshore marine conditions. A pronounced influx of freshwater-derived palynomorphs, including abundant Pediastrum and rare Azolla, marks an abrupt increase in fluvial input during the Late Campanian. This interval coincides with the development of a regionally significant deepwater sand system, interpreted as gravity flow deposits equivalent to the Batanga Sands.
Overall, the palynological record captures a transition from terrigenous-influenced Late Cretaceous systems to more stable open marine conditions in the Palaeogene, modulated by episodic increases in continental input and basin dynamics.