ABSTRACT: Quantitative palynofloral analysis of 42 core chip samples from upper Barremian and Aptian sediments of the Heslerton No. 2 shallow borehole (Speeton Clay Formation, Eastern England) and Gannet Field well 22/26a-2 (Valhall Formation, United Kingdom Sector, Central North Sea) has yielded very rich and diverse marine assemblages composed largely of dinocysts and acritarchs. The high biostratigraphic resolution achieved has allowed detailed correlation between the sections analysed and with third-party data from the Wiechendorf 1/86 borehole (Lower Saxony Basin), a distance of approximately 700 km; the positions and extent of several hiatuses have been assessed within this framework. The Barremian/Aptian boundary has been discussed and "conventional" palynological criteria assessed with respect to contrary microfaunal and nannofloral evidence. Close spacing of samples has allowed some assessment of inter- and intra-species trends and, although palaeoenvironmental change profoundly influences assemblages, specific controls remain poorly understood. Over-prescriptive generic placement of taxa based on what are essentially subjective criteria is critically discussed. The zonation scheme proposed by Duxbury (2001) has been re-visited and significantly refined; recognition of additional marker events has allowed further sub-division of several zones to subzonal level, allowing a better understanding of late Barremian palynostratigraphy. Seventy-nine key palynofloral events have now been recognised between the late Barremian and "mid" Aptian, including many first occurrences. One genus, 23 species and 2 subspecies of dinocysts are described as new, nine new combinations have been effected and the diagnoses of two species have been emended; one species has been reduced to sub-species rank.
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