Palynofloras, palaeoenvironmental change and the inception of the Paleocene Eocene Thermal Maximum; the record of the Forties Fan, Sele Formation, North Sea Basin

Abstract

The Paleocene–Eocene Thermal Maximum (PETM) has previously been recorded in marine density flow sedimentary rocks of the Forties Member, Sele Formation, North Sea Basin. Two cored well sections with existing δ 13 C records were analysed for their total palynofloras. Using statistically defined microplankton groups and diversity data, the Sele Formation Unit S1 depositional sequence and its maximum flooding surface was identified in both wells. This highlighted that deposition of the Forties Fan complex began significantly earlier than the inception of the PETM in the proximal fan area. Palynofloras from the Central and West Axial fairways of the Forties Fan have previously been used to indicate increased rainfall, erosion and onset of Forties Fan deposition at the PETM inception. However, winterwet floodplain communities typify the coeval East Axial Fairway, whereas the dominance of swamp-derived communities in the West and Central Axial Fairway sediments reflects source palaeogeography overriding the regional winterwet climate signal. Palynofloras reflecting regional increased seasonality and lower moisture availability increase immediately before the PETM CIE onset, but reflect climate warming over the hyperthermal. However, there is no correlation between Forties Fan initiation and the PETM. NE Atlantic margin basin flank uplift in response to synrift volcanism is indicated as the driving mechanism behind Forties Fan inception. Supplementary material : Raw data, DCA graphs for microplankton, pollen and spore data and δ 13 C data for well 22/6-1 are available at https://doi.org/10.6084/m9.figshare.c.6080873