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 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 δ13C 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 prior to the inception of the PETM in the proximal fan area. Palynofloras from the central and western 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, the dominance of swamp-derived communities in the west and central axial fairway sediments reflecting source paleogeography 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. Northeast Atlantic margin basin flank uplift in response to syn-rift volcanism is indicated as the driving mechanism behind Forties fan inception.Supplementary material, including raw data, DCA graphs for microplankton, pollen and spore data and δ13C data for well 22/6-1 are available at https://doi.org/10.6084/m9.figshare.c.6080873

Stratigraphic expression of the Paleocene-Eocene Thermal Maximum climate event during long-lived transient uplift—An example from a shallow to deep-marine clastic system in the Norwegian Sea

“…A fundamental shift in depositional style to larger channels and lobes, combined with increased transport distance of clastic material observed in the Froan and Gimsan basins, is thus in line with recent work from other locations in the North Atlantic where the PETM was associated with higher onshore weathering rates, increased erosion and delivery of sand and clay to the marine realm (Pogge von Strandmann et al, 2021;Rush et al, 2021;Jin et al, 2022). As the fluvial system delivered sediment directly to the shelf edge during the PETM, more seasonal variations in discharge (Eldrett et al, 2014;Jolley et al, 2022) could have resulted in rapid deposition and slope failure on the upper slope together with larger and more frequent hyperpycnal flows (Petter and Steel, 2006;Henriksen et al, 2011), triggering the inferred change in gravity-flow size and composition inferred during the PETM. However, in contrast to Jin et al (2022) who demonstrated increased sand delivery to the deep-water North Sea basin, the Froan example documents increased mud-delivery to the distal deep-water Gimsan basin during the PETM.…”

“…However, it is possible that the indication of base-level rise observed in Figure 7C, section B marks the waning phase of the PETM when the sediment supply rate decreased. Interestingly, a maximum flooding surface has also been interpreted above a sand-rich PETM succession in the deepmarine part of the North Sea (Vieira and Jolley, 2020;Jolley et al, 2022).…”

“…Studies of the PETM suggest that this hypothermal event was associated with increased onshore weathering rates, higher seasonal variability in fluvial discharge and change in sediment delivery to shallow and deepwater basins (Pujalte et al, 2015;Carmichael et al, 2017;Rush et al, 2021;Jin et al, 2022), producing a stratigraphic response that can be distinguished from more long-term tectonic forcing (Samanta et al, 2016). Even though the PETM has been recognized several places in wells and outcrops in the North Atlantic (e.g., Beerling and Jolley, 1998;Dypvik et al, 2011;Harding et al, 2011;Kender et al, 2012;Eldrett et al, 2014;Stokke et al, 2021;Jolley et al, 2022), little is known about how the PETM influenced the dynamics of sedimentary systems in this region. However, recent studies from the North Sea suggest increased sediment supply and a change in depositional style during the event (Sømme et al, 2019;Vieira and Jolley, 2020;Jin et al, 2022).…”

Integrated photogrammetry, lava geochemistry and palynological re-evaluation of the early evolution of the topographically constrained Mull Lava Field, Scotland

“…Thin bright coals (<0.3 cm) occur at the top of some fining upwards beds, but are completely composed of drifted and possibly burnt wood. Together, this evidence indicates that the Ardtun Interbed equivalent was deposited in a low-energy lacustrine environment with the lowermost interval revealing an estuarine or tidal channel influence (e.g., similar palynofloral compositions within the Hvannhagi Formation of the Faroe Islands; Jolley et al 2022aJolley et al , 2022b.…”

Paleogeography and 3D variability of a dynamically uplifted shelf: observations from seismic stratigraphy of the Paleocene East Shetland Platform

“…This has important implications for studies on sedimentation rates across the North Atlantic (e.g. Jin et al, 2022;Jolley et al, 2023;Sømme et al, 2023), as uplift-driven erosion still needs to be disentangled from the climatic signal for a clearer understanding of their impacts on sediment fluxes.…”