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

Abstract

Seismic geomorphology and stratigraphic analysis can reveal how source-to-sink systems dynamically respond to climatic and tectonic forcing. This study uses seismic reflection data from the Norwegian Sea to investigate the stratigraphic response to a short-lived (0.2 Myr) period of climate change during the Paleocene-Eocene Thermal Maximum (PETM), superimposed on a long-lived (∼8 Myr) period of hinterland uplift. The data show that long-term uplift resulted in ∼300 m of relative sea-level fall, forced regression and formation of incised valleys during the latest Paleocene-earliest Eocene. The short-lived PETM climate perturbation at ∼56 Ma changed the transport dynamics of the system, allowing sediment to be bypassed to wide channel complexes on the basin floor, feeding a large mud-rich basin-floor fan more than 50 km into the basin. Our analysis also suggest that sediment supply was up to four times higher during the PETM compared to earlier and later periods. Maximum regression at ∼55.5 Ma resulted in the formation of a subaerial unconformity. The style of subaerial incision was dictated by shelf accommodation and proximity to the area of direct sediment input. Out-of-grade shelves and slopes sourced by littoral drift were prone to incision, but direct-fed and graded shelves and slopes were not. Despite maximum regression, sediments were not transported significantly beyond the toe-of-slope aprons, suggesting that rapid climate change was more efficient in bypassing sediment to the deep-water than low stands of sea level. As long-term accommodation increased after the PETM, deltas were still able to reach shelf edge, but periods of maximum regression were not associated with deep incisions along the outer shelf and only smaller canyons and gullies formed. The shelf-slope wedge was finally transgressed at ∼51 Ma. The age of deep valley incisions overlaps with the time of subaerial erosion in the East Shetland and Faroe-Shetland basins, suggesting a common mechanism for North Atlantic uplift around 55–56 Ma. Other seismic stratigraphic surfaces do not seem to be regionally time-equivalent, highlighting the importance of local controls on internal architecture of shelf-slope wedges. This study demonstrates the high-resolution stratigraphic response to long- and short-term external forcing together with intrinsic processes and can help identify similar relationships in other areas.

Flexural isostatic response of continental-scale deltas to climatically driven sea level changes

“…The results of our simulations demonstrate that climateforced sea level changes result in self-sustaining creation and destruction of accommodation into which sediment is deposited and therefore plays a major role in delta morphology and stratigraphic architecture. This self-sustaining process might help explain the discrepancies between clinothem thicknesses, relative sea level, and global mean sea level estimates (Sømme et al, 2023).…”

The interplay between siliciclastic and carbonate depositional systems: Maastrichtian to Danian basin‐floor sediments of the mid‐Norwegian Møre Basin

“…Two prominent ridges, the Bylgja Ridge and the Ervik Ridge, separates the Bylgja Sub‐basin to the west from the Ervik Sub‐basin in the center and the Runde Sub‐basin to the east (Figure 1). Paleo‐bathymetric studies suggest that the water depth around the late Cretaceous to Early Paleogene ranged around 150–300 m, but is complicated by the uncertainty regarding the effect of dynamic support from an anomalously hot mantle (Kjennerud & Vergara, 2005; Roberts et al., 2009; Sømme et al., 2023; Wien & Kjennerud, 2005). The mid‐Norwegian margin underwent basin inversion throughout the Cenozoic which formed domes, such as the Helland‐Hansen Arch (e.g.…”

Carbon isotope chemostratigraphy, geochemistry, and biostratigraphy of the Paleocene–Eocene Thermal Maximum, deepwater Wilcox Group, Gulf of Mexico (USA)

“…Development of the proto-GOM basin began in Triassic-Early Jurassic times with crustal extension and terrigenous sedimentation across a wide zone of continental crust extension before the modern-day Yucatán Peninsula rifted from the rest of Laurentia during a relatively brief period (ca. 166-142 Ma) during the breakup of Pangea (Pindell, 1985;Salvador, 1987Salvador, , 1991Buffler and Thomas, 1994;Bird, 2005;Stern and Dickinson, 2010;Minguez et al, 2020;Pindell et al, 2021). From that time onward, the basin captured a nearly continuous depositional record of local and supraregional tectono-sedimentary events and changing continental landscapes (Galloway, 2008, and references therein).…”

“…10). Sømme et al (2023) used a combination of three-dimensional reflection seismic data and well penetrations in the Norwegian Sea to show that the PETM was manifested by progradation of large, mud-rich basin-floor fan with rates of sediment supply increasing as much as 4-fold relative to background values. Most open-marine, non-terrigenous PETM localities also show an increase in clay relative to carbonate during the PETM that is thought to reflect a combination of carbonate dissolution due to ocean acidification and enhanced rates of terrestrial sediment delivery to the global ocean (Zachos et al, 2005;Sluijs et al, 2008a).…”

“…For example, Armitage et al (2013) conducted a numerical experiment that predicted Milankovitchperiod cyclicity (20-400 kyr) to be dampened in most of the world's largest rivers, which have equilibrium timescales on the order of 10 4 -10 6 years (Castelltort and van der Dressche, 2003). However, several field studies have demonstrated transmission of climate-driven signals within large deep-sea fans, including changing sediment provenance and sediment flux (Goodbred, 2003;Hessler et al, 2018;Mason et al, 2019;Sømme et al, 2023;Vimpere et al, 2023). Tofelde et al (2021) suggested that this apparent contradiction may be related to differences in what is meant by a "signal" and the fact that a measurable change in each signal may occur well before the upstream landscape equilibrates.…”