Assessing the Impact of Local Versus Global Volcanic Events on Redox Conditions Within the Viking Corridor, North Sea Basin During Early to Middle Jurassic

We present new, high resolution, continuous 13Corg, mercury (Hg) and redox-sensitive elements (RSE) data from the Viking Corridor, North Sea (NS) to provide insight on the spatial and temporal evolution of redox conditions between Early-Middle Jurassic. We assess a global and regional eventthe Early Jurassic Toarcian Oceanic Anoxic Event (TOAE), and the Early-Middle Jurassic uplift of the North Sea Dome (NSD; ~182-170 Ma), respectively. The TOAEmarked by a -ve 13C and a major warming episode, is often linked to the release of CO2 from the Karoo-Ferrar Large Igneous Province (KF-LIP) that resulted in anoxic marine conditions. To date, extensive research is focused on the TOAE, however, these records are 1) limited from NW European epicontinental shelf; 2) solely based on 13C; 3) low-resolution; or 4) spanning short intervals. There is also a critical gap in records that provide a broader context of the TOAE, specifically during Early-Middle (186-169 Ma) Jurassic and the NSD in the Viking Corridor, NS. The localized NSDa domal uplift of the central NS, that acted as a barrier to heat flow patterns between Tethyan and Boreal Seas, has been invoked as a key mechanism triggering two cooling modes during the Pliensbachian and Aalenian stages. While we understand the role that the NSD in the tectonostratigraphic configuration of the NS, the impact on redox conditions during its onset and evolution remains elusive. Our data confirms the presence of TOAE that coincides with the onset of KF-LIP along with elevated Hg from proximal and distal locations. Theres a spatial heterogeneity within the Hg trend across a basinal transect, where proximal settings are elevated in Hg and RSE. Temporally, in proximal settings, post-TOAE successions are Hg-enriched across the Early-Middle Jurassic, possibly linked to the NSD. Alternatively, enhanced weathering may have a role in bringing terrestrially derived Hg into the marine system. Moreover, RSE enrichment factors (Mo, V and U) suggest a particulate shuttle mechanism acting beneath an oxygen-minimum zone. Distal settings, however, have punctuated peaks of slightly elevated Hg during Aalenian, suggesting a NSD signal. Together, this work provides insights on the interplay between TOAE, LIP, and Hg-RSE systems during an important transition in the Earths biogeochemical history.