Partial paleobathymetric restriction from the local North Sea Dome in the Viking Corridor during the Early-Middle Jurassic
The Early-Middle Jurassic (∼201–161.5 Ma) was characterized by major fluctuations in Earth's climate, tectonic activity, and large-scale magmatic events. There has been considerable focus on understanding the mechanisms that triggered the Early Jurassic Toarcian Oceanic Anoxic Event (TOAE; ∼183...
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| Published in: | Global and planetary change Vol. 230; p. 104255 |
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| Main Authors: | , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier B.V
01-11-2023
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | The Early-Middle Jurassic (∼201–161.5 Ma) was characterized by major fluctuations in Earth's climate, tectonic activity, and large-scale magmatic events. There has been considerable focus on understanding the mechanisms that triggered the Early Jurassic Toarcian Oceanic Anoxic Event (TOAE; ∼183 Ma)—a warming episode associated with a perturbation of the carbon cycle. This was marked by a negative δ13C isotope excursion (CIE) and CO2 release from the Karoo-Ferrar Large Igneous Province (KF-LIP)—resulting in widespread organic carbon burial under strong euxinic marine conditions. Despite extensive study of the TOAE from the NW European epicontinental shelf, less focus has been placed on the influence of North Sea Dome (NSD) uplift (late Toarcian-early Aalenian) and eruption (Bajocian-Bathonian) on Jurassic paleoceanography. The NSD is a local feature commonly invoked as a driver of regional paleoclimatic conditions—a bathymetric barrier between warm Tethyan Ocean and cooler Boreal Sea waters. This study contributes new, high-resolution geochemical data derived from Viking Corridor (VC) cores and cuttings that fills a critical spatial and temporal gap in records spanning the Early-Middle Jurassic. Redox-sensitive trace elements (RSTEs; Mo/Al, U/Al, V/Al) as well as Cd*Mn and Cd/Mo ratios were used to reconstruct paleoceanographic and redox conditions. We track magmatic events and their implications using the relative enrichment of Hg, and attempt to decouple global versus regional/local volcanic systems with the enrichment factor values of mafic trace metals (MTM-EFs; Co, Cu, Ni, and Cr). Varying concentrations of RSTEs and a particulate shuttle mechanism during the Early-Middle Jurassic suggest that the VC had fluctuating paleoredox conditions, and that the NSD did not fully restrict the VC. We document a negative CIE as well as high Hg influxes during the TOAE—likely associated with KF-LIP eruptions (Early Jurassic). In addition, pulses of elevated Hg and MTM-EF values were observed during the Aalenian and Bajocian (Middle Jurassic) that were likely a result of NSD uplift and eruptions. The subaerial exposure of the NSD created progressively restricted conditions during the Aalenian-Bajocian, but the seaway between the VC and European epicontinental shelf remained open. Together, this work provides evidence that the NSD had a critical role in driving paleobathymetric and paleoceanographic conditions during the Early-Middle Jurassic. Furthermore, this study provides a geochemical insight into the interplay between δ13C isotope excursions, the KF-LIP, the NSD, and Hg-RSTE-MTM systems during an important transition in the Earth's biogeochemical history.
•Multiproxy analysis of fluctuating redox conditions in Viking Corridor, North Sea.•Presence of the Toarcian and Bajocian carbon isotope excursions.•North Sea Dome is a driver of paleobathymetric and paleoceanographic conditions.•Limited restriction between warm Tethyan Ocean and cooler Boreal Sea.•Use of mafic trace mineral enrichment factors to identify volcanism. |
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| ISSN: | 0921-8181 1872-6364 |
| DOI: | 10.1016/j.gloplacha.2023.104255 |