Title
Enhanced Arctic-Tethys connectivity ended the Toarcian Oceanic Anoxic Event in NW Europe
Author
van de Schootbrugge, B.
Houben, A.J.P.
Ercan, F.E.Z.
Verreussel, R.
Kerstholt, S.
Janssen, N.M.M.
Nikitenko, B.
Suan, G.
Publication year
2019
Abstract
The Toarcian Oceanic Anoxic Event (T-OAE, c. 182 Ma) represents a major perturbation of the carbon cycle marked by widespread black shale deposition. Consequently, the onset of the T-OAE has been linked to the combined effects of global warming, high productivity, basin restriction and salinity stratification. However, the processes that led to termination of the event remain elusive. Here, we present palynological data from Arctic Siberia (Russia), the Viking Corridor (offshore Norway) and the Yorkshire Coast (UK), all spanning the upper Pliensbachian - upper Toarcian stages. Rather than a 'dinoflagellate cyst black-out', as recorded in T-OAE strata of NW Europe, both the Arctic and Viking Corridor records show high abundance and dinoflagellate diversity throughout the T-OAE interval as calibrated by C-isotope records. Significantly, in the Arctic Sea and Viking Corridor, numerous species of the Parvocysta and Phallocysta suites make their first appearance in the lower Toarcian Falciferum Zone much earlier than in Europe, where these key dinoflagellate species appeared suddenly during the Bifrons Zone. Our results indicate migrations of Arctic dinoflagellate species, driven by relative sea-level rise in the Viking Corridor and the establishment of a S-directed circulation from the Arctic Sea into the Tethys Ocean. The results support oceanographic models, but are at odds with some interpretations based on geochemical proxies. The migration of Arctic dinoflagellate species coincides with the end of the T-OAE and marks the arrival of oxygenated, low-salinity Arctic waters, triggering a regime change from persistent euxinia to more dynamic oxygen conditions. © Cambridge University Press 2019.
Subject
Geological Survey Netherlands
2015 Energy
Toarcian Oceanic Anoxic Event
Dinoflagellate cysts
Carbon isotopes
Mesozoic
Palaeoceanography
Arctic
To reference this document use:
http://resolver.tudelft.nl/uuid:c1536792-9d49-4e03-a6c5-92515da1726b
DOI
https://doi.org/10.1017/s0016756819001262
TNO identifier
871879
Publisher
Cambridge University Press
ISSN
0016-7568
Source
Geological Magazine, 1-19
Document type
article