TY - JOUR

T1 - Enhanced Arctic-Tethys connectivity ended the Toarcian Oceanic Anoxic Event in NW Europe

AU - Van De Schootbrugge, B.

AU - Houben, A. J.P.

AU - Ercan, F. E.Z.

AU - Verreussel, R.

AU - Kerstholt, S.

AU - Janssen, N. M.M.

AU - Nikitenko, B.

AU - Suan, G.

N1 - Publisher Copyright: © Cambridge University Press 2019. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2020/10/1

Y1 - 2020/10/1

N2 - 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.

AB - 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.

KW - Arctic

KW - carbon isotopes

KW - dinoflagellate cysts

KW - Mesozoic

KW - palaeoceanography

KW - Toarcian Oceanic Anoxic Event

KW - NEUQUEN BASIN

KW - CARBON-ISOTOPE EXCURSION

KW - RECORD

KW - STRATIGRAPHY

KW - SEA

KW - LUSITANIAN BASIN

KW - BOUNDARY

KW - PHYTOPLANKTON

KW - DINOFLAGELLATE CYST BIOSTRATIGRAPHY

KW - CYCLE

UR - http://www.scopus.com/inward/record.url?scp=85076487969&partnerID=8YFLogxK

U2 - 10.1017/S0016756819001262

DO - 10.1017/S0016756819001262

M3 - Article

AN - SCOPUS:85076487969

VL - 157

SP - 1593

EP - 1611

JO - Geological Magazine

JF - Geological Magazine

SN - 0016-7568

IS - 10

ER -