An open ocean record of the Toarcian oceanic anoxic event

D R Gröcke, R S Hori, J Trabucho-Alexandre, D B Kemp, L Schwark

Research output: Contribution to journalArticle

53 Citations (Scopus)
3 Downloads (Pure)

Abstract

Oceanic anoxic events were time intervals in the Mesozoic characterized by widespread distribution of marine organic matter-rich sediments (black shales) and significant perturbations in the global carbon cycle. These perturbations are globally recorded in sediments as carbon isotope excursions irrespective of lithology and depositional environment. During the early Toarcian, black shales were deposited on the epi- and pericontinental shelves of Pangaea, and these sedimentary rocks are associated with a pronounced (ca. 7 ‰) negative (organic) carbon isotope excursion (CIE) which is thought to be the result of a major perturbation in the global carbon cycle. For this reason, the lower Toarcian is thought to represent an oceanic anoxic event (the T-OAE). If the TOAE was indeed a global event, an isotopic expression of this event should be found beyond the epi- and pericontinental Pangaean localities. To address this issue, the carbon isotope composition of organic matter (σ 13Corg) of lower Toarcian organic matter-rich cherts from Japan, deposited in the open Panthalassa Ocean, was analysed. The results show the presence of a major (6 ‰) negative excursion in σ 13Corg that, based on radiolarian biostratigraphy, is a correlative of the lower Toarcian negative CIE known from Pangaean epiand pericontinental strata. A smaller negative excursion in σ 13Corg (ca. 2‰) is recognized lower in the studied succession. This excursion may, within the current biostratigraphic resolution, represent the excursion recorded in European epicontinental successions close to the Pliensbachian/Toarcian boundary. These results from the open ocean realm suggest, in conjunction with other previously published datasets, that these Early Jurassic carbon cycle perturbations affected the active global reservoirs of the exchangeable carbon cycle (deep marine, shallow marine, atmospheric).

Original languageEnglish
Pages (from-to)245-257
Number of pages13
JournalSolid earth
Volume2
Early online date11 Nov 2011
DOIs
Publication statusPublished - 1 Dec 2011

Fingerprint

Carbon Isotopes
carbon cycle
carbon isotopes
Toarcian
open ocean
isotopes
oceans
Carbon
carbon isotope
Biological materials
perturbation
shales
carbon
organic matter
Sediments
sediments
Biostratigraphy
sedimentary rocks
Sedimentary rocks
Lithology

ASJC Scopus subject areas

  • Stratigraphy
  • Palaeontology
  • Geophysics
  • Geology
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Soil Science

Cite this

Gröcke, D. R., Hori, R. S., Trabucho-Alexandre, J., Kemp, D. B., & Schwark, L. (2011). An open ocean record of the Toarcian oceanic anoxic event. Solid earth, 2, 245-257. https://doi.org/10.5194/se-2-245-2011

An open ocean record of the Toarcian oceanic anoxic event. / Gröcke, D R; Hori, R S; Trabucho-Alexandre, J; Kemp, D B; Schwark, L.

In: Solid earth, Vol. 2, 01.12.2011, p. 245-257.

Research output: Contribution to journalArticle

Gröcke, DR, Hori, RS, Trabucho-Alexandre, J, Kemp, DB & Schwark, L 2011, 'An open ocean record of the Toarcian oceanic anoxic event', Solid earth, vol. 2, pp. 245-257. https://doi.org/10.5194/se-2-245-2011
Gröcke DR, Hori RS, Trabucho-Alexandre J, Kemp DB, Schwark L. An open ocean record of the Toarcian oceanic anoxic event. Solid earth. 2011 Dec 1;2:245-257. https://doi.org/10.5194/se-2-245-2011
Gröcke, D R ; Hori, R S ; Trabucho-Alexandre, J ; Kemp, D B ; Schwark, L. / An open ocean record of the Toarcian oceanic anoxic event. In: Solid earth. 2011 ; Vol. 2. pp. 245-257.
@article{374ed39187a141f9a6d6670ed64c1558,
title = "An open ocean record of the Toarcian oceanic anoxic event",
abstract = "Oceanic anoxic events were time intervals in the Mesozoic characterized by widespread distribution of marine organic matter-rich sediments (black shales) and significant perturbations in the global carbon cycle. These perturbations are globally recorded in sediments as carbon isotope excursions irrespective of lithology and depositional environment. During the early Toarcian, black shales were deposited on the epi- and pericontinental shelves of Pangaea, and these sedimentary rocks are associated with a pronounced (ca. 7 ‰) negative (organic) carbon isotope excursion (CIE) which is thought to be the result of a major perturbation in the global carbon cycle. For this reason, the lower Toarcian is thought to represent an oceanic anoxic event (the T-OAE). If the TOAE was indeed a global event, an isotopic expression of this event should be found beyond the epi- and pericontinental Pangaean localities. To address this issue, the carbon isotope composition of organic matter (σ 13Corg) of lower Toarcian organic matter-rich cherts from Japan, deposited in the open Panthalassa Ocean, was analysed. The results show the presence of a major (6 ‰) negative excursion in σ 13Corg that, based on radiolarian biostratigraphy, is a correlative of the lower Toarcian negative CIE known from Pangaean epiand pericontinental strata. A smaller negative excursion in σ 13Corg (ca. 2‰) is recognized lower in the studied succession. This excursion may, within the current biostratigraphic resolution, represent the excursion recorded in European epicontinental successions close to the Pliensbachian/Toarcian boundary. These results from the open ocean realm suggest, in conjunction with other previously published datasets, that these Early Jurassic carbon cycle perturbations affected the active global reservoirs of the exchangeable carbon cycle (deep marine, shallow marine, atmospheric).",
author = "Gr{\"o}cke, {D R} and Hori, {R S} and J Trabucho-Alexandre and Kemp, {D B} and L Schwark",
year = "2011",
month = "12",
day = "1",
doi = "10.5194/se-2-245-2011",
language = "English",
volume = "2",
pages = "245--257",
journal = "Solid earth",
issn = "1869-9510",
publisher = "Copernicus Gesellschaft mbH",

}

TY - JOUR

T1 - An open ocean record of the Toarcian oceanic anoxic event

AU - Gröcke, D R

AU - Hori, R S

AU - Trabucho-Alexandre, J

AU - Kemp, D B

AU - Schwark, L

PY - 2011/12/1

Y1 - 2011/12/1

N2 - Oceanic anoxic events were time intervals in the Mesozoic characterized by widespread distribution of marine organic matter-rich sediments (black shales) and significant perturbations in the global carbon cycle. These perturbations are globally recorded in sediments as carbon isotope excursions irrespective of lithology and depositional environment. During the early Toarcian, black shales were deposited on the epi- and pericontinental shelves of Pangaea, and these sedimentary rocks are associated with a pronounced (ca. 7 ‰) negative (organic) carbon isotope excursion (CIE) which is thought to be the result of a major perturbation in the global carbon cycle. For this reason, the lower Toarcian is thought to represent an oceanic anoxic event (the T-OAE). If the TOAE was indeed a global event, an isotopic expression of this event should be found beyond the epi- and pericontinental Pangaean localities. To address this issue, the carbon isotope composition of organic matter (σ 13Corg) of lower Toarcian organic matter-rich cherts from Japan, deposited in the open Panthalassa Ocean, was analysed. The results show the presence of a major (6 ‰) negative excursion in σ 13Corg that, based on radiolarian biostratigraphy, is a correlative of the lower Toarcian negative CIE known from Pangaean epiand pericontinental strata. A smaller negative excursion in σ 13Corg (ca. 2‰) is recognized lower in the studied succession. This excursion may, within the current biostratigraphic resolution, represent the excursion recorded in European epicontinental successions close to the Pliensbachian/Toarcian boundary. These results from the open ocean realm suggest, in conjunction with other previously published datasets, that these Early Jurassic carbon cycle perturbations affected the active global reservoirs of the exchangeable carbon cycle (deep marine, shallow marine, atmospheric).

AB - Oceanic anoxic events were time intervals in the Mesozoic characterized by widespread distribution of marine organic matter-rich sediments (black shales) and significant perturbations in the global carbon cycle. These perturbations are globally recorded in sediments as carbon isotope excursions irrespective of lithology and depositional environment. During the early Toarcian, black shales were deposited on the epi- and pericontinental shelves of Pangaea, and these sedimentary rocks are associated with a pronounced (ca. 7 ‰) negative (organic) carbon isotope excursion (CIE) which is thought to be the result of a major perturbation in the global carbon cycle. For this reason, the lower Toarcian is thought to represent an oceanic anoxic event (the T-OAE). If the TOAE was indeed a global event, an isotopic expression of this event should be found beyond the epi- and pericontinental Pangaean localities. To address this issue, the carbon isotope composition of organic matter (σ 13Corg) of lower Toarcian organic matter-rich cherts from Japan, deposited in the open Panthalassa Ocean, was analysed. The results show the presence of a major (6 ‰) negative excursion in σ 13Corg that, based on radiolarian biostratigraphy, is a correlative of the lower Toarcian negative CIE known from Pangaean epiand pericontinental strata. A smaller negative excursion in σ 13Corg (ca. 2‰) is recognized lower in the studied succession. This excursion may, within the current biostratigraphic resolution, represent the excursion recorded in European epicontinental successions close to the Pliensbachian/Toarcian boundary. These results from the open ocean realm suggest, in conjunction with other previously published datasets, that these Early Jurassic carbon cycle perturbations affected the active global reservoirs of the exchangeable carbon cycle (deep marine, shallow marine, atmospheric).

UR - http://www.scopus.com/inward/record.url?scp=84858333146&partnerID=8YFLogxK

U2 - 10.5194/se-2-245-2011

DO - 10.5194/se-2-245-2011

M3 - Article

VL - 2

SP - 245

EP - 257

JO - Solid earth

JF - Solid earth

SN - 1869-9510

ER -