Dynamics of the Largest Carbon Isotope Excursion During the Early Triassic Biotic Recovery

Details

Ressource 1Download: 2020 Widmann Frontiers.pdf (7285.03 [Ko])
State: Public
Version: Final published version
License: CC BY 4.0
Serval ID
serval:BIB_98E2D2A7FA4C
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Dynamics of the Largest Carbon Isotope Excursion During the Early Triassic Biotic Recovery
Journal
Frontiers in Earth Science
Author(s)
Widmann Philipp, Bucher Hugo, Leu Marc, Vennemann Torsten, Bagherpour Borhan, Schneebeli-Hermann Elke, Goudemand Nicolas, Schaltegger Urs
ISSN
2296-6463
Publication state
Published
Issued date
09/06/2020
Peer-reviewed
Oui
Volume
8
Language
english
Abstract
The dynamics of the carbon cycle across different timescales is crucial for understanding past and present global climate changes. Following the Permian–Triassic boundary mass extinction (PTBME), the carbon cycle changed profoundly during the following 5.4 Myr, with magnitudes of changes comparable to those of the Precambrian. In pace with the successive cycles of the carbon budget, the recovery of the marine nekton underwent several evolutionary diversification and extinction cycles accompanied by eustatic sea-level changes and profound ecological reorganization of land plants, all indicative of climatic changes. Additional eruptive bursts of the Siberian Large Igneous Province (SLIP) are traditionally called upon as a plausible trigger for these climatic oscillations but firm evidence for coeval SLIP volcanism is still lacking. Based on new precise and accurate U-Pb zircon ages, we establish a high-resolution temporal calibration of the biggest positive carbon isotope excursion (CIE) spanning about 600 kyr in the late Smithian. The age of the Smithian-Spathian boundary (SSB) is established between 249.29 ± 0.06 and 249.11 ± 0.09 Ma. Our oldest U-Pb zircon ages indicate no overlap in time between the middle Smithian onset of the thermal maximum and the youngest available U-Pb zircon ages from SLIP volcanism. The constructed time line also indicates a duration of the global unconformity at the SSB that is compatible with glacio-eustatism. Potential cooling mechanisms such as a volcanic winter, the biological pump and the cessation of volcanism are discussed in the light of this new time line. In the low latitudes, the onset of the positive CIE remarkably predates the temperature drop by some 100 to 125 kyr. However, as long as the magnitude of such offset – if any – is unknown for the high latitudes, relations between the CIE and the cooling will remain an open question associated with largest Triassic extinction of the nekton.
Keywords
Early Triassic, Smithian-Spathian boundary, U-Pb geochronology, carbon cycle, carbon isotopes, biochronology, Bayesian age-depth model
Web of science
Open Access
Yes
Create date
18/11/2021 15:34
Last modification date
10/01/2023 6:50
Usage data