Dynamics of the Largest Carbon Isotope Excursion During the Early Triassic Biotic Recovery
Détails
Etat: Public
Version: Final published version
Licence: CC BY 4.0
ID Serval
serval:BIB_98E2D2A7FA4C
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Dynamics of the Largest Carbon Isotope Excursion During the Early Triassic Biotic Recovery
Périodique
Frontiers in Earth Science
ISSN
2296-6463
Statut éditorial
Publié
Date de publication
09/06/2020
Peer-reviewed
Oui
Volume
8
Langue
anglais
Résumé
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.
Mots-clé
Early Triassic, Smithian-Spathian boundary, U-Pb geochronology, carbon cycle, carbon isotopes, biochronology, Bayesian age-depth model
Web of science
Open Access
Oui
Création de la notice
18/11/2021 16:34
Dernière modification de la notice
18/05/2024 6:59