Geological Society of America

T153 Mesozoic Earth System and Timescale

Tuesday, 24 September 2024
8:00 AM - 12:00 PM
212A

MARINE STRONTIUM ISOTOPE EVOLUTION AT THE TRIASSIC-JURASSIC TRANSITION LINKS TRANSIENT CHANGES IN CONTINENTAL WEATHERING TO VOLCANISM OF THE CENTRAL ATLANTIC MAGMATIC PROVINCE

Paper number: T153-4
Program: Technical Sessions
Time: 8:40 AM – 8:55 AM

Authors

Bernát Heszler
University of Bristol, Bristol
Joachim Katchinoff
Yale University, New Haven, CT
László Palcsu
HUN-REN Institute for Nuclear Research, Debrecen
Anikó Horváth
HUN-REN Institute for Nuclear Research, Debrecen
Zsolt Vallner
Eötvös Loránd University, Budapest
Emma Blanka Kovács
Trinity College Dublin, The University of Dublin, Dublin, Dublin
Noah J. Planavsky
Yale University, New Haven, CT
Jozsef Palfy Presenting Author
Eötvös Loránd University, Budapest

Abstract

The end-Triassic extinction (ETE) is one of the most severe biotic crises in the Phanerozoic. This event was synchronous with volcanism of the Central Atlantic Magmatic Province (CAMP), the ultimate cause of the extinction and related environmental perturbations. However, the continental weathering response to CAMP-induced warming remains poorly constrained. Strontium isotope stratigraphy is a powerful correlation tool that can also provide insights into the changes in weathering regime but the scarcity of ⁸⁷Sr/⁸⁶Sr data across the Triassic-Jurassic boundary (TJB) hindered the use of this method. Here we present new high-resolution ⁸⁷Sr/⁸⁶Sr data from bulk carbonates at Csővár, a continuous marine section that spans 2.5 Myrs across the TJB. We document a continuing decrease in ⁸⁷Sr/⁸⁶Sr ratio from the late Rhaetian to the ETE, terminated by a 300 kyr interval of a flat trend and followed by a transient increase in the early Hettangian that levels off. We suggest that the first in the series of perturbations is linked to the influx of non-radiogenic Sr from the weathering of freshly erupted CAMP basalts, leading to a delay in the radiogenic continental weathering response. The subsequent rise in ⁸⁷Sr/⁸⁶Sr after the TJB is explained by intensified continental crustal weathering from elevated CO₂ levels and reduced mantle-derived Sr flux. Using Sr flux modeling, we also find support for such multiphase, prolonged continental weathering scenario. Aggregating the new dataset with published records employing an astrochronological age model results in a highly resolved Sr isotope reference curve for an 8.5 Myr interval around the TJB.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-404030

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