Ma, Xingyu;
Huang, Kangjun;
Chen, Yan;
Sun, Yadong;
Zhou, Ying;
Shields, Graham A;
Huang, Fang;
(2025)
Magnesium isotopic evidence for intensified continental chemical weathering during the Smithian-Spathian transition.
Chemical Geology
, 698
, Article 123133. 10.1016/j.chemgeo.2025.123133.
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Abstract
The Smithian-Spathian (S-S) transition (∼249.7 to 248.7 Ma) of the Early Triassic was marked by profound paleoenvironmental upheavals, including a pronounced temperature decline following the hyperthermal event in the late Smithian, a major positive excursion in carbonate carbon isotope composition (δ13Ccarb), and a significant biotic crisis. Yet, the mechanisms and causal linkages underlying these coeval phenomena remain elusive. In this study, we present high-temporal-resolution magnesium isotope data from siliciclastic residues within carbonate rocks (δ26Mgresidue), a well-established proxy for continental chemical weathering intensity, across the S-S boundary in the Waili and Jiarong sections in South China. Our results document a distinct positive δ26Mgresidue shift in the lowermost Spathian in both sections, signifying intensified continental chemical weathering. This isotopic shift broadly coincides with the positive δ13Ccarb excursion and the recovery of terrestrial ecosystems but postdates the late Smithian thermal maximum. We interpret this temporal sequence to suggest that the recovery of terrestrial ecosystems, particularly the expansion of vascular land plants, acted as a primary driver of enhanced continental chemical weathering. The resulting increase in continental chemical weathering likely amplified nutrient flux to the ocean, potentially promoting local marine anoxia and climate cooling observed in the earliest Spathian. These findings underscore the critical role of terrestrial-marine coupling in modulating Early Triassic biogeochemical feedbacks and global climate evolution.
| Type: | Article |
|---|---|
| Title: | Magnesium isotopic evidence for intensified continental chemical weathering during the Smithian-Spathian transition |
| DOI: | 10.1016/j.chemgeo.2025.123133 |
| Publisher version: | https://doi.org/10.1016/j.chemgeo.2025.123133 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | ATMOSPHERIC CO2, CARBON-CYCLE, EARLY MARINE DIAGENESIS, Early Triassic, FRACTIONATION, Geochemistry & Geophysics, Marine anoxia, MASS EXTINCTION, MG ISOTOPES, MINERAL FORMATION, NANPANJIANG BASIN, Paleoclimate, PERMIAN-TRIASSIC BOUNDARY, Physical Sciences, Science & Technology, South China, SOUTH CHINA, Terrestrial-marine teleconnection |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10219184 |
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