@article{33e47d139dff4471b5115859ccf584d5,
title = "Calcium isotopes reveal shelf acidification on southern Neotethyan margin during the Smithian-Spathian boundary cooling event",
abstract = "The Smithian-Spathian transition of the late Early Triassic was a critical period of environmental and biological upheavals, following the end-Permian mass extinction. Changes in carbonate deposition during this period have been attributed to intensified upwelling along shelf margins, but relevant studies are scarce. Here, we present calcium isotopes of bulk marine carbonate (δ44/40Cacarb) from a Smithian–Spathian boundary (SSB) succession (Guryul Ravine section, Kashmir) on the southern margin of the Neo-Tethys. Our smoothed δ44/40Cacarb curve reveals a ∼ 0.2‰ negative shift (from ∼ − 1.1‰ to ∼ − 1.3‰) across the SSB, concurrent with a ∼ +10‰ shift in δ13Ccarb. While increased Ca isotopic fractionation could play a role, we specifically examine potential impacts due to changes in marine Ca fluxes. Using a Ca-cycle mass balance model, we explore scenarios of decreased carbonate burial flux (Fcarb), decreased riverine flux (Friv), and a combination of these processes. The modeling suggest that a pulse decrease in Fcarb by 40% over ∼0.06 Myr match the negative shift in δ44/40Cacarb at Guryul Ravine. We infer that this decrease was likely related to intensified upwelling of acidic deep seawater due to invigorated global-oceanic circulation during the SSB cooling event. We suggest that the regionally diverse excursions in δ44/40Cacarb in the Tethyan region could be attributed to spatially varied upwellings in the shelf margin. The upwelling of acidic and anoxic deep seawater may have driven the second-order extinction of ammonoids and conodonts at the beginning of the SSB cooling event.",
keywords = "Acidification, Biotic extinction, Climate cooling, Early Triassic, Guryul Ravine, Upwelling",
author = "Feihong Ye and Laishi Zhao and Lei Zhang and Ying Cui and Algeo, {Thomas J.} and Chen, {Zhong Qiang} and Zhengyi Lyu and Yuangeng Huang and Bhat, {Ghulam M.} and Aymon Baud",
note = "Funding Information: We thank Editor-in-Chief Maoyan Zhu for handling this manuscript, and two anonymous reviewers for their constructive comments, which greatly improved the quality of the manuscript. We are grateful to Fang Liu, Bin Luo for the calcium isotope analysis, to Xiangdong Wang, He Zhao and Ziheng Li from GUG-Wuhan, and to Ceng Yi from the College of Resources and Environment, Huazhong Agricultural University, for the helpful discussions. This study is supported by NSFC ( National Natural Science Foundation of China ) grant (NO. 92055212 , 41977264 , 42073073 , 41930322 , 41673011 , 41803011 ), the MOST Special Fund (MSF-GPMR2022-7) of the State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan. We thank Tea Kolar-Jurkov{\v s}ek for her assistance of sampling in the field. This is a contribution to the IGCP 630: Permian- Triassic climatic and environmental extremes and biotic responses. Funding Information: We thank Editor-in-Chief Maoyan Zhu for handling this manuscript, and two anonymous reviewers for their constructive comments, which greatly improved the quality of the manuscript. We are grateful to Fang Liu, Bin Luo for the calcium isotope analysis, to Xiangdong Wang, He Zhao and Ziheng Li from GUG-Wuhan, and to Ceng Yi from the College of Resources and Environment, Huazhong Agricultural University, for the helpful discussions. This study is supported by NSFC (National Natural Science Foundation of China) grant (NO. 92055212, 41977264, 42073073, 41930322, 41673011, 41803011), the MOST Special Fund (MSF-GPMR2022-7) of the State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan. We thank Tea Kolar-Jurkov{\v s}ek for her assistance of sampling in the field. This is a contribution to the IGCP 630: Permian- Triassic climatic and environmental extremes and biotic responses. Publisher Copyright: {\textcopyright} 2023",
year = "2023",
month = aug,
doi = "10.1016/j.gloplacha.2023.104138",
language = "English",
volume = "227",
journal = "Global and Planetary Change",
issn = "0921-8181",
publisher = "Elsevier",
}
