Geological Society of America

T80 Advances in Non-Traditional Stable Isotope Measurements and Utility as Proxies in Modern and Paleo-Settings

Monday, 10 October 2022
8:00 AM - 12:00 PM
506

PERSISTENT LATE PERMIAN TO EARLY TRIASSIC WARMTH LINKED TO ENHANCED REVERSE WEATHERING

Paper number: T80-7
Program: Technical Sessions
Time: 9:20 AM – 9:35 AM

Authors

Xiao-Ming Liu Presenting Author
University of North Carolina, Chapel Hill, Chapel Hill, NC
Cheng Cao
Nanjing University, Nanjing
Cheng Cao
104 South RD., 213 Mitchell Hall, Chapel Hill, NC
Clement P. Bataille
University of Ottawa, Ottawa, ON
Haijun Song
China University of Geosciences, Wuhan
Matthew Saltzman
Ohio State University, Columbus, OH
Kate Tierney
University of Iowa, Iowa City, IA
Huaichun Wu
China University of Geosciences (Beijing), Beijing
Christoph Korte
University of Copenhagen, Copenhagen
Zhaofeng Zhang
Chengdu University of Technology, Chengdu

Abstract

Chemical weathering and reverse weathering are two critical processes controlling biogeochemical cycles of silicon and carbon. Geochemical and stratigraphic records suggest that these processes might have varied considerably during the Permian to Early Triassic period influencing biogeochemical cycles during this critical interval of Earth’s history. Here we present newly derived seawater lithium and strontium isotope records of bulk carbonates and fossil brachiopods spanning the Permian to Early Triassic period (300 Ma to 247 Ma). The lithium isotope composition of seawater remained constant for most of the Permian until a sharp decrease in the Changhsingian (~ 254 – 252 Ma), reaching a minimum value of around 5‰ near the Permian-Triassic boundary (PTB, ~ 251.92 Ma). This decline occurred several million years prior to the PTB but low seawater Li isotope values (~10‰) persisted throughout the Early Triassic. Based on steady-state box modeling of the marine Li isotope budget, changes in the fluxes and isotopic composition of Li inputs alone (i.e., chemical weathering and hydrothermal) are unable to explain the abrupt decline in seawater Li isotopes. Rather, increased reverse weathering rates could explain the failure of chemical weathering to drawdown atmospheric CO₂ levels during the Early Triassic leading to protracted biotic recovery from the Permian-Triassic mass extinction.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-380868

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