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Paleocene-Eocene Thermal Maximum lacustrine sediments in deep drill core SKD1 in the Jianghan Basin: A record of enhanced precipitation in central China
Global and Planetary Change ( IF 3.9 ) Pub Date : 2021-08-17 , DOI: 10.1016/j.gloplacha.2021.103620
Xiaohua Teng 1 , Chunlian Wang 2 , Chenglin Liu 2 , Kai Yan 2 , Zeng Luo 3
Affiliation  

Global warming has a significant effect on global and regional hydrological cycles and is expected to exacerbate the uneven distribution of rainfall in various regions, thereby influencing water-related human activities (e.g., agriculture) and the development of human society, especially in densely populated East Asia. As an analog to predict the future impact of global warming on hydrological regimes, the Paleocene-Eocene Thermal Maximum (PETM) at ~56 Ma is the most prominent and extensively studied Paleogene hyperthermal event, and it featured rapid and extreme global warming that caused intense environmental effects. However, the contradictory effects/mode of precipitation during the PETM has constrained our understanding of the hydrological response to global warming. Moreover, compared with marine records, continental sedimentary records of the PETM are very limited, and most are typically limited to weathered, often discontinuous, outcrop exposures, and relevant records of environmental perturbations in Asia are lacking. This study presents the first detailed record of the PETM in the Jianghan Basin, central China, and identifies the environmental and hydrological changes across the PETM. Based on high-resolution carbon and oxygen isotopes in the lacustrine carbonates (mainly calcite and dolomite) in the deep drill core SKD1, we identified the PETM event at the boundary of the Shashi and Xingouzui Formations. The carbon isotopic values of carbonate (δ13Ccarb) and calcite (δ13Ccalcite) show large negative excursions (~10.7‰ and 8.7‰, respectively) during the PETM. The oxygen isotopic values of carbonate (δ18Ocarb) and calcite (δ18Ocalcite) also show large negative excursions (7.9‰ and 6.1‰, respectively), indicating increased precipitation and a wetter climate across the PETM, as evidenced by the disappearance of evaporites and the dominance of calcite in the carbonates. Increased precipitation with elevated pCO2 concentration might have caused the anomalous large negative excursion of the δ13Ccarb values in the SKD1 core and provided favorable living conditions for the oldest known primate, whose fossil was found in the Jianghan Basin. The δ18Ocarb and δ18Ocalcite values increase and show high-frequency and large-amplitude fluctuations above the PETM interval, indicating rapid shifts between wet and dry climatic conditions in an overall arid climate after the PETM.

更新日期:2021-08-20
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