Early Jurassic climate and atmospheric CO 2 concentration in the Sichuan paleobasin, southwestern China

Li, Xianghui; Wang, Jingyu; Rasbury, Troy; Zhou, Min; Wei, Zhen; Zhang, Chaokai

Climatic oscillations have been developed through the (Early) Jurassic from marine sedimentary archives but remain unclear from terrestrial records. This work presents investigation of climate-sensitive sediments and carbon and oxygen isotope analyses of lacustrine and pedogenic carbonates for the Early Jurassic Ziliujing Formation taken from the Basin in southwestern China. Sedimentary and stable isotope proxies manifest that an overall secular (semi)arid climate dominated the Sichuan Basin during the Early Jurassic, except for the Hettangian. This climate pattern is similar to the arid climate in the Colorado Plateau region in western North America but is distinct from the relatively warm and humid climate in northern China and at high latitudes in the Southern Hemisphere. The estimated atmospheric COinline-formula2 concentration (inline-formulapCOinline-formula2) from carbon isotopes of pedogenic carbonates shows a range of 980–2610 ppmv (inline-formula∼3.5–10 times the pre-industrial value) with a mean of 1660 ppmv. Three phases of inline-formulapCOinline-formula2 (the Sinemurian 1500–2000 ppmv, the Pliensbachian 1000–1500 ppmv, and the early Toarcian 1094–2610 ppmv) and two events of inline-formulapCOinline-formula2 rapidly falling by inline-formula∼1000–1300 ppmv are observed, illustrating the inline-formulapCOinline-formula2 perturbation in the Early Jurassic. The perturbation of inline-formulapCOinline-formula2 is compatible with seawater temperature and carbon cycle from the coeval marine sediments, suggesting a positive feedback of climate to inline-formulapCOinline-formula2 through the Early Jurassic.

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Li, Xianghui / Wang, Jingyu / Rasbury, Troy / et al: Early Jurassic climate and atmospheric CO2 concentration in the Sichuan paleobasin, southwestern China. 2020. Copernicus Publications.

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