Multiproxy Paleosol Evidence for Jurassic Paleoclimate Fluctuations in the Sichuan Basin,SW China  

作　　者：LI Jun WEN Xingyue PAN Yuanyuan HUANG Chengmin 

机构地区：[1]Department of Environmental Science and Engineering,Sichuan University,Chengdu 610065,China [2]College of Urban Environment,Lanzhou City University,Lanzhou 730070,China [3]School of Environmental Science and Engineering,China West Normal University,Nanchong,Sichuan 637002,China

出　　处：《Acta Geologica Sinica(English Edition)》2022年第6期2105-2124,共20页地质学报（英文版）

基　　金：support from the National Natural Science Foundation of China(Grant Nos.41371225 and 41901066).

摘　　要：Paleoclimate reconstruction of continental environments has been hampered by the limited evidence.A thick sequence of Jurassic continental deposits in the Sichuan Basin,Southwest China yields abundant paleosols that may offer valuable insights regarding Jurassic climate scenarios.A succession of 169 paleosols belonging to Protosols,Calcisols,and Argillisols from 23 detailed stratigraphic sections was recognized and characterized macro-and micromorphologically and assessed for mineral and geochemical compositions.Quantitative paleoclimate reconstructions using bulk geochemical proxies,the depth to and the stable oxygen isotopic composition of paleosol carbonates indicated a predominant alternation of semiarid and arid cool/warm-temperate climatic conditions punctuated by several episodes of subhumid and humid climates that generally prevailed in the Sichuan Basin during the Jurassic.The estimated paleoatmospheric CO_(2)concentrations(pCO_(2))from calcic paleosols yielded a low range of~104±58 to~610±152 ppmv during the Middle Jurassic.The terrestrial paleotemperature changes in the Sichuan Basin coincided with the pCO_(2)variations,which probably resulted from global geological events(e.g.,volcanic activities,magmatic and oceanic events,and the ephemeral caps development)in the Middle Jurassic.Jurassic climatic fluctuations in the basin were likely attributed to true polar wander due to global plate motion,megamonsoon effect linked to global and regional paleogeography,and regional paleotopography.

关 键 词：JURASSIC CLIMATIC CONTINENTAL 

分 类 号：P534.52[天文地球—古生物学与地层学]