四川盆地中生代古气候变化:来自深时古土壤证据  

Mesozoic Paleoclimate Reconstruction in Sichuan Basin,China:Evidence from deep-time paleosols

作　　者：李军 黄成敏[2] 文星跃[3] 张茂超[4] LI Jun;HUANG ChengMin;WEN XingYue;ZHANG MaoChao(College of Urban Environment,Lanzhou City University,Lanzhou 730070,China;Department of Environmental Science and Engineering,Sichuan University,Chengdu 610065,China;School of Land and Resource,China West Normal University,Nanchong,Sichuan 637002,China;Chongqing Vocational Institute of Engineering,Chongqing 402260,China)

机构地区：[1]兰州城市学院城市环境学院,兰州730070 [2]四川大学环境科学与工程系,成都610065 [3]西华师范大学国土资源学院,四川南充637002 [4]重庆工程职业技术学院,重庆402260

出　　处：《沉积学报》2021年第5期1157-1170,共14页Acta Sedimentologica Sinica

基　　金：国家自然科学基金(41901066,41371225);国家重点基础研究发展计划(973计划)项目(2012CB822003)。

摘　　要：定量的古气候重建可为当前及未来可能的气候/环境变化提供基础性参考。发育自四川盆地中生代地层的古土壤蕴藏了丰富的陆相古气候信息,利用古土壤的地球化学指数、钙质古土壤成壤碳酸盐结核深度及其氧同位素组成与年均降水量、温度之间的关系,定量重建四川盆地中生代(晚三叠世晚期—白垩纪)年均降水量与温度的变化。结果表明:四川盆地中生代年均降水量变化较大,为145~1400 mm;年均温度变化幅度相对较小,为7℃~15℃;总体上属于温带干旱—湿润交替的气候环境但以温带半干旱、干旱气候为主。其中晚三叠世晚期年均降水量为1180~1400 mm,年均温度为9℃~15℃,侏罗纪年均降水量为150~1140 mm,年均温度为7℃~15℃,早白垩世早期与晚白垩世晚期的年均降水量与温度分别为150~720 mm、8℃~12℃和150~575 mm、10℃~11℃。区域陆相气候变化原因分析显示,波动的气候一方面与东亚季风环流、行星环流、区域构造运动导致的盆地内部山系隆起及古地理格局引起的焚风效应有关,另一方面还与区域构造运动引起海岸山脉裂解有关。Quantitative reconstruction of paleoclimates provides basic references for future environmental and climate-change forecasts.Abundant paleosols preserved in Mesozoic strata across the Sichuan Basin were examined to reveal the deep-time terrestrial paleoclimate during that era.Paleoclimates(mean annual precipitation(MAP)and mean annual temperature(MAT))inferred from the geochemical composition of paleosol horizons,depth to carbonate nodules,and stable oxygen isotopic composition of pedogenic carbonates,were quantitatively reconstructed.The reconstructed MAP values fluctuated significantly between 145 and 1400 mm.MATs were generally between 7℃ and 15℃,displaying relatively narrow variability throughout the Mesozoic.These variations imply alternating aridhumid climate conditions overall,but with predominant semi-arid and arid temperate climate.MAPs were 11801400 mm and MATs were 9℃-15℃ in the late Upper Triassic in the Sichuan Basin.In the Jurassic,the MAPs ranged from 150 to 1140 mm and MATs were between 7℃ and 15℃.The MAPs and MATs in the Lower Cretaceous and the late Upper Cretaceous were 150-720 mm,8℃-12℃ and 150-575 mm,10℃-11℃,respectively.Such climatic changes in the Sichuan Basin were possibly related to monsoonal circulation in eastern Asia and planetary circulation,and rain-shadow effects as a result of the uplift of the mountain belts driven by regional tectonism,and the opening of the coastal cordillera and mountain ranges.

关 键 词：四川盆地 中生代 深时古土壤 古温度 古降水量 

分 类 号：P532[天文地球—古生物学与地层学] S151[天文地球—地质学]