四川盆地晚中生代古淋溶土发生学特征与形成因素研究  

Pedogenesis of Argosol-like Paleosol Formation in the Late Mesozoic Sichuan Basin

作　　者：李军 黄成敏[2] 杨国林 潘园园[2] 王熠哲 文星跃 LI Jun;HUANG Cheng-min;YANG Guo-lin;PAN Yuan-yuan;WANG Yi-zhe;WEN Xing-yue(College of Urban Environment,Lanzhou City University,Lanzhou 730070,China;Department of Environmental Science and Engineering,Sichuan University,Chengdu 610065,China;BaiLie School of Petroleum Engineering,Lanzhou City University,Lanzhou 730070,China;School of Environmental Science and Engineering,China West Normal University,Nanchong,Sichuan 637002,China)

机构地区：[1]兰州城市学院城市环境学院,甘肃兰州730070 [2]四川大学环境科学与工程系,四川成都610065 [3]兰州城市学院培黎石油工程学院,甘肃兰州730070 [4]西华师范大学环境科学与工程学院,四川南充637002

出　　处：《土壤通报》2022年第1期1-11,共11页Chinese Journal of Soil Science

基　　金：国家自然科学基金项目(41901066,41771248,41371225)资助。

摘　　要：【目的】理解和揭示深时古土壤的形成与演化有助于了解地球宜居性的形成与演化、促进土壤发生学理论的发展。【方法】以四川盆地晚中生代侏罗系和白垩系地层发育的古土壤为研究对象,通过对典型剖面的形态与微形态、矿物组成、颗粒组成以及地球化学等发生学特征的观察与分析,开展深时古土壤发生学特征与分类研究,并基于母质、气候、生物、地形和时间等成土因素,进一步探讨深时古土壤的形成过程。【结果】结果表明:(1)四川盆地晚中生代古土壤具有根系、土层色调变化、土壤结构和黏化层等成壤特征。(2)古土壤矿物组成以石英、长石、绿泥石、针铁矿、伊利石和云母类矿物为主。(3)沿古土壤剖面自上而下,伴随着土层化学风化指数(CIA-K和方解石为主,含少量蒙脱石、绿泥石、针铁矿、伊利石和云母类矿物)。(3)沿古土壤剖面自上而下,伴随着土层化学风化指数(CIA-K)值的增强,铝硅比和淋溶率(Ba/Sr)随之增加,而淋溶指数(ΣBases/Al)相应降低。【结论】成土因素分析表明古土壤发育于植被类型丰富且排水条件良好的林地地区,为侏罗系和白垩系沉积岩在温暖(10±4.4℃~13±4.4℃)湿润(515±182 mm a^(−1)~1140±182 mm a^(−1))的气候环境下,经10 ka以上时间的风化产物。[Objective]Understanding and revealing the details of genesis and evolution of soils in deep time can help us know the formation and evolution of the habitable Earth and advance the development of theory in soil genesis.[Method]In this paper,a total of 30 paleosol profiles,developed on the Jurassic and Cretaceous strata of the Mesozoic Era in the Sichuan Basin,Southwest China,were identified and characterized macro-and micromorphologically and assessed for mineral,particle size distribution,and geochemical compositions to summarize their pedogenic characteristics,to perform their classification and reference,and to further discuss the deep-time paleosol-forming processes based on the soil-forming factors(i.e.,paleoclimate,topographic setting,organisms,parent material,and time).[Result]The investigated paleosols of the late Mesozoic Sichuan Basin comprise distinctive pedogenic characteristics that include the evidence of root traces,presence of color variations,and development of soil structures and argillic horizons.All the paleosol horizons were predominantly made up of quartz,feldspar and calcite in mineralogy with minor proportions of smectite,chlorite,goethite,illite and muscovite.From top of the paleosol profile to bottom,as the CIA-K value increased,it was accompanied by an increase in clayeyness(Al_(2)O_(3)/SiO_(2))and leaching(Ba/Sr)and consequently lessens in base loss(ΣBases/Al)values.[Conclusion]Formation factors of paleosols showed that paleosols formed in well-drained environments of the abundant vegetation ranging from woodland to open forest.Moreover,these paleosols are weathering products of sedimentary and residual deposits which developed under climates of MATs ranging from 10±4.4℃to 13±4.4℃and MAPs ranging between 515±182 mm year^(−1) and 1140±182 mm year^(−1).The time factor lasted for over 10 ka,allowing paleosols to develop with Bt-horizons and block structures.

关 键 词：古土壤 白垩系 侏罗系 土壤发生 四川盆地 

分 类 号：S151[农业科学—土壤学]