基于地质建造的西南山区成土母质分类方案——以大凉山区为例

Classification of soil parent materials in mountain areas of Southwest China based on geological formations:A case study of Daliangshan region

为适应生态地质调查和评价工作对成土母质研究的要求,以四川大凉山区为例,提出基于地质建造的成土母质分类方案,即以地质构造演化和地质建造环境为依据,结合残坡积物的成因类型对成土母质进行分类。大凉山区的成土母质可划分为第四纪冲洪积物、新近纪—第四纪砂泥岩类残坡积物、侏罗纪—白垩纪泥质岩类残坡积物、三叠纪砂泥岩类残坡积物、中生代中酸性岩类残坡积物、二叠纪基性—超基性岩类残坡积物、震旦纪—三叠纪砂泥岩类残坡积物、震旦纪—三叠纪碳酸盐岩类残坡积物、元古宙中酸性岩类残坡积物、元古宙火山碎屑岩类残坡积物、元古宙基性—超基性岩类残坡积物、元古宙变质岩类残坡积物等12类。研究表明,大凉山区成土母质和土壤存在差异性,但同一成土母质上的不同土壤类型具有一定相似的地球化学特征,不同成土母质形成的同一种土壤类型存在较大的地球化学差异。因此,基于地质建造的成土母质分类方案既能有效反映不同构造背景和成岩环境下的成土母质差异,又能有效表征成土母质与其上土壤的内在联系。

In this paper,taking Daliangshan region of Sichuan Province as a case study,the authors put forward the classification of soil parent materials based on geological formation,which takes the tectonic evolution and geological formation environment as foundation,and combines with the genetic type of eluvium and slope deposit.The soil parent materials in Daliangshan region are classified into 12 types,including Quaternary alluvial-diluvial deposit,Neogene-Quaternary sandstone and mudstone eluvium and slope deposit,Jurassic-Cretaceous mudstone eluvium and slope deposit,Triassic sandstone and mudstone eluvium and slope deposit,Jurassic-Cretaceous acidic magmatic eluvium and slope deposit,Triassic intermediate-acidic magmatic eluvium and slope deposit,Permian basic-ultrabasic eluvium and slope deposit,Sinian-Triassic sandstone and mudstone eluvium and slope deposit,Sinian-Triassic carbonate eluvium and slope deposit,Proterozoic intermediate-acidic eluvium and slope deposit,Proterozoic basic-ultrabasic eluvium and slope deposit,and Proterozoic metamorphic eluvium and slope deposit.The results show that there are differences between parent material and soil,While different soil types of same parent material have similar geochemical characteristics,and same soil types of different parent material have different geochemical characteristics.Therefore,the classification of soil parent materials based on geological formation can not only effectively reflect the difference of parent materials under diffe-rent tectonic setting and diagenetic environment,but also effectively present the internal relationship between pa-rent material and soil.