成都粘土地球化学特征及其对物源和风化强度的指示  

Geochemical characteristics of Chengdu clay and their implications for provenance and weathering intensity

作　　者：应立朝[1,2] 梁斌[1,2] 王全伟[2] 朱兵[2] 郝雪峰[2] 刘亮[1] 文龙[1] 燕钟林[1] 付小方[2] 

机构地区：[1]西南科技大学环境与资源学院,四川绵阳621010 [2]四川省地质调查院,四川成都610081

出　　处：《中国地质》2013年第5期1666-1674,共9页Geology in China

基　　金：中国地质调查局1:25万成都幅区域地质调查项目(1212010880704);四川省国土资源厅重点项目(批准号:KJ-2010-5)共同资助

摘　　要：成都平原晚更新世成都粘土地球化学分析表明,不同剖面样品的化学组成具有较好的一致性,以SiO2(平均75.24%)、Al2O3(平均14.12%)、Fe2O3(平均5.81%)为主,地球化学特征与UCC基本相似。与北方黄土相比,成都粘土具有较高的TiO2/Al2O3、Zr/Al、Zr/Ti和Y/Al以及较低的Eu/Eu*、LaN/SmN和La N/YbN比值,这些特征与成都平原第四系深层土壤样品组成一致,表明成都粘土来源于当地,与北方黄土物源不同。成都粘土CIA平均值为78.59,高于北方黄土平均值(69.34),经历了中期的K迁移阶段,在风化过程中Ca、Na、Mg和K是主要的活动性元素。与北方黄土相比,成都粘土Na、Mg、K和Ca亏损较大,表明经历了更强的化学风化。-The chemical composition of late Pleistocene Chengdu clay in Chengdu plain shows that SiO2 （75.24% on average）, Fe203 （14.12% on average） and A1203 （5.81% on average） are dominant chemical compositions, Chengdu clay has an overall similarity in geochemical characteristics to the UCC. In comparison with the loess of northern China, Chengdu clay has higher TiO2/A1203, Zr/A1, Zr/Ti and Y/A1 ratios, and lower Eu/Eu ＊, LaN/ SmN and LaJYbN ratios. These features coincide with those of the Quatemary deep soil in Chengdu plain, which suggests local sources for the Chengdu clay in this region; nevertheless, Chengdu clay is quite different from the loess of northern China. The average chemical index of alteration （CIA） of Chengdu clay is 78.59, higher than that of the loess of northern China. Chengdu clay has experienced the intermediate K removal weathering stage, and Ca, Na, Mg and K seem to have been the main mobile elements in the weathering process. In comparison with the loess of northern China, Chengdu clay has greater depletion of Na, Mg, K and Ca, indicating a stronger weathering intensity.

关 键 词：成都粘土 地球化学特征 物源 风化强度 成都平原 

分 类 号：P642.13[天文地球—工程地质学]