辽南黄土化学风化特点及其环境意义  

CHEMICAL WEATHERING OF THE LOESS IN THE SOUTH OF LIAONING PROVINCE AND ITS IMPLICATIONS FOR ENVIRONMENTAL CHANGE

作　　者：张威[1] 董应巍[1] 于洋[1] 刘蓓蓓[1] 李永化[1] 李媛媛[1] 王美霞[1] 

机构地区：[1]辽宁师范大学城市与环境学院,大连116029

出　　处：《海洋地质与第四纪地质》2013年第5期163-171,共9页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金项目(40571016;40971010;40271093;41230743);辽宁省教育厅计划项目(20060468)

摘　　要：对辽南地区周家沟黄土剖面的常量与微量元素进行测试,系统分析了化学蚀变指数、Na/K和元素迁移在剖面中的变化,结合矿物、粒度分析,与黄土高原和东部陆架黄土的化学特征(全样、酸不溶相)进行比较,结果表明:辽南地区黄土中的SiO2、Al2O3、TFe2O3、MgO、CaO、Na2O含量与黄土高原明显不同,而MgO、CaO、Na2O含量与我国南部滨海黄土以及洛川古土壤的含量比较接近,K2O、MnO、TiO2含量各地比较一致;辽南地区黄土的化学风化基本完成早期去Na、Ca风化过程,并进入中期去K、Si风化阶段;周家沟黄土剖面元素的迁移和富集在马兰黄土和离石黄土中表现完全不同,说明辽南地区在中更新世晚期和晚更新世气候发生了明显的变化,由暖湿的气候环境突变为冷干的气候环境。化学风化程度由强至弱依次为:镇江下蜀黄土、陆源页岩、辽南地区、洛川黄土(酸不溶相)、洛川黄土(全样)、上部陆壳。镇江下蜀黄土的化学风化程度最强,辽南地区黄土的风化程度略高于酸不溶相的洛川黄土,而明显大于全样的洛川黄土,主要差异来源于风化过程中不同的气候条件以及粒度效应。Chemical elements of the Zhoujiagou loess in the south of Liaoning province are analyzed. Ac- cording to the chemical indexes of alteration （CIA）, Na/K, and the element migration orders, together with the grain size and mineralogy of the deposits, we studied the weathering features of the Zhoujiagou lo- ess profile. Results show that the contents of SiO2, A1203, TFe203 in the south of Liaoning province are obviously higher than those in Luochuan of Shanxi province, while the contents of MgO, CaO, Na20, which are close to the loess in Zhenjiang and the paleo-soil in Shanxi province, are lower in the south of Li- aoning province. The change in K20,MnO,TiO2 is not obvious in all the regions studied, while the con- tent of P20〉 is lower in the south of Liaoning than that in Zhenjiang. It is deduced that the chemical weath- ering in the south of Liaoning province is characterized by the leaching of not only Na and Ca, but also K and Si to some extent. The early stage of chemical weathering, which is featured by leaching of Na and Ca, is completed, and at present it is in the stage of leaching K and Si out comparing to the elements mi- gration pattern in the Luochuan loess. The migration and accumulation of elements are different in the Lishi and Malan loess in the Zhoujiagou profile. The evolution of the chemical weathering in the profiles indicates that the paleo-climate changed abruptly from warm and humid in Middle Pleistocene to cold and dry in Late Pleistocene. The intensity of chemical weathering in these study regions are in an order of the Xiashu loess 〉PAAS〉Luochuan loess （not including the acid dissolution components）〉Luochuan loess （total samples）〉UCC. These differences were caused by the climate conditions during Late Quaternary.

关 键 词：化学风化 更新世 辽南黄土 

分 类 号：P595[天文地球—地球化学]