摘要
Abstract
Based on studying the distribution of trace elements in the dioritic weathered crust of Zigui area,the authors have divided the trace elements into three types. The first type consists of inactive elements which include Sc,V,Cr,Co,Ni,Cu,Zn,Zr,Hf,Nb and Ta,U,Th,Mo,W. During the weathering process,they can be effectively preserved- Due to the influence of redox condition variation,U,Cr and Cu sometimes show local enrichment,without obvious regularity. The second type is composed of active elements such as Ca,Rb,Cs,Sr,Ba,Pb,Ga,Gd,and Tl,which are gradually leached from profiles along with the weathering. The third type is represented by REE,which are leached from the upper section downward,and enrichment is observed in the mid-lower section,with the leaching degree of HREE higher than that of LREE. Eu gradually changes from positive anomalies in parent rocks into negative anomalies on the surface due to the weathering leaching of plagioclase in parent rocks under the oxidation environment. Under the surface oxidation condition,Ce easily produces tetravalence oxides (cerianite) and shows obvious surface enrichment,and the variation of the redox conditions leads to the undulate variation of Ce.关键词
闪长岩/风化壳/微量元素/稀土元素/秭归地区Key words
diorite/weathering crust/trace elements/REE/Zigui area分类
天文与地球科学
