华南扬子与华夏陆块古-中元古代基底地壳微量元素地球化学示踪探讨  

Geochemical discussion on Paleo-Mesoproterozoic basement crust of Yangtze and Cathaysia cratons in southern China: Using trace elements as tracers

作　　者：马振东[1] 陈颖军[1] 

机构地区：[1]中国地质大学地球化学研究所,湖北武汉430074

出　　处：《地球化学》2000年第6期525-531,共7页Geochimica

基　　金：国家自然科学基金资助项目!( 49473187);国土资源部资助项目!( K1.4-1-3)

摘　　要：从早期地壳以垂向分异增长为主的思路出发，将华南扬子陆块和华夏陆块变质基底中相似岩类（陆源碎屑岩、变基性火山岩夹层和晋宁期花岗岩类）作为研究对象，选择了相容性接近的 7对元素（ Rb/Cs、 Sr/Ba、 Th/U、 Nb/Ta、 Zr/Hf、 Pd/Pt和 Cr/Ni）作为示踪手段，对华南大陆古-中元古代基底的物源特征和后期演化进行了探讨，得出了几点初步认识： (1)扬子、华夏两陆块前元古宙“原始”地壳具有相近的物质组成； (2)在古-中元古代期间（尤其是中元古代），华南大陆的扬子、华夏陆块处于各自不同的构造位置，华夏陆块较扬子陆块经历了更为强烈的后期叠加和改造作用。The origin and growth of continental crust is one of the hot points for geologists. A vast amount data discloses that early stage continental crust grew up gradually by the intrusion or extrusion of the magma that results from mantle partial melting. However, the crosswise growth of the later stage crust is the partly adjustment based on the early growth of vertical differentiation. Therefore, the geochemical conduct of the close compatibility elements traces the material-source and later process of various geologic bodies in the same area of lithosphere. Following this idea, the similar rocks (terrigeous clastic rocks, meta-basic volcanic rocks and Jinning period granitoid) that derived from the metamorphism basement of southern China Yangtze craton and Cathaysia craton were considered as objects of study, and seven couples of close compatibility elements (Rb/Cs, Sr/Ba, Th/U, Nb/Ta, Zr/Hf, Pd/Pt and Cr/Ni) are selected as tracer elements. The discussion of characterization of the material-source and later growth of the Paleo-Mesoproterozoic basement of southern China continent indicates that (1) the similarity of overall characterization of high field strength elements of terrigeous clastic rock of the paleo-Mesoproterozoic basement of Yangtza-Cathaysia cratons traces the similar material composition of the initial crust of the two cratons of Paleoproterozoic. However, the ratio of high field strength elements of granite of the two cratons of Jinning period is nearly consistent with that of terrigeous clastic rocks of the basement, maybe indicates that high field strength elements are significant to trace the inheritance of continent source material. It also indicates that (2) the change of the content and ratio of the large ion lithophile elements of Cathaysia craton in the basement continent-derived clastic rocks and Jinning period granitoid, evidentially differs from that of Yangtze craton, which possibly traces that① Yangtze and Cathaysia cratons occupy different structural position;② Cathaysia craton ex

关 键 词：微量元素 元古宙 扬子陆块 华夏陆块 地球化学 

分 类 号：P595[天文地球—地球化学]