西藏南部中酸性岩中锆石铀-铅计时讨论  

A DISCUSSION ON ZIRCON U-Pb DATING OF INTERMEDIATE ACID ROCKS IN SOUTHERN XIZANG

作　　者：陈毓蔚 许荣华 

出　　处：《地球化学》1981年第2期128-135,共8页Geochimica

摘　　要：U-Pb isotopie geological ages were determined on more than 30 specimens of zircon,feldspar, sphene and apatite from the Kangdeee rock belt and its eastern Bome-Zayu areas in Xizang (Tibet). The study of common lead derivation and its mode of occurrence in zircon indicates that large amounts of common lead occur as sulphide-faeies minerals er exist in the cyrstal lattice of zircon, rather than introduced by contamination during analytical procedure. Described in this paper is the validity of subtracting zircon-containing common lead from the isotopie components of syngenetic galena, consequently leading te the conelusion that intermediate-acid rocks in the studied region are brought forth by late Yenshanian (120--80 m. y.) movement, It is suggested from the quantity of common lead and the difference in lead isotopic composition that the western segment of the Kangdese belt and its eastern Beme-Zayu areas may have two different material sources.U-Pb isotopic geological ages were determined on more than 30 specimens of zircon, feldspar, sphene and apatite from the Kangdese rock belt and its eastern Bome-Zayu areas in Xizang (Tibet). The study of common lead derivation and its mode of occur-rence in zircon indicates that large amounts of common lead occur as sulphide-facies minerals or exist in the cyrstal lattice of zircon, rather than introduced by contamina-tion during analytical procedure. Described in this paper is the validity of subtracting zircon-containing common lead from the isotopic components of syngenetic galena, con-sequently leading to the conclusion that intermediate-acid rocks in the studied region are brought forth by late Yenshanian (120-80 m. y.) movement. It is suggested from the quantity of common lead and the difference in lead isotopic composition that the western segment .of the Kangdese belt and its eastern Bome-Zayu areas may have two different material sources.

关 键 词：中酸性岩 锆石 铅向位素 铀 

分 类 号：P588.121[天文地球—岩石学] P597[天文地球—地质学]