西藏羌塘中部都古尔花岗质片麻岩同位素年代学研究  

ISOTOPIC CHRONOLOGY OF DUGUER GRANITIC GNEISS OF CENTRAL QIANGTANG,TIBET

作　　者：李才[1] 王天武[1] 杨德明[1] 和钟铧[1] 任云生 

机构地区：[1]长春科技大学地球科学学院,吉林长春130026

出　　处：《长春科技大学学报》2000年第2期105-109,共5页Journal of Changchun University of Science and Technology

基　　金：原地矿部"九五"重大基础项目!(95 0 110 1- 0 5 );中国石油天然气集团公司"九五"科技工程!(QZ - 97-2 0 410 2 )资助

摘　　要：都古尔片麻岩是最近发现和确定的一个非正式岩石单位 ,是西藏羌塘地区目前唯一确定的片麻岩产地 ,由花岗质片麻岩和角闪斜长片麻岩组成 ,两类片麻岩均发生韧性变形。选择变形较弱的花岗片麻岩进行了同位素年代学研究 ,获得单颗粒锆石U -Pb谐合线年龄 384 4Ma ,黑云母4 0 Ar -3 9Ar坪年龄 135 9Ma ,认为都古尔花岗岩 (片麻岩 )在相对稳定的环境中缓慢冷却 ,侏罗纪末、白垩纪初 (135Ma± )抬升到距地表约 10km处 ,与羌塘盆地转换期一致。Duguer gneiss (Dgn) was recently discovered and defined as an informal rock unit. It is the only one locality of gneiss in Qiangtang area. This rock unit is composed of granitic gneiss and hornblende-plagiogneiss,both of them have gone through ductile deformation. By studying the isotopic chronology of the granite-gneiss which have less deformation, the single granula zircon U-Pb concordia age (384.4 Ma) and biotite 40 Ar- 39 Ar plateau age (135.9 Ma) were obtained. It is suggested that Duguer granite-gneiss have slowly cooldowned in an relative stable enviroment and uplifted to the locality about 10 km under the surface in the late Jurassic to early Cretaceous (135 Ma±) which harmonized with the conversion period of Qiangtang basin. Up to know there is no evidence to prove the existence of a paleo-crystallized basement in Qiantang area.

关 键 词：西藏 都古尔片麻岩 同位素年代学 花岗质片麻岩 

分 类 号：P588.345[天文地球—岩石学] P597[天文地球—地质学]