西藏日土北部松西—胜利山—带燕山期高钾钙碱性花岗岩的地球化学特征及构造环境

Geochemical features and tectonic setting of Yanshanian high-K calc-alkaline granite in the Songxi-Shenglishan area,northern Rutog,Tibet,China

西藏羌塘北部松西—胜利山一带的花岗闪长岩和黑云母二长花岗岩属高钾钙碱性岩石系列。其重稀土元素亏损,花岗闪长岩的LREE／HREE比值在8.67～33.08之间,平均16.62,黑云母二长花岗岩在9.16～30.97之间,平均21.76,二者的Eu负异常均不明显;微量元素具有富集Rb、Th和亏损Ba、Sr、Zr、Ti的地球化学特点。花岗闪长岩和黑云母二长花岗岩总体上显示I型花岗岩的特点,其形成的构造环境很可能与冈底斯和羌塘地块在晚体罗世—早白垩世发生的碰撞作用有关。

Granodiotite and biotite monzogranite in the Songxi-Shenglishan area, north Qiangtang, Tibet, belongs to a high- K calc-alkaline series. The rocks are HREE-depleted. The LREE/HREE ratios of granodiorite range from 8.67 to 33.08, with an average of 16.62, and those of biotite monzogranite range from 9.16 to 30.97, with an average of 21.76. The Eu anomalies of the two types of rock are neither pronounced. For the trace elements, the rocks are enriched in Rb and Th and depleted in Ba, Sr, Zr and Ti. Granodiorite and biotite monzogranite generally exhibit the features of Ⅰ-type granite and their tectonic environment is very likely to be related to collision between the Gangdise and Qiangtang blocks during the Late Jurassic to Early Cretaceous.