青藏高原西部燕山晚期花岗岩地球化学特征及其大地构造意义

对青藏高原西部燕山晚期花岗岩进行了地质、地球化学综合研究。结果表明 ,燕山晚期早白垩世花岗岩为 I型 ,形成于火山弧环境 ,岩石组合为石英二长闪长岩 -花岗闪长岩 -二长花岗岩 ,岩石系列为高钾钙碱性系列 ,A/ CNK<1,稀土元素含量中等 ,并且属轻稀土富集型 ,铕亏损不明显 ,L IL E有选择地得到富集 ,HFSE相对亏损 ;晚白垩世花岗岩为 S型 ,形成于同碰撞环境 ,岩石组合为二云母二长花岗岩 -二云母花岗岩 ,岩石系列为高钾钙碱性系列 ,但 A/CNK>1.1,稀土元素含量较低 ,铕亏损明显 ,微量元素中以 Rb和 F含量高为显著特征。为研究喀喇昆仑山构造演化提供了限定条件

Geochemistry of late Yanshanian granite and its tectonic significance in the western Qinghai-Tibet Plateau

Geology and geochemistry of the late Yanshanian granite in the western Qinghai Tibet Plateau have been systematically studied in this paper. The results indicate that the early Cretaceous granite belongs to I type and generated in the volcanic arc environment. Its rock association is quartz monzodiorite granodiorite monzonitic granite. The rock series is K high calc alkaline with A/CNK<1, middle content of REE, LREE>HREE, no obvious Eu anomaly, rich LILE and lean HFSE. The late Cretaceous granite belongs to S type and generated in the syn collisional environment. Its rock association is two mica monzonitic granite two mica granite. The rock series is K high calc alkaline with A/CNK>1.1, low content of REE, obvious Eu anomaly, high contents of Rb and F. This research furnishes tectonic evolution of Karakorum Mts with new constraints.