西藏羌塘地块西北部银利沟早白垩世钾玄质侵入岩的发现——来自地球化学和锆石U-Pb年龄的证据  

Discovery of an Early Cretaceous shoshonitic pluton in Yinligou, northwestern Qiangtang, Tibet, China-evidence from geochemical data and zircon U-Pb ages

作　　者：钟华明[1] 夏军[1] 邱军强[1] 童劲松[2] 鲁如魁[1] 

机构地区：[1]安徽省地质调查院,安徽合肥230001 [2]中国地质大学地球科学与资源学院,北京100083

出　　处：《地质通报》2007年第4期427-432,共6页Geological Bulletin of China

基　　金：中国地质调查局<1:25万松西幅区域地质调查>项目(基[2002]002-20)资助

摘　　要：银利沟二长岩分布于西藏羌塘西北部,岩石具有高碱、低Ti的特征,在SiO2-K2O图解中位于钾玄岩区。二长岩的锆石U-Pb同位素年龄为121.3Ma±0.6Ma,具有富集LIL、LIEE及显著的Ta-Nb-Ti负异常的地球化学特征,表现出与俯冲有关的钾玄岩的地球化学特征,形成于晚造山—后造山构造背景。这种背景很可能与冈底斯和羌塘地块在晚侏罗世—早白垩世发生的碰撞作用有关。The Yinligou monzonite is distributed in northwestern Qiangtang, Tibet. The rock has the high-alkali and low-Ti features and plots in the shoshonite field of the SiO2-K2O diagram. The monzonite has a zircon U-Pb age of 121.3±0.6 Ma and is enriched in LIL and LIEE with pronounced Ta-Nb-Ti negative anomalies, showing the geochemical characteristics of shoshonite related to subduction and a late orogenic-postorogenic tectonic setting. This tectonic setting is very likely related to the collision between the Gangdise and Qiangtang blocks during the Late Jurassic to Early Cretaceous.

关 键 词：西藏西部银利沟 钾玄质岩石 二长岩 晚造山-后造山期 

分 类 号：P534.53[天文地球—古生物学与地层学] P588.122[天文地球—地质学]