东昆仑都兰县可可沙地区加里东期石英闪长岩锆石LA-ICP-MS U-Pb年龄及其意义

LA-ICP-MS zircon U-Pb age of quartz diorite at the Kekesha area of Dulan County, eastern section of the East Kunlun orogenic belt, China and its significance

摘要: 野外调研和室内综合分析表明，出露于东昆仑造山带东段都兰可可沙地区的加里东期石英闪长岩体包括4种岩石类型：①灰—深灰色中粒石英闪长岩；②灰色中粒片麻状石英闪长岩；③灰色中粗粒角闪石英闪长岩；④浅肉红色中细粒似斑状二长花岗岩。用LA-ICP-MS法进行了锆石U-Pb同位素年龄测定，样品11013的锆石206Pb/238U加权平均年龄为515.2Ma±4.4Ma（MSWD=2.5），限定该石英闪长岩体的形成时代为中寒武世，表明东昆仑造山带加里东早期存在一期岩浆活动事件。

Abstract: After detailed field survey and indoor analysis, the quartz diorites exposed at the Kekesha area of Dulan, eastern section of the East Kunlun orogenic belt, include four types of rocks: (1)Gray-dark gray medium grained quartz diorite; (2) Gray medium grained gneissic quartz diorite; (3)Gray medium-coarse grained amphibole quartz diorite; (4)Light flesh-red medium-fine grained porphraceous adamellite. LA-ICP-MS method is used to determine the zircon U-Pb isotope age of the rock, which shows that the zircon 206Pb/238U weighted average age of the sample 11013 is 515.2±4.4Ma (MSWD=2.5) and defines the crystallization age of the rocks in Middle Cambrian period. It indicated that East Kunlun orogenic belt had experienced a magmatism event during the early Caledonian.