祁漫塔格肯德可克火山岩锆石LA-ICP-MS U-Pb、^(40)Ar/^(39)Ar年龄及地质意义  

A STUDY ON ZIRCON LA-ICP-MS U-PB AND ^(40)AR/^(39)AR AGES OF VOLCANIC ROCKS FROM KENDEKEKE,QIMANTAGE AND THE GEOLOGICAL SIGNIFICANCE

作　　者：马帅 陈世悦[1] 孙娇鹏[2] 汪峰 单腾飞 

机构地区：[1]中国石油大学(华东)地球科学与技术学院,山东青岛266555 [2]西北大学大陆动力学国家重点实验室,陕西西安710069

出　　处：《地质力学学报》2017年第4期558-566,共9页Journal of Geomechanics

基　　金：中国地质调查局项目([2014]03-025-002)

摘　　要：通过对采集到的肯德可克上泥盆统契盖苏群火山岩样品进行锆石LA-ICP-MS U-Pb测年和^(40)Ar/^(39)Ar定年,结合区域地质特征,本文对祁漫塔格构造带的多旋回构造演化进行了总结分析。研究表明,契盖苏群流纹岩形成于晚泥盆世(384.9±6.0 Ma),而契盖苏群的形成时间不晚于晚泥盆世。767±15 Ma、915±18 Ma两个继承性锆石年龄证明研究区响应了Rodinia超大陆聚合—裂解。地层、沉积、变质及变形等证据不支持祁漫塔格地区存在晚古生代洋盆或裂陷槽,晚古生代祁漫塔格地区是发育在柴达木西南缘的陆表海。样品^(40)Ar/^(39)Ar有效坪年龄为220.3±1.7 Ma,代表研究区最后一次埋深达约8000 m。晚三叠世火山活动之后,研究区发生大规模抬升,随后叠加了印支晚期、燕山、喜山等多期构造事件导致中新生代缺少大规模沉降。陆内造山持续到32 Ma左右,随后由于库木库里盆地的伸展,祁漫塔格造山带与东昆仑造山带分离。Zircon LA-ICP-MS U-Pb dating and 40 r /39Ar dating were made on the volcanic samples of Qigaisu group from Kendekeke in upper Devonian. Combined with regional geological features, multicyclic tectonic evolution of Qimantag tectonic zone are summarized and analyzed. The results show that, rhyolites in Qigaisu group formed in late Devonian （384.9 ±6.0 Ma ） ,while Qigaisu group formed no later than late Devonian. The two inherited zircon ages 767 ±15 Ma and 915 ±18 Ma certify that the study area responded to supercontinent aggregation-cracking,but evidence from stratum, sedimentation, metamorphism and deformation do not support the existence of the late Paleozoic ocean or aulacogen in Qimantag area, and Qimantag area in late Paleozoic was an epeiric sea located at the southwest margin of Qaidam. The 40 Ar/39 Ar effective plateau age of the samples is 220. 3 ± 1. 7 Ma,which shows the latest burial depth is about 8000 m. Large-scale uplift events happened after the late Triassic volcanism, multiphase tectonic events, such as late Indosinian, Yanshanian and Himalayanian, caused the lack of large-scale settlement in Mesozoic and Cenozoic. Intra-continent orogeny lasted to 32 Ma or so. Because of the extension of Kumukuli basin afterwards, Qimantage orogenic belt separated from East Kunlun orogenic belt.

关 键 词：肯德可克 火山岩 锆石U-Pb年龄 Ar40/Ar39年龄 地质意义 

分 类 号：P597[天文地球—地球化学]