东昆仑三道湾流纹英安斑岩锆石U-Pb年龄及其地质意义  

ZIRCON U-Pb DATING OF THE RHYOLITE-DACITE PORPHYRY IN THE SANDAOWAN OF EAST KUNLUN MOUNTAINS AND ITS GEOLOGICAL SIGNIFICANCE

作　　者：周春景[1] 胡道功[1] Barosh P J 吴珍汉[3] 张永清 耿建珍[4] 郝爽 倪晋宇[1] 张耀玲[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]P J Barosh and Associates [3]中国地质科学院,北京100037 [4]中国地质调查局天津地质调查中心,天津300170

出　　处：《地质力学学报》2010年第1期28-35,共8页Journal of Geomechanics

基　　金：中国地质调查局地质调查项目(编号:1212010711510);科技部重点国际科技合作项目(编号:2006DFB21330)资助

摘　　要：东昆仑格尔木河西三道湾流纹英安斑岩构成火山通道侵出相,侵入到纳赤台群哈拉巴依沟组碎屑岩系中,其形成时代对于造山带火山作用的研究和限定哈拉巴依沟组地层时代均具有重要的意义。采用激光烧蚀多接收器电感耦合等离子体质谱(LA-MC-ICP MS)方法,对三道湾流纹英安斑岩进行了锆石U-Pb定年,结果表明,流纹英安斑岩中25个岩浆锆石206 Pb/238 U加权平均年龄为425.9±2.6 Ma,它被解释为流纹英安斑岩的结晶年龄,说明三道湾次火山岩所代表的火山通道为早古生代造山晚期牦牛山组火山岩形成时的火山喷发中心之一,而非晚侏罗世次火山岩。野外地质关系和次火山岩年龄可以限定哈拉巴依沟组形成于中志留世之前。The Sandaowan rhyolite-dacite porphyry,located to the west of the Golmud River,about 55 km from south of Golmud City,is an intrusive vein of volcanic craters.It intruded into the clastic rocks,named Habalayigou group as one of the Nachitai unit in this region.A sample No.B727-1 was collected from the Sandaowan rhyolite-dacite porphyry rock.We used the LA-MC-ICPMS method of Zircon U-Pb Dating in this article.The 25 zircons from No.B727-1 yield a mean value of（425.9 ± 2.6） Ma of 206Pb/238U,which is interpreted as the age of the volcanism.The result shows that the volcanic crater was one of the eruptive center during Late collision of the Early Paleozoic in this region.Besides,it reveals a low time restrict to the Habalayigou group,implying that the Habalayigou strata formed before the Middle Silurian.These results conflict with previous 40Ar /39Ar whole rock ages of 147.96Ma for the rhyolite-dacite porphyry from the same rock.

关 键 词：流纹英安斑岩 锆石U-PB年龄 中志留世 东昆仑造山带 

分 类 号：P597[天文地球—地球化学]