宗务隆山达肯大坂变质侵入体LA-ICP-MS锆石U-Pb定年及其地质意义  

LA-ICP-MS Zircon U-Pb dating of metamorphic and intrusive rock( system) of Zongwulongshan Intruded into Dakendaban and its geological significance

作　　者：严玉峰[1] 许海全[1] 杨波[1] 李焕学[1] 李五福[1] 

机构地区：[1]青海省地质调查院,青海省青藏高原北部地质过程与矿产资源重点实验室,青海西宁810012

出　　处：《青海大学学报（自然科学版）》2017年第6期102-108,共7页Journal of Qinghai University(Natural Science)

基　　金：中国地质调查局地质大调查项目(12120113033005)

摘　　要：为探讨柴北缘宗务隆山地区构造岩浆带发展演化,在开展1∶5万区域地质矿产调查中,于宗务隆山地区古元古代达肯大坂岩群中,发现了一套变质侵入体,通过LA-ICP-MS方法测得英云闪长岩锆石U-Pb同位素年龄为(803±18)Ma,时代为新元古代,岩石中Si02含量为63.70%~74.40%,σ为1.29~2.26,山德指数(A/CNK)为1.73~2.64,总体显示为强过铝质钙碱性岩;稀土元素总量较高,属轻稀土富集的配分曲线,轻重稀土分馏强烈,重稀土亏损,具强烈的负Eu异常,具有地壳重熔的特点,反映岩石经历了强烈的结晶分异过程;其成因分析,该变质侵入体为同碰撞环境下岩浆作用的产物。高精度锆石U-Pb同位素年龄值的获得为柴达木盆地东北缘地区新元古代岩浆热事件提供了新的年代学资料。In order to explore Zongwulongshan tectonic magmatic evolution development zone in northern Qaidam basin, metamorphic intrusive rocks into Dakendaban rock group of the Paleo - prot- erozic were found. The isotope age determination shows they are the Neoproterozoic. Compositional-ly , SiO2 content is from 63. 7 0 % to 74. 4 0 % , a from 1. 29 to 2. 26, and A/CNK from 1. 73 to 2. 64, suggesting it is aluminum calc - alkaline rock. High amount of rare earth elements suggests it belongs to the distribution curve of light rare earth concentration. Light and heavy rare earth frac-tionation is strong with heavy rare earth losses, strong negative Eu anomaly and the characteristics of crustal remelting. The rock has experienced strong crystallization differentiation process. Origin a-nalysis shows it is resulted from a tectonic environment of syn - chronous collision. The high - preci-sion zircon U - Pb isotopic age value obtained can provide new chronology information for Neoprot-erozoic magmatic thermal event at the northeast Qaidam basin margin area.

关 键 词：变质侵入体 英云闪长岩 同碰撞环境 宗务隆 

分 类 号：P62[天文地球—地质矿产勘探]