青海省窑洞山地区五路沟岩体岩石地球化学特征及地质意义  

Geochemical Characteristics and Geological Significance of Wu Lu Gou Rock Mass in Yaodongshan Area of Qinghai Province

作　　者：杨雪松 余福承[1,2] 孟红 王国良[1,2] 李根军 YANG Xuesong;YU Fucheng;MENG Hong;WANG Guoliang;LI Genjun(Key Laboratory of Geological Processes and Mineral Resources in the Northern Part of the Qinghai-Tibet Plateau in Qinghai Province,Xining,Qinghai 810012,China;Qinghai Institute of Geological Survey,Xining,Qinghai 810012,China)

机构地区：[1]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 [2]青海省地质调查院,青海西宁810012

出　　处：《中国锰业》2019年第6期15-22,共8页China Manganese Industry

基　　金：中国地质调查局大调查项目(12120113033014)

摘　　要：通过青海省格尔木市窑洞山区调项目,从窑洞山地区五路沟志留纪岩体中解译出一套中奥陶世花岗闪长岩和英云闪长岩,岩体中Si O2介于65.01×10^-2~71.86×10^-2,σ=1.20~5.43,为钙碱性-碱性系列;Al2O3>Ca O+K2O+Na2O,A/CNK=1.62~1.77,为过铝质岩石;LREE/REE=4.89~11.31,Sm/Nd=0.17~0.27,均小于0.3,δEu=0.52~1.05,为弱亏损;微量元素中大离子亲石元素K、Rb、Ba、Th、Ta富集,Y、Yb、Nb亏损,表明源岩为壳幔混合型,为俯冲环境的岛弧花岗岩;利用LA-ICP-MS方法,首次在花岗闪长岩体中测得锆石U-Pb年龄为471 Ma±2 Ma,时代为中奥陶世,为东昆洋开始向北俯冲消减的地质演化史提供精确的年代学依据,弥补了东昆仑地区中奥陶世构造-岩浆演化的空白。Through the regional geological survey project of Yaodongshan area in Golmud City,Qinghai Province,a set of Middle Ordovician granodiorite and tonalite have been interpreted from the Silurian rocks in Wulugou.Si O2content is between 65.01×10^-2~71.86×10^-2andσ=1.20~5.43 in the rock mass which is Calc-alkaline series;Al2O3>Ca O+K2O+Na2O,A/CNK=1.62~1.77,which is peraluminous rock;LREE/REE=4.89~11.31,Sm/Nd=0.17~0.27,all less than 0.3,δEu=0.52~1.05,which is weak depletion.The large ion lithophile elements as K,Rb,Ba,Th,Ta are enrichment,Y、Yb、Nb are depletion.It indicates that the source rock is crust mantle mixed type,and it is the island arc granite of subduction environment.Using LA-ICP-MS method,the U-Pb age of zircon in granodiorite is 471 Ma±2 Ma for the first time.The age of zircon is Middle Ordovician,which provides precise chronological basis for the geological evolution history of the East Kunlun Ocean which began to subduct northward.It makes up for the gap of Middle Ordovician tectonic-magmatic evolution in the East Kunlun area.

关 键 词：钙碱性系列 岛弧花岗岩 LA-ICP-MS 

分 类 号：P534[天文地球—古生物学与地层学]