新疆青河县阿克布拉克花岗闪长岩年代学、地球化学特征及其构造意义  

Geochronology,Geochemistry and Tectonic Interpretation of Akebulake Plutons in Qinghe County,Northern Xinjiang

作　　者：王硕[1,2] 魏均启 郭花利[3] 李睿华 WANG Shuo;WEI Junqi;GUO Huali;LI Ruihua(School of Earth Science and Resources,Chang’an University,Xi’an 710054,Shaanxi,China;Key Laboratory of Rare Mineral,Ministry of Land and Resources,Wuhan 430034,Hubei,China;China Chemical Geology and Mine Bureau Shaanxi Geological Prospecting Institute,Xi’an 710065,Shaanxi,China;MLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,CAGS,Beijing 100037,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]国土资源部稀土稀有稀散矿产重点实验室,湖北武汉430034 [3]中化地质矿山总局陕西地质勘查院,陕西西安710065 [4]中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点实验室,北京100037 [5]北京大学地球与空间科学学院,北京100871

出　　处：《西北地质》2020年第2期147-162,共16页Northwestern Geology

基　　金：国家自然科学基金项目“西秦岭北缘李子园-太阳寺构造带变形特征与成矿作用关系研究”(41872219);中国地质调查局区域地质调查项目“吉黑东部区域成矿规律综合研究”(1212011085485);中国地质调查局项目“东天山昌吉—双沟山地区区域地质调查”(2019-003)联合资助。

摘　　要：阿克布拉克岩体位于新疆阿尔泰造山带中段青河县大青格里河昆格依特西南,岩性主要为花岗闪长岩。LA-ICP-MS锆石U-Pb分析结果表明其形成于早泥盆世(397.6±5.2)Ma,为阿尔泰造山带晚古生代早期大规模岩浆活动的产物。地球化学分析结果表明,该岩体SiO2含量为69.17%~74.70%,A/CNK值为0.97~1.09,属准铝质钙碱性-高钾钙碱性系列岩石。岩体富集K、Rb、Th、La、Ce、Nd等元素,相对亏损Ba、Nb、Ta、Ti、Sr等,微量元素蛛网图与稀土元素配分曲线均显示为明显的右倾型,正/负Eu异常均可见(δEu=0.58~1.23),其中花岗闪长岩多为负Eu异常,黑云母花岗闪长岩则全部为正Eu异常,应为岩浆结晶分异不同阶段的结果,与岛弧岩浆岩特征一致。结合前人研究成果,笔者认为阿尔泰造山带南缘早泥盆世阿克布拉克岩体形成于古亚洲洋俯冲背景下的陆缘弧构造环境,岩体中的暗色微粒包体及地球化学属性推断其为幔源基性岩浆底侵加热下地壳使之熔融,形成的混合岩浆分异演化的产物。The Akebulake plutons,outcropped in Qingeli River in Qinghe County of southern margin of Altay orogenic belt,are mainly granodiorite.LA-ICP-MS zircon U-Pb indicates that the plutons were formed in the early Devonian(397.6±5.2Ma),which is a large scale magmatic event in the Altay orogenic belt in Devonian.The SiO 2 contents range from 69.17%to 74.70%and A/CNK from 0.97 to 1.09,indicating that the plutons are metaluminou,mid-high K calc-alkaline series rock.In addition,the plutons are enriched in K,Rb,Th,La,Ce and Nd,obvious negative anomaly in Ba,Nb,Ta,Ti,Sr and Eu(δEu=0.58—1.23),which are consistant with the characteristics of granitoid rocks formed in island-arc.Based on the previous studies,this paper suggests that the Akebulake plutons were generated from the tectonic environments of continental margin arc by the subduction of the Paleo-Asian Ocean plate.Dark-coloured inclusion bodies in the rocks and the geochemical properties suggest that the plutons are the mixing and differentiation of the mantle magma melting the lower crust.

关 键 词：阿尔泰 阿克布拉克 花岗闪长岩 LA-ICP-MS锆石U-PB定年 构造意义 

分 类 号：P595[天文地球—地球化学]