东昆仑祁漫塔格鸭子沟地区花岗岩类岩石年代学、地球化学及地质意义  

Zircon U-Pb Geochronology,Geochemistry and Geological Significance of Granitoids in the Yazigou,Qimantage Area of East Kunlun Mountains

作　　者：王盘喜[1,2,3] 郭峰 王振宁 WANG Panxi;GUO Feng;WANG Zhenning(Zhengzhou Institute of Multipurpose Utilization of Mineral Resources,CAGS,Zhengzhou,Henan450006,China;National Research Center of Multipurpose Utilization of Nonmetallic Mineral Resources,Zhengzhou,Henan450006,China;Northwest China Center for Geoscience Innovation,Xi'an,Shaanxi710054,China)

机构地区：[1]中国地质科学院郑州矿产综合利用研究所,河南郑州450006 [2]国家非金属矿资源综合利用工程技术研究中心,河南郑州450006 [3]西北地质科技创新中心,陕西西安710054

出　　处：《现代地质》2020年第5期987-1000,共14页Geoscience

基　　金：中国地质调查局地质调查项目“长江中游黄石—萍乡—德兴矿山集中区综合地质调查”(DD20190269);“青海祁漫塔格金属矿集区综合地质调查”(DD20160073)。

摘　　要：为加深对东昆仑区域构造演化和成矿规律的认识,选取祁漫塔格鸭子沟地区花岗岩类岩石开展岩相学、年代学和岩石地球化学研究,探讨其岩石成因、构造背景及与铅锌矿成矿的关系。结果表明,黑云石英二长闪长岩的SIMS锆石U-Pb年龄为(415.5±2.6)Ma,属早泥盆世早期。正长岩、二长花岗岩和石英二长岩与闪长岩相比,具有硅、钾、全碱含量高,低钙、镁、全铁和钛,铝含量相当,闪长岩K2O含量小于Na2O,其他岩石K2O含量大于Na2O的特点。岩石为准铝质-弱过铝质岩石,既有亚碱性系列也有碱性系列。∑REE平均为305×10^-6;δEu为0.26~1.03,平均为0.61,多数岩石具有Eu负异常;稀土元素球粒陨石标准化配分模式图上呈轻稀土元素富集的右倾型曲线,轻、重稀土发生了分馏作用;岩体明显富集大离子亲石元素Cs、Rb、K,活泼的不相容元素U、Th,轻稀土元素和Pb;相对亏损高场强元素Nb、Ta、Zr、P和Ti,大离子亲石元素Ba和Sr。鸭子沟花岗岩类岩石为以幔源分异为主、少量壳源物质加入的壳幔混合成因,应该是加里东造山期后陆缘裂陷幔源物质上侵形成的岩浆岩。结合区域构造特征和地质背景,推测该岩体形成于后碰撞陆内伸展阶段,并与区域铅锌矿成矿密切相关;在今后的矿产勘查中应重视华力西早期花岗岩类岩石。To enhance our understanding on the regional tectonic evolution and metallogenic regularity in the east Kunlun mountains,The authors report a synthesis of the petrology,geochronology and geochemistry of grani-toids in Yazigou area,Qimantage,and discuss the petrogenesis,tectonic setting and its metallogenic relations.Zircon grains from the monzodiorite with biotite and quartz yielded 206Pb/238U age of(415.5±2.6)Ma,indicating that the rock was formed in the earliest Devonian.Comparing syenite and adamellite with diorite,they all have similarly high SiO2,K2O,and total alkali,and low CaO,MgO,FeOT,and TiO2.They have similar Al2O3 content.The K2O content is lower than Na2O in diorite,but higher Na2O in the other rock types.The rocks are meta-aluminous to weakly peraluminous,and are either subalkalic or alkaline.They have average total∑REE content of 305×10^-6,and mostly negative Eu anomaly(δEu=0.26-1.03,average 0.61).The chondrite-normalized REE patterns are right-inclining with LREE enrichments and LREE/HREE fractionation.The rocks have significant enrichments in large ion lithophile elements(LILEs,e.g.Cs,Rb,K,U,and Th),LREEs and Pb,but depletions in high field strength elements(HFSEs,e.g.Nb,Ta,Zr,P,and Ti),Ba,and Sr.The Yazigou granitoids may have derived mainly from a mantle source with little crustal material input,belonging to a crust-mantle mixed origin.The rocks were likely formed by upward ascent of mantle-derived materials along continental margin rift under the Caledonian post-orogenic setting.Considering the structural features and regional geological setting,it is inferred that the intrusive body was formed in a post-collisional extension environment,and closely related to Pb-Zn mineralization,Attention should be paid to the Early Variscan granitoids in future mineral exploration.

关 键 词：花岗岩类 年代学 地球化学 祁漫塔格 

分 类 号：P588.1[天文地球—岩石学] P59[天文地球—地质学]