东天山小尖山金矿床侵入岩年代学、岩石地球化学及其地质意义  

Geochronology and Geochemistry of Intrusive Rocks of Xiaojianshan Gold Deposit in the East Tianshan Mountains and Its Geological Significance

作　　者：蒋东祥 毛启贵[2] 刘家军[1] 于明杰[2] 卫晓峰 程志龙[2] Jiang Dongxiang;Mao Qigui;Liu Jiajun;Yu Mingjie;Wei Xiaofeng;Cheng Zhilong(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Beijing Institute of Geology for Mineral Resources,Beijing 100012,China;The Sixth Gold Detachment of China Armed Police Force,Xining 810000,China)

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]北京矿产地质研究院,北京100012 [3]武警黄金第六支队,青海西宁810000

出　　处：《地球科学》2018年第9期3049-3064,共16页Earth Science

基　　金：国家重点研发计划(No.2017YFC0601201);国家重点基础发展研究计划(973计划)项目(No.2014CB440803);中国地质调查局公益性地质调查项目(No.DD20160071)

摘　　要：小尖山金矿床位于东天山康古尔塔格金矿带中段,目前其成矿作用与矿区侵入岩的关系尚不明确.通过岩相学、岩石地球化学及年代学特征的系统研究,结果表明小尖山矿区花岗岩脉SiO_2含量为66.30%~68.31%,Al2O3含量为16.65%~18.28%,K_2O含量为3.25%~4.00%,Na_2O含量为2.38%~3.46%,K_2O/Na_2O比值为0.94~1.68(平均值1.41),属于过铝质高钾钙碱性系列;岩石富集轻稀土元素((La/Yb)N=7.68~9.04),并且富集Rb、K等大离子亲石元素,相对亏损Ta、Th、U、Nb、Ti等高场强元素,具δEu正异常(1.02~1.25),δCe负异常(0.79~0.86),具有岛弧岩浆稀土微量地球化学特征.Nb-Y图解中,样品投点落在火山弧-同碰撞花岗岩区;Rb-(Y+Nb)图解中,样品投点落在火山弧花岗岩区.LA-ICP-MS锆石U-Pb定年揭示岩脉的结晶年龄为257.0±2.3Ma,形成于晚二叠世,与康古尔金矿带挤压走滑构造和成矿作用时间一致.样品的Zr/Hf(31.90~37.60)和Nb/Ta(4.96~11.28)结果显示地壳的部分熔融来源特征;结合区域构造演化过程与成矿时代可知,矿区花岗岩脉为深部地壳的部分熔融产物,侵入就位过程与金成矿作用有密切关系.The Xiaojianshan gold depost is located in the Kanggurtag gold belt of the East Tianshan mountains,but the relationship between the mineralization and the intrusive rocks in the mining area is not clear.Based on the systematic study of petrography,petrogeochemistry and chronology,the results show that Xiaojianshan granite is dominated by adamellite,with SiO2 concentrations of 66.30%-68.31%,Al2O3 of 16.65%-18.28%,K2O of 3.25%-4.00%,Na2O of 2.38%-3.46%,and K2O/Na2O（0.94-1.68）with an average value of 1.41,belonging to peraluminous high-K cale-alkaline series.The granite is enriched in the light rare earth elements（（La/Yb）Nvalues of 7.68-9.04）and LILEs like Rb and K,but is relatively depleted in the high field strength elements（Ta,Th,U,Nb and Ti）.This granite has negligible Eu anomalies（δEu=1.02-1.25）andweak negative Ce anomaly（δCe=0.79-0.86）.In the Nb-Y diagram,the samples all fall into the area of the volcanic arcsyncollisional granite;In the Rb-（Y＋Nb）diagram,the samples fall into the area of volcanic arc granite;LA-ICP-MS zircon U-Pb dating shows that granite age is 257.0±2.3 Ma and formed in Late Permian and concordance with the extrusion strike slip structure and metallogenic time of the Kanggur gold belt.The Zr/Hf（31.90-37.60）and Nb/Ta（4.96-11.28）values of the samples show the characteristics of the partial melting of the crust,therefore,the granite is the partial melting product of the tectonic compression of the deep crust,and the emplacement process is closely related to gold mineralization.

关 键 词：锆石U-PB测年 地球化学 小尖山金矿 东天山 康古尔塔格 

分 类 号：P588.12[天文地球—岩石学] P597.3[天文地球—地质学]