黑龙江跃进山矽卡岩型铜金矿床花岗闪长岩的年代学和地球化学特征  

Chronological and geochemical characteristics of granodiorite from Yuejinshan skarn-type copper-gold deposit in Heilongjiang Province

作　　者：王崇一 郝宇杰[1] 商青青 史雨凡 高煜 任云生[1,2] WANG Chong-yi;HAO Yu-jie;SHANG Qing-qing;SHI Yu-fan;GAO Yu;REN Yun-sheng(College of Earth Sciences,Jilin University,Changchun 130061,China;College of Earth Sciences,Institute of Disaster Prevention,Sanhe 065201,Hebei,China)

机构地区：[1]吉林大学地球科学学院,长春130061 [2]防灾科技学院地球科学学院,河北三河065201

出　　处：《世界地质》2021年第1期29-40,共12页World Geology

基　　金：国家重点研发项目(2017YFC0601304)。

摘　　要：对跃进山铜金矿床与矽卡岩型矿化有关的花岗闪长岩开展了LA-ICP-MS锆石U-Pb定年、锆石Lu-Hf同位素及岩石地球化学研究。结果表明,花岗闪长岩中26个锆石测点的^(206)Pb/^(238)U加权平均年龄为(118.96±0.77) Ma (MSWD=0.29);岩体中锆石的ε_(Hf)(t)值均为正值(+1.4~+3.2),且具有较年轻的Hf二阶段模式年龄(t_(DM2)=1.09~0.98 Ga);花岗闪长岩表现为富Al、高K和Na以及低Ti、P、Ca的钙碱性I型花岗岩地球化学特征,显示出轻稀土富集、重稀土元素亏损的稀土元素组成特征;样品锆石的ε_(Hf)(t)的值为偏低的正值,表明岩浆物质来源应为壳幔混源。结合岩石地球化学投图以及区域构造背景演化认为,花岗闪长岩和花岗斑岩均属于后碰撞-火山弧花岗岩,研究区的成矿成岩作用与太平洋板块强烈俯冲背景下的下岩石圈地幔拆沉有直接关系。The LA-ICP-MS zircon U-Pb dating and Lu-Hf isotopic analyses as well as whole-rock geochemistry study were carried on the granodiorite related to skarn mineralization in Yuejinshan copper-gold deposit.The results show that the weighted average age of206Pb/238U of 26 zircon points in the granodiorite is (118.96±0.77) Ma (MSWD=0.29).TheεHf(t) values of zircons in the rock mass are all positive (+1.4~+3.2),with young Hf two-stage model age (TDM2=1.09~0.98 Ga).Geochemically,the granodiorite is rich in Al,K,Na,and depleted in Ti,P,Ca,indicating calcium alkaline I-type granite.For rare earth elements (REE) composition,the granodiorite is enriched in light REE and depleted in heavy REE.Combined with the low positiveεHf(t) values,it is indicated that the magma is from a mixing source between crust and mantle.Based on the petrogeochemical mapping and the evolution of the regional tectonic background,both the granodiorite and granite porphyry belong to post-collision volcanic arc granites.The metallogenic diagenesis of the study area is directly related to the lower lithosphere mantle delamination under the tectonic environment of intense subduction of the Paleo-Pacific Ocean plate.

关 键 词：LA-ICP-MS锆石U-PB定年 LU-HF同位素 岩石地球化学 跃进山铜金矿床 

分 类 号：P595[天文地球—地球化学]