吉林汪清夹皮沟斑岩型钼矿床的形成时代与成矿构造背景  

Metallogenic epoch and tectonic setting of Jiapigou porphyry molybdenum deposit in Wangqing area,Jilin Province

作　　者：王辉[1] 任云生[1] 孙振明[1] 郝宇杰[1] 李超[2] 

机构地区：[1]吉林大学地球科学学院,吉林长春130061 [2]国家地质实验测试中心,北京100037

出　　处：《矿床地质》2013年第3期489-500,共12页Mineral Deposits

基　　金：国家973项目(2013CB429802课题);中国地质调查局项目(1212011085485)资助成果

摘　　要：夹皮沟钼矿床是吉林省汪清县近年来发现的一个中型斑岩型钼矿床。矿体赋存在受北东向断裂控制的似斑状黑云母二长花岗岩内。含矿岩体中锆石LA-ICP-MSU-Pb加权平均年龄为(193·1±1·0)Ma(MSWD=1·02),矿石中辉钼矿Re-Os等时线年龄为(188·6±4·7)Ma(MSWD=0·41),表明夹皮沟钼矿床形成于早侏罗世,与区域内其他斑岩型钼矿床(成岩成矿时代介于190~160Ma)同属于燕山早期大规模构造-岩浆-成矿事件的产物。似斑状黑云母二长花岗岩具有高硅〔w(SiO2)=72·29%~72·81%〕、富碱〔w(Na2O+K2O)=7·62%~7·71%〕的特点,属于弱过铝质的高钾钙碱性岩石系列;稀土元素分布型式呈明显的右倾型,轻、重稀土元素分馏明显(LREE/HREE为6·41~7·34),Eu异常中等(δEu=0·33~0·40);微量元素组成上表现为富集大离子亲石元素(LILE),亏损高场强元素(HFSE)。似斑状黑云母二长花岗岩属于I型花岗岩,矿床成岩成矿物质可能源于俯冲背景下增厚的下地壳。结合区域地质构造演化,认为夹皮沟钼矿形成于古亚洲洋构造体制与环太平洋构造体制叠加与转换的构造背景下,成岩成矿作用与燕山早期古太平洋板块的俯冲作用关系密切。Located in Wangqing area of Jilin Province, the Jiapigou molybdenum deposit is one of the newly discovered porphyry deposits. The molybdenum ore bodies are hosted in the porphyraceous biotite monzogranite which is controlled by NE-trending faults. The weighted mean LA-ICP-MS U-Pb age of zircons separated from ore-bear- ing rock is （193.1 ± 1.0） Ma （MSWD= 1.02）, and the Re-Os isochron age of molybdenites collected from ores is （188.6 ± 4.7） Ma （MSWD = 0.41 ）. The results indicate that the Jipigou deposit was formed in early Juras- sic period. It resulted from large-scale tectonic-magmatic-metallogenic event in early Yanshanian period together with other porphyry molybdenum deposits having isotopic ages of 190- 160 Ma. The porphyraceous biotite monzogranite is characterized by high silica （SiO2 = 72.29 % - 72.81% ） and alkali （Na2O ＋ K2O = 7 69 %.7.71% ） belonging to the weakly peraluminous and the high-K calc-alkaline series. The REE patterns are right- oblique with significant fractionation between LREE and HREE （LREE/HREE = 6.41 -7.34） and medium negative Eu anomalies （Eu = 0.33--0.40）. Trace elements are on the whole characterized by relative enrich- ment of large ion lithophile elements （LILEs） and depletion of high field strength elements. The rock geochemi- cal characteristics imply that the granite belongs to I-type granite, and the rock-forming and ore-forming materi- als probably resulted from the melting of the lower part of the compressional and thickened crust. In combination with the regional tectonic evolution, the authors have reached the conclusion that the Jipigou molybdenum de- posit was formed under the setting of transition and superimposition of tectonic regime, and the rock-forming and ore-forming processes were widely influenced by the subduction of the Paleo-Pacifie nl^to.

关 键 词：地球化学 锆石U-PB年龄 辉钼矿RE-OS年龄 成矿构造背景 夹皮沟钼矿 吉林汪清 

分 类 号：P618.65[天文地球—矿床学] P597.3[天文地球—地质学]