黑龙江省老柞山金矿区花岗闪长岩成因及其对成矿的启示——锆石U-Pb同位素定年和岩石地球化学特征  

Genesis of Granodiorite and Its Implications for Mineralization in Laozuoshan Gold Deposit, Heilongjiang Province: Zircon U-Pb Isotopic Dating and Geochemical Characteristics

作　　者：李怡欣 耿瑞 肖风利 柏城璘 孙景贵[2] Li Yixin;Geng Rui;Xiao Fengli;Bai Chenglin;Sun Jinggui(Shandong Gold Group Co.,Ltd.,Jinan 250000,China;College of Earth Sciences,Jilin University,Changchun 130061,China)

机构地区：[1]山东黄金集团有限公司,济南250000 [2]吉林大学地球科学学院,长春130061

出　　处：《吉林大学学报（地球科学版）》2023年第3期809-821,共13页Journal of Jilin University：Earth Science Edition

基　　金：国家自然科学基金项目(42072085)

摘　　要：黑龙江省老柞山金矿床是一座位于佳木斯地块中北部的大型岩金矿床,矿体与矽卡岩关系密切,主要赋存在花岗闪长岩与麻山群的接触构造带以及北西向、北西西向张性断裂等控矿构造内。矿床地质、岩相学、锆石U-Pb同位素年代学、岩石地球化学特征研究结果揭示:老柞山金矿床发育华力西期中二叠世晚期矽卡岩型矿化+燕山期热液型矿化两期叠加成矿,与主成矿期矽卡岩型金成矿作用密切相关的岩浆热事件为花岗闪长岩,成岩时代为(262.6±3.9) Ma;矿区华力西期花岗闪长岩地球化学特征表现为属弱过铝质高钾钙碱性岩系,具有较高的w(SiO_(2)),低Mg^(#)值,贫MgO,富集大离子亲石元素和轻稀土元素,亏损高场强元素和重稀土元素,表现出I型花岗岩特征,岩浆源区起源于地壳物质的部分熔融。综合研究认为,老柞山金矿床矽卡岩型矿化和岩浆作用发生于由洋陆俯冲消减向陆陆碰撞的构造体制转换期,花岗闪长岩是地壳物质部分熔融的产物。Laozuoshan gold deposit in Heilongjiang Province is a large-scale gold deposit located in the north-central part of Jiamusi block,Xing-Meng orogenic belt.The ore bodies are closely related to skarn,and hosted in the contacting belt between granodiorite and calcium marble and gneiss schist of Mashan Group,as well as in the ore-controlling structures such as the NW and NWW-trending extensional fractures.The studies of deposit geology,petrography,zircon U-Pb isotope chronology and geochemical characteristics reveal that Laozuoshan gold deposit develops two superimposed mineralization stages,including the skarn-type mineralization in late Middle Permian of Variscan and the hydrothermal mineralization in Yanshan Peried.The skarn-type mineralization during the main metallogenic period is closely related to the granodiorite,and its diagenetic age is(262.6±3.9)Ma.The Variscan granodiorite in this deposit is a kind of weak peraluminous and high potassium calc-alkaline rock series,characterized by high w(SiO_(2)),low Mg^(#) value and MgO,with features of enrichment of large ion lithophile elements and light rare earth elements,while depletion of high field strength elements and heavy rare earth elements,showing the characteristics of I-type granite,and the magma source originates from partial melting of crustal materials.The comprehensive studies show that the Variscan skarn-type mineralization and magmatism occurred during the transition period of the tectonic regime from ocean-continent subduction to continental collision,and the granodiorite is the product of partial melting of crustal materials.

关 键 词：老柞山金矿床 花岗闪长岩 锆石U-PB年代学 地球化学 成矿作用 岩石成因 

分 类 号：P597[天文地球—地球化学] P611[天文地球—地质学] P581