大兴安岭北段晚中生代斑岩铜钼矿床成矿岩体黑云母地球化学特征及地质意义  

Mineral Geochemistry of Biotites from the Mineralized Intrusive Bodies in the Late Mesozoic Porphyry Cu-Mo Deposits,Northern Great Xing’an Range and Its Geological Implications

作　　者：孟凡波 邓昌州 冯雨周 田振东 李成禄 龚林 陈旭升 吕凤彤 MENG Fan-bo;DENG Chang-zhou;FENG Yu-zhou;TIAN Zhen-dong;LI Cheng-lu;GONG Lin;CHEN Xu-sheng;LYU Feng-tong(Qiqihar Institute of Geological Exploration of Heilongjiang Province,Qiqihar Heilongjiang 161006,China;Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;Heilongjiang Institute of Natural Resource Survey,Harbin 150036,China)

机构地区：[1]黑龙江省齐齐哈尔地质勘查院,黑龙江齐齐哈尔161006 [2]中国科学院地球化学研究所,贵阳550081 [3]中国科学院广州地球化学研究所,广州510640 [4]黑龙江省自然资源调查院,哈尔滨150036

出　　处：《矿物岩石地球化学通报》2021年第4期914-924,共11页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：黑龙江省自然资源厅国土科研项目(201701)。

摘　　要：为了解大兴安岭北段晚中生代斑岩型铜钼矿床的成矿信息,利用电子探针对晚侏罗世霍洛台铜钼矿床和早白垩世宝泉矿床成矿岩体中的黑云母开展了地球化学研究。结果表明,这些黑云母均为镁质黑云母,成矿岩浆为活动陆缘构造背景下壳幔熔体混合的产物。黑云母温压计计算结果显示,霍洛台和宝泉黑云母的结晶温度和压力分别为738~761℃、67~95 MPa和725~749℃、102~141 MPa,对应的深度分别为2.55~3.60 km和3.85~5.33 km。黑云母氧逸度位于HM缓冲剂附近,指示岩浆具有较高的氧逸度。而黑云母适中的lg(fHF/fHCl)、lg(fH2O/fHCl)和lg(fH2O/fHF)等卤素逸度比值,指示岩浆具有同时产生Cu和Mo矿化的条件。黑云母地球化学特征显示,大兴安岭北段地区晚中生代良好的构造和岩浆条件触发了斑岩型铜钼矿床的形成。Compositions of biotites from mineralized intrusive bodies of the late Mesozoic Huoluotai and Baoquan Cu-Mo deposits in the northern Great Xing’an range were measured here by using the electron probe micro-analyzer with the aim to understand the metallogenic information of these deposits.The results show that the biotites from the Huoluotai and Baoquan deposits belong to the magnesium biotites.The biotite-bearing mineralized porphyry bodies are products of mixtures of crust and mantle melts formed in the active continental margin setting.The calculation results by using the biotite thermobarometer show that crystallization temperatures of biotites of the Huoluotai and Baoquan deposits range from 738 to 761℃and 725 to 749℃,respectively.Their solidification pressures are 67-95 MPa and 102-141 MPa,respectively,corresponding to the depths of 2.55-3.60 km and 3.85-5.33 km,respectively.Oxygen fugacities of the studied biotites are near the HM buffer,indicating the relatively high oxygen fugacity environments for those magmas.Moderate lg(fHF/fHCl),lg(fH2O/fHCl)and lg(fH2O/fHF)values of the biotites indicate that those magmas have favorable conditions for the simultaneous Cu and Mo mineralization.Biotite geochemical characteristics indicate that the northern Great Xing’an range has beneficial tectonic and magmatic conditions for the formation of late Mesozoic porphyry Cu-Mo deposits.

关 键 词：黑云母 地球化学 斑岩型铜钼矿 成岩成矿 大兴安岭北部 

分 类 号：P588.1[天文地球—岩石学]