哈萨克斯坦科翁腊德矿集区贫矿和成矿岩体性质对比及其对成矿的启示  

Comparison of natures of barren and fertile intrusions in the Kounrad ore district,Kazakhstan and its implication for mineralization

作　　者：李昌昊[1,2,3] 潘鸿迪 索青宇[1,2,3] 楚翔凯 SEITMURATOVA Eleonora LI ChangHao;PAN HongDi;SUO QingYu;CHU XiangKai;SEITMURATOVA Eleonora(Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;College of Earth Sciences,Chang an University,Xi an 710054,China;Laboratory of Geological Formations,K.Satpaev Institute of Geological Sciences,Almaty 050010,Kazakhstan)

机构地区：[1]中国科学院地质与地球物理研究所,中国科学院矿产资源重点实验室,北京100029 [2]中国科学院地球科学研究院,北京100029 [3]中国科学院大学地球与行星科学学院,北京100049 [4]长安大学地球科学与资源学院,西安710054 [5]沙特巴耶夫地质研究所地层实验室,阿拉木图050010

出　　处：《岩石学报》2023年第11期3263-3283,共21页Acta Petrologica Sinica

基　　金：中国科学院国际合作局国际伙伴计划(132A11KYSB20190070);国家自然科学青年基金项目(42002092);国家重点研发计划政府间国际科技创新合作专项(2021YFE0190600);国家自然科学基金重大研究计划重点支持项目(91962213);上海合作组织国际科技合作计划项目(2020E01043)联合资助。

摘　　要：中亚造山带发育众多大型-超大型斑岩型Cu矿床。尽管这些矿床通常发育时代相近的大规模岩浆作用,但只存在少数成矿岩浆。因此,如何区分矿区内的成矿和贫矿岩浆对于找矿勘查至关重要。为了探讨这一问题,本文对哈萨克斯坦科翁腊德矿集区石炭纪的贫矿岩浆岩和成矿花岗闪长斑岩中的磷灰石、角闪石、黑云母和斜长石进行结构和成分分析,对弱蚀变岩石开展全岩主量元素分析。测试结果显示,贫矿岩浆岩和成矿花岗闪长斑岩均为富H_(2)O的(>~4%)氧化性(>~ΔNNO+1.63)岩浆,属于中钾或高钾钙碱性系列岩石。贫矿岩浆岩中斜长石An值存在显著变化(ΔAn在26~34)并与FeO含量呈正相关,表明其经历了明显的岩浆混合作用,而该过程在成矿花岗闪长斑岩中不明显。磷灰石、角闪石和黑云母成分对比显示,成矿花岗闪长斑岩的氧逸度和H_(2)O含量与贫矿岩浆岩没有显著差别,但它具有更高的岩浆Cl和S含量。岩浆矿物结构和成分研究表明,在岩浆迁移至地壳浅部仍含有充足的Cl、S和成矿元素是科翁腊德矿集区斑岩型Cu矿床形成的关键。在科翁腊德矿集区,具有一定成矿潜力的岩浆(如合适的氧逸度、H_(2)O含量和存在基性岩浆补给)由于在深部过早的发生流体出溶造成Cl、S和成矿元素从岩浆中散失(如贫矿辉长岩、闪长岩、花岗闪长岩),或者岩浆中Cl含量和Cu溶解度过低造成岩浆运移和富集成矿元素能力低(如贫矿花岗岩),最终不能形成斑岩型Cu矿床。本文研究结果表明,岩浆的Cl和S含量是区分科翁腊德矿集区成矿和贫矿岩体的有效标识,而岩浆的氧逸度、H_(2)O含量和F含量在两者间没有明显差异。Numerous large to giant porphyry Cu deposits have developed in the Central Asian Orogenic Belt.Although these deposits usually developed large-scale magmatism at similar ages,there is usually only a few magmatism associated with mineralization.Therefore,distinguishing between mineralized and barren magmas in the ore district is crucial to prospecting.To investigate this question,this study performs textural and compositional analyses of apatite,amphibole,biotite,and plagioclase and whole-rock major element analyses of weakly altered rocks from the Carboniferous barren intrusions and fertile granodiorite porphyry in the Kounrad ore district,Kazakhstan.Results show that both the barren intrusions and fertile granodiorite porphyry are H_(2)O-rich(~4%)oxidized(~ΔNNO+1.63)magmas,which belong to the medium K or high K calcium-alkaline series rocks.Significant An values variations in plagioclase(ΔAn in the range of 26~34)and positive correlation with FeO content in barren intrusions suggest that it underwent magma mixing during the intrusion formation,whereas this process was not evident in the fertile granodiorite porphyry.Comparison of apatite,amphibole,and biotite compositions shows that the oxygen fugacity and H_(2)O content of the fertile granodiorite porphyry is not significantly different from that of the barren intrusions,but the fertile granodiorite porphyry has higher Cl and S content.Studies on the texture and composition of magmatic minerals indicate that the magma that migrates to the shallow part of the crust still contains sufficient Cl,S,and metal elements is the key to the formation of porphyry Cu deposits in the Kounrad ore district.In Kounrad ore district,magmas with favorable Cu mineralization conditions(e.g.,suitable oxygen fugacity,H_(2O)content,and presence of mafic magma recharge)may lose Cl,S,and metal elements from the magma because of early fluid exsolution at deeper depths(e.g.,barren gabbro,diorite,granodiorite),or the magma has a low Cl content and low Cu solubility,resulting in low abili

关 键 词：斑岩型Cu矿床 磷灰石 角闪石 黑云母 斜长石 中亚造山带 

分 类 号：P575.1[天文地球—矿物学] P588.12[天文地球—地质学] P618.41