岩浆岩对矽卡岩型铜钼矿化的贡献:以云南金平长安冲铜钼矿为例  

Contribution of magmatic rocks to skarn Cu-Mo mineralization:A case study of Chang'anchong Cu-Mo deposit in Jinping,Yunnan Province

作　　者：邓家方 辛未 毛光周 李良[4] Deng Jiafang;Xin Wei;Mao Guangzhou;Li Liang(Key Laboratory of Gold Mineralization Processes and Resource Utilization,MNR,Ji'nan 250013;Shandong Provincial Key Laboratory of Metallogenic Geological Process and Resource Utilization,Ji'nan 250013;College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao,Shandong 266590;School of Earth Sciences,Yunnan University,Kunming 650504)

机构地区：[1]自然资源部金矿成矿过程与资源利用重点实验室,济南250013 [2]山东省金属矿产成矿地质过程与资源利用重点实验室,济南250013 [3]山东科技大学地球科学与工程学院,山东青岛266590 [4]云南大学地球科学学院,昆明650504

出　　处：《地质科学》2023年第2期598-616,共19页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：自然资源部金矿成矿过程与资源利用重点实验室项目(编号:KFKT202122);山东省金属矿产成矿地质过程与资源利用重点实验室项目(编号:KFKT202122)资助。

摘　　要：长安冲铜钼矿床位于中国西南部哀牢山构造带南段,区内斑岩型/矽卡岩型Cu-Mo-Au矿床广泛出露。前人已对这些矿床成矿斑岩体物理化学条件进行了大量的研究。然而,前人研究主要依据为副矿物锆石主微量元素,对主要造岩矿物关注较少,导致对成矿岩浆演化早期物理化学条件缺乏制约。此外,成矿物质来源也需要更多同位素数据制约。因此,我们对成矿斑岩体开展了系统的单矿物(长石、云母、角闪石)电子探针分析和硫化物S-Pb同位素研究,以制约岩浆岩对矽卡岩型铜钼矿化的贡献。研究表明,角闪石水压计计算结果表明角闪石结晶时岩浆水含量约为3.7%~4.2%,说明成矿岩浆含水量较高。根据角闪石成分分析计算氧逸度值介于?NNO=+1.2~+1.8之间,表明含矿岩浆具有较高的氧逸度。通过角闪石压力计得出角闪石结晶压力为61~106 MPa,通过黑云母压力计得出黑云母结晶压力为32~123 MPa,对应成岩成矿深度为1.3~4.6 km,这一结果与前人流体包裹体研究成果基本一致。主成矿阶段硫化物Pb同位素与成矿斑岩源区的下地壳角闪岩分布一致,δ34S同位素介于0.2‰~1.5‰之间,为岩浆硫。综上,岩浆岩是长安冲铜钼矿床的主要成矿物质来源,成矿岩浆岩高氧逸度和水含量是成矿金属富集的重要因素,单矿物压力计是估算矽卡岩型矿床成矿深度可行方法。Chang'anchong Cu-Mo deposit is located in the southern part of Ailaoshan structural belt in Southwest China.Porphyry/skarn Cu-Mo-Au deposits are widely exposed in the area.Predecessors have done a lot of research on the physical and chemical conditions of ore-bearing porphyries of these deposits.However,the predecessors mainly based on the accessory mineral zircon,and paid less attention to the main rock forming minerals,which had weak constraints on the physical and chemical conditions in the early evolution of the magmatic system.In addition,the source of ore-forming materials also needs to be restricted by more isotope data.Therefore,we have carried out systematic electron microprobe analysis of single minerals(feldspar,mica,amphibole)of the metallogenic porphyry and sulfide S-Pb isotope studies to restrict the contribution of magmatic rocks to skarn type Cu-Mo mineralization.The calculation results of amphibole water pressure gauge show that the water contents of magma during amphibole crystallization is about 3.7%~4.2%.The oxygen fugacity value calculated according to the composition analysis of amphibole is between∆NNO=+1.2~+1.8,indicating that the ore-bearing magma has a high oxygen fugacity.The amphibole pressure gauge shows that the crystallization pressure of amphibole is between 61~106 MPa,and the crystallization pressure of biotite is 32~123 MPa according to the biotite pressure gauge,with the corresponding diagenetic and metallogenic depth is 1.3~4.6 km,consistent with the previous research results of fluid inclusions.The Pb isotope of sulfide in the main metallogenic stage is consistent with the amphibolite in the metallogenic porphyry source area,and the S isotopes of sulfides are between 0.2~1.5,which is magmatic sulfur.To sum up,magmatic rocks are the main source of ore-forming materials for Chang'anchong Cu-Mo deposit.The high oxygen fugacity and water content of ore-forming magmatic rocks are important factors for the enrichment of ore-forming metals.Amphibole and biotite pressure gauge is a

关 键 词：岩浆物理化学条件 斑岩/矽卡岩型矿床 成矿物质来源 S-Pb同位素 

分 类 号：P59[天文地球—地球化学]