【作者】 郎兴海；

【导师】 陈毓川；

【作者基本信息】 成都理工大学 ， 矿物学、岩石学、矿床学， 2012， 博士

【摘要】 西藏冈底斯带记录了青藏高原自古特提斯至新特提斯和印度-亚洲大陆碰撞造山作用以来的构造-岩浆演化而备受地质学家的重视，数千平方公里的火山-岩浆带，为成矿提供了得天独厚的流体和物质来源，成矿地质条件优越。雄村斑岩型铜金矿集区的大地构造位置位于南冈底斯带中段南缘，其南侧紧邻日喀则弧前盆地，行政区划属西藏日喀则地区谢通门县荣玛乡。矿区的成矿地质环境是与新特提斯洋洋壳岩石圈的洋内俯冲作用有关的岛弧环境，类似于现在的西南太平洋岛弧带。矿床类型属产于岛弧环境的斑岩型铜金矿床，其包括：1）产于斑岩体及接触带凝灰岩中的铜金矿体，目前发现有Ⅰ、Ⅱ、Ⅲ号矿体，以及Ⅳ、Ⅴ号矿化体；2）产于斑岩成矿系统外围的热液型金矿脉，目前仅发现洞嘎金矿。雄村矿区的成矿作用可以划分早、晚两期，早期成矿作用发生于中侏罗世早期（166.9~179.3Ma），与170~184M侵位的角闪石英闪长玢岩有关，形成Ⅱ、Ⅲ号矿体以及Ⅴ号矿化体等，属氧化性斑岩铜矿床，以形成大量的磁铁矿、石膏、缺乏磁黄铁矿为特征；晚期成矿作用发生于中侏罗世晚期（157.8~165.8Ma），与162.4~172.9Ma侵位的晚期含眼球状石英斑晶的角闪石英闪长玢岩有关，形成雄村Ⅰ号矿体、Ⅳ矿化体以及洞嘎金矿等，属还原性斑岩铜金矿床，以形成大量的磁黄铁矿、缺乏磁铁矿和石膏为特征。矿床形成主要与早-中侏罗世新特提斯洋洋壳岩石圈的洋内俯冲作用有关，早期含矿斑岩体（角闪石英闪长玢岩）起源于俯冲的新特提斯洋洋壳源区，矿物组合为石榴石+斜长石+角闪石+辉石+含钛矿物，以饱和水和高氧逸度为特征，其部分熔融形成饱和水、氧逸度高的长英质岩浆，导致角闪石英闪长玢岩出现钙碱性系列的富硅趋势，并冷凝结晶分离出氧逸度较高的氧化性含矿流体，形成氧化型斑岩铜矿床。晚期含矿斑岩体（晚期含眼球状石英斑晶的角闪石英闪长玢岩）起源于弧底部的新生玄武质岩层，源区矿物组合为石榴石+斜长石+角闪石+辉石+含钛矿物组合，以水不饱和和低氧逸度为特征，形其部分熔融成的长英质岩浆水不饱和、氧逸度低，导致晚期含眼球状石英斑晶的角闪石英闪长玢岩显示出与拉斑玄武岩系列相似的富铁趋势，并冷凝结晶分离出氧逸度较低的还原含矿流体，形成还原性斑岩铜矿床。矿床的成矿物质主要来源于斑岩体自身，成矿流体主要来源于岩浆水，并有大气降水的加入，大气降水的加入以及温度、压力的降低是矿质沉淀的重要原因。雄村矿区早、晚两期成矿作用形成的氧化型斑岩斑岩铜矿床和还原型斑岩铜矿床在成矿特征差别较大，它们分别以Ⅱ号矿体和Ⅰ号矿体为代表，为此分别建立了两类斑岩型铜矿床的综合找矿模型，即Ⅰ号矿体式综合找矿模型和Ⅱ号矿式综合找矿模型。以综合找矿模型为指导，根据矿区及外围已完成的土壤、岩石地球化学测量成果，对矿区及其外围进行了成矿预测，发现了多处矿化异常带，对这些矿化异常带今后的找矿方向提出了思路。更多还原

【Abstract】 Gangdese belt recorded the tectonic-magmatic evolution since the Paleo-Tethysto the new Tethys and India-Asia continental collision. Geologists pay much attationto this belt. Volcano–magma in Gangdese provide abundant ore-forming fluid andmaterial for mineralization. The Xiongcun district is located in the middle of thesouthern margin of southern Gangdese. Its southern margin is Shigatse forearc basin.Its administrative division belongs to Xiongcun Village, Rongma township,Xietongmen County, Rikaze, Xizang.The metallogenic tectonic setting of district is the island arc environment,associated with inner-oceanic subduction of the Neo-Tethyan oceanic crustlithosphere similar to the present South-West Pacific island arc belt. The genetic typeof the deposit belongs to porphyry Cu-Au deposit occures in the island arcenvironment, including:1) Cu-Au mineralization occurs in porphyry and tuff locatedin contact zone, presently, we have found I, II, III orebody, and IV and V mineralizedbody;2) epithermal gold veins occurs in the porphyry mineralization systemperipherals, we have only found the Dongga gold deposit so far. The mineralization ofXiongcun district can be divided into early and late mineralized periods.The earlymineralizition occurred in the early Jurassic (166.9~179.3Ma), related to hornblendequartz diorite porphyry emplaced in170~184Ma,and formed II, III orebody and Vmineralized body, which belong to the oxidized porphyry copper deposit with thecharacteristics of forming a large number of magnetite, gypsum and absent pyrrhotite;late mineralization occurred in the late Jurassic (157.8~165.8Ma), related to the latehornblende quartz diorite porphyrite with big quartz phenocrysts emplaced in162.4~172.9Ma,formed the Xiongcun I orebody, IV mineralized body and the Dongga golddeposit, which belong to reduced porphyry Cu-Au deposit, with the characteristics offorming a large number of pyrrhotite and lack of magnetite and gypsum. The formation of deposit related to inner-oceanic subduction of the Neo-Tethyanoceanic crust lithosphere in the Early-Middle Jurassic.The early mineralized porphyry(hornblende quartz diorite porphyry) originated from the subducted Neo-Tethyanoceanic crust,with the mineral assemblage is garnet, plagioclase, hornblende,pyroxene and titanium minerals, which has the characteristic of saturated water andhigh oxygen fugacity, partial melting form the saturated water, high oxygen fugacityfelsic magma, resulting in the hornblende quartz diorite porphyry has the trend ofsilicon-rich of calc-alkaline series, and condensation, crystallization, fractionation ofoxidised ore-bearing fluids with higher oxygen fugacity, and formed the oxidizedporphyry copper deposit. Late ore-bearing porphyry (late hornblende quartz dioriteporphyry with big quartz phenocrysts) originated from jiuvenile basaltic strata at thebottom of arc. The mineral assemblages of the source region aregarnet,hornblende,pyroxene, plagioclase and titanium minerals, characterized byunsaturated wate and low oxygen fugacity, partial melting form felsic magma withunsaturated wate and low oxygen fugacity, leading to the late hornblende quartzdiorite porphyry with big quartz phenocrysts shows the trend of iron-rich of thetholeiitic series, and condensation, crystallization, fractionation of reducedore-bearing fluids with lower oxygen fugacity, and formed the reduced porphyrycopper deposit. Metallogenic materials in the deposit originated from the porphyryitself, the ore-forming fluids mainly from magmatic water and adding meteoric water.Adding meteoric water and reduction of temperature and pressure are the significantfactors to make mineral precipitate.The oxidized porphyry copper deposit and the reduced porphyry copper depositin the Xiongcun district have great diffirence in the metallogenic characteristics,formed in the early and late mineralized periods, which respectively represent IIorebody and I orebody. Therefore, respectively, comprehensive prospecting modelof the two types of porphyry copper deposits were established, that is comprehensiveprospecting model of I orebody and II orebody. With the instruction of comprehensiveprospecting model, according to the geochemical survey results of the soil and rock inxiongcun district and its peripheral areas, the author have conducted metallogenicprediction for theose area and found many mineralization abnormities zone. Theauthor also proposed methods of prospecting for theose mineralization abnormities.更多还原