云南中甸普朗斑岩铜矿矿床地球化学

GYIG OpenIR > 研究生 > 学位论文

	云南中甸普朗斑岩铜矿矿床地球化学
其他题名	Ore geochemistry of the Pulang porphyry copper deposit, Yunnan Province, China
	王守旭
	2008-05-16
学位授予单位	中国科学院地球化学研究所
学位授予地点	地球化学研究所
学位名称	博士
关键词	普朗斑岩铜矿印支期地球化学同位素流体包裹体矿床年代学
摘要	中甸格咱地区是在晚三叠世甘孜-理塘洋盆向西俯冲过程中所形成的中甸弧的主弧带，区内岛弧火山活动和岩浆侵入活动均非常强烈，广泛分布有印支期斑岩体，同时发育有众多的与其有关的斑岩型和矽卡岩型矿床或矿点。普朗斑岩铜矿就是近年来在该区发现的一个大型乃至超大型矿床，目前已圈定5个矿化体，7个工业矿体，其中，主矿体探明铜资源量436.5万吨。本论文主要从区域地质背景、矿床地质特征、元素地球化学、同位素地球化学、流体包裹体地球化学、矿床年代学及成矿机理等角度对普朗斑岩铜矿进行了较为系统的研究，主要获得如下认识：普朗复式岩体具明显的多次脉动侵入特征，可分为三期：第一期为大面积分布的石英闪长玢岩（部分为二长闪长玢岩），第二期为岩体中心的石英二长斑岩和花岗闪长斑岩，第三期为岩脉状闪长玢岩。岩体具有典型的斑岩铜矿蚀变分带特征，由内向外依次为强硅化带（局部）→钾化硅化带→绢英岩化带→青磐岩化带。矿化石英二长斑岩的锆石离子探针U-Pb年龄约为226～228Ma；钾化硅化带中黑云母的40Ar-39Ar坪年龄约为210～216Ma；含矿石英脉中辉钼矿Re-Os等时线年龄约为214Ma。普朗岩体总体显示I型花岗岩类特征，属典型的钙碱性系列岩石。锶、钕、铅同位素特征显示其岩浆源区具有幔源物质（占主要地位）与壳源物质较为均匀混合的特征。金属硫化物的硫、铅同位素特征显示成矿元素与岩体具有密切的亲缘关系。脉石矿物的氢、氧、碳同位素特征和流体包裹体特征显示成矿流体自钾化阶段至网脉状矿化阶段均具岩浆流体特征。根据不同期次的含矿石英脉中的流体包裹体特征，主要发现有四种流体：高盐度岩浆流体（盐度：34～54wt%NaCl）、含CO2低盐度流体（盐度：2.7～6.4wt%NaCl，XCO2：0.04～0.25）、中等盐度流体（盐度：19～25wt%NaCl）以及低盐度水溶液（盐度：＜10wt%NaCl）。这些流体可能主要是原始岩浆流体演化至不同阶段的产物。原始岩浆流体可能有两种来源：其一是斑岩侵入过程中自身分异的流体，其二是岩浆房中分异的流体。其中，岩浆房来源的岩浆流体对普朗岩体的蚀变及矿化作用起到了主导性作用。主成矿期金属硫化物的沉淀主要与流体系统开放后因其物理化学条件的变化而产生的流体相分离作用及流体对围岩的蚀变作用有关。
其他摘要	The Geza area of the Zhongdian lies on the Zhongdian volcanic arc of the southern part of the Yidun island arc which was formed in the process of westward subduction of the Ganzi-Litang oceanic basin during Late Triassic. Due to strong island arc volcanic and intrusive activities, many small Indosinian porphyry bodies are widely distributed in the area. There are lots of porphyry-type or skarn-type deposits associated with some of those Indosinian porphyry bodies. The Pulang porphyry copper deposit is a deposit in large to superlarge scale discovered recently in the area. At present, five mineralizd bodies and seven ore bodies have been outlined, with 4.36 million tons of contained copper resource in the main ore bodies. The author has systematically studied the Pulang porphyry copper deposit in various aspects including regional geological setting, deposit geology, elemental geochemistry, isotope geochemistry, fluid inclusions geochemistry and geochronology, and discussed its ore-forming mechanism. The Pulang porphyry complex is characterized by three phases of intrusions, with first phase of major quartz diorite porphyry and minor monzo-diorite porphyry, second phase of quartz monzonite porphyry and granodiorite porphyry in the center of the complex, and third phase of diorite porphyry dykes. The Pulang porphyry complex is characterized with typical alteration zones of porphyry copper deposit, with alteration types outwards varying from strong silicification (locally), potassic- silicic alteration, quartz-sericite-pyrite alteration, to propylytic alteration respectively. The SHRIMP U-Pb dating age of the zircon from mineralized quartz monzonite porphyry is about 226～228 Ma. The 40Ar-39Ar age of the biotite samples separated from potassic-silicic zone is about 210～216 Ma, and the Re-Os isochrone age of molybdenite from ore-bearing quartz veins is about 214 Ma. Rocks of the Pulang complex are generally characterized with features of I-type granite. They belong to calc-alkaline rock series. Their strontium, neodymium, lead isotope data indicate that the magma may be formed by mixing of mantle material (dominated) and crust material. Sulfur and lead isotopes of sulfides show that the copper and iron mineralization is closely associated with the porphyries. The data of hydrogen, oxygen, and carbon isotopes as well as inclusion fluids have revealed that the ore-forming fluids in various stages of mineralization or alteration (from potassic alteration to quartz veining) are characterized with features of magmatic fluid. Four kind of fluids trapped in various inclusions in sulfide-bearing quartz veins have been identified through microthermometry and Laser Raman microspectroscopy. They include high salinity magmatic fluid (with salinities of 34～54wt%NaCl), low salinity CO2-bearing fluid (with salinities of 2.7～6.4wt%NaCl and XCO2 of 0.04～0.25), intermediate salinity fluid (with salinities of 19～25%NaC1), and minor very low salinity water (with salinities <10wt%NaCl). They mainly may be the results of evolution of primary magmatic fluids in different stages. Magmatic ore-forming fluids of the Pulang deposit could be sourced from the Pulang porphyry bodies in the process of intrusion, or/and derived from the magma chamber. The magmatic fluid derived from magma chamber underneath porphyry bodies dominantly affected the wall rock alteration and mineralization in the Pulang porphyry copper deposit. The precipitation of sulfides in the main ore stage is mainly and closely associated with the phase separation of the high salinity magmatic fluid and CO2-bearing magmatic fluid induced by the variation of physico-chemical condition due to the opening of the system, and the wall rock alteration caused by the magmatic fluid.
页数	112
语种	中文
文献类型	学位论文
条目标识符	http://ir.gyig.ac.cn/handle/352002/3390
专题	研究生_研究生_学位论文
推荐引用方式 GB/T 7714	王守旭. 云南中甸普朗斑岩铜矿矿床地球化学[D]. 地球化学研究所. 中国科学院地球化学研究所,2008.

条目包含的文件
文件名称/大小	文献类型	版本类型	开放类型	使用许可
10001_20051800651402（2015KB）			暂不开放	--	请求全文