【作者】 杨宗喜；

【导师】 毛景文；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2009， 硕士

【摘要】 云南个旧是世界上最大的锡多金属矿田,近20年来关于其成矿作用有多种认识,除了传统上与燕山期花岗岩有关外,还有海底喷流成矿和玄武岩成矿的新认识。矿床成因成为一个急需解决的科学问题。本次工作以个旧矿区卡房铜矿为研究对象,通过野外地质工作、电子探针分析测试、流体包裹体、稳定同位素地球化学、放射性同位素年代学等方法和手段,主要研究了成矿流体性质和来源、成矿物质来源、成矿年代、矿床成因等方面内容,并取得如下主要成果:1)卡房铜矿主要的矿床类型有两类:玄武岩层中或玄武岩与大理岩层间的似层状矿体以及花岗岩与围岩接触带矿体。围岩蚀变主要有夕卡岩化、阳起石化和金云母化。2)电子探针分析结果显示,卡房铜矿夕卡岩中的辉石主要为透辉石-钙铁辉石系列,石榴子石端元组分以钙铝榴石-钙铁榴石为主。3)流体包裹体及氢、氧同位素研究显示,从石英-硫化物阶段到方解石-硫化物阶段,流体温度有显著降低(从260~360℃到160~280℃),流体密度有略微增大的趋势(从0.56~0.97g/cm3到0.78~1.03g/cm3),而流体盐度则基本保持不变(从1.74~12.51wt%到1.74~11.93wt%)。氢、氧同位素组成表明,早期成矿流体主要以岩浆水为主,而晚期成矿流体可能在上升过程中与地层中的大气降水相混合。4)硫同位素分析结果表明,卡房铜矿似层状矿体中硫化物的硫来源于三叠系玄武岩,而燕山期花岗岩和三叠纪玄武岩共同为卡房铜矿接触带矿体提供了成矿所需的大部分的硫。铅同位素分析结果显示,卡房铜矿似层状矿体的成矿物质主要来源于三叠系玄武岩,而接触带矿体的铅可能主要来源于燕山期花岗岩。5)辉钼矿Re-Os同位素等时线年龄为83.4±2.1Ma,与老卡岩体锆石LA-ICP-MS年龄(85±0.85Ma)接近,表明卡房铜矿的形成与老卡岩体有密切的成因联系。6)右江褶皱带内的个旧锡多金属矿床、都龙锡锌矿床、白牛厂银多金属矿床、广西大厂锡多金属矿床以及大明山矿集区王社铜钨矿床的成矿作用发生在95~80Ma,暗示它们的形成受控于相同的地球动力学背景。成矿作用的动力学背景是岩石圈的伸展,是华南中生代白垩纪晚期大规模成矿作用的结果。更多还原

【Abstract】 Gejiu is the largest tin polymetallic ore-field over the world. It has been known as the Yanshanian granite-related deposit for long time, but recently some researchers argued that it is a syngenetic deposit formed by marine exhalation or it is a basalt-related. The genesis of deposit is an imortant problem to resolve ugly. Based on detailed field study of Kafang copper deposit, using some feasible methods such as EMPA, fluid inclusion homotemperature measuring, stable isotope measuring and radioactive isotope measuring, this thesis recognizes its characteristics and source of ore-forming fluid, source of ore-forming materials, the age of the Kafang copper deposit, and then gives a reasonable explanation about its genesis. The main conclusions that we got are as follow:1) There are two kinds of ore-body in Kafang copper deposit. One is stratiform-like ore-body, and the other is contact ore-body. Its wall rock alteration contains skarnization, actinolitization and phlogopitization.2) The analytical results of electron microprobe show that the clinopyroxene is diopside-andradite series. The end member of garnet is dominated by andradite and grossular, with minor spessartine and almandine.3) Fluid inclusion analysis indicate that the temperature of ore-forming fluid decreased significantly(260~360℃to 160~280℃), the salinity of ore-forming fluid increased slightly( 0.56 ~0.97g/cm3 to 0.78 ~1.03g/cm3), and the salinity of ore-forming fluid keeps constant basically(1.74~12.51wt% to 1.74~11.93wt%) from quarz-sulfide stage to calcite-sulfide stage. Hydrogen isotope analysis and oxygen isotope analysis show that the ore-forming fluid dominated by magmatic water in the early stage, but in late stage, it could be produced by mixing magmatic and meteoric water.4) The compositons of sulfur isotope show that sulfur of stratiform-like ore-body was derived from Triassic basalt, yet Triassic basalt and Yanshanian granite provide sulfur for contact ore-body together. The compositions of lead isotope show that the source of ore-forming matierial of stratiform-like ore-body is Triassic basalt, yet the source of lead of contact ore-body is Yanshanian granite.5) Re-Os dating of five molybdenite separated from the Kafang copper deposit gives an isochron age of 83.4±2.1Ma. This age is in good agreement with Laoka granite zircon LA-ICP-MS U-Pb age(85±0.85Ma). These ages suggest that the mineralization in the Kafang copper deposit was genetically associated to the Laoka granite.6) Based on the geochronological data of Dulong Sn-Zn deposit, Bainiuchang Ag giant deposit, Dachang tin polymetallic ore field and Wangshe Cu-W deposit and analysis of tectonic evolution of Southeast of Yunnan Province, we propose that these deposits occurred at the same geodynamic framework as a result of large scale extension during late Mesozoic in South China.更多还原