云南个旧锡矿集中区地质地球化学研究

【作者】 贾润幸；

【导师】 赫英；

【作者基本信息】 西北大学 ， 地球化学， 2005， 博士

【摘要】 个旧锡多金属矿是世界级超大型矿床,包括马拉格、松树脚、高松、老厂和卡房五大矿田。矿床类型较为齐全,主要有接触带型矿床、脉状矿床和层状矿床等。由于长期的开采,目前已面临资源严重不足的局面,本次研究的目的在于为个旧锡多金属矿床地质-地球化学综合找矿模型的建立提供新的理论依据和认识,从中探索我国危机矿山新一轮找矿的新理论和新思维。本文重点以老厂矿田中的接触带锡铜矿床和脉状矿床为研究对象,采用化学分析、ICP-MS、X射线粉晶衍射分析、电子探针等测试手段,对本区与成矿相关的基性-超基性火山岩、花岗岩、夕卡岩、电气石-石榴石等进行了系统的地质地球化学研究,研究表明: 个旧矿区中三叠纪个旧组地层中的火山岩为钙碱性玄武岩-拉斑玄武岩系列,岩石为辉石-角闪石-长石-绿泥石-金云母组合;本区的花岗岩为过铝质花岗岩,主要与燕山期碰撞造山作用有关,锡多金属成矿与形成时代最晚、分异较好的花岗岩（如老卡岩体）关系密切; 本区夕卡岩中的有用共（伴）生组份随着夕卡岩类型及其矿物组合的不同具有明显的分带性。在夕卡岩水平分带中,石榴石带和辉石带交替出现的现象主要与岩浆期后热液对碳酸盐岩围岩的渗滤交代作用有关,同时还与碳酸盐岩围岩中存在大理岩和灰质白云岩互层带有关。 不同产状的电气石及其环带状结构分别与来自岩浆期后热液和盆地流体及其混合所产生的“化学振荡”作用有关;在夕卡岩水平分带中,石榴石化学成分的变化除与岩浆热液在演化过程中自身的物理-化学条件发生变化外,可能还与岩浆热液在对围岩进行渗滤交代的过程中有盆地流体的加入有关。 在本区不同类型的夕卡岩（矿石）中,Sn与∑LREE及Cs、Nb、Rb、Sr等大离子亲石元素之间具线性正相关关系,而与U、Th等放射性元素呈明显的负相关性。锡在石榴石夕卡岩矿石中主要以类质同象的方式存在于钙铁榴石中,且随Fe/Fe+Al比值的增大而增大,少数则以锡石（SnO₂）包裹体的形式存在。更多还原

【Abstract】 The Gejiu tin-polymetallic district consisting of five ore fields （Malage, Songshujiao, Gaosong, Laochang and Kafang） in Yunnan province, is one of the most important tin-producing region in the world. The district mainly contains skarn, vein-type and stratabound carbonate-hosted ore. Now, the mine resource in Gejiu tin-polymetallic district has become serious lack for long-time mining. The aim of this study is to provide some new information for the establishing of gechemical model in Gejiu tin-polymetallic district and to research some new theory and new thinking in the second round exploitation for the old mines in our country. In this paper, the petrology, mineralogy and geochemistry of basic-ultrabasic volcanic rock, granite and skarn related to the Sn-Cu skarn-type ore and the vein-type ore in Laochang ore field have been researched systematically, some conclusions are summarized as follows:In Gejiu tin-polymetallic district, the middle Triassic volcanic rocks belonging to calc-alkaline basalt-tholeiite serie, mainly consist of pyroxene, hornblende, feldspar, chlorite and phlogopite; All the granites are peraluminous granites related to the Yanshanian collision-orogeny. Laoka granite closely related to the tin-polymetallic deposits emplaced in the post- orogenic.The metal elements show obviously vertical zones with the variety of skarn types in dimensional extension; The occurrence of garnet skarn and diopside skarn alternately developed in the horizontal zones of the contact between granite and carbonatite are mainly related to two factors: one factor is the infiltration metasomatism of post-magmatic hydrothermal solution, the another is the metrical strata of marble and calcic-dolomite developed in country rocks. The infiltration metasomatism of post-magmatic hydrothermal solution makes the marbles to form garnet skarn zone and the calcic-dolomites to form diopside skarn zone.Schorl in the granite and dravite in carbonatite are respectively related to the magmatic fluid and basin fluid, while the tourmaline with optical and chemical zones in vein ore is mainly due to the mix of post-magmatic hydrothermal solution and basin fluid; The chemical composition variety of garnet in the horizontal zones are mainly related to the post-magmatic hydrothermal solution and the accessorial fluid from sedimentary basin.In different type skarns including altered granite and massive skarn, there are positive linear correlations between Sn and ∑LREE, majority LILEs （such as Cs, Nb, Rb and Sr） or negative linear correlations between Sn and radioactive elements （such as U, Th）. In garnet skarn, Sn mainly substituted Fe into andradites and its concentration always increased with the enlargement of Fe/Fe+Al ratio, minority of Sn existed in andradites as cassiterite （SnO₂） inclusions.更多还原