【作者】 李建康；

【导师】 张德会； 王登红；

【作者基本信息】 中国地质大学（北京） ， 地球化学， 2006， 博士

【摘要】 川西地区是我国重要的伟晶岩成矿省,产有国内锂储量最大的甲基卡超大型锂矿床、可尔因大型锂铍矿床和丹巴大型白云母矿床等著名伟晶岩型矿床。这三个典型矿床同位于松潘-甘孜造山带,均形成于中生代,且矿种、规模各不相同,是研究伟晶岩型矿床的成矿作用及其与大陆动力学背景关系的理想对象。但是,该地区位置偏僻,交通极为不偏,地质研究程度很低。因此,本人所在项目组先后两次到川西开展野外考察,采集了大量的岩石样品。在室内也做了大量测试和研究工作:①由于区域缺乏精确的定年结果,论文做了7件白云母40Ar/39Ar定年;②针对伟晶岩熔体(流体)演化过程,本人亲自做了约50天的包裹体测温工作,并测定了流体的成分和碳氢氧同位素;③对各矿区的伟晶岩及花岗岩进行了岩石化学分析,由其推断成岩成矿的地质过程;④对各矿区的白云母进行了全面的岩石化学分析,从单矿物的角度分析了成岩成矿的地质过程;⑤搜集了大量的地质资料。通过这些工作取得了一些新认识:1.系统地研究了甲基卡矿床、可尔因矿床和丹巴矿床,认为三者的成因分别属于“岩浆液态不混溶”、“岩浆结晶分异”和“岩浆+变质混合型”。2.岩浆演化过程的不同是造成甲基卡和可尔因矿床矿种相同,规模不等的主要原因。相对于岩浆结晶分异作用,岩浆液态不混溶作用分离出的高度富挥发分的熔体对稀有金属具有很高的富集作用,更易于形成大型、超大型矿床。3.在松潘-甘孜造山带,造山过程、岩浆活动、成矿作用之间存在内在联系。甲基卡矿床形成于造山带主体的外围,主要受到单向构造应力影响,构造运动期次较少,构造环境相对封闭,表现为岩浆的一次性侵位,为岩浆液态不混溶作用的发生提供了可能;可尔因矿床位于造山带主体内部,受到自西向东和自北向南的构造应力的影响,遭受多期构造运动,易于发生多期多阶段的岩浆结晶分异作用;丹巴位于造山带主体的东缘中心部位,是自西向东和西北向南双向构造应力在晚期汇聚的中心,该地区的地壳厚度大,构造应力较弱,深部岩浆难以上升侵位,因此,变质作用对伟晶岩矿化具有很大的贡献。更多还原

【Abstract】 Western Sichuan is an importan pegamatite province in China. There are manypegmatite type deposits in the region, such as: Jiajika rare metal deposit with thelargest lithium reserve in China, Ke’eryin large-medium scale rare metal deposit, andDanba large scale muscovite deposit. The three deposits locate in Songpan-GanziOrogenic Zone, mineralize in Mesozoic, and have different commodity, andmineralizing scale. Thus, they are the ideal objects to study the mineralizions andtheir backgrounds.But, the location of Chuanxi is remote, and geolocial study degree is very low. Inorder to get the first hand data, the project group have worked in field there morethan one month. Furthermore, much testing work have been done,such as: ①Becauseof lacking precise dating data, 7 40Ar/39Ar dating experiments have been done;②Inorder to tracing the evolving process of mineralizing fluid, I have worked about 50days to measure the homogeneous temperature of about 1500 fluid inclusions, andfluid component, C, H, O isotope were also been measured;③Petrochemistry studyon pegmatites and granites have been done, by which mineralizing process can bededuced;④the components of Muscovite were analyzed, too, which can prove thereseach result by other means;⑤Great deal of geological data were been colected.By these work, several inclusion were got, such as:1. The mineralization of Jiajika, Ke’eryin and Danba deposits respectivelybelong to “magma liquid immiscibility”, “magma fractional crystallization” and“magmatism+metamorphism”.2. The difference of magma evolving process is the key reason for the differentmineralizing scale between Jiajika and Ke’eryin deposit. Comparing to magmafractional crystallization, magma liquid immiscibility can separate an highly richvolatile melt, wich can enrichment rare metal greatly. So magma liquid immiscibilitycan forming large scale ore deposits more impossible than magma fractionalcrystallization..3. There are close relation among orogeny, magmation and mineralization ofpegmatite in Songpan-Ganzi Orogenic Zone. Jiajika deposit formed in outer place ofmain part in Songpan-Ganzi orogenic zone. Thus Jiajika area underwent one directiontectonic stress, and located a close environment. These provide possibility for magmaliquid immiscibility. Ke’eryin formed in the interior of main part in Songpan-Ganziorogenic zone, and underwent two direction tetonic sterss, Thus, the regionunderwent several phase tectonic movements. In this condition, Ke’eryin depositformed by magma fractional crystallization in multi-period and multi-phaes. Danbadeposit formed in the center of eastern main part in Songpan-Ganzi orogenic zone.The region is the place of two direciton tectonic stress. Thus in Chuanxi, thelithosphere of Danba region is the thickest, and tectonic stress is weak. Therefore thedeep magma is not able to invade, and metamorphism play an importan role in theprocess of mineralization.更多还原