广西栗木花岗岩岩浆气—液分异作用与成矿作用

发布时间：2018-03-21 02:21

本文选题：稀有金属花岗岩　切入点：岩相学　出处：《地质论评》2017年01期 　论文类型：期刊论文

【摘要】：广西栗木花岗岩是华南地区具有代表性的含锡、钨、钽、铌矿的稀有金属花岗岩,发育一些紧密共生但结构有明显差异的岩石。在岩相学研究的基础上,运用热动力学原理对这些特殊地质现象进行成因分析以了解相应的岩浆演化过程,得出的结论构成了岩浆演化的动态证据链并相互印证,且与热动力学方程检验结论相吻合。研究结果表明,气—液分异是稀有金属花岗岩最重要的成岩与成矿作用机制。当富水岩浆上升侵位时,岩浆发生大规模的气—液分异作用,形成新的熔体相和大量夹带气相的气泡。新的熔体相因饱和水压尸(H_2O)的突然降低而过冷却结晶形成斑状结构岩石,气泡则上升迁移至不同部位,随后破裂再次发生气—液分异形成残余气流体和残余熔体相。残余气流体进一步交代先结晶的斑状结构岩石形成蚀变带花岗岩,或者结晶形成伟晶岩。残余气流体还是金属成矿元素迁移的主要载体,岩体内带的蚀变花岗岩型锡铌钽矿的成矿作用主要与残余气流体对花岗岩的自交代作用有关,而岩体顶上带的岩脉型钨锡矿的成矿作用主要与残余气流体在围岩裂隙中的结晶作用有关。
[Abstract]:The Qimu granite in Guangxi is a typical rare metal granite containing tin, tungsten, tantalum and niobium ore in South China. In order to understand the corresponding magmatic evolution process, the thermodynamics principle is used to analyze the origin of these special geological phenomena. The conclusion is a dynamic evidence chain of magmatic evolution and is verified by each other. The results show that gas-liquid differentiation is the most important mechanism of diagenesis and mineralization of rare metal granites. A new melt phase and a large number of bubbles entrained in the gas phase were formed. The new melt phase was supercooled and crystallized to form porphyry structure rocks due to the sudden decrease of saturated water pressure, and the bubbles rose and migrated to different parts. Then the gas-liquid differentiation occurred again to form the residual airflow and the residual melt phase. The residual gas bodies further replaced the crystalline porphyry rocks to form altered zone granites. Or crystallization to form pegmatite. The residual airstream is also the main carrier of the migration of metallogenic elements. The mineralization of altered granitic tin niobium-tantalum ore in the rock body zone is mainly related to the self-metasomatism of the residual airstream to the granite. The mineralization of the vein type tungsten tin ore in the top zone of rock mass is mainly related to the crystallization of residual airflow body in the fissure of surrounding rock.
【作者单位】：中国有色桂林矿产地质研究院有限公司;中国地质科学院岩溶地质研究所国土资源部/广西壮族自治区岩溶动力学重点实验室;
【基金】：全国危机矿山接替资源勘查项目“广西恭城县栗木锡矿接替资源勘查”(编号:200645091) 广西区大规模地质找矿项目“广西恭城县五福锡钽铌矿普查”(编号:[2010]604)的成果~~
【分类号】：P588.121;P618.6

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