粤北师姑山钨矿床地球化学特征与成因探讨

发布时间：2018-03-30 20:32

  本文选题：师姑山钨矿床　切入点：粤北　出处：《东华理工大学》2017年硕士论文

【摘要】：粤北师姑山钨矿床位于南岭中东段,该区钨矿资源丰富,为“广东始兴钨、锡矿矿集区”的重要组成部分。矿石类型属石英脉型黑钨矿,以石英大脉型、兼有细脉带产出。本文基于总结师姑山钨矿区地质背景与成矿地质特征,系统开展了元素地球化学、流体包裹体以及稳定同位素地球化学研究,综合以上分析矿床的成矿物质、成矿流体的来源,探讨矿床的成因,得出如下主要认识:(1)师姑山燕山期花岗岩具有富硅、富碱、弱过铝质、高分异的特征,具有壳源特征;花岗岩具有大离子亲石元素Rb、Cs、K富集,高场强元素Th、U、Pb、Li含量高,Sr、P、Ti明显亏损的特征;稀土元素总量在106.8×10-6~163.9×10-6之间,平均135.8×10-6,轻稀土元素相对富集,Eu明显亏损,稀土元素分布模式图呈现为左右基本对称的“V”字型。(2)寒武系的浅变质岩─板岩是师姑山矿床的重要的围岩。板岩的微量元素地壳丰度标准化蛛网图显示,板岩中W、Sn、Pb、Zn、Bi等成矿元素显著富集。(3)黄铁矿微量元素数据显示其属于热液成因,辉钼矿微量元素数据显示其来自壳源。黄铁矿的稀土元素分布型式图与岩浆岩的相似,说明了成矿物质继承自矿区岩浆岩,轻稀土元素在辉钼矿中相对强烈富集,说明流体中多含有还原性质的气相成分和CO2、Cl、F等成分。(4)流体包裹体研究显示,矿区成矿温度最为集中在180℃到360℃之间,具多峰值,说明师姑山钨矿床形成中成矿流体作用具多期性;深部岩浆提供了成矿流体,且在流体的演化过程中,混入了如大气降水等低温低盐度的流体;流体的盐度、密度分别集中在2.5wt%~7.5wt%NaCleqv和0.80g/cm3~0.90g/cm3,均较低;通过计算得出师姑山钨矿床成矿压力集中分布在10MPa~35MPa,成矿深度集中在1.5km~4.5km之间。低温低盐的流体混入,沸腾作用的发生,说明成矿流体的温度、压力、化学成分等因素发生过显著的改变,流体的这种变化可能会导致成矿元素卸载,进而在合适位置聚集成矿。(5)稳定同位素研究得出:δ34S值介于-0.4‰~1.0‰之间,平均值为0.5‰,数据近于零且分布集中,与深部来源硫的特征(0±3‰)相符合,说明硫的来源较为稳定单一,且来自于深部;C-O同位素数据显示,成矿流体中的碳源自深部的岩浆水,混入了部分有机性质的碳。(6)师姑山钨矿床属于典型的岩浆热液矿床,燕山期的岩浆活动主导了矿化作用发生。通过系统地对师姑山钨矿床的区域地质、矿床地质、成岩成矿时代、控矿因素、成矿物质与成矿流体的来源以及成矿机制等进行研究探讨,表明师姑山钨矿床成矿物质、成矿流体主要来自深源岩浆,寒武纪的变质岩贡献了一部分的成矿物质。来自深源的岩浆可以直接带来成矿物质;同时又为成矿物质的活化、运移提供了热源与能量,进而在适当的位置富集沉淀成矿。
[Abstract]:The Shigushan tungsten deposit in northern Guangdong is located in the middle and eastern part of Nanling, which is rich in tungsten resources and is an important part of "Shixing tungsten and tin ore concentrated area in Guangdong".The ore type belongs to quartz vein type wolframite.Based on the summary of the geological background and metallogenic geological characteristics of the Sigushan tungsten ore area, a systematic study of elemental geochemistry, fluid inclusions and stable isotope geochemistry has been carried out in this paper.After discussing the genesis of the deposit, it is concluded that the Yanshanian granites in Shigu Mountain have the characteristics of rich silicon, alkali, weak peraluminous, high differentiation and crust origin, and that the granites are enriched with the large ion lithophile element RbCsfen K, and that the granites are rich in silicon, alkali-rich, weak peraluminous, and highly differentiated, and have the characteristics of crust origin.The characteristics of obvious depletion of high field strength element Th, U, Pb, Li, Sr, P, and Ti, the total amount of rare earth elements between 106.8 脳 10 ~ (-6) and 163.9 脳 10 ~ (-6) with an average of 135.8 脳 10 ~ (-6), and the relative enrichment of light rare earth elements, the depletion of EU is obvious.The REE distribution pattern is presented as a left and right symmetrical "V" zigzag.) the Cambrian shallow metamorphic rock-slate is an important surrounding rock of the Sigushan deposit.The normalized cobweb diagram of crustal abundance of trace elements in slate shows that the trace elements of WSn-Sn-PbPbZn-Bi are enriched significantly.) the data of trace elements of pyrite indicate that it belongs to hydrothermal origin, and the trace element data of molybdenum is from the crust source.The REE distribution pattern of pyrite is similar to that of magmatic rock, indicating that the ore-forming material inherits from the magmatic rock of the mining area, and the LREE is relatively strongly enriched in molybdenum ore.The results show that the ore forming temperature of the ore area is between 180 鈩，

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