南岭东段岩前矽卡岩型钨矿成矿流体研究
DOI:
作者:
作者单位:

地球科学与资源学院,中国地质大学, 北京; 国土资源部成矿作用与资源评价重点实验室,中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点实验室,中国地质科学院矿产资源研究所,防灾科技学院,江西省地质矿产勘查开发局, 赣南地质调查大队,江西省地质矿产勘查开发局, 赣南地质调查大队,地球科学与资源学院,中国地质大学,北京

作者简介:

通讯作者:

中图分类号:

基金项目:

国家自然科学基金项目(面上项目,重点项目,重大项目)


Metallogenic Fluid Study of the Yanqian Skarn Type Tungsten Deposit in Eastern Nanling Region
Author:
Affiliation:

Department of Earth Science and Resources, China University of Geoscience, Beijing; MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resource, Chinese Academy of Geological Sciences,MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resource, Chinese Academy of Geological Sciences,Institute of Disaster Prevention,Gannan Geological Party,JBED GMR,Gannan Geological Party,JBED GMR,Department of Earth Science and Resources, China University of Geoscience, Beijing

Fund Project:

  • 摘要
  • |
  • 图/表
  • |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • |
  • 资源附件
  • |
  • 文章评论
    摘要:

    南岭东段以石英脉型钨矿集中产出而闻名于世,岩前钨矿是该地区新近发现的中型矽卡岩型钨矿。本文在详细矿床地质和成矿期次研究基础上,对矽卡岩型矿体各成矿阶段的代表性矿物石榴子石、白钨矿、石英、方解石及矽卡岩附近白钨矿黑钨矿石英脉中石英的流体包裹体进行了系统的岩相学、显微测温、激光拉曼光谱分析和氢氧同位素地球化学研究。岩前钨矿流体包裹体类型主要为富液相两相水溶液I型包裹体和含CO2三相水溶液Ⅳ型包裹体,石榴子石和石英中I型包裹体中偶见子晶。白钨矿黑钨矿石英脉中的石英相比矽卡岩型矿体中的石英具有更多的Ⅳ型包裹体。早期矽卡岩阶段的流体参数为温度300~510℃、压力32~108 MPa、平均盐度7.64%、平均密度0.69g/cm3,白钨矿主成矿阶段(晚期矽卡岩阶段)的流体参数为温度230~300℃、压力21~64 MPa、平均盐度6.99%、平均密度0.87g/cm3,石英硫化物碳酸盐阶段的流体参数为温度100~230℃、压力10~62 MPa、平均盐度5.81%、平均密度0.95g/cm3。白钨矿黑钨矿石英脉的形成温度集中于110~320℃,其上限高于矽卡岩型白钨矿的温度上限,推断石英脉型黑钨矿形成温度更高。岩前钨矿成矿流体在从高温至低温的演化过程中,盐度逐渐降低、密度逐渐增大、压力逐渐降低,整体为低盐度、低密度的流体。氢氧同位素分析表明,成矿流体来源主要为岩浆水,晚期有少量大气水的加入。岩前钨矿成矿机制主要包括流体不混溶作用、流体与围岩相互反应、流体自然冷却、流体混合和压力下降,其中以CO2逸失为特征的流体不混溶作用为重要的成矿机制。岩相学观察、显微测温、激光拉曼光谱分析证实了矽卡岩型矿体及白钨矿黑钨矿石英脉中石英的包裹体中都含有CO2。I型包裹体与Ⅳ型包裹体共存、高盐度包裹体与低盐度包裹体共存及部分I型包裹体中含子晶证明岩前钨矿成矿过程中存在流体不混溶作用。成矿过程为:成矿初期,岩浆上侵分异出富钨岩浆热液,热液与碳酸盐质围岩发生了剧烈的接触交代作用,引起了围岩中Ca2+的释放以及pH和氧逸度的升高,同时发生了大规模隐爆作用并导致了CO2流体不混溶作用。CO2参与形成了可作为W运移载体的碱金属水溶液,另外其逸失导致pH升高和氧逸度降低。成矿初期的含矿热液为高温、高压、高盐度、富钨、富钙、富挥发份、pH相对较高、偏还原之后偏氧化的流体,在温压下降及氧逸度降低的条件下白钨矿大量沉淀。白钨矿黑钨矿石英脉由于靠近矽卡岩,所以热液中含Ca2+,但Ca2+的含量还不足以形成单一的白钨矿,所以出现了白钨矿和黑钨矿共存。对岩前钨矿成矿流体的研究进一步厘定了该区矽卡岩型钨矿的成因机制,同时有益于拓展南岭东段钨矿的找矿方向。

    Abstract:

    The Eastern Nanling region is famous for forming quartz- vein type tungsten deposit. The Yanqian tungsten deposit is a newly discovered middle- scale skarn type tungsten deposit in this area. On the basis of detailed deposit geology and metallogenic period study, petrography, microthermometry, Laser Raman spectroscopy analysis and hydrogen- oxygen isotope geochemistry study are carried out systematically for representative minerals of each metallogenic stage in skarn type orebody including garnet, scheelite, quartz and calcite, and quartz in scheelite- wolframite quartz- vein near the skarn. The type of fluid inclusions in the Yanqian tungsten deposit mainly consists of type I fluid inclusion which is two- phase with rich liquid phase type aqueous solution fluid inclusion, type IV fluid inclusion which is three- phase type containing CO2 type aqueous solution fluid inclusion. In addition, a few type I fluid inclusions contain daughter crystal in garnet and quartz. The quartz in scheelite- wolframite quartz- vein contains more type IV fluid inclusion than the quartz in skarn type orebody. In early skarn stage, the temperature is 300~510℃, the pressure is 32~108 MPa, the average fluid salinity is 7.64%, and the average fluid density is 0.69g/cm3. In main metallogenic stage of scheelite (late skarn stage), the temperature is 230~300℃, the pressure is 21~64 MPa, the average fluid salinity is 6.99%, and the average fluid density is 0.87g/cm3. In quartzsulfidecarbonate stage, the temperature is 100~230℃, the pressure is 10~62 MPa, the average fluid salinity is 5.81%, and the average fluid density is 0.95g/cm3. The formation temperature of scheelitewolframite quartz- vein concentrates in 110~320℃, whose upper limit is higher than the temperature upper limit of skarn type scheelite, indicating that the quartz- vein type wolframite has a higher formation temperature. For the Yanqian tungsten deposit, during the evolution of the ore- forming fluid from high temperature to low temperature, the salinity gradually decreased, the density is gradually increasing, and the pressure is gradually decreased. The H- O isotope indicates that the ore- forming fluid is mainly magmatic water, and little meteoric water is involved in the late stage. The metallogenic mechanisms of Yanqian tungsten deposit mainly comprise fluid immiscibility, fluid- surrounding rock interaction, fluid naturally cooling, fluid mixing and pressure decline, espicailly the fluid immiscibility characterized by CO2 loss is important metallogenic mechanism. The petrography, microthermometry and Laser Raman spectroscopy analysis confirm that the quartz fluid inclusions both in skarn type orebody and scheelite- wolframite quartz- vein contain CO2. The coexistence of type I fluid inclusion and type IV fluid inclusion, the coexistence of high salinity fluid inclusion and low salinity fluid inclusion, and a few type I fluid inclusions contain daughter crystal indicate that the fluid immiscibility exists in the ore- forming process of Yanqian tungsten deposit. The ore- forming process is: at the early stage of the mineralization, the magma invades accompanied by separating out the tungsten rich magmatic hydrothermal fluid, strong contact metasomatism occurs between the hydrothermal fluid and the carbonate surrounding rock leading to the release of Ca2+ in surrounding rock and the increase of pH and oxygen fugacity at the same time, largescale cryptoexplosion occurs leading to CO2 fluid immiscibility. The CO2 participates the forming of the alkali metal aqueous solution which can serve as the migration process of tungsten, in addition, the loss of CO2 leads to increase of pH and decrease of oxygen fugacity. The ore- bearing hydrothermal fluid in the early stage of deposit formation is high temperature, high pressure, high salinity, tungsten- rich, calcium- rich, volatile- rich, relatively high pH and slight reductive and then slight oxidative fluid, and a large amount of scheelite precipitates under the condition of decreasing temperature and pressure and increasing pH. Scheelite- wolframite quartz- vein is close to skarn, so the hydrothermal fluid contains Ca2+, but the content of Ca2+ is not enough to form only scheelite, so scheelite and wolframite coexist. The study on the metallogenic fluid of the Yanqian tungsten deposit further confirms the formation mechanism of the skarn tungsten deposit in this area, and is beneficial to the exploration direction of tungsten deposit in the Eastern Nanling region.

    参考文献
    相似文献
    引证文献
引用本文

刘畅,赵正,陆丽娜,曾载淋,刘翠辉,许虹.2018.南岭东段岩前矽卡岩型钨矿成矿流体研究[J].地质学报,92(12):2485-2507.
LIU Chang, ZHAO Zheng, LU Lina, ZENG Zailin, LIU Cuihui, XU Hong.2018. Metallogenic Fluid Study of the Yanqian Skarn Type Tungsten Deposit in Eastern Nanling Region[J]. Acta Geologica Sinica,92(12):2485-2507.

复制
分享
文章指标
  • 点击次数:
  • 下载次数:
  • HTML阅读次数:
  • 引用次数:
历史
  • 收稿日期:2018-05-20
  • 最后修改日期:2018-09-09
  • 录用日期:2018-11-20
  • 在线发布日期: 2018-11-20
  • 出版日期: