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青海省肯德可克多金属矿床特征及成因分析

Characteristics and Genesis of the Kendekeke Polymetallic Deposit, Qinhai Province

【作者】 黄敏

【导师】 赖健清;

【作者基本信息】 中南大学 , 构造地质学, 2010, 硕士

【摘要】 肯德可克多金属矿床地处柴达木盆地的西南缘—塔柴板块的祁漫塔格弧后裂陷构造带中部的加里东期火山盆地,是近年来祁漫塔格地区发现的最有价值的矿床之一。论文以肯德可克多金属矿床为研究对象,在对区域地质背景和矿床地质特征基础上,运用地球化学、流体包裹体岩相学、温度测试及成分分析等方法,开展了矿区成岩成矿机制、成矿流体特征、矿床成因及成矿作用等方面的研究。研究表明,肯德可克多金属矿床主要经历了4个成矿期,分别是:热水喷流—沉积作用期;矽卡岩化热液活动期(包括矽卡岩阶段、氧化物阶段和硫化物阶段);晚期构造热液活动期以及表生氧化作用期。不同阶段的流体包裹体特征各异。流体包裹体大小以4-10μm为主,最大40μm。包裹体的形态以椭圆形为主,少数为负晶形。根据包裹体的特征,将其划分为:液相水溶液包裹体、水溶液-二氧化碳包裹体和稀薄二氧化碳相包裹体3种类型。矿床流体包裹体气相成分以H2O和CO2为主,含少量有机气体;液相成分中,阳离子以Ca2+.Na+.K+离子为主,阴离子则以Cl-、N03-.S042-为主。成矿溶液属于CO2-Ca2+(Na+、K+)-Cl--(S042-、F-)-H20体系。第一阶段的成矿流体具高盐度(19-25wt%NaCl equiv.)高密度(0.817-1.033g/cm3)特征,来源于岩浆热液,温度较高且变化范围较宽。第二阶段的流体为中低盐度(1-12wt%NaCl equiv.)中低密度(0.632-0.982g/cm3)流体,主要来源于为混合水,特别是岩浆水与地下水混合所形成的热液,或是来源于地下热卤水,温度从高温向低温过渡。该阶段发生了CO2不混溶现象,大量CO2分离出来,对矿床部分金属成矿起到很好的叠加富集作用。

【Abstract】 Kendekeke polymetallic deposit, located in the southwestern margin of the Chaidamu Basin-the Caledonian volcanic basin in the middle part of the tectonic fault depression zone of Qimantage back-arc of the Tarim-Chaidamu plate, is one of the most valuable deposit which has been discovered recently in Qimantage area. The geochemistry, fluid-inclusion petrography, micro-thermometry, and component analysis were used to research on rock-forming and metallogenic mechanisms, characteristics of ore-forming fluids, genesis of deposit, mineralization and etc., based on regional geological setting and geological features of the deposit.According to study, the deposit mainly has 4 mineralization periods: hydrothermal exhalative sedimentation period, skarnized hydrothermal activity period (include skarn-stage, oxide stage and sulfide-stage), late tectonic hydrothermal activity period and hypergene oxidation period. There are various characteristics of inclusions at different stages. The size of inclusions mainly varied from 4 to lOμm, with maximum size of 40μm. Most of inclusions are ellipse in shape and a few have a negative crystal shape. Three types of fluid inclusions have been recognized according to the different characteristics:aqueous, aqueous-CO2, and rarefied CO2 vapor inclusions.The gas phase is mainly composed of H2O and CO2, with minor organic gas; the main anions in the liquid composition are Cl-, NO3- and SO42-, the cations are Ca2+, Na+and K+. The ore-forming solutions belong to the CO2-Ca2+(Na+, K+)-Cl--(SO42-,F-)-H2O type.The ore-forming solution of the first stage, which originated from magmatic hydrothermal fluid, is characterized by high salinity (19-25wt% NaCl equiv), high density (0.817-1.033g/cm3), and high temperature with a wide variation range. The ore-forming solution of the second stage is medium-low-salinity (1-12wt% NaCl equiv) and medium-low-density (0.632-0.982g/cm3), mainly originated from mixed water, especially the mixture of groundwater and magmatic water or the underground thermal brine, and the transition of temperature changes from high to low. The immiscibility of CO2 made a large amouts of CO2 separate from the fluid during this stage what played a good role in superposition and enrichment of mineralization of partial metals.

  • 【网络出版投稿人】 中南大学
  • 【网络出版年期】2011年 03期
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