四川省丹巴燕子沟金矿床流体包裹体研究
发布时间：2019-06-10 09:39
【摘要】：四川丹巴燕子沟金矿床的大地构造位置属松潘-甘孜造山带的二级构造单元丹巴逆冲-滑脱深层叠置岩片,地层区划上属于巴颜喀拉-南秦岭区。区域构造上处于东谷断层、两河口断层、牦牛沟断层与永西穹窿一起组成的构造骨架中。含矿岩系为泥盆系的危关群第四岩组的千枚岩、板岩,主要的控矿构造为断裂构造和穹窿构造,还有褶皱和顺层滑脱剪切破碎带,并与矿区内基性-超基性侵入岩及玄武岩关系密切。矿区自北向南分为肖家沟-燕子沟、磨子沟和泥冲沟三个矿段。矿体形态有脉状和层状-似层状,按矿石类型可分为含金石英脉型和炭质板岩型。常见的矿石构造结构为浸染状构造、脉状构造、它形晶结构、交代残余结构,围岩蚀变主要有硅化、黄铁绢英岩化,矿石类型有沉积作用、热液作用、动力作用、表生风化作用形成的矿石。矿床成矿作用分为热水沉积期、热液成矿期和表生期,主成矿期为热液成矿期,可划分为自然金-黄铁矿-石英阶段、自然金-多金属硫化物-石英阶段和石英-方解石网脉阶段。本矿床的流体包裹体以CO_2-H_2O包裹体为主,另有H_2O包裹体和CO_2包裹体共生。共生的H_2O包裹体和CO_2包裹体成矿温度和成矿压力为393℃、148.5~179.0MPa,CO_2-H_2O包裹体的完全均一温度、盐度、密度和均一压力为276.3~359.8℃、0.83~3.52wt%NaCleqv、0.68~0.925g/cm3、160.3~181MPa,pH值5.427~5.620,Eh值0.0502~-0.0583V,显示出成矿流体为呈酸性的高温度、高压力、低盐度、低密度的NaCl-CO_2-H_2O热水体系,成矿环境从氧化变为还原。流体包裹体成分及氢氧同位素δ~(18)O_(H2O)值与δD_(H2O)值,黄铁矿的As、Co、Ni含量及其比值均显示出丹巴燕子沟金矿床成矿流体具变质热液的性质。成矿流体具有典型的造山型金矿的特征,为富含CO_2低盐度变质热液,且多发生流体不混溶。本矿床中富H_2O相与富CO_2相CO_2-H_2O包裹体共存,且它们的均一方式各不相同,均一温度及均一压力接近,说明矿床成矿流体发生了CO_2和NaCl-H_2O的不混溶。富含CO_2的流体在断裂构造环境及大气降水的加入下物理化学条件及成分发生改变,温度压力降低,CO_2和NaCl-H_2O相分离,流体中挥发分逸出,CO_2减少会引起pH值的升高和f_(O2)降低,H_2S减少会使金硫络合物失稳分解,最终导致自然金以及金属氧化物、硫化物的沉淀,进而发生成矿作用。
[Abstract]:The geotectonic position of Yanzigou gold deposit in Danba, Sichuan belongs to the secondary tectonic unit of Songpan-Ganzi orogenic belt, Danba thrust-slippage deep superimposed rock slice, and the stratigraphy belongs to Bayan Kara-South Qinling area. The regional structure is located in the structural skeleton composed of the east valley fault, the two estuary faults, the yakugou fault and the Yongxi fornix. The ore-bearing rocks are thousands of rocks and slate of the fourth rock formation of Weiguan Group of Devonian system, and the main ore-controlling structures are fault structure and fornix structure, as well as fold and bedding slippage shear fracture zone. It is closely related to basic-ultra-basic intrusive rocks and basalts in the mining area. From north to south, the mining area is divided into three sections: Xiaojiagou Yanzigou, Mozigou and Nichonggou. The orebodies are vein-like and layered-like, which can be divided into gold-bearing quartz vein type and carbonaceous slate type according to the ore type. The common ore structural structures are disseminated structure, vein structure, its crystal structure, metasomatic residual structure, surrounding rock alteration is mainly silicified, yellow iron sericite, ore type has sedimentation, hydrothermal action, dynamic action, An ore formed by superficial weathering. The mineralization of the deposit can be divided into hydrothermal sedimentary stage, hydrothermal metallogenic period and supergenetic stage, and the main metallogenic period is hydrothermal metallogenic stage, which can be divided into natural gold pyrite quartz stage. Natural gold-polymetallic sulfides-quartz stage and quartz-calcite network vein stage. The fluid inclusions in this deposit are mainly CO_2-H_2O inclusions, in addition to H 2O inclusions and CO_2 inclusions symbiosis. The metallogenic temperature and pressure of symbiotic H _ 2O inclusions and CO_2 inclusions are 393 鈩，
本文编号：2496368
[Abstract]:The geotectonic position of Yanzigou gold deposit in Danba, Sichuan belongs to the secondary tectonic unit of Songpan-Ganzi orogenic belt, Danba thrust-slippage deep superimposed rock slice, and the stratigraphy belongs to Bayan Kara-South Qinling area. The regional structure is located in the structural skeleton composed of the east valley fault, the two estuary faults, the yakugou fault and the Yongxi fornix. The ore-bearing rocks are thousands of rocks and slate of the fourth rock formation of Weiguan Group of Devonian system, and the main ore-controlling structures are fault structure and fornix structure, as well as fold and bedding slippage shear fracture zone. It is closely related to basic-ultra-basic intrusive rocks and basalts in the mining area. From north to south, the mining area is divided into three sections: Xiaojiagou Yanzigou, Mozigou and Nichonggou. The orebodies are vein-like and layered-like, which can be divided into gold-bearing quartz vein type and carbonaceous slate type according to the ore type. The common ore structural structures are disseminated structure, vein structure, its crystal structure, metasomatic residual structure, surrounding rock alteration is mainly silicified, yellow iron sericite, ore type has sedimentation, hydrothermal action, dynamic action, An ore formed by superficial weathering. The mineralization of the deposit can be divided into hydrothermal sedimentary stage, hydrothermal metallogenic period and supergenetic stage, and the main metallogenic period is hydrothermal metallogenic stage, which can be divided into natural gold pyrite quartz stage. Natural gold-polymetallic sulfides-quartz stage and quartz-calcite network vein stage. The fluid inclusions in this deposit are mainly CO_2-H_2O inclusions, in addition to H 2O inclusions and CO_2 inclusions symbiosis. The metallogenic temperature and pressure of symbiotic H _ 2O inclusions and CO_2 inclusions are 393 鈩，
本文编号：2496368
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