發(fā)布時(shí)間：2019-06-10 09:39

【摘要】：四川丹巴燕子溝金礦床的大地構(gòu)造位置屬松潘-甘孜造山帶的二級(jí)構(gòu)造單元丹巴逆沖-滑脫深層疊置巖片,地層區(qū)劃上屬于巴顏喀拉-南秦嶺區(qū)。區(qū)域構(gòu)造上處于東谷斷層、兩河口斷層、牦牛溝斷層與永西穹窿一起組成的構(gòu)造骨架中。含礦巖系為泥盆系的危關(guān)群第四巖組的千枚巖、板巖,主要的控礦構(gòu)造為斷裂構(gòu)造和穹窿構(gòu)造,還有褶皺和順層滑脫剪切破碎帶,并與礦區(qū)內(nèi)基性-超基性侵入巖及玄武巖關(guān)系密切。礦區(qū)自北向南分為肖家溝-燕子溝、磨子溝和泥沖溝三個(gè)礦段。礦體形態(tài)有脈狀和層狀-似層狀,按礦石類型可分為含金石英脈型和炭質(zhì)板巖型。常見(jiàn)的礦石構(gòu)造結(jié)構(gòu)為浸染狀構(gòu)造、脈狀構(gòu)造、它形晶結(jié)構(gòu)、交代殘余結(jié)構(gòu),圍巖蝕變主要有硅化、黃鐵絹英巖化,礦石類型有沉積作用、熱液作用、動(dòng)力作用、表生風(fēng)化作用形成的礦石。礦床成礦作用分為熱水沉積期、熱液成礦期和表生期,主成礦期為熱液成礦期,可劃分為自然金-黃鐵礦-石英階段、自然金-多金屬硫化物-石英階段和石英-方解石網(wǎng)脈階段。本礦床的流體包裹體以CO_2-H_2O包裹體為主,另有H_2O包裹體和CO_2包裹體共生。共生的H_2O包裹體和CO_2包裹體成礦溫度和成礦壓力為393℃、148.5~179.0MPa,CO_2-H_2O包裹體的完全均一溫度、鹽度、密度和均一壓力為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,顯示出成礦流體為呈酸性的高溫度、高壓力、低鹽度、低密度的NaCl-CO_2-H_2O熱水體系,成礦環(huán)境從氧化變?yōu)檫�原。流體包裹體成分及氫氧同位素δ~(18)O_(H2O)值與δD_(H2O)值,黃鐵礦的As、Co、Ni含量及其比值均顯示出丹巴燕子溝金礦床成礦流體具變質(zhì)熱液的性質(zhì)。成礦流體具有典型的造山型金礦的特征,為富含CO_2低鹽度變質(zhì)熱液,且多發(fā)生流體不混溶。本礦床中富H_2O相與富CO_2相CO_2-H_2O包裹體共存,且它們的均一方式各不相同,均一溫度及均一壓力接近,說(shuō)明礦床成礦流體發(fā)生了CO_2和NaCl-H_2O的不混溶。富含CO_2的流體在斷裂構(gòu)造環(huán)境及大氣降水的加入下物理化學(xué)條件及成分發(fā)生改變,溫度壓力降低,CO_2和NaCl-H_2O相分離,流體中揮發(fā)分逸出,CO_2減少會(huì)引起pH值的升高和f_(O2)降低,H_2S減少會(huì)使金硫絡(luò)合物失穩(wěn)分解,最終導(dǎo)致自然金以及金屬氧化物、硫化物的沉淀,進(jìn)而發(fā)生成礦作用。
[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，

本文編號(hào)：2496368