北祁连山与斑岩有关的碲金型金矿床地质特征和成因模型

The geological features and genetic pattern of Te-Au deposit related to porphyry in North Qilian Mts

车路沟金矿床是北祁连山发现的首例与斑岩有关的碲 -铋 -金型矿床。金矿床成矿地质特征显示 ,矿床形成于岛弧火山期后次火山 -深成中酸性侵入岩体中 ,直接赋存于浅成 -超浅成英安斑岩内 ,其成矿背景为碰撞造山环境。矿床受区域断裂裂隙、同建造期古火山穹隆边缘继承性断裂裂隙 ,尤其受次火山岩体边缘节理、裂隙及接触破碎带控制。同位素研究资料显示 ,成矿流体 δ18OH2 O为 - 6 .5 8‰～ - 2 .30‰ ,δD为 - 5 8.2‰～ - 4 1.8‰ ,δ3 4S为 - 3.84‰～ + 3.2 0‰ ,δ13 CPDB为 - 8.5 4‰～ - 1.32‰ ,盐度为9.37‰～ 11.83‰ [w (Na Cl) eq],密度为 0 .982～ 1.0 0 6 g/ cm3 ,均一温度为 137.6～199.4℃。成矿流体总特征为低温、低气相、中 -高密度、并含有较高 CO2 的 H2 O- CO2 -Na Cl (KCl)体系。厘定了成岩年龄为 4 2 7.7± 4 .5 Ma,成矿年龄在 35 0～ 4 10 Ma。矿床是在岩体固结定位后 ,由深部岩浆房 (源 )分异出的富含 Au、Te、Cu等成矿元素 ,CO2 、SO2 、H2 O等挥发组分的岩浆热液沿控岩构造裂隙带上升 ,不断从沿途已固结的英安斑岩及围岩中萃取成矿物质 ,并与大量大气降水混合作用的产物。矿床成因类型属与斑岩有关的低温热液型碲金矿。

Chelugou gold deposit is the first Te Bi Au deposit related to porphyry found in North Qilian orogenic belt The gold deposit forms in post volcanic intermediate acidic intrusive rocks of island arc,and directly occurs in hypabyssal ultrahypabyssal dacite porphyry The diagenetic age is 427 7±4 5 Ma, and the metallogenetic age is 350~410 Ma The research indicates that the deposit could be produced by mixing with magmatic hydrothermal and atmospheric water After magma positioning and solidifying, the magmatic hydrothermal differentiated from deep magma chamber(source),riching in metallogenic elements of Au,Te,Cu and volatile components of CO 2,SO 2,H 2O,ascends through tectonic fissures,mixed with atmospheric water,and constantly extracts ore forming matter from solidified dacite porphyry and adjoining rocks Generally,the metallogenic fluid is a kind of low temperature,less vapor phase,medium high density,higher salinity H 2O CO 2 NaCl(KCl) system The genetic type of the deposit is a hypabyssal epithermal Te Au deposit related to porphyry