摘要
产于西秦岭南缘的大水金矿是一个新型金矿床。作者在前人研究的基础上,通过对大水金矿床流体包裹体的较系统研究认为,大水金矿床的方解石中的包裹体以气液包裹体为主。流体包裹体气相成分的CH4、CO、H2的含量反映属氧化环境;液相成分中阴离子以SO42-为主,Cl-次之;阳离子以K+为主,Na+次之。Au在成矿流体中以AuSO42-络合物的形式迁移。矿床成矿温度为120℃～220℃,属中低温范畴。w(NaCleq)盐度为2.7%～9.1%,密度为0.875～0.970g/cm3。流体水的δD值为-101‰～-61‰,δ18O(SMOW)为-0.3‰～19.42‰,δ18OH2O为-4.32‰～8.33‰,显示早期成矿流体来源于岩浆水,晚期成矿流体为岩浆水与大气降水的混合;δ13C值趋向热液成因。综合分析认为该矿床为一层控—浅成-超浅成岩浆期后中低温热液交代型金矿床,为多次构造—岩浆作用的产物。
Dashui gold deposit is located in the south margin of west Qinling. On the basis of the study done by former experts, after studying systematically fluid inclusions of deposit, the authors supposes that the most inclusions within calcite are gaseous and fluid inclusions. In the inclusions contained gaseous composition include CH4, CO and H2, which indicate the oxidizing environment, and the fluid composition is composed of anions as SO4^-2 first and Cl^- second, cations as K^＋ first, Na^＋ second. Au migrated in the complex of AuSO4 within the metallogenetic fluid. The metallogenetic temperature is 120℃-220℃, within the range of low temperature. Salinity,w （NaCleq）, is 2.7%-9.1%, and density is 0.875-0.970g/cm^3. The results, δD=-101%--61%, δ^18 O （SMOW）=-0.3%-19.42% ,δ^18OH2O=2.7%-9.1%, show that the metallogenetic fluid in early stage originated from magmatic water, and the metallogenetic fluid in later stage was the mixture of magmatic water and meteoric water, the value of δ^13C indicate as the genesis hydrothermal. According to the result of comprehensive analysis, it is supposed that this deposit is a strata-bound, shallow-supershallow-seated, post-magamtic, hydrothermal metasomatic deposit which is a product of multi-stage tectonomagmatic process.
出处
《甘肃地质》
2009年第1期21-27,共7页
Gansu Geology
关键词
流体包裹体
金矿床
西秦岭
甘肃大水
fluid inclusions
gold deposit
West Qinling
Dashui of Gansu Province
