贵州贞丰水银洞金矿含矿岩系元素地球化学特征

Geochemistry of elements of ore-bearing rock series in the Shuiyindong gold d eposit,Guizhou Province

贵州贞丰水银洞金矿为赋存于二叠系龙潭组煤系地层所夹的不纯灰岩中的盲金矿床,含矿岩系为一套陆源碎屑岩与不纯碳酸盐岩多层交替出现的组合。矿石类型主要为凝灰质生物碎屑灰岩等,金品位高。矿体SiO2含量平均21.78%,CaO+MgO含量超过30%,围岩SiO2含量平均41.58%,CaO+MgO含量平均不到15%。含矿岩系岩石具有高镁铁、低Na2O、K2O远大于Na2O的特征;As、Ag和Tl均有不同程度的富集,矿石中Au与As、Tl有较高的正相关关系;矿体∑REE平均21.8μg/g,δEu值平均1.03,无Eu异常或正异常,围岩∑REE平均241.9μg/g,δEu值平均1.00,无异常。模式图上,矿体比较明显地富集中稀土元素(Sm—Ho)。水银洞金矿地质、元素地球化学组成特征及参数反映了含矿岩系形成时的特定的沉积环境或经历了特殊成矿作用过程。

The Shuiyindong gold deposit is located in Zhenfeng County, Guizhou Pr ovince. Its high gold grade orebodies are hosted in impure limestone within the coal-series of Upper Permian Longtan Formation. Its ore-bearing rock series ar e composed of a series of terrigenous clastic rocks interbedded with impure carb onates. Tuffaceous-bioclastic limestone is the main type of ore-bearing rock. The average composition of the ores consists of 21.78%of SiO2 and over 30%of C aO+MgO, whereas that of the country rocks consists of 41.58%of SiO2 and less t han 15%of CaO+MgO. The ore-bearing rocks are characterized by high contents o f Mg, Fe, low contents of Na2O, and high ratios of K2O/Na2O. As, Tl and Ag are m ore or less enriched in the ore-bearing rocks. The Au grade is positively corre lated with the contents of As and Tl in the ores. The average ∑REE content and 銭u value are 21.77 靏/g and 1.03 for the ores, 241.90靏/g and 1.00 for the c ountry rocks, respectively. The REE distribution patterns of ores show obvious M REE (from Sm to Ho) enrichment and more or less positive Eu anomaly. The geologi cal and elemental geochemical characteristics of the ore-bearing rock series in the Shuiyindong gold deposit indicate that the ore-bearing rock series were fo rmed in a special sedimentary environment or were experienced a special ore-for ming process.