黔西北铅锌矿床的地质地球化学特征

GEOLOGICAL AND GEOCHEMICAL FEATURES OF LEAD-ZINC DEPOSITS IN NORTHWESTERN,GUIZHOU

矿床产于晚古生代裂谷带中，矿体受地层层位、岩性和层间滑动构造控制，含矿岩石主要为灰岩、泥灰岩和菱铁矿岩。矿石与围岩稀土元素组成特点相似，∑ＲＥＥ较低，∑Ｃｅ＞∑Ｙ，δＣｅ和δＥｕ明显亏损，硫同位素离散度较大；铅同位素组成均一。包体温度为１００～２５０℃。成矿溶液盐度不高，为富Ｃａ（２＋），ＳＯ４２－的弱酸－弱碱性热水．矿床为热水沉积－构造改造成因。

The ore deposits are located in the late Paleozoic rift zone. Ore bodies are controlled by strata, lithology and interlayer-gliding structures. The major ore-bearing rocks are limestone, marl and siderite rock. The REE geochemical features of lead-zinc ores and wallrocks are similar. The total amounts of REE are relatively low and the amoumts of LREE are higher than that of HREE. The anomaly parameters of Eu and Ce are sharp-depleted. The Ph isotopic composition of ores is homogeneous, but the S isotopic composition is more dispersive. Mineralizing fluid is a hot water with the temperature of 100～250℃, relatively low satinily, higher Ca, SO and slightly acidity and alkalinity. It is believed that the ore deposits are formed as a result of hydrothermal-sedimentary and reformation by tectonic processes.