浙西南治岭头斑岩钼矿体流体包裹体研究

The Fluid Inclusions Study on Zhilingtou Molybdenum Deposit in Southwest Zhejiang Province

江治岭头矿床自20世纪中叶勘查开发黄铁矿起,陆续发现了黄铁矿、铅锌矿及金银矿等矿床。在近些年的地质勘察和深部探矿中,在治岭头矿区深部发现了斑岩型钼矿。钼矿体主要产于斑岩体外接触带八都群变质岩中,从矿体部位向外围发育典型的斑岩蚀变分带,从内向外依次是钾化黑云母化带—黄铁绢英岩化带—绿泥石碳酸盐化带。成矿流体分为成矿早期、主成矿期、成矿晚期3个阶段,成矿早期以Ⅰa型包裹体为代表,其均一温度为354～442℃,具有中等盐度,为12.3～19.4wt%NaCl;主成矿期发育Ⅱ型和III型包裹体,其中II型包裹体均一温度329～406℃,盐度为3.5～6.2 wt%NaCl,Ⅲ型包裹体均一温度为305～375℃,盐度为30.6～45.8 wt%NaCl;成矿晚期Ⅰb型包裹体,其均一温度为187～285℃,盐度为3.5～8.4wt%NaCl。成矿期发生了强烈的流体沸腾作用,导致钼矿化。激光拉曼探针结果显示,治岭头钼矿三期石英中流体主要为H2O-NaCl流体。氢氧同位素,成矿流体由成矿前、成矿期的岩浆热液演化为成矿后的大气降水。

Since pyrite was found in the Zhilingtou deposit, Zhejiang Province in the mid-20th century, lead-zinc and gold-silver ore-bodies have been discovered as well. In recent years, a porphyry molybdenum deposit has been found beneath the gold silver orebodies in Zhilingtou area. Molybdenum ore bodies mainly occur in the Badu Group in the outer contact zone of the granite porphyry. Similarly with the typical porphyry-type alteration zoning, the alteration types from molybdenum ore body to wall rock is from potassium-biotitization through beresitization to chloritization-carbonation. Ore fluids can be divided into early mineralization stage, the main mineralization stage, and the late mineralization stage. Fluid inclusions in the early mineralization stage are mainly Ia type ones with the homogenization temperatures from 354 to 442 ℃ and salinities from 12.3 to 19.4 wt% NaC1. Fluid inclusions in the mineralization stage include type II and III. The homogenization temperatures of type lI range from 329 to 406 % and the salinities vary between 3.5 and 6.2 wt% NaC1; the homogenization temperatures of type III range from 305 to 375 ℃ and the salinities vary between 30.6 and 45.8 wt% NaC1. Fluid inclusions in late mineralization stage belong to type Ib with the homogenization temperatures from 187 to 285℃ and the salinities from 3.5 to 8.4 wt% NaC1. Fluid boiling processes played an important role in metal precipitation of the Zhilingtou molybdenum deposit. The Raman spectra show that ore fluids are I-I20-NaC1 fluids. The hydrogen-oxygen isotopes data show that mineralizing fluids were magmatic fluids during the early and main mineralization stages and meteoric water was added in the late stage.