八宝山金银矿床地质特征、成因及找矿规律

Geological Characteristics,Genesis and Prospecting Regularity of Babaoshan Gold-Silver Deposit

以龙泉八宝山金银矿床为研究对象,在现场地质调查的基础上,结合同位素分析等室内试验,着重探讨了该矿床的矿化带构成,成矿温度以及找矿规律。结果表明：1该矿床大体可划分为5条主要矿化带,2种矿化类型（蚀变岩型和石英脉型）和5个成矿阶段。2该矿床中石英斑岩含金量（2.7×10^-9）明显高于其他矿物,矿床矿化程度与地层关联度较低,矿化类型明显受构造控制。3通过研究该矿床的成矿温度、同位素组成、矿物标型以及其他特征,发现黄铁矿w（Co）/w（Ni）值大于1,且As含量较高;闪锌矿为含铁闪锌矿,铁含量3.4%~6.3%;方铅矿的热电系数为-369.2~619.2μV/℃;矿床主要矿化带的形成温度为150~300℃;由此可知,该矿床为与燕山中晚期火山（岩浆）活动有关的中—低温次火山热液矿床。结合控矿因素认为找矿工作应在富钾的钙碱性系列中—酸性火山碎屑岩脉发育和断裂活动强烈的地区进行,重点找矿部位为石英斑岩出露地带,另外应注意多金属硫化物石英脉。

In order to study the metallogenic regularity of the medium-low temperature volcanic hydrothermal deposit,taking the Babaoshan gold-silver deposit located in Longquan city,Zhejiang province as the research example,based on filed geological survey and isotope analysis method,the mineralization belts,ore-forming temperature and prospecting regularity of the Babaoshan gold-silver deposit are discussed emphatically. The results show that： 1the regional geological conditions of the Babaoshan gold-silver deposit can be divided into five main mineralized zones,two mineralization types（ altered rock type and quartz vein type） and five mineralization stages; 2quartz porphyry gold content（ 2. 7 ×10^-9） of the Babaoshan gold-silver deposit is significantly higher than other minerals,correlation between mineralization degree of the deposit and stratum is low,the mineralization types are controlled by tectonic obviously; 3by analyzing the metallogenic temperature,isotopic composition,typomorphic minerals and other characteristics,it is found that the w（ Co） / w（ Ni） value of pyrite is greater than 1,and As content is high; the sphalerite is iron sphalerite with iron content of about from 3. 4% to 6. 3%; the galena thermoelectric coefficient varies from-369. 2μV / ℃ to 619. 2 μV / ℃; the formation temperature of the main mineralization belts of deposits roughly from 100 ℃ to 300 ℃; therefore,the deposit is the medium-low temperature subvolcanic hydrothermal deposit that related to Yanshan period volcanic（ magma）. Combing with the ore-controlling factors,it is concluded that the prospecting work should be conducted in the area that the potassium-rich calcium alkali series medium-acid volcanic clastic dyke have strong development and the fault activities,and the key prospecting portion is quartz porphyry exposed area. In addition,the polymetallic sulfide quartz vein should also be paid attention.