Investigation on evaluation for mineralization potential of magmatic hydrothermal systems

为了建立岩浆热液系统成矿潜力的评价方法，对几个重要系统的系统演化和控制金属富集的因素进行了研究，着重研究了系统的三维结构、沸腾带分布和浅部信息。主要地区包括莱潘托/FSE-Victoria、Kasuga、Hishikari、Kushikino、Fuke、Cibaliung、Iwami、北方昆士兰州、星野和Noya。结合实验工作，得到了以下重要结果.在串野、星野和岩见地区发现埃达克质火山岩。对火山岩和矿石的裂变径迹、K-Ar和~（13）<40>Ar/~<39>（14）Ar法年龄测定清楚地表明，某地区的热液活动始于火山活动开始后约50万年，持续约50万年，并有间歇性断裂形成.如果系统的浅部保存完好，则可能存在烧结矿，烧结矿中较高的金含量表明可能存在金矿化。热液蚀变分带构造了热液系统的区域热结构。由150-200 C等温线界定的区域指示断裂系统，并延伸3公里乘4公里。叶片状方解石/石英、冰长石和斜方长石的产出以及流体包裹体特征指示了沸腾带.流通式高压釜实验表明，热液沃茨中Si、Al和Ca的浓度在裂缝形成过程中瞬时增加. Al和Fe（III）氢氧化物对金的吸附实验表明，金的沉积受吸附过程的强烈控制。

To develop the evaluation procedure for the mineralization potential of magmatic hydrothermal systems the evolution of systems and factors controlling concentration of metals were examined on several important systems, emphasizing three dimensional structures, distribution of the boiling zone and information of the shallow part of systems. Major areas include Lepanto/FSE-Victoria, Kasuga, Hishikari, Kushikino, Fuke, Cibaliung, Iwami, Northern Queensland, Hoshino and Noya. Together with some experimental works the following important results were obtained.1. Adakitic volcanic rocks were found in the areas of Kushikino, Hoshino and Iwami.2. Age determination using fission track, K-Ar and ^<40>Ar/^<39>Ar methods for volcanic rocks and ores clearly showed that in a certain area the hydrothermal activity starts about 500,000 years after the commencement of the volcanic activity, and continues about 500,000 years with intermittent fracture formation.3. If shallow part of a system is preserved, sinters may exist and the higher gold content of sinters indicates the possible gold mineralization.4. The regional thermal structure of a hydrothermal system is constructed by hydrothermal alteration zoning. The area bounded by 150-200 C isotherms indicates the fracture system and extends for 3 km by 4 km.5. Boiling zones are indicated by occurrence of bladed calcite/quartz, adularia and truscottite, and also by characteristics of fluid inclusions.6. Flow-through type autoclave experiments indicate that concentrations of Si, Al and Ca in hydrothermal waters increase transiently during fracture formation.7. Adsorption experiments of gold on Al and Fe(III) hydroxides suggest that deposition of gold is strongly controlled by adsorption process.