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Characteristies and time-spatial analysis of epitharmal Au-Ag mineralization and acid-sulfate alteratin

上皮金银矿化及酸性硫酸盐变化特征及时空分析

基本信息

批准号：
09640561
负责人：
MATSUEDA Hiroharu
金额：
$ 2.18万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

On the genesis and formation process of the epithermal Au-Ag deposits related to young volcanic activities in the island arc geologic environ- ment, it is investigated to clarify the formation environment and con- centration process of the elements from the viewpoints of ore geology, geochemistry and petrology based on the field and laboratory works. Basic experiments are also conducted in order to improve and obtain high accuracy in chemical analyses.Both low- and high-sulfidation types of gold mineralizations in epi- and meso-thermal conditions are investigated on their assemblages of ore and alteration minerals to determine the physicochemical conditions and time-spatial relationships of the both types. Study fields are also extended to the same types in northeast Japan and Indonesia to make comparative study.As a concluding remarks, it is clarified that the high-sulfidation type gold mineralization is stongly affected by the magmatic fluids, but the low-sulfidations is by meteoric water. The former is prior to the latter and is located closer to the intrusive rock. Both types of gold mineralizations are strongly related to the magmatic acitivity, and the originated high temperature fluids dissolving various metals in the style of sulfide complexes might have effectively precipitated them due to the boiling by pressure decrease and/or mixing with meteoric water to cause cooling, oxidation or dilution in shallow environment.

本文在野外和实验室工作的基础上，对岛弧地质环境中与年轻火山活动有关的浅成低温热液金银矿床的成因和形成过程，从矿床地质学、地球化学和岩石学的角度进行了探讨，阐明了矿床的形成环境和元素富集过程。为了提高化学分析的准确性，还进行了基础实验，研究了浅成热液条件下的低硫化型和高硫化型金矿化的矿石和蚀变矿物组合，确定了这两种类型金矿化的物理化学条件和时空关系。并将研究范围扩大到日本东北部和印度尼西亚的同类金矿化进行对比研究，明确了高硫化型金矿化受岩浆流体的影响较大，而低硫化型金矿化受大气降水的影响较大。前者先于后者，且位置更靠近侵入岩。这两种类型的金矿化都与岩浆活动密切相关，由于压力降低和（或）与大气降水混合引起的沸腾冷却、氧化或稀释作用，起源于高温流体的硫化物络合物形式溶解了各种金属，从而有效地沉淀了它们。