青海北祁连山基性、超基性岩含金性研究

依据区内岩体及围岩662个微金样品分析结果,笔者对基性、超基性岩的含金性及其中金的赋存规律进行了详细研究。确认该区基性、超基性岩体的金背景含量普遍偏高,而且明显高于围岩。同时指出,三条蛇绿岩带金元素丰度呈现自北而南、自东而西递增的趋势。经对金富集地质条件的分析,认为区内金的活化迁移主要受控于与超基性岩带分布近于一致的两条韧性剪切带,并指出断裂破碎带、强蚀变超基性岩体与围岩接触带、热液蚀变带、金属硫化物产出部位及砂金(铂)异常与Au、As、Sb、Cu异常重叠部位是找金的有利地段。在上述地段发现了川刺沟、撒拉河金矿点两处和含金超基性岩体20处。提出四个预测区和七个找金部位。依据硫同位素、矿物包裹体等资料及金矿(化)体的赋存部位,首次提出该区金矿总体可称为蛇绿岩型金矿。成因类型主要属中温变质热液型。

ON THE GOLD-BEARING PROPERTY OF BASIC AND ULTRABASIC ROCKS FROM NORTH QILIAN MOUNTAINS OINGHAI CHINA

According to analytic data of six hundred and sixty-two trace-gold samples, the authors study in detail on gold-bearing property of basic and ultrabasic rocks at North Qilian Mountains area in Qinghai Province, and on gold distribution regularity in these rocks. It is pointed out that average gold background of these rocks is on the high side, which is greater than their surrounding rocks, and that gold abundance in three ophiolitic zones show a tendency to gradually increase from north to south, east to west, respectively. After analysing geological conditions which make gold concentrate, It is considered that two tough-shear zones which are about consistant with ultrabasic belts in distribution control activation and movement of gold and that favourable positions of looking for gold deposits are in faultfracture zones, in strongly altered ultrabasic rocks contacting with surrounding rocks, and in which various alteration, sulfides, placer-gold(or platinum)anomaly as well as Au, As, Sb, Cu anomaly simultaneously occur. Two gold occur- rences of Chuancigou and Sala River, twenty gold-bearing ultrabasic bodies are discovered and four forecast areas, seven gold-prospecting places are suggested. On the basis of places in which gold ore-bodies occur and information of surpher isotope and mineral inclusions, the authors first put forward that the gold deposit is overall called an ophiolitic type in this area. The genesis of it is middle-temperature metamorphic hydrothermal.