摘要
夕卡岩金矿床主要分布于中国东部，特别是在长江中下游地区，并常和夕卡岩铜（铁或多金属）矿床共生。它们产生的有利构造环境为地台边缘的拗陷和褶皱带以及地台内部的深大断裂附近地区。主要控矿地层为石炭－二叠纪和三叠纪碳酸盐岩。有关侵入岩为钙－碱性闪长岩、石英闪长岩、石英二长闪长岩、花岗闪长岩、二长花岗岩及其浅成相，大多属燕山期。含金夕卡岩以钙夕卡岩为主，镁夕卡岩次之。在夕卡岩及其邻近的围岩中叠加有较强的退化热液蚀变，并常伴有Ｃｕ、Ａｕ、Ｆｅ、Ｍｏ、Ｐｂ、Ｚｎ、Ａｇ等矿化，显示明显的交代分带。总的矿化分带序列为：Ｆｅ（Ｃｕ）→Ｃｕ（Ｍｏ）→Ｃｕ、Ａｕ→Ａｕ→Ａｕ、Ｐｂ、Ｚｎ。在许多矿床中，发现有碲化物、铋化物和硒化物。因此，Ｃｕ、Ａｕ、Ｔｅ、Ａｓ、Ｂｉ、Ｐｂ、Ｚｎ、Ａｇ、Ｓｅ等元素在夕卡岩金矿床中相对富集。
In the past decade,progress has been made in the exploration of gold skarn deposits in China and some large deposits have been discovered,such as Jiguanzui and Jilingshan in Hubei Province and Xinqiao in Anhui Province.The reserves of gold skarn deposits account for about 20% of the total gold reserves in China,indicating that auriferous skarn deposits now constitute one of the major types of gold deposits in China. Gold skarn deposits may be further divided into two subtypes:independent gold skarn deposits and associated gold skarn deposits.They are mainly distributed in the eastern part of China,especially in the middle lower reaches of the Yangtze River,and are usually associated with copper(iron or polymetal)skarn deposits.Their favorable tectonic settings are depressions and fold belts of platform margins as well as areas near deep faults within the platform. The related intrusives are chiefly calc alkaline diorite,quartz diorite,quartz monzodiorite,granodiorite,monzogranite,and rocks of their hypabyssal facies.Most of them are of Yanshanian age.According to the strontium and oxygen isotope data and REE distribution patterns of some major gold skarn deposits,the magma of related intrusives mainly came from the upper mantle,and might have been contaminated by silicic crustal materials. The auriferous skarn may be calcic or magnesian,the former being predominant.On the skarns and their adjacent wall rocks are usually superimposed strong retrograde hydrothermal alterations,such as epidotization,actinolitization,silicification,chloritization,carbonatization,serpentinization,sericitization and talcization,which are usually associated with Au,Cu,Fe,Mo,Pb and Zn mineralization,showing distinct metasomatic zoning.The zonality of the major gold skarn deposits is Fe(Cu)→Cu(Mo)→Cu,Au→Au→Au,Pb,Zn. In many deposits,tellurides,bismuthids and selenides are identified.Therefore,Cu,Au,As,Te,Bi,Co,Zn,Pb and Ag are more specific metallic elements in gold skarn deposits and are referred to as important geochemical ore searching indicators. The study of fluid inclusions and the compositions of coexisting pyroxenes and garnets suggest that auriferous skarns were formed by solutions with rather high oxygen fugacity and lower acidity.
出处
《矿床地质》
CAS
CSCD
北大核心
1997年第3期193-203,共11页
Mineral Deposits
基金
国家自然科学基金
关键词
夕卡岩矿床
地质特征
区域分布
金矿
skarn gold deposit,distribution,geological characteristic.zonality,China
