四川石棉西部地区金矿床形成时代  

The Formation Age of Gold Ore Deposits in Western Shimian,Sichuan

作　　者：应汉龙[1] 骆耀南[2] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]四川省地质矿产勘查开发局,成都610081

出　　处：《地质论评》2007年第2期273-280,共8页Geological Review

基　　金：国家重点基础研究项目(编号G1999043200)的成果

摘　　要：四川石棉西部地区金矿床和矿点分布在扬子地块盖层碳酸盐岩和基底元古宙变质闪长岩以及中生代石英斑岩中的北北西和北北东走向断裂中。矿脉为含金黄铁矿—(黝铜矿)—多金属硫化物—石英脉、含金黄铁矿—石英脉和含金硅化糜陵岩等,围岩蚀变为硅化、白(绢)云母化、碳酸盐化、绿泥石化和黄铁矿化等。用^(40)Ar/^(39)Ar阶段加热法测定瓦斯沟、黄水沟、大岩房、金洞子和金台子5个金矿床蚀变白云母^(40)Ar/^(39)Ar坪年龄分别为约22Ma、25～28Ma、20Ma、20Ma和32～34Ma,代表该地区主要金矿床的矿化蚀变时间。石棉西部地区金矿床是在渐新世和中新世早期的伸展构造背景下形成的。The gold ore deposits and prospects occur within the nearly NW-striking faults in the carbonate rocks of the cover of the Yangtze block, Proterozoic metamorphosed quartz diorite of basement of Yangtze block and Mesozoic quartz porphyry in western Shimian, Sichuan Province. Ore veins include gold-bearing pyrite （tetrahedrite）--polymetal sulfide--quartz vein, pyrite--quartz vein and gold-bearing mylonite. Wallrock alterations are recognized as silicification, muscovitization, carbonatization, chloritization and pyritization. In order to confine ore formation age, muscovite formed by wallrock alteration from Wasigou, Huangshuigou, Dayanfang, Jindongzi and Jintaizi gold deposits is timed by stepwise 40^Ar/39^Ar geochrometry. 40^Ar/39^Ar plateau-like ages of the muscovite from the five gold deposits are about 22Ma, 25 -28Ma, 20Ma, 20Ma and 32 - 34Ma respectively, which are identical to the ages of the gold mineralization and alteration in the region. The gold ore deposits in the region was formed in Oligocene and early Miocene of Cenozoic under extensional tectonic background.

关 键 词：金矿床 成矿时代 40^Ar/39^Ar定年 白云母 石棉 四川 

分 类 号：P618.51[天文地球—矿床学]