内蒙古自治区扎赉特旗登吉屯铜矿床地质特征及其区域找矿意义

Geological characteristics and regional prospecting significance of Dengjitun copper deposit in Jalaid Banner,Inner Mongolia Autonomous Region

大兴安岭中段是我国重要的成矿带之一,具有形成斑岩型铜矿的成矿背景,但长期以来,勘查进展不大。在1∶5万区域矿产地质调查的基础上,经矿产预查、精细地质填图和探矿工程控制,新发现了登吉屯铜矿床。通过对其赋矿围岩、矿体空间分布规律、矿石结构构造及围岩蚀变等地质特征研究后发现,其矿体主要呈脉状赋存于中侏罗世早期花岗闪长斑岩中,铜矿化类型以稀疏浸染状或星点状铜矿化为主,围岩蚀变广泛且呈面状分布,主要有绿泥石化、绿帘石化、绢云母化、硅化等,具有斑岩型铜矿床浅部的成矿和蚀变特征,矿床成因为斑岩型;其含矿花岗闪长斑岩的锆石加权平均年龄为(172.6±2.0)Ma,推断成矿时代可能为中侏罗世早期。这些特征和研究结果表明,区内确实存在寻找斑岩型铜矿的潜力。

The middle part of Da Hinggan Mountains is one of the important metallogeny in China.It has the metallogenic background of porphyry copper deposit,but for a long time,the exploration has not made much progress.On the basis of 1∶5 million regional mineral geological survey,the copper mine of Dengjitun is newly discovered by means of pre-survey of mineral resources,fine geological mapping and exploration engineering.After studying the geological characteristics of the surrounding rock,the spatial distribution law of orebody,the structure of ore and the alteration of surrounding rock,it is found that the orebodies are mainly vein type occurred in the granodiorite porphyry of early Middle Jurassic epoch.The types of copper mineralization are mainly sparsely disseminated or star shaped,and the surrounding rock alteration is widely distributed in a face like style,mainly including chioritization,epidotization,sericitization and silicification,which have the characteristics of mineralization and alteration in the shallow part of the porphyry copper deposit.The deposit is due to porphyry,and the average age of zircon with the ore bearing granodiorite porphyry is（172.6 ±2）Ma,which is infer that the mineralization age may be in the early Middle Jurassic.These characteristics and research results indicate that there is indeed potential for porphyry copper deposits in the area.