吉林磐石三道岗含铜镍硫化物矿床岩体群年代学意义

Chronology Significance of the Intrusion Group in Sandaogang Cu-Ni Sulfide Deposit,Panshi,Jilin Province

吉林省中南部产出系列铜镍硫化物矿床,形成于中生代早期的含矿镁铁-超镁铁质岩体在含矿岩体空间上受断裂构造控制,并且在一定范围内集中出现,构成具有成因联系的含矿岩体群。三道岗含矿岩体主要岩石类型为闪长岩、辉长岩、角闪辉石岩-辉石岩、含长角闪橄榄岩等组合,侵位于下二叠统范家屯组浅变质岩系中。辉长岩中LA-ICP-MS锆石原位定年得到(232.75±0.95)Ma(MSWD=0.87)的岩体结晶年龄,同时,角闪石单矿物40Ar-39Ar法测年得到(121.45±2.52)Ma的蚀变年龄,暗示三道岗含矿岩体群与红旗岭一样形成于印支中亚造山晚期,燕山期岩浆活动产生的热液叠加蚀变对矿床形成产生重要影响。

A series of Cu-Ni sulfide deposits was discovered in south-central Jilin Province and some of the ore-bearing mafic-ultramafic intrusions were formed in the Early Mesozoic.Controlled by faults and concentrated in a certain area,the ore-bearing intrusions make up a few genetically related intrusion clusters.These ore-bearing intrusions,include diorite,gabbro,hornblende pyroxenite-pyroxenite and feldspathic hornblende-peridotite,etc,were intruded into the metamorphic rocks of the Fanjiatun Formation of the Lower Permian Series.The crystallization age of(232.75±0.95) Ma(MSWD=0.87) obtained by LA-ICP-MS zircon dating in situ,as well as the alteration age of(121.45±2.52) Ma obtained by hornblende 40Ar-39Ar dating,suggest that the ore-bearing intrusions in the studied area be formed at the same time as those in Hongqiling,that is,the Late Orogenic Indochina Epoch in Central Asia.In addition,the superimposed hydrothermal alteration caused by magmatic activities in Yanshan Epoch had also an important impact on the formation of the deposit.