湖南大义山花岗岩南体黑云母40Ar-39Ar定年及地质意义

大义山岩体是一个多时代形成的复式岩体,习惯有大义山南体和北体之分.岩体内外接触带产有较多的W、Sn、Cu、Pb、Zn等多金属矿产.长期以来对南体主体形成的时代归属存在较大的差异,一部分人认为是印支期的产物,另一部人认为是燕山期的产物,这种结果对该区成矿作用的研究和指导找矿都带来很大的不利.本次研究通过对岩体的解体以及精确的黑云母氩氩法定年,确切地将大义山南体归属于两个不同的时代,即南体的北部为中侏罗世,南部为晚三叠世.这一成果对该岩体和成矿作用的研究都具有重要的现实意义.

40Ar-39Ar dating of biotitie in south Dayishan granite and its geological significance

Dayishan granite pluton is regarded as multi-aged compound granite body.It is divided into two parts,south body and north body.W-Sn-Cu-Pb-Zn-polymetallic deposits occurred in the inside and outside contact zones.The forming time of the south body was in controversy for a long time.Some considered it as Indosinian;others as Yanshanian.Based on the accurate biotitic ~(40)Ar-~(39)Ar dating,the Dayishan southbody is confirmed two times.The North of southbody belongs to the Middle Jurassic and the south of southbody belongs to the Late Triassic.The data has significance in understanding the pluton and mineralization.