南岭诸广山北体复式花岗岩锆石SHRIMP U-Pb年龄及多期岩浆活动

Zircon SHRIMP U-Pb geochronology of granitoids from northern Zhuguangshan granitic composite batholith, Hunan Province

诸广山复式花岗岩基位于湘、赣、粤三省交界处,是南岭花岗岩的重要组成部分,由南体和北体组成,出露面积大于5000 km2,形成于加里东期、印支期、燕山期3个时代。通过对诸广山北体3期花岗岩锆石SHRIMP U-Pb定年,结果表明,加里东期花岗闪长岩锆石SHRIMP U-Pb年龄为(414.5±4.5)Ma(n=13,MSWD=0.52)、(417.3±4.8)Ma(n=12,MSWD=0.84),形成于晚志留世末。印支期黑云母二长花岗岩锆石SHRIMP U-Pb年龄(207.5±2.7)Ma(n=10,MSWD=1.6),形成于晚三叠世末。燕山期二云母二长花岗岩锆石SHRIMP U-Pb年龄(148.2±1.7)Ma(n=13,MSWD=0.93),形成于晚侏罗世。该成果为南岭地区构造-岩浆演化及成矿作用研究,提供了重要的花岗岩年代学依据。

Zhuguangshan granitic composite batholith situated in Hunan-Jiangxi-Guangdong border area is an important part of Nanling large granite province,with the total area of northern and southern body being greater than5000km2.The results of zircon SHRIMP U-Pb geochronology of granitoids of northern Zhuguangshan show that the granitic body was formed in three periods with ages varying from the Caledonian through Indosinian to Yanshannian.Caledonian granodiorite was formed in late Silurian period,Indosinian biotite adamellite was formed in late Triassic period and Yanshannian dimicaceous adamellite was formed in late Jurassic period,with SHRIMP zircon U-Pb ages being(414.5±4.5)Ma,(417.3±4.8)Ma,(207.5±2.7)Ma,and(148.2±1.7)Ma respectively.The results obtained by the authors provide important geochronologic basis for the study of geology and mineralization in this area.