江西南部鹤仔片麻状花岗岩类Pb—Pb同位素年龄及地质意义

The Pb-Pb isotopic ages and geologic significance of gneissic granite in Hezi,Jiangxi

江西南部鹤仔一带的片麻状花岗岩体是在武夷山西南坡江西境内发现的最古老的片麻状花岗岩体。选取晶形好 ,无磁性锆石进行了Pb—Pb同位素年龄测定 ,获得片麻状黑云母二长花岗岩体 1848± 2 0Ma、1774± 2 0Ma ,片麻状花岗闪长岩体为 996± 2 9Ma。它对进一步认识该区“中条”至“晋宁”期岩浆活动构造背景 ,中深变质岩时代确定等具有一定的意义。

The gneissic granite near Hezi in the south of Jiangxi province is the oldest one in the southwest part of Wuyi Mountain. The Pb-Pb isotope ages of nonmagnetism zircon crystal grains, which are formed perfectly in biotite adamellite, are 1 848±20 Ma and 1 774±20 Ma, and the Pb-Pb isotope age of nonmagnetism zircon crystal grains,which are formed perfectly in gneissic granodiorite, is 996±29 Ma.The results provide some information for studying on magmatic activity,tectonic setting and the age of medium-grade metamorphic rocks in 'Zhongtiao' and 'Jinning' tectonic stage.