湖北省随州三里岗地区二长花岗岩Rb-Sr、^(40)Ar/^(39)Ar同位素年龄  

Rb-Sr and 40Ar/39Ar Ages of the Adamellite in Sanligang Area

作　　者：石玉若[1] 张宗清[1] 刘敦一[1] 唐索寒[1] 王进辉[1] 陈文[1] 张思红[1] 刘新宇[1] 

机构地区：[1]中国地质科学院地质研究所,北京100037

出　　处：《地球学报》2005年第1期17-20,共4页Acta Geoscientica Sinica

基　　金：国家自然科学基金资助项目(编号:49732080)资助

摘　　要：三里岗二长花岗岩与花山蛇绿混杂岩中的基性火山岩呈侵入接触关系,其年龄的确定可解决花山蛇绿混杂岩中基 性岩形成年龄的上限问题。本文对三里岗二长花岗岩分别进行了Sm、Nd同位素研究及Rb-Sr、40Ar/39Ar同位素年龄测定。3 个全岩样品的Nd模式年龄平均值为1 064±105 Ma;12个全岩样品的Rb-Sr等时线年龄为422±53(2d)Ma;二长花岗岩中所 含角闪石矿物的40Ar/39Ar坪年龄为141.4±0.3 Ma,等时线年龄为142±2 Ma。这些结果暗示了花山蛇绿混杂岩中基性火山 岩的形成年龄不可能晚于422 Ma。The Sanligang adamellite is one of the main tectonic blocks of the Huashan ophiolitic melange and has an intrusive contact with the basic volcanic rocks. The determination of the isotopic age of this adamellite can lead to determining the upper limit of the isotopic chronology of the Huashan ophiolitic melange. The ages of the adamellite in Sanligang area were measured by Sm-Nd, Rb-Sr and 40Ar/39Ar methods. The mean age of the model ages tDM determined by 3 samples is 1 064±105 Ma. 12 whole-rock samples present a Rb-Sr isochron age of 422±53(2o)Ma. Hornblende picked out from the adamellite gives an 40Ar/39Ar age of 141.4±0.3 Ma. The results indicate that the age of the volcanic rocks of the Huashan ophiolitic melange is older than 422 Ma.

关 键 词：蛇绿混杂岩 花岗岩 等时线年龄 基性火山岩 形成年龄 AR同位素 Nd同位素 岗地 石矿 湖北 

分 类 号：P588[天文地球—岩石学] P618.440.5[天文地球—地质学]