东秦岭“武关岩群”斜长角闪岩Sm-Nd同位素年龄及其地质意义

Sm Nd AGES AND GEOLOGICAL SIGNIFICANCE OF AMPHIBOLITES OF THE WUGUAN GROUP COMPLEX ON THE SOUTHERN SIDE OF THE SHANGDAN FAULT ZONE IN THE EAST QINLING MOUNTAINS

摘要: 东秦岭商丹断裂带南侧的“武关岩群”是从原泥盆系刘岭群北侧解体出来的变质沉积—火山岩系。已获得该构造岩石地层单位中斜长角闪岩（变质基性火山岩）ＳｍＮｄ同位素等时线年龄为（１３８２±３０）Ｍａ，钕同位素初始比值ＩＮｄ＝０．５１１１８６±１（２σ），εＮｄ（Ｔ）＝＋６．５１。表明武关岩群”变质岩系主体形成时代为中元古代，这一结果必将导致人们重新认识秦岭造山带的构造发展演化过程

Abstract: The “Wuguan Group Complex" is a metamorphosed sedimentary volcanic series disintegrated from the north part of the original Devonian Liuling Group.The amphibolites （metabasic volcanic rocks） in this tectono lithostratigraphic unit have been determined to have a Sm Nd isochron age of（1382±30） Ma with I Nd =0.511186±1（2σ） and ε Nd （T）=+6.51, indicating that the bulk of the metamorphic series of the “Wuguan Group Complex" was formed in the Middle Proterozoic.This result reflects the process of tectonic development and evolution of the Qinling orogenic belt in the Middle Proterozoic.