北秦岭东段峡河岩群中斜长角闪岩Sm－Nd同位素年龄

详细信息

THE Sm-Nd AGE OF AMPHIBOLITES IN THE XIAHE GROUP COMPLEX IN NORTH QINLING

摘要: 北秦岭造山带东段的牌楼沟地区，峡河岩群中的斜长角闪岩（原岩为基性火山岩）测得全岩Ｓｍ－Ｎｄ同位素等时线年龄为１６０５±７６Ｍａ，钛同位素初始比值为εＮｄ（Ｔ）＝＋５．３，表明峡河岩群变质岩系形成于中元古代。斜长角闪岩来源于亏损的地幔源区。上述测定结果，为阐明北秦岭造山带在中元古代时期的构造演化提供了佐证。

Abstract: Amphibolite（whose protolith is basic volcanics ）from the Xiahe Group Complex in the Pailougou area on the Henan-Shanxi border in the eastern sector of the North Qinling orogenic belt has been determined to have a whole-rock Sm-Nd isochron age of 1605±76Ma with εNd（T）= + 5. 3. This indicates that the metamorphic series of the Xiahe Group Complex was formed in the Middle Proterozoic and that the amphibolite was derived from the depleted mantle.The aforesaid data provide evidence for discussing the Middle Proterozoic tectonic evolution in the North Qinling orogenic belt.