Whole—rock Sm—Nd ,Rb—Sr and Zircon Pb—Pb Dating of the Metamorphic Complex in the Interior of Qinling Orogenic Belt,Westrn Henan,and Their Implications with Regard to Crustal Evolution

摘要

The comprehensive results of whole-rock Sm-Nd and Rb-Sr and zircon Pb-Pb dating suggest that the Qinling Group in the Qinling orogenic belt, northwestern Henan was formed at about 1200Ma.The complex in the interior of the orogenic belt experienced strong reworking in response to two great thermal cycles-the Jinningian and Caledonian cycles.Further disintegration of the Qinling Group delineated at present seems highly possible.