THECONFIRMATION OFGRANITIC ORTHOGENEISSES IN THE QINLING GROUP AND THEIR SIGNIFICANCE

Field geological mapping and indoor analysis indicate that there exist granitic gneisses in theQinling Group. These gneisses are represented by augen and banded biotiteplagioclase gneiss andmonzonitic gneiss. Their occurrence,composition,enclaves,palimpsest structure and intrusive con-tact relationships prove that they are ancient granitic plutons which now occur in the form ofgneisss. This confiramtion has significance for the understanding of the composition of the origi-nal Qinling Group and study of the early evolution of the crust.