GEOLOGICAL CHARACTERISTICS OF THE HONGYEJIA THRUST SHEAR ZONE NORTHWEST OF HEIHE IN THE HEILONGJIANG RIVER VALLEY AND ITS SIGNIFICANCE

The Hongyejia thrust shear zone northwest of Heihe in the Heilongjiang River valley extends in an E-W direction in the junction between the southern side of the Luomahu median uplift and the northern margin of the Paleozoic Handaqi fold belt.According to the degree of deformation the north,central and south strong deformation belts may be distinguished.Macroscopic observations indicate that the sense of shear movement is south-directed.Three samples of rocks of different ages in the strong strain belts give K-Ar ages of 155 to 158 Ma,suggesting that the age of the thrust shear is terminal Middle Jurassic.The discovery of this tectonic zone supports the view that the influence of the Paleo-Asiatic tectonic domain on the Northeast China microblock persisted till the Middle Jurassic.