THE GEOLOGICAL CHARACTERISTICS OF LONGWANG ZHUANG A-TYPE GRANITE AND ITS SIGNIFICANCE
Lu Xingxiang(Henan Research Institute of Geology, Zhengzhou)
Along the southern margin of North China old block at the northern side of the east Qing-ling there is an alkaline rock zone. Longwang Zhuang alkaline granite is the largest one of A-type granites in this zone. It is rich in K, Na and Fe and poor in Ca, Mg, Al and water, the confents of F and REE are also high. It is characterized by alkaline dark minerals appearing in Longwang Zhuang granite. It is nonorogenic granite within plate. The age of the granite dated to Jinning period (1035Ma by Rb-Sr method)oThe discovery of Long Wang Zhuang A-type granite and its study shows that there was a tensile rift system which occurred along the southern margin of the Northern China plateform in the middle or late Proterozoic which provides a prospecting area for the raremetals and rare-earth element deposits.