THE RELATIONSHIP BETWEEN GOLD MINERALIZATION AND CHARACTERISTICS OF GRANITE IN NORTH HULUNBER LEAGUE OF INNER MONGOLIA AUTONOMOUS REGION

North Hulunber League of Inner Mongolia is rich in placer gold deposits, where dozens of small-madium scale deposits have been explored. There exists two stages of granits, i.e., Caledonian stage (442 Ma) and Hercynian stage (383-230 Ma). Based on its characteristics on petrology, lithochemistry, Sr-isotope and rare earth elements, the granitic rocks can be divided into two types of genesis, i.e., anatectic type (Ⅰ) and continental crust transformation type (S).The S-type contain higher abundance of gold, because it metasomatized and remelted basement rock with high gold abundance (slate, schist, etc.) This proves that the S-type provided gold source directly to placer gold deposits in this region. Moreover, the fact that natural gold grains are found in artifical heavy placer minerals from S-type granite also confirms that a part of gold exist in natural form.These suggest that we should pay attention to searching gold deposit in the area where S-type granite is developed.