THE GEOLOGICAL CHARACTERISTICS OF GEZHEN INTRUSIVE MASS IN WESTERN HAINAN AND ITS SIGNIFICANCE
DING Shijiang (Hainan Exploration Institute of Geosciences, Haikou 570005)
Investigating regional geology, the author discovered Gezhen old intrusive mass in middle proterozoic Baoban migmatite of western Hainan, which is composed of mon-zonitic granite and granodiorite, and discussed the geological occurence, petrography, accessory minerals and geochemistry of the intrusive mass. The zircon Pb-Pb isochron age of 1397**46 Ma from the- gcanodiorite indicates that in Hainan there exist changcheng metamorphic rocks as a part of Cathaysia. The intrusion of Lime-alkali magma in the end of Changcheng is a record of orogenic movement. Therefore the author Proposed the concept of Hainan Craton.