华南武功山中生代花岗岩体热史及隆升机制研究

根据全岩Rb－Sr和黑云母、钾长石、全岩K－Ar、磷灰石裂变径迹同位素年龄测定结果，结合地质构造证据，分析了华南武功山花岗岩体的冷却历史。假定岩体冷却和地温梯度降低同步，估算出武功山中生代岩体的原始侵位深度为6km。在岩浆冷却过程中，岩体冷却上升速率逐渐降低。该岩体在180．8Ma。热侵位结晶，以较快的速率冷却上升，冷却速率为10．7C／Ma。，上升速率为0．11mm／a。经过28Ma后，岩体上升至地下约3km深处，转为缓慢冷却，平均冷却速率为1．7C／Ma，平均上升速率为0．02mm／a。最后对武功山地区晚中生代构造演化过程、热演化模式及其大地构造意义进行了讨论。

A STUDY ON GEOTHERMAL HISTORY AND UPLIFTING MECHANISM FOR THE WUGONGSHAN GRANITE IN WUGONGSHAN MOUNTAIN, SOUTH CHINA IN THE MESOZOIC

Through extensive dating by Rb-Sr method for whole-rock, K-Ar method for biotite,whole rock and K-feldspar and fission-track method for apatite, integrated with geological data, the authors analyze the cooling history of the granite body in the Wugongshan mountain in south China. Postulating the rock cooled in step with the decreasing of geothermal gradient, this text estimates that the primitive intruding depth of the granite body is 6 km.During the cooling process, the cooling rate and uplifting speed decreased gradually. A history of cooling and uplifting is given: The granite body intruded 180. 8 Ma ago followed by rising at a rather great speed of 0. 11 mm/a and a cooling rate of 10. 7℃/Ma. After 28 Ma,this body rose to a depth of 3 km below the surface and cooled more slowly at an average rate of 1. 7℃/Ma. The uplifting speed decreased to 0. 02 mm/a. Finally. the authors discuss the tectonics and geothermal evolution of the Wugongshan belt during the late Mesozoic and its tectonic significance.