大别造山带构造超压形成的碰撞力学机理

提出了大别山构造超压形成的点碰撞模型，简要分析了大陆碰撞带构造运动引起的粘性介质中粘性应力和平均应力随岩石物性的变化规律。探讨了构造压力对超高压的贡献及对成岩深度的重要意义。研究表明：构造运动引起的岩石圈中的附加压力可能与静岩压力有相同的数量级，大陆造山带两陆块不规则边界的碰撞会引起局部应力集中，产生较大的构造压力，岩石介质的流变学分析表明，在相同外力作用下，岩石圈上部的高粘度性质决定了其在构造活动期间增温效果显著，但增压效果有限；而粘性较低的岩石圈下部则增压效果明显，为此，在下地壳与上地幔之间的低粘度带内有可能发生超高压变质作用。

COLLISIONAL MECHANISM OF FORMING THE ULTRA-HIGH PRESSURE IN DABIE OROGENIC BELT

a mechanical model of point collision is given for explaining the formation of ultra high pressure in Dabie orogenic belt, central China. During the collision of the continents deviatoric stresses and average pressure in visco fluid are studied respectively. The contribution of the tectonic pressure to ultra high pressure and its implication to exhumation of the UHP rocks are also discussed. The results show that tectonic pressure due to crustal movements may be equal in magnitude order to lithostatic pressure. The collision of the irregular boundary between two continents will produce local stress concentration. Rheological analysis of rock material have proved that in the crust the effect of increasing pressure is not very noticeable during the tectonic movements, but in upper mantle it may be noticeable owing to the lower viscosity. So it is possible that metamorphism of UHP can be occurred in lower viscose rocks between the lower crust and upper mantle.