软流层部分熔融岩浆竖向迁移模型分析

针对地幔蠕动过程中，软流层部分熔融岩浆上升这一地质背景，从力学的基本原理出发，将软流层岩石抽象为一类充满液体的多孔介质，并假定其以均匀速度上升，对岩石中部分熔融岩浆的迁移机理进行了分析，得到了一组简化的公式，并进行了计算。结果表明在此简化模型下，可以得到一个临界速度值的表达式。当岩石上升的速度低于该临界数值时，部分熔融岩浆将在一定的界面上形成；若大于这个临界数值，部分熔融岩浆的形成将滞后到一段竖向区域内完成。同时简单的计算结果也说明部分熔融岩浆的迁移运动是实现热量及成矿物质元素向上迁移的重要原因。其结果和某些岩浆过程的地质分析是一致的，这对进一步研究地幔蠕动及其成矿动力学具有重要的意义。

Dynamical Analysis of Vertical Transport for Partially Molten Magma in Asthenosphere

The research on mantle mass creep is one of the most important subjects in the field of geology and ore forming dynamics. It has received a considerable attention in the past century. A new tendency in this aspect is the development of mathematical modeling analysis for the movement of partially molten magma. For the magma ascent by asthenosphere rock flow, some simplified dynamical models are studied and discussed in this paper. Firstly, the complex magma movement is simplified to one dimensional problem of vertical movement so that the basic physical process might be understood. Secondly, some assumptions are made to get a series of simplified formulae according to the basic principles of fluid flow in a porous medium, for example, the asthenosphere rock is treated as a porous medium saturated with liquid (partially molten magma) and supposed to move vertically at a constant velocity. Therefore, some characteristics related to the mechanism of transport of partially molten magma could be obtained from these formulae. It is worthy to emphasize that a formula of critical velocitiy could be yielded. It shows that the partially molten magma would be produced at some level planes while the rock velocities are smaller than the critical velocity; and it would be produced in some delayed region while the rock velocities are greater than the critical velocity. Finally, some simple numerical calculations have been done by applying the formulae to the partially molten magma of basalt. All these conclusions show the reasons why the energy and the metallogenetic materials could move upward from the asthenosphere to the earth's surface, which is consistent with the geologic background and observation, and the magma transport might be of great importance for the further research on mantle creep flow and the dynamics of ore forming processes.