The Cooling and Dynamic Stability of Magma in Sheetlike Magma Chamber
席状岩浆房中的岩浆冷却及动力稳定性

The modes of the fractional crystallization in magma chamber were discussed for many years. The main reason is that there are several different views on the cooling and convection patterns caused by the heat instability of magma system. Considering the fundamental physical ptoperties of sheetlike magma chamber, a dynamic pattern of magma cooling is established in this paper. Based on the laws of transformation and conservation of energy, we put forward a new analysis method for the heat instability of magma system. Panzhihua layered intrusion is taken as an example, the calculations of temperature field, density field and viscosity field, strength, region and duration of convection are Perpormed and the influence of the yield strength on the characteristic parameters of convection is discussed. The calculations indicates that the convection was very weak and transient and could not affect the middle and lower region of the magma chamber, if convection could ever occur spontaneously. This conclusion is consistent with the actual observation.