花岗伟晶岩结构结晶动力学的研究进展

在地质流体演化方面，花岗伟晶岩位于花岗岩与热液石英脉的过渡位置，对其结构的实验研究对理解火成岩结构具有重要意义。长期以来，花岗伟晶岩被认为是花岗岩浆平衡结晶、缓慢冷却的结果，但近年来的一系列结晶动力学计算和实验发现伟晶岩在过冷却状态下快速生长，其结构主要受到结晶动力学参数的制约，F、B、P等助熔剂和H2O是影响这些参数的主要因素,富助溶剂的硅酸盐水溶液可作为伟晶岩的结晶介质。但由于快速淬火式实验设备的弊端，这些实验只能由淬火后的实验产物估算各类结晶动力学参数，只能以易淬火成玻璃的含水硅酸盐熔体作为结晶介质，只能静态地研究某一过冷却度下的结晶动力学状态。近年来，最新式热液金刚石压腔已经定型，可以模拟包括富助溶剂硅酸盐水溶液在内的各类伟晶岩结晶介质，能够在控制冷却速率的同时原位观测和微束分析晶体生长的动态特征，是模拟伟晶岩结构的理想工具，具有广阔的应用前景。

Research developments of crystallization dynamics for pegmatitic texture

From the view point of geological fluid evolution,granitic pegmatite is located at the transition from granite to hydrothermal quartz veins.So,the experimental researches on pegmatite texture have great significance for understanding the texture of igneous rocks.For a long time,granitic pegmatite was regarded as equilibrium crystallization in low cooling rate.But recent calculation of thermodynamic and experimental consequences showed that crystals of pegmatite grow in rapid rate at undercooling condition,and the crystallization texture is mainly constrained by the parameters of crystallization dynamics,such as H2O and fluxes of F,B,P and so on.Furthermore,flux-rich and silicate-dissolving aqueous fluid can act as the crystallization media.But because of the limitation of rapid quenching experimental equipment,such experiments had to estimate parameters of crystallization dynamics after quenching,had to take silicate melt as crystal-growing media for it is easy to be quenched into glass,and had to observe crystallization state only in undercooling conditions in static state.Recently,the newest type hydrothermal diamond-anvil cell(HDAC) had been designed successfully.It can take flux-rich and silicate-dissolving aqueous fluid as crystal-growing media,can control the cooling rate,and can observe and detect the crystal-growing process in situ.Therefore,the newest HDAC is an ideal experimental equipment for the research of pegmatite texture with a good application prospect.