Structure and physical properties of magma

采用实验方法和理论计算方法对岩浆的结构和物理性质进行了研究。实验：改进了高压下测量岩浆粘度的X射线阴影法，并在高压下测量了翡翠熔体的粘度。高压实验表明，地幔条件下的水溶解了大量的氧化物组分，类似于含水岩浆，我们用高温量热法直接测定了某些岩石的熔化热和橄榄石固溶体的混合性质。在高压条件下获得了硅酸盐熔体与共存矿物之间元素分配的系统数据。在高压下淬火的硅酸盐玻璃的热力学性质表明，与高配位硅相关的晶格常数增加。利用高温显微红外光谱技术研究了岩浆的脱水行为。天然流纹岩玻璃的反应速率和活化能进行了测定，并给出了合理的扩散系数，我们评估了一个典型的时间尺度的火山deathing.Theoretical/prostitational：分子轨道计算进行了解岩浆中的化学键。我们建立了一个适用于Na_2 O-CaO-MgO-Al_2 O_3-SiO_2和Na_2 O-SiO_2-H_2 O体系晶体和液体的可转移势模型，并成功地用可转移势模型进行了分子动力学模拟，预测了该体系中各种晶体和液体的结构和热力学性质。

We performed the study of structure and physical properties of magma by means of experimental methods and theoretical/computational methods.EXPERIMENTAL : The X-ray shadowgraph method to measure the viscosity of magma at high pressure has been improved, and the viscosity of jadeite melt was measured at high pressure. High pressure experiments showed that water at mantle condition dissolves large amount of oxide components and it is similar to hydrous magma.We have directly measured heats of fusion of some rocks and mixing properties of olivine solid solution by high temperature calorimetry. Systematic data of element partitioning between silicate melts and coexisting minerals have been obtained at high pressure. Thermodynamic properties of silicate glasses quenched at high pressure show increase of the enthalpies correlated with high coordinated silicon. High temperature infrared microspectroscopy has been developed, and dehydration behaviors of magmas was investigated. Reaction rates and activation energies were determined for natural rhyolitic glasses, and gave reasonable diffusion coefficients and we evaluate a typical time scale of volcanic degassing.THEORETICAL/COMPUTATIONAL : Molecular orbital calculations were performed to understand the chemical bonds in magma. We have developed a transferable potential model applicable to both crystals and liquids in the systems Na2o-CaO-MgO-Al2O3-SiO2 and Na2O-SiO2-H2O,and have successfully used the molecular dynamics simulations with the transferable model to predict the structural and thermodynamic properties of a wide variety of crystals and liquids in the systems.