Structural and Chemical study on magma crystallization and mineral melting processes.

对岩浆结晶和矿物熔融过程进行了初步研究。a)玻璃结构研究首先分析了岩浆主要组分之一Al_2O_3-SiO_2体系的玻璃结构。这些玻璃中的许多Al原子呈四面体，而八面体Al的数量可能很少。这一结果与蒙特卡罗模拟得到的模型结构一致。分析了长石（NaAlSi_3O_8-CaAl_2Si_2O_8）玻璃的结构。结果表明，随着Ca和Al原子的增加，密度增大，摩尔体积减小，这可以解释为玻璃结构中T- o -T角（T=Si, Al）的减小。b)通过x射线衍射和拉曼光谱测量研究了阴极射线管玻璃中富硅酸盐meltSb μ尺寸晶体的结晶，发现该晶体具有罗梅铁矿型结构。分析了围绕罗梅石晶体的富Sb玻璃相的结构。很明显，这种玻璃的网络结构发生了相当大的扭曲，这种扭曲可能与罗梅石的结晶有关。并对天然火山玻璃（onsidian）的结构进行了分析。结果表明，该黑曜石具有亚μ尺寸相，不含正常液相。该相可能与黑曜石的晶相有关。采用二元硅酸盐体系结晶数值实验研究了火山岩结构的形成过程。火山岩和深成岩的结构差异可能是由于它们的冷却速率不同造成的。c)这些结果经过了所有项目成员的讨论，并撰写了一些科学论文。

Principle results on the study on magma crystallization and mineral melting processes were followed.a) Structural studies of glassesFirstly, The glass structures of Al_2O_3-SiO_2 system that is one of the principle components of magma were analyzed. Many Al atoms in these glasses have tetrahedra and the number of octahedral Al may be small. This result is consistent with the model structure derived from Monte Carlo Simulation. The structures of feldspar (NaAlSi_3O_8-CaAl_2Si_2O_8) glasses were also analyzed. From the observations, it was evident that the density increase and molar volume decrease with increases of Ca and Al atoms could be explained by decrease of T-O-T angle (T=Si, AL) in the glass structure.b) Study on crystallization of silicate meltSb rich μ size crystals in cathode ray tube glass were investigated by X-ray diffraction and Raman spectra measurements and revealed that this crystal had romeite type structure. The structure Sb rich glass phase surrounding romeite crystal was also analyzed. It was evident that the network structure of this glass was rather distorted and this distortion may relate to crystallization of romeite. The structure of natural volcanic glass (onsidian) which had liquid and small crystalline phases was also analyzed. Obtained results show that this obsidian has sub-μ size phase which is not included normal liquid phase. This phase may be related in crystallite phase in obsidian. Numerical experiments on crystallization for binary silicate system were adopted for study on formation process of textures of volcanic rocks. The texture differences between volcanic and plutonic rocks may be caused by their different cooling rate.c) These results were discussed by all project members and we prepared some scientific papers.