Crystal Chemistry of Some Silicates and Carbonates

将遵循三个主要研究方向：1)高压下的反应机制和扩散过程，主要通过测量不同条件下的氧同位素交换速率来考察质子的作用：2)部分结合上述内容测定感兴趣矿物中的氧同位素分馏系数；3)硅酸盐中的有序-无序现象，钠长石中Al/Si有序中间态的合成，然后在高温下进行溶液量热，以获得有序-无序过程的能量学信息。这将涉及铝浓度对扩散和反应速率的影响，氢(质子)的可用性的变化，以及4和6铝配位变化的矿物的交换率的检查，所有这些都是与CO2或CaCO3交换的氧。将特别研究红柱石、硅线石和蓝晶石、斜长石系列、黄长石系列和绿柱石-堇青石对。分馏系数也将被确定。为了获得有序-无序过程的能量学数据，将对在高压下合成的Al/Si有序程度可控和可变的AlBite(NaAlSi3O8)进行量热工作。

Three principle direction of research will be followed: 1) Reaction mechanisms and diffusional processes at high pressures, and the role of protons will be examined for the most part by measuring rate of oxygen isotope exchange under different conditions; 2) Determination of oxygen isotope fractionation factors in minerals of interest, in part in conjunction with the above; 3) Order-disorder phenomena in silicates, and synthesis of intermediate states of Al/Si order in albite followed by solution calorimetry at high temperatures for information on the energetics of the order-disorder process. This will involve the effect of Al-concentration on diffusion and reaction rates, the varying availability of hydrogen (protons), and examination of rates of exchange in minerals with variation of 4 and 6 Al coordinations, all to be oxygen exchanged with CO2 or CaCO3. Specifically studied will be andalusite, sillimanite and kyanite, the plagioclase series, the melilite series, and the pair beryl- cordierite. Fractionation factors will also be determined. Calorimetric work will be carried out on albites (NaAlSi3O8) synthesized at high pressures with controlled and variable degrees of Al/Si order to obtain data on the energetics of the order-disorder process.