Orign of growth chemial 3oning in minerals

矿物在生长过程中由于化学不均匀性而产生的内部结构，为研究矿物和岩石的历史以及行星的演化提供了不可缺少的信息。本研究旨在通过对矿物化学分带的观察，分析矿物生长过程中化学分带的成因，建立矿物生长过程中化学不均一性形成的基础理论。具体的方案是在统计力学的基础上构造一个新的理论，并对分带进行描述，以与理论进行比较。(1)利用自行购置的扫描电镜对火成岩和变质岩中矿物的化学分带进行了观察。(2)同时考虑到母相中的扭折动力学和扩散，给出了固溶体生长的一般方程。将该理论推广到二元系熔体生长的情况。我们用分子动力学方法研究了相关系。这些研究揭示了生长界面非平衡现象的本质。对孪晶生长进行了理论研究。(3)在观察和建立新理论的基础上，从生长化学分带的角度阐明了几种矿物形成过程的变化。

Internal texture in minerals due to chemical heterogeneity induced during the growth gives information which is indispensable for studying the history of minerals and rocks and the evolution of planets. The aim of the present research is to analyze the origin of growth chemical zoning based on the observation of chemical zoning in minerals and the construction of a basic theory on the formation of chemical heterogeneity during the growth. A concrete plan is toconstrict a new theory based on the statistic mechanics and to describe the zoning to compare it with the theory.We have carried out the following studies during the research period.(1) Chemical zoning in minerals in igneous and metamorphic rocks were observed under a scanning electron microscope bought in the present project.(2) A general equation for the growth of a solid solution was given by taking into considerations of both kink kinetics and diffusion in the mother phase. The theory was extended to the case of melt growth of a binary system. We study the phase relation by using the molecular dynamics. These studies reveal the essence of the non-equilibrium phenomena on the growth interfaces. A theoretical study on the growth ofa twinned crystal was also carried out.(3) The changes of the formation processes of a few minerals were clarified from the growth chemical zoning, based on the observation and the construction of the new theory.