Crystallization Kinetics: Quantitative Analysis and Numerical Simulation of Metamorphic Textures

我们试图通过使用高分辨率x射线计算机断层扫描（CT）来研究成卟啉结构来确定变质反应的机制和速率。通过对晶体尺寸和位置的统计测量，电子探针对晶体成分分带模式的分析，以及与不同动力学控制下结晶数值模拟的预测结果进行比较，从x射线CT数据中提取结晶机理。新的数值模型将比以前更接近自然界的结晶，这些模型将适合CT数据来约束绝对反应速率。本研究的主要目标是：(1)收集变质岩的结构特征，这些岩石的地质环境使它们有可能揭示温度、压力、流体渗透、变形、加热速率、前驱体粒度、内部扩散竞争和界面反应速率对结晶动力学的影响；(2)建立数值模拟结晶的模型，以捕捉在每种情况下变质反应的基本特征；(3)利用这些新的数值模拟方法来解释织构数据，阐明变质反应的机理并量化决定其速率的关键动力学参数。

9902682CarlsonWe seek to determine the mechanisms and rates of metamorphic reactions by using high-resolution X-ray computed tomography (CT) to study porphyroblastic textures. Mechanisms of crystallization will be extracted from the X-ray CT data by means of statistical measures of the sizes and locations of crystals, electron-microprobe analysis of compositional zoning patterns in them, and comparison with the predictions of numerical simulations of crystallization under diverse kinetic controls. New numerical models will be constructed to approximate crystallization in nature more closely than was possible before, and these models will be fit to the CT data to constrain absolute reaction rates. The principal objectives of the research are: (1) to assemble a broad inventory of textural features in metamorphic rocks whose geologic settings makes them likely to reveal information about the effects on crystallization kinetics of temperature, pressure, fluid infiltration, deformation, heating rates, precursor grain size, internal diffusional competition, and interfacial-reaction rates; (2) to create models for numerical simulation of crystallization that capture the essential character of metamorphic reaction in each of these settings; and (3) to use those new methods of numerical simulation to interpret textural data, clarifying mechanisms of metamorphic reactions and quantifying the critical kinetic parameters that determine their rates.