Self-Organization in Agate: Textures, Composition, and Dynamic Crystallization Modelling

这个项目将研究火山玛瑙中重复的、自组织的纹理和组成模式的起源。这些模式被认为是相互关联的。一个非平衡系统的自组织包括一个重复模式的自发产生，没有预先存在的结构或周期性的外部原因。待探索的主要模式是(a)由扭曲的玉髓纤维组成的条带与由非扭曲的纤维组成的条带的系统互层，(b)由我们目前的模型预测并通过阴极发光显示的相关振荡小元素剖面，以及(c)玛瑙石英的系统纤维状，长度快速的习惯。本研究包括玛瑙自催化结晶的定量动力学建模、结晶前沿的形态不稳定性分析、显微观察以及离子探针的痕量和微量元素分析。这些分析将在麻省理工学院由美国国家科学基金会资助的离子探测器进行。本项目将阐明具有地球化学、晶体化学和岩石学意义的自组织系统的动力学，以及控制晶体形态和晶体结构的地球化学因素。

This project will investigate the genesis of repetitive, self- organization patterns of texture and composition in volcanic agates. These patterns are believed to be interlinked. Self- organization of a non-equilibrium system involves the spontaneous generation of a repetitive pattern without preexisting structures or periodic outside causes. The main patterns to be explored are (a) the systematic interlayering of bands made up of twisted chalcedony fibers with bands consisting of non-twisted fibers, (b) the associated oscillatory minor-element profile predicted by our present model and revealed by cathodoluminescence, and (c) the systematically fibrous, length-fast habit of agate quartz. The proposed research consists of quantitative dynamical modeling of agate crystallization by an autocatalytic mechanism, morphological instability analysis of the crystallization front, microscopic observations, and trace- and minor-element analyses by ion probe. These analyses will be carried out with the NSF-funded ion probe at MIT. This project will clarify the dynamics of a self- organizing system with geochemical, crystallochemical, and petrological significance, and geochemical factors controlling crystal morphology and crystalline textures.