Collaborative Research: Novel Isotopic Tests of the Mechanisms of Non-equilibrium Crystal Growth

合作研究：非平衡晶体生长机制的新同位素测试

• 批准号: 1118996
• 负责人: John Eiler
• 金额: $ 16.39万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-10-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1118996&HistoricalAwards=false
• 关键词: Collaborative; Research; Novel; Isotopic; Tests

Natural crystals (minerals) have stories to tell about the conditions that prevailed during their growth, and so play a key role in the study of past climates, ancient and modern volcanism, the plate tectonic motions responsible for ancient mountain belts, among other problems. However, mineral chemistry must be interpreted through some understanding of how environmental properties get imprinted on compositions of growing crystals. It is generally assumed that equilibrium thermodynamics controls the mineral-chemical archive. But emerging evidence indicates that non-equilibrium processes, such as diffusion or irreversible reactions, dominate the chemistry of many key minerals. And, it is possible that the poorly understood thermodynamic properties of surfaces rather than the well-studied properties of bulk solids and fluids control compositions of some minerals. The goal of the Caltech-RPI proposal is to understand these phenomena at an atomic (molecular) scale. Its results will advance interpretations of mineral chemistry as constraints on the environments of mineral growth, and thereby advance the study of Earth?s chemical systems and past environmentsThis study will focus its attention on the zonation of isotopes (particularly naturally occurring isotopes of O and Si) and trace elements in the mineral quartz, grown from natural or synthetic water-rich solutions. Oxygen and silicon atoms make up most of the three dimensional structure of quartz (and most other minerals), and proportions of their ?light? and ?heavy? isotopes provide some of the most widely used records of the geologic past. The distribution of these isotopes in individual minerals are not always uniform. This heterogeneity, particularly differences in composition between adjacent simultaneously growing crystal faces, tells us that some influence other than environmental factors may have affected the growth of the crystal?some manifestation of non-equilibrium growth. The Caltech-RPI study will use the most recent advances in analytical geochemistry to document the co-variations of O and Si isotopes associated with intracrystalline heterogeneities, and their relationship to heterogeneities in trace element abundances. The resulting chemical data will yield a sort of fingerprint for mechanisms responsible for non-equilibrium growth. The study will then construct first-principles chemical-physics models of mineral growth, constructed to replicate and explain these chemical fingerprints.

天然晶体（矿物）有关于其生长过程中普遍存在的条件的故事，因此在研究过去的气候、古代和现代的火山活动、古代山脉的板块构造运动等问题中发挥着关键作用。 然而，必须通过对环境特性如何影响生长晶体的成分的一些理解来解释矿物化学。通常认为平衡热力学控制着矿物化学档案。但新出现的证据表明，非平衡过程（例如扩散或不可逆反应）主导着许多关键矿物的化学性质。而且，有可能是人们对表面的热力学性质知之甚少，而不是经过充分研究的散装固体和流体的性质控制了一些矿物的成分。加州理工学院-RPI 提案的目标是在原子（分子）尺度上理解这些现象。 其结果将推进对矿物化学作为矿物生长环境限制的解释，从而推进对地球化学系统和过去环境的研究。这项研究将重点关注同位素的分区（特别是天然存在的 O 和 Si 同位素） ）和矿物石英中的微量元素，从天然或合成的富含水溶液中生长。氧和硅原子构成了石英（以及大多数其他矿物）的大部分三维结构，以及它们的“光”比例。和？重？同位素提供了一些最广泛使用的地质历史记录。这些同位素在各个矿物中的分布并不总是均匀的。 这种异质性，特别是相邻同时生长的晶体面之间的成分差异，告诉我们除了环境因素之外的一些影响可能影响了晶体的生长——非平衡生长的一些表现。 加州理工学院-RPI 研究将利用分析地球化学的最新进展来记录与晶内异质性相关的 O 和 Si 同位素的共同变化，以及它们与微量元素丰度异质性的关系。由此产生的化学数据将产生一种导致非平衡生长的机制的指纹。然后，该研究将构建矿物生长的第一原理化学物理模型，用于复制和解释这些化学指纹。