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（矿物质）有故事可以讲述其成长过程中普遍存在的状况，因此在研究过去的气候，古代和现代火山的研究中起着关键作用，造成古代山带的板块构造运动以及其他问题。 但是，必须通过了解如何将环境特性印在生长晶体的组成上，从而解释矿物化学。通常认为平衡热力学控制矿物化学档案。但是新兴的证据表明，非平衡过程（例如扩散或不可逆反应）主导着许多关键矿物质的化学性质。并且，可能不理会表面的热力学特性，而不是散装固体和流体控制某些矿物质的组成的良好特性。 Caltech-RPI提案的目的是在原子（分子）量表上了解这些现象。 它的结果将推动对矿物化学对矿物生长环境的限制的解释，从而推进对地球化学系统和过去的环境的研究，这将把其注意力集中在同位素的分区上（尤其是O和SI的自然同位素），以及从天然或合成水上溶液中的矿物石英中的痕量元素和痕量元素。氧气和硅原子构成了石英（以及大多数其他矿物）的三维结构中的大部分，以及它们的光的比例？而？重？同位素提供了一些地质过去最广泛使用的记录。这些同位素在各个矿物质中的分布并不总是均匀的。 这种异质性，尤其是邻近同时生长的晶体面之间的组成差异，告诉我们，除了环境因素以外的某些影响可能影响了晶体的生长？某些表现出非平衡生长的表现。 CALTECH-RPI研究将利用分析地球化学的最新进展来记录与晶体内异质性相关的O和Si同位素的共同变量，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指纹，用于导致非平衡生长的机制。然后，该研究将构建矿物生长的第一原理化学物理模型，以复制和解释这些化学指纹。