Monitoring Magma Differentiation Through Crystal Isotope Stratigraphy

9526903戴维森特定岩浆系统中的分异细节(熔融、分离结晶、岩浆混合和混染)通常很难破译。确定开放系统进程的一个特别有用的工具是使用同位素比率。同位素不同组分之间的相互作用改变了所产生的差异的同位素组成，但对岩石的整体分析通常无法确定所涉及的终端成员。如果这些成分的遗迹保持其物理特征(来自随后杂交的岩浆的早期形成的晶体，来自同化物的捕虏晶，等等)。然后，它们还可以保留其原始的同位素组成。复杂的情况产生于持续的--如果不是持续的--增长阶段，通过复杂的分化情景。原则上，岩浆系统的大部分演化历史都锁定在从它结晶出来的阶段。确定这些阶段内的同位素变化可能有助于阐明这些历史，特别是在与空间相关的主要和微量元素数据相结合时。私家侦探们建议改进进行此类分析的方法，并概述一些可能说明其潜力的具体研究。

9526903 Davidson The details of differentiation (melting, fractional crystallization, magma mixing and contamination) in a given magma system are commonly difficult to decipher. One particularly useful tool in identifying open system processes is the use of isotopic ratios. Interaction between isotopically diverse components modifies the isotopic compositions of resulting differentiates, but bulk analyses of the rocks typically fail to identify the end members involved. If vestiges of these components retain their physical identity (early-formed crystals from magmas that have subsequently hybridized, xenocrysts from assimilants, etc.) then they may also retain their original isotopic compositions. Complications arise from the for continued - if not constant - growth phases through complex differentiation scenarios. In principle, much of the evolutionary history of a magma system is locked into phases crystallizing from it. Determining isotopic variations within these phases may help elucidate such histories, particularly when integrated with spatially correlated major and trace element data. The P.I.s propose to improve on methods to perform such analyses, and outline some specific studies that may illustrate its potential.