Argon Transport in Chain and Sheet Silicates: A Combined Laser Microprobe and TEM

链状和片状硅酸盐是变质矿物中的重要矿物 岩石，因为它们的共同存在和它们的有用性， 同位素测年法 大多数放射性矿物年代测定记录了 这些矿物质通过它们的阻塞温度冷却， 同位素扩散和这些不同的各种同位素， 各种链状和片状硅酸盐。 地质学家利用这一点 描述“温度-时间”历史的可变性 变态的怪物。 计算的阻塞温度 然而，对于许多矿物，例如对于角闪石中的氩， 云母，是很差的限制，除非有人假设扩散 反映这些硅酸盐晶格的各向异性的几何形状， 以及反映它们的扩散尺寸（或半径）。 微观结构的均匀性 通过测量氩的空间 天然和水热处理样品中的分布 角闪石、黑云母和白云母， 计划对这些财产进行估算。 这些估计数将 通过观察矿物的显微结构进行进一步测试， 透射电子显微镜（TEM） 结果 受控加热实验也将有助于 空间信息的解释来自于 40 Ar/39 Ar激光微探针。

Chain and sheet silicates are important minerals in metamorphic rocks because of their common occurence and their usefulness in isotopic dating. Most radiometric mineral dates record the times which the minerals cooled through their blocking temperatures for isotopic diffusion and these differ for the various isotopes and the various chain and sheet silicates. Geologists exploit this variability to delineate the "temperature versus time" histories of metamorphic terranes. The calculated blocking temperatures for many minerals, however, such as for argon in hornblende and micas, is poorly constrained unless one assumes a diffusion geometry reflecting the anisotropy of these silicate lattices, and a diffusion dimension (or radius) reflecting their microtextural homogeneity. By measuring the argon spatial distribution in both natural and hydrothermally treated samples of hornblende, biotite, and muscovite with the laser microprobe, it is planned to estimate these properties. These estimates will be further tested by observing microtextures of the minerals with the transmission electron microscope (TEM). Results from the controlled heating experiments will also facilitate interpretation of the spatial information being derived from 40Ar/39Ar laser microprobes.