Collaborative Research: RUI: Fe-Mg Interdiffusion in Orthopyroxene and Olivine: A Study Using Rutherford Backscattering to Measure Fe-Mg Diffusion Coefficients at 600-900 Degrees C

如果已知感兴趣的矿物的Fe/(Fe+Mg)相互扩散速率，则可以用矿物的Fe/(Fe+Mg)值的化学分带来约束各种地质过程的速率和性质。本项目的目标是测量Fe-Mg在常见矿物正辉石和橄榄石中的相互扩散速率作为温度和氧逸度的函数。卢瑟福后向散射将用于测量实验室实验中产生的Fe/(Fe+Mg)剖面。这将允许非常短（200nm）的成分轮廓测量。由于正硝石的扩散速度相对较慢，以往测量正硝石中Fe-Mg相互扩散系数的尝试都是不成功的。由于已发表的橄榄石扩散数据集存在分歧，因此还将研究橄榄石中的扩散，并将测量范围扩展到较低温度（600-900摄氏度）。

BradyEAR-0229552Chemical zoning of minerals in terms of their Fe/(Fe+Mg) value can be used to constrain the rates and nature of a variety of geological processes, if the rate of Fe-Mg interdiffusion is known for the minerals of interest. The goal of this project is to measure Fe-Mg interdiffusion rates for the common minerals orthopyroxene and olivine as a function of temperature and oxygen fugacity. Rutherford backscattering will be used to measure the Fe/(Fe+Mg) profiles produced in laboratory experiments. This will permit very short (200 nm) compositional profiles to be measured. Because of the comparatively slow rate of diffusion in orthopyroxene, previous attempts to measure Fe-Mg interdiffusion coefficients for orthopyroxene have been unsuccessful. Diffusion in olivine will also be studied because of disagreement among published diffusion data sets for olivine and to extend the range of measurements to lower temperatures (600-900 degrees C).