Experimental calibration of garnet- and pyroxene-diffusion-chronometry and -thermometry for applications to terrestrial and planetary samples

适用于陆地和行星样品的石榴石和辉石扩散计时和测温的实验校准

• 批准号: 321555708
• 负责人: Professor Dr. Sumit Chakraborty, Ph.D.
• 金额: --
• 依托单位: Department of Materials
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/321555708?language=en
• 关键词: Experimental; calibration; garnet; pyroxene; diffusion

There is an increasing recognition that many geological processes occur in pulses, or are too short to be captured by long-lived radiogenic isotopes. Moreover, thermal histories in many high temperature settings in the Earth (e.g. metamorphic, plutonic and volcanic systems) as well as in planetary systems such as asteroid parent bodies or the lunar or Martian interior often follow non-linear paths. These require tools that can monitor processes continuously and over a range of different timescales. Diffusion chronometry is one such tool that is being increasingly used to address these issues. In spite of the rapid developments, there remain critical experimental parameters that are needed for the determination of timescales in all of the above settings that could not be collected so far because of experimental limitations. New experimental developments now make it possible to determine these critical parameters. In this project we wish to use these novel experimental advances to determine diffusion coefficients and partition coefficients (required as geothermometers for use as boundary conditions in diffusion models) in the garnet- orthopyroxene-clinopyroxene system, which can be widely used in all of the above settings. Therefore, results from this study would considerably expand the scope of diffusion chronometry. An added advantage of studying this system is that compositions of these phases are used to determine pressures, temperatures and fluid activities. Thus, timescales obtained from diffusion chronometry with these minerals can be directly related to specific processes and conditions that a rock experienced during its evolution.

人们越来越认识到，许多地质过程发生在脉冲中，或者太短而无法被长寿命的放射性同位素捕获。此外，在地球的许多高温环境（如变质、深成和火山系统）以及行星系统（如小行星母体或月球或火星内部）中，热历史往往遵循非线性路径。这些都需要能够在一系列不同的时间尺度上持续监测流程的工具。扩散计时法就是这样一种工具，越来越多地用于解决这些问题。尽管发展迅速，但由于实验的局限性，迄今为止无法收集到确定上述所有环境中的时间尺度所需的关键实验参数。新的实验发展现在使确定这些关键参数成为可能。在这个项目中，我们希望使用这些新的实验进展，以确定在石榴石-斜方辉石-单斜辉石系统中的扩散系数和分配系数（需要作为地质温度计，用作扩散模型中的边界条件），这可以广泛用于所有上述设置。因此，这项研究的结果将大大扩大扩散计时法的范围。研究该系统的另一个优点是，这些相的组成用于确定压力，温度和流体活动。因此，从这些矿物的扩散测时法获得的时间尺度可以直接与岩石在其演化过程中经历的特定过程和条件有关。