Diffusion controlled evolution of reaction microstructures: potential geospeedometers for garnet granulite xenoliths from the lower crust.

匈牙利西部巴科尼-巴拉顿-高地火山岩区的石榴麻粒岩捕虏体为潘诺尼亚盆地下地壳提供了极好的样品。这些捕虏体的矿物共生序列表明，它们经历了一个初始的高温高压阶段，然后是加热和减压阶段。这一证据与潘诺尼亚盆地的中新世构造演化有很好的对应关系。它们通常含有合晶和斜长石的特征扩散环带，这两种现象都表明了扩散控制的反应动力学，因此具有作为地质速度计的巨大潜力。通过对这些现象的分析，我们试图得出潘诺尼亚盆地中新世演化期间地壳深部活动的成岩作用的时间尺度和速率。预期的结果将允许改进耦合地壳和地幔过程的地球动力学模型的参数化，这些过程最终塑造了今天的地形。预期的研究将涉及详细的矿物化学和微观结构/纹理调查，重点是高空间分辨率技术。它还将涉及到采用广义扩散理论来描述地质材料中的输运控制反应动力学。

Garnet granulite xenoliths from the Bakony-Balaton-Highland Volcanic Field (Western-Hungary) provide excellent samples of the lower crust beneath the Pannonian Basin. Thesequence of mineral parageneses of these xenoliths testifies to an initial high temperaturehigh pressure stage followed by heating and decompression. This evidence can becorrelated very well with the Miocene tectonic evolution of the Pannonian Basin. Thexenoliths frequently contain symplectites and characteristic diffusion zoning of plagioclase.Both of these phenomena indicate diffusion controlled reaction kinetics and thus have greatpotential as geospeedometers. From the analysis of these phenomena we intend to derivetime scales and rates of the petrogenetic processes that were active in the deep crust duringthe Miocene evolution of the Pannonian Basin. The expected outcomes will allow to refinethe parameterization of geodynamic models of the coupled crust and mantle processes thatultimately shaped the present day topography. The intended research will involve detailedmineral chemical and microstructural/textural investigation with a focus on high spatialresolution techniques. It will also be concerned with the adoption of a generalized diffusiontheory to describe transport controlled reaction kinetics in geological materials.