Quantitative study of textures and micro- structures of olivine- rich achondrites as indication for cumulate formation and early solid-state deformation in asteroids.

基于我们在闪长岩工作中对固态塑性变形的意外发现(Tkalcec等人。(2013)，这将对小行星和原行星形成早期阶段的热史、化学和结构平衡产生几个深远的影响，我们建议对显示出明确晶格取向的一种亚类未闪长岩进行全面的定量结构和结构研究，并将对这类岩石的微观和纳米结构清单进行表征和量化。这使得能够解开热和结构演化的细节以及有效的变形机制。电子背散射衍射(EBSD)和大面积电子显微镜(TEM)将被用来测量晶体择优取向的细节，并将它们与织构形成过程如结晶、压实、冲击效应和变形机制联系起来。这些过程对于理解行星的分化、地幔的混合或混合以及小行星和行星胚胎的初始冷却是至关重要的。铀辉石是这一尝试的理想候选者，因为它们代表了第二种最常见的非球粒陨石类型，类似于富含橄榄石的地幔岩石，并且从它们的初始条件快速冷却保留了大部分原始的组构和微结构。

Based on our unpredicted finding of solid state plastic deformation during our work on diogenites (Tkalcec et al. 2013), which will have several far reaching consequences on the thermal history, chemical and structural equilibration in the early stages of asteroid and protoplanet formation, we propose to perform a comprehensive quantitative structural and textural study of a sub-type of unbreciated, ureilites showing a well defined crystal lattice orientation.A characterization and quantification of the micro and nano structural inventory of this rock type will be performed. This enables to unravel details of the thermal and structural evolution and the effective deformation mechanism. A combination of electron backscatter diffraction (EBSD) and large area transmission electron microscopic (TEM) will be applied in order to measure details of the crystallographic preferred orientation and relate them to texture forming processes like crystallization, compaction, shock effects and deformation mechanism. These processes are essential for the understanding of planetary differentiation, mantle mingling or mixing and initial cooling of asteroids and planetary embryos.Ureilites are ideal candidates for this attempt as they represent the second most common type of achondrites, resemble olivine-rich mantle rocks and the fast cooling from their initial conditions preserve most of the original fabric and microstructure.