Quantitative study of microstructures and microtextures of Ol-Diogenites (Harzburgites and Dunites). Eyewitnesses of early mantle processes in Vesta-like asteroids

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Based on our unpredicted finding of solid state plastic deformation via pencil glide during our preliminary work on the harzburgitic diogenite NWA 5480, which will have several far reaching consequences on the thermal history, chemical and structural equilibration in the early stages of asteroid formation, we propose to perform a comprehensive quantitative structural and textural study of olivine-rich diogenites (harzburgites and dunites) which most likely represent mantle rocks originated from the differentiated Vesta or a Vesta-type asteroid.For the first time a characterization and quantification of the complete micro and nano structural inventory of this rare rock type will be performed. This enables to unravel details of the thermal and structural evolution and some cases 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. In the broader framework of NASAs Dawn mission to Vesta this study will help to better understand the formation mechanism and evolution of differentiated asteroids.