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PI : Falko Langenhorst

Title : Analytical transmission electron microscopic study of pyroxene grains from the regolith of asteroid 25143 Itokawa: mineralogy, space weathering and shock metamorphism

Abstract

To pursue our electron microscopic studies of Hayabusa grains we request here new particles that are mostly composed of low- and high-Ca pyroxene. Our previously requested particles were mostly made of olivine, showing traces of shock metamorphism (c dislocations) and space weathering (polycrystalline surface nanolayers). Due to their low symmetry, miscibility gaps, and cation ordering, pyroxenes can contain a wealth of microstructures such as deformation-induced lattice defects (e.g. dislocations, stacking faults, twins) and exsolution lamellae. We intend to study these microstructures as well as mineral inclusions by a combination of FIB preparation and analytical transmission electron microscopy. The results will provide important clues to collisional fragmentation, regolith formation, space weathering, and thermally activated parent body processes.

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