Poster Number 63
See more from this Division: General Discipline Sessions
See more from this Session: Mineralogy/Crystallography; Petrology, Experimental; Igneous; Metamorphic (Posters)
Abstract:
The analysed microlite crystals vary in color and several grains show distinct light honey-yellow rims with dark brown-to-black cores; other grains show more discontinuous or patchy domains of light and dark, and some grains are entirely black. Kikuchi pattern image quality (IQ) measurements from spot analyses, line profiles, and beam-raster maps across multiple microlite crystals show significant variation and are interpreted to reflect variation in the degree of crystallinity within individual crystals. Kikuchi pattern formation does not occur in the black domains consistent with a lack of crystallinity due to radiation damage. These darker colored domains are associated with UO2 contents greater than about 1 wt. %, and significant chemical alteration and cracking is observed in the these domains indicative of radiation damage. Kikuchi patterns were observed within lighter colored domains (UO2 < 1 wt. %) and IQ gradients were measured. IQ values generally decrease with increasing U content consistent with gradients in radiation damage across the crystals.
The IQ parameter associated with EBSD analyses appears to provide a qualitative measure of crystallinity in naturally occurring microlites and may be a useful parameter to characterize the spatial distribution and the relative amount of radiation damage in crystalline substances at the mm-scale.
See more from this Division: General Discipline Sessions
See more from this Session: Mineralogy/Crystallography; Petrology, Experimental; Igneous; Metamorphic (Posters)