Structure and texture of silica of the Kara astrobleme impactites

The microstructural investigation and phase diagnostics of different silica segregations from impactites of the Kara astrobleme were conducted using the methods of petrographic analysis, X-ray diffraction, infrared (IR) and Raman spectroscopy. The studied collection of siliceous isolations covers a number of impact transformations of quartz - from quartz veins, which preserved their original structure, up to strongly transformed fragments of quartz and silica deposits in the postimpact hydrothermal process also. The peculiarities of quartz and other silica modifications, representing the major stages of impact metamorphism in rocks of the coptogeneous complex: planar cracks, planar deformation elements, coesite, newly formed and crystallized diaplectic glasses, crystallized glass of melting postimpact chalcedony and cristobalite-tridymite allocations were revealed. Coesite and diaplectic quartz glass are in the paragenetic association, which was preserved in its primary state in the siliceous lithoclasts of suevites. The textural characteristics and data of structure-phase diagnostics of silica from the impactites can be used as standards to identify similar formations located outside the modern boundaries of the impact structure.