IMPACT-SHOCKED ZIRCONS - DISCOVERY OF SHOCK-INDUCED TEXTURES REFLECTING INCREASING DEGREES OF SHOCK METAMORPHISM

Textural effects specifically characteristic of shock metamorphism in zircons from impact environments have not been reported previously. Ho wever, planar deformation features (PDF) due to shock metamorphism are well documented in quartz and other mineral grains from these same en vironments. An etching technique was developed that allows SEM visuali zation of PDF and other probable shock-induced textural features, such as granular (polycrystalline) texture, in zircons from a variety of i mpact shock environments. These textural features in shocked zircons f rom K/T boundary distal ejecta form a series related to increasing deg rees of shock that should correlate with proportionate resetting of th e U-Pb isotopic system.