Microscopic studies of ultra-high pressure glasses from impactites of the Kara astrobleme

Abstract

UHPHT natural glasses are interesting not only to geologists and mineralogists, but also to physicists, chemists, and materials scientists from the point of view of the fundamental problem of the existence of matter under extreme PT-conditions. The specificity of the structure of such materials requires complex study. In this work we used optical, electron and atomic force microscopy, as well as Raman spectroscopy to assess the phase separation in UHPHT glasses of the Kara astrobleme. Their microscopic images show the separation of disordered aluminosilicate and silicate phases, their heterogeneous and partially heterogeneous structure with domain sizes of several tens of nanometers. The revealed highest structural homogeneity at the nanoscale level of UHPHT vein silica impact glasses, compared to high-pressure and low-pressure silica-rich glasses, confirms the specificity of the formation of UHPHT glasses and indicates promising further physical studies of this natural material to analyze the matter at ultra-high pressure conditions.