Mineralogical Features of Ultrahigh Pressure Impact Glasses of the Kara Astrobleme (Pay-Khoy, Russia)

Abstract

The behavior of the disordered systems in the conditions of the strong compression attracts particular interest in materials science. Natural impact glasses, being with a metastable state, can keep features of the structure for millions of years, form essential volumes compare to experimentally possible high-pressure products. The complex analysis of geological, mineralogical-petrographic, petrochemical features and degree of crystallinity of tagamites, vein glasses and vitro-clastic formations of the origin type of melt impactites of the Kara astrobleme including their phase state composition have been studied. The melt Kara impactites have dependence on the initial character of the melted sedimentary target and cooling velocity of an impact melt. The lowest order has been described for ultrahigh pressure vein-type glasses which contain silica drops with single crystalline coesite and firstly found melt-crystallized high pressure variety of smectite. The vein melt impactites consist of solidified impact melt presented by totally amorphous alumina silicate glass with augite microcrystallites and ultrahigh pressure silica glass with coesite microcrystals and “drops” of firstly found melt-crystallized high pressure variety of smectite. The boundary between alumina silicate and silica glass is characterized with liquated amorphous Fe-rich drops. The special feature of the studies melt impactites is low alteration in spite of 70 Ma age and high content of water. The large volumes of an impact melt created massive tagamite bodies have longer cooling underwent with the almost complete crystallization. The obtained data indicate the specific nature of melt glasses of vein type and prospects of their further research for fundamental study of amorphous state under ultrahigh pressure and propose new materials.