ВОЛХОВИТЫ - НОВЫЙ ТИП ТЕКТИТОПОДОБНЫХ СТЕКОЛ

Abstract

Volkhovites are the tektite-like glasses of mafic and ultramafic composition; for the first time wc have discovered them among fluvial-glacial sediments of Valday glaciations (10-65 thousand years) at the right side of the river Volkhov (32°0Г в. д., 59°27'с. ш.). Volkhovitc particles are characterized by small size (0.1-3.0 mm), varied microtectite aerodynamic (spherules, drop-shaped, dumbbell-like) and irregular forms, and the perfect safety indicating their postglacial age. Single or rare volkhovite grains (up to 20 pieces per 1 kg of loam) were detected at the area 1.0 X 1.5 km; some samples, from an area 20 X 30 m, have shown the anomalous concentrations - up to 1700 grains per 1 kg of loam. Together, in association with volkhovites, there were found some thin metal spherules (titanium-ferrous, iron, copper-gold), various form clastic grains of frothed glasses and slags, fragments of minerals from rocks of Precambrian and Paleozoic basement. The suggested cryptomagmatic model assumes that formation of glasses and slags had taken place in the pre-Holocenc period, but volkhovites were formed later, in the post-glacial time, as a result of outburst of the fluidisite slag-stone-melt-mud-gas mixture from the asthcnospherc up to surface. Meanwhile, drops of the melt have immediately solidified in the air as those tektite-like glasses, and the erupted tuffisitc-like mixture intermixed with the flu-vio-glacial loams.