by Vladimir POPOV, Cand. Sc. (Geol. & Miner.), leading scientist, Laboratory of Volcanic Petrology, Far Eastern Geological Institute, RAS Far Eastern Branch, Vladivostok
Volcanic glass (obsidian) is a most interesting rock formation shedding light on eruptive rock formative processes. On the other hand, it helps to trace the migratory paths of ancient man using this mineral in tool making. Thus we are able to access the territorial scales and periods of prehistoric events. In our country the main deposits of obsidian are found in the Maritime Region of the Far East. An international think tank representing the RAS Far Eastern and Siberian Divisions and universities of the USA, Australia and New Zealand working in this region since the 1990s has laid a groundwork for detailed studies of the local volcanic glass. The findings of geologists, archeologists, paleogeographers and physical chemists have been published in 28 articles in journals and collection of works in Russian and English, and also in two joint monographs.
Just a few words about the subject-matter of research. Depending on its chemical composition, volcanic glass can be called obsidian, hyalomelane, perlite or pitchstone. The first two varieties of rhyolite and basalt composition are remarkable for their high technological properties, which makes them suitable for tool manufacture. Rhyolite volcanic glass usually occurs in archeological monuments of the Mediterranean, Caucasus, Japan, Kamchatka, the western coast of North and South America and other regions of the young and present volcanism. However, basalt volcanic glass (hyalomelane) and instruments made of it are found much less often. As a rule, volcanic glass originates in lava outflows to water and ice when a quenching of magmatic melt and crust formation take place. Mass volcanic eruptions which occurred 13-11 mln years ago in the territory of southern Primorye (Maritime Region) and eastern Sikhote Alin were accom ... Читать далее