RELICS OF PALEOFLORA IN IMPACT MELT ROCKS OF THE EL’GYGYTGYN CRATER IN CHUKOTKA (RUSSIA)

• Дата: 2019
• Автори: Gurov, Y.P., Permiakov, V.V.
• Формат: Стаття
• Мова: rus
• Опубліковано: Institute of Geological Sciences, NAS of Ukraine 2019
• Теми: імпактний кратер; ударнорозплавлена порода; рослинні залишки; клітинна тканина; 523.681.8; импактный кратер; ударнорасплавленная порода; растительные остатки; клеточная ткань; impact crater; shock melted rock; floral residues; cell tissue
• Онлайн доступ: http://geojournal.igs-nas.org.ua/article/view/169935
• Назва журналу: Geological journal

Relics of paleoflora were discovered in impact melt rocks of the El’gygytgyn crater in Chukotka. The El’gygytgyn impact crater, 18 km in diameter and 3.6 Ma old, was formed in volcanic strata of the Ochotsk-Chukotka Volcanic Belt, north-eastern Russia. Impact rocks of the crater were preserved as redeposited in the terraces of a crater lake. Impactites of the El’gygytgyn crater are represented by glassy bombs, impact melt rocks, and shock-metamorphosed volcanic rocks of the crater target. Remnants of fossil flora were discovered by electron microscopy of impact melt rocks from the eastern, southern, and north-western lacustrine terraces of the crater basin. Floral relics occur within gas vesicles in glassy matrix of impact melt rocks in form of dense accumulations of plant fibers, cell tissue fragments, and some other types of floral fragments, partly preserving the morphology of the original plant particles. The size of individual particles and their clusters range from a few micrometers to the first hundreds of micrometers. Carbon (50-70 wt %) and oxygen (30-40 wt %) are the main components of the floral remnants composition.  For the first time relics of paleoflora in impact melt rocks were distinguished by Schultz and Harris in 2005 in impactite debris forming seven local horizons in the Neogene sedimentary strata of the Argentinian pampa. The source of the impact structures is still unknown. Floral prints were described in 2007 by Osinsky with coauthors in impact glasses of Dakhleh, Egypt. These impact glasses were diagnosed as long-range emissions from not yet distinguished impact structure. So, El’gygytgyn crater is the first impact structure on the Earth surface, in which floral remains in impact melt rocks were discovered. Our data confirm the role of impact process in reliable conservation and long-term preservation of traces of ancient life on the surface of the Earth and other planets.