Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
enabled [disable] Abstract
Number of results

Results found: 5

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

Search:
in the keywords:  impactites
help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Publication available in full text mode
Content available

Wybuchowe kratery meteorytowe

100%
EN
The article contains the description of the most important features of explosive craters of meteorites.
EN
The complex Puchezh-Katunki (PK) structure was created in the area of the Vladimir-Vyatka dislocation zone on the crystalline basement of the East European platform. The crater ca 80 km in diameter is located north of the city Nizhny Novgorod and is covered by thick layers of Mesozoic sediments. Shocked rocks, mainly gneisses, have been described. Recrystallised feldspar-quartz melt is the most common component in specimens of impactites. The melt is preserved in the form of various clasts showing wavy nebulous contacts within the surrounding microcristalline or isotropic matrix. Planar deformation features (PDFs) were observed in the quartz grains, including toasted quartz. Their number ranges from one to three. The PDF lines are limited to the grain boundaries or cross them. A few ‘kinky’ cracks have been noted in the biotite plates. Lobate inter-grain contacts prove that quartz is recrystallised by grain-boundary migration. The recrystallized quartz also occurs in the form of ballen quartz and trydimite. Both types of quartz are numerous in the material under study. Tridymite tiles show patchy extinction. Various matrices formed from rock melts are microcrystalline (clay minerals) and contain fragments of isotropic glass, also in the form of spherules. In matrix, some clasts are in the form of the ballen quartz, sometimes with relics of PDFs. Matrices of recrystallized rock melts are characterised by different colours, number of clasts and are distinctly separated from each other. The melts during the impact process are immiscible. Secondary mineralization is more frequent in the rock melts and less frequent in the metamorphosed gneisses. Magnetite, pyrite and zeolites are the most common secondary minerals.
3
75%
EN
The Kara crater is located near the Kara Sea. Together with the Ust-Kara crater, both structures are considered a twin structure, which is rarely found on Earth. The Ust-Kara is an undersea crater, while the Kara was formed in sedimentary rocks, in wet tundra. This environment determines the distinct petrological characteristics of the Kara impactites. Large shatter cones are a characteristic feature of an impact crater. High- and low-temperature tagamites with variable amounts of melt or glass and with the fluidal texture of rocky clasts were described from the crater. The mineralization represented by pyrite and chalcopyrite occurs in the suevite breccias expressing variable amounts of glass fragments. A special feature of the Kara impactites is the presence of coal clasts and carbonate rocks as well as a secondary crystallization of calcite in the form of globules.
EN
The Janisjarvi impact structure is located on the northern edge of Ladoga Lake, in Karelia, Russia. This research was carried out to study the biotite-quartz-feldspar-garnet-staurolite schist and several impact-metamorphosed rocks. In schist, biotite inclusions in garnet, pleochroic fields in biotite and asymmetry in the staurolite-biotite contact were observed. These characteristics were related to regional metamorphism of the target rock, and impact-induced features were not detected. No ‘kinky’ bands were observed in biotite. Fluidal structures and undulose extinction were rare in the analysed specimens. Injections of the tagamite melt into the clasts of cataclased recrystallising glass were noted. Fine-grained grey impact rock was cemented by a glassy micro-net with specimens of recrystallising quartz paramorphosis. In most of the analysed impactites, isotropic spherules and ‘ballen quartz’ structures, as well as sets of PDF (planar deformation features) and PF (planar fractures) in tagamite and quartz paramorphosis specimens were recognised. Except in schist, dynamic recrystallisation by ‘boundary migration’ was common. Secondary mineralisations were found for iron oxides, chlorite and calcite.
PL
Struktura uderzeniowa Janisjarvi znajduje się na północnym skraju jeziora Ładoga w rosyjskiej Karelii. Analizowano łupek typu biotyt-kwarc-skaleń-granat-staurolit ze skał podłoża struktury oraz kilka skał poddanych metamorfozie uderzeniowej. W łupku odkryto inkluzje biotytowe w granacie, pola pleochroiczne w biotycie i asymetrię kontaktu staurolit-biotyt. W biotycie nie zaobserwowano pasm typu ‘kinky’. Struktury fluidalne i faliste wygaszanie światła były rzadkie w analizowanych okazach. Odnotowano injekcje stopu tagamitu w klasty skataklazowanego rekrystalizującego szkliwa. Okaz rekrystalizującej paramorfozy kwarcu był scementowany z drobnoziarnistą skałą impaktową mikrosiecią szkliwa. W większości analizowanych impaktytów rozpoznano izotropowe sferule i struktury ’kwarcu groniastego’, a w tagamicie i paramorfozach kwarcu także od jednego do trzech zestawów lameli deformacji planarnych (PDF) oraz spękania planarne (PF). Spękania planarne były znacznie rzadsze niż deformacje i powstawały w stadium postimpaktu. Z wyjątkiem łupku, dynamiczna rekrystalizacja poprzez „migrację falistych granic ziarn” była powszechna. Stwierdzono wtórne mineralizacje tlenków żelaza, chlorytu i kalcytu.
5
63%
EN
The complex Ilyinets crater is an example of the small impact structure formed in crystalline target rocks of the Ukrainian Shield. Its impactites are characterised by examples of metamorphosed gneisses, granites, fine-grained polymict breccia and suevites. In the breccia and suevite matrix, fluidal clasts present their earlier brecciation. Lobate contacts between quartz grains show recrystallisation by grain-boundary migration. Shock structures, PFs, PDFs and “ballen quartz” are not very frequent. The monomict suevite breccia was determined among impactites.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.