ACKERMAN, Lukas, Petr ŠPAČEK, Gordon Jr MEDARIS, Ernst HEGNER, Martin SVOJTKA and Jaromír ULRYCH. Geochemistry and petrology of pyroxenite xenoliths from Cenozoic alkaline basalts, Bohemian Massif. Journal of Geosciences. Praha: Czech geol.Soc, 2012, vol. 57, No 4, p. 199-219. ISSN 1802-6222. Available from: https://dx.doi.org/10.3190/jgeosci.125.
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Basic information
Original name Geochemistry and petrology of pyroxenite xenoliths from Cenozoic alkaline basalts, Bohemian Massif
Authors ACKERMAN, Lukas, Petr ŠPAČEK, Gordon Jr MEDARIS, Ernst HEGNER, Martin SVOJTKA and Jaromír ULRYCH.
Edition Journal of Geosciences, Praha, Czech geol.Soc, 2012, 1802-6222.
Other information
Original language English
Type of outcome Article in a journal
Confidentiality degree is not subject to a state or trade secret
Impact factor Impact factor: 0.804
Organization unit Faculty of Science
Doi http://dx.doi.org/10.3190/jgeosci.125
UT WoS 000314230100001
Keywords in English pyroxenite; xenolith; Cenozoic; basalt; Sr-Nd isotopes; geothermobarometry
Tags International impact, Reviewed
Changed by Changed by: Mgr. Petr Špaček, Ph.D., učo 18763. Changed: 18/3/2013 15:36.
Abstract
Pyroxenites occur as rare, but important, mantle xenoliths within Cenozoic volcanic rocks of the Central European Volcanic Province (CEVP). We report the petrography, geothermobarometry, mineral chemistry as well as clinopyroxene trace-element and Sr-Nd isotopic compositions of six pyroxenite xenoliths hosted by Tertiary-Quaternary volcanic rocks from Kozakov (NE Bohemia), Dobkovicky and Kuzov (Ohre/Eger Rift), and Lutynia (SW Poland). Three Kozakov xenoliths record a complex nature and evolution. As suggested by contrasting estimated temperatures (596-663 degrees C and 1008-1067 degrees C) and textures, olivine clinopyroxenite and one websterite were likely derived from different depths and may represent crystallization products of transient melts. Another websterite contains symplectite pseudomorphs after garnet which originated by exsolution from highly aluminous clinopyroxene, and the garnet breakdown was associated with melt introduction. This websterite P-T conditions (17.3 to 21.4 kbar and 1080-1200 degrees C) correspond to derivation from depths of 55-69 km. The composition of websterite from Dobkovicky suggests its origin as a cumulate from melt derived from a highly depleted mantle source with a composition similar to Depleted MORB Mantle (DMM). The position and petrological significance of websterite from Kuzov remains unclear because of a lack of data from associated peridotites. At Lutynia, cryptic metasomatism of peridotites by a CO2-bearing alkaline melt was described previously, and the composition of melt calculated to be in equilibrium with Lutynia websterite clinopyroxene is very similar to that in equilibrium with metasomatized amphibole-bearing peridotite. Therefore, the Lutynia websterite may represent a cumulate from percolating melt that metasomatized the lithospheric mantle in this area.
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