J 2012

Geochemistry and petrology of pyroxenite xenoliths from Cenozoic alkaline basalts, Bohemian Massif

ACKERMAN, Lukas; Petr ŠPAČEK; Gordon Jr MEDARIS; Ernst HEGNER; Martin SVOJTKA et. al.

Základní údaje

Originální název

Geochemistry and petrology of pyroxenite xenoliths from Cenozoic alkaline basalts, Bohemian Massif

Autoři

ACKERMAN, Lukas; Petr ŠPAČEK; Gordon Jr MEDARIS; Ernst HEGNER; Martin SVOJTKA a Jaromír ULRYCH

Vydání

Journal of Geosciences, Praha, Czech geol.Soc, 2012, 1802-6222

Další údaje

Jazyk

angličtina

Typ výsledku

Článek v odborném periodiku

Utajení

není předmětem státního či obchodního tajemství

Impakt faktor

Impact factor: 0.804

Organizační jednotka

Přírodovědecká fakulta

UT WoS

000314230100001

Klíčová slova anglicky

pyroxenite; xenolith; Cenozoic; basalt; Sr-Nd isotopes; geothermobarometry

Příznaky

Mezinárodní význam, Recenzováno
Změněno: 18. 3. 2013 15:36, Mgr. Petr Špaček, Ph.D.

Anotace

V originále

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.