Two contrasting lithologies in off-rift subcontinental lithospheric mantle beneath central Europec-the Krzeniów (SW Poland) case study

Autor(en)
Magdalena Matusiak-Malek, Jacek Puziewicz, Theodoros Ntaflos, Michel Gregoire, Mathieu Benoit, Andreas Kluegel
Abstrakt

Miocene basanite from Krzeniów (SW Poland, eastern part of Cenozoic Central European Volcanic Province) contains scarce, small (usually <4 cm in diameter) spinel harzburgite and dunite mantle xenoliths. Two groups are defined based on the forsterite (Fo) content in olivine: group A (Fo

90.4-91.7) and group B (Fo

88.0-89.8). Both group A and B rocks are either clinopyroxenefree or clinopyroxene-poor. The group A orthopyroxene (mg# 0.91-0.92) is Al-poor and strongly light rare earth element (LREE) depleted [(La/Lu)

N<0.42]. The mg# of group A clinopyroxene varies from 0.92 to 0.94 and is negatively correlated with its Al content. The trace element compositions of clinopyroxene define two patterns: A1, U-shaped [(La/Lu)

N=20.23-64.73]; A2, almost linear LREE enriched [(La/Lu)

N=11.91-14.00]. The group B orthopyroxene is also Al poor and LREE depleted [(La/Lu)

N=0.03-0.04], but its mg# is lower than that in group A orthopyroxene (0.90-0.92).The mg# of group B clinopyroxene (0.90-0.92) is lower than that in group A, whereas theAl content is similar. The REE patterns of group B clinopyroxene mimic those of subgroup A2 [(La/Lu)

N=5.64-11.30]. The group A harzburgites and dunites represent spinel-facies lithospheric mantle that underwent metasomatism by CO

2-bearing silicate melts subjected to chromatographic fractionation. Locally carbonatite-silicate immiscible melts were generated. The peridotites in the distal parts of the chromatographic system were little affected by metasomatism and preserve much of their pre-metasomatic, depleted characteristics. The group B rocks are similar to those of group A except for the lower mg# of orthopyroxene and olivine. They were affected by percolating alkaline silicate melt undersaturated in clinopyroxene, which lowered the mg# of the olivine and orthopyroxene ('Fe metasomatism'). The A and B peridotites are representative of the Miocene lithospheric mantle close to the margins of the neighbouring Eger Rift.

Organisation(en)
Department für Lithosphärenforschung
Externe Organisation(en)
Uniwersytet Wrocławski, Université Toulouse III Paul Sabatier, Universität Bremen
Journal
Journal of Petrology
Band
55
Seiten
1799-1828
Anzahl der Seiten
30
ISSN
0022-3530
DOI
https://doi.org/10.1093/petrology/egu042
Publikationsdatum
09-2014
Peer-reviewed
Ja
ÖFOS 2012
105105 Geochemie, 105120 Petrologie
Schlagwörter
ASJC Scopus Sachgebiete
Geochemistry and Petrology, Geophysics
Link zum Portal
https://ucrisportal.univie.ac.at/de/publications/736497b1-3f5d-4864-b758-f1669ac8ae08