TY - JOUR
T1 - Two contrasting lithologies in off-rift subcontinental lithospheric mantle beneath Central Europec-the Krzeniów (SW Poland) case study
AU - Matusiak-Malek, Magdalena
AU - Puziewicz, Jacek
AU - Ntaflos, Theodoros
AU - GréGoire, Michel
AU - Benoit, Mathieu
AU - KlüGel, Andreas
PY - 2014/9
Y1 - 2014/9
N2 - 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 (Fo90.4-91.7) and group B (Fo88.0-89.8). 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 CO2-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.
AB - 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 (Fo90.4-91.7) and group B (Fo88.0-89.8). 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 CO2-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.
KW - Carbonatite metasomatism
KW - Central European volcanic province
KW - Lithospheric mantle
KW - Silicate melt
UR - http://www.scopus.com/inward/record.url?scp=84906877573&partnerID=8YFLogxK
U2 - 10.1093/petrology/egu042
DO - 10.1093/petrology/egu042
M3 - Article
AN - SCOPUS:84906877573
SN - 0022-3530
VL - 55
SP - 1799
EP - 1828
JO - Journal of Petrology
JF - Journal of Petrology
IS - 9
M1 - egu042
ER -