Metasomatism-induced wehrlite formation in the upper mantle beneath the Nógrád-Gömör Volcanic Field (Northern Pannonian Basin): evidence from xenoliths

Levente Patkó, Nóra Liptai, László Előd Aradi, Rita Klébesz, Eszter Sendula, Robert J. Bodnar, István János Kovács, Károly Hidas, Bernardo Cesare, Attila Novák, Balázs Trásy, Csaba Szabó*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)
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Abstract

Clinopyroxene-enriched upper mantle xenoliths classified as wehrlites are common (~20% of all xenoliths) in the central part of the Nógrád-Gömör Volcanic Field (NGVF), situated in the northern margin of the Pannonian Basin in northern Hungary and southern Slovakia. In this study, we thoroughly investigated 12 wehrlite xenoliths, two from each wehrlite-bearing occurrence, to determine the conditions of their formation. Specific textural features, including clinopyroxene-rich patches in an olivine-rich lithology, orthopyroxene remnants in the cores of newly-formed clinopyroxenes and vermicular spinel forms all suggest that wehrlites were formed as a result of intensive interaction between a metasomatic agent and the peridotite wall rock. Based on the major and trace element geochemistry of the rock-forming minerals, significant enrichment in basaltic (Fe, Mn, Ti) and high field strength elements (Nb, Ta, Hf, Zr) was observed, compared to compositions of common lherzolite xenoliths. The presence of orthopyroxene remnants and geochemical trends in rock-forming minerals suggest that the metasomatic process ceased before complete wehrlitization was achieved. The composition of the metasomatic agent is interpreted to be a mafic silicate melt, which was further confirmed by numerical modelling of trace elements using the plate model. The model results also show that the melt/rock ratio played a key role in the degree of petrographic and geochemical transformation. The lack of equilibrium and the conclusions drawn by using variable lherzolitic precursors in the model both suggest that wehrlitization was the last event that occurred shortly before xenolith entrainment in the host mafic melt. We suggest that the wehrlitization and the Plio–Pleistocene basaltic volcanism are related to the same magmatic event.

Original languageEnglish
Pages (from-to)943-964
Number of pages22
JournalGeoscience Frontiers
Volume11
Issue number3
DOIs
Publication statusPublished - May 2020

Bibliographical note

Copyright the Publisher 2019. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • Wehrlite xenoliths
  • Upper mantle metasomatism
  • Mafic silicate melt
  • Trace element modelling

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