EGU22-4679, updated on 27 Mar 2022
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Deciphering multiple metasomatism beneath Mindszentkálla (Bakony-Balaton Highland Volcanic Field, western Pannonian Basin) revealed by upper mantle peridotite xenoliths

Levente Patkó1,2,3, Zoltán Kovács3, Nóra Liptai1,2, László E. Aradi1,3, Márta Berkesi1,2, Jakub Ciazela4, Károly Hidas5, Carlos J. Garrido6, and István J. Kovács1,2
Levente Patkó et al.
  • 1MTA FI Lendület Pannon LitH2Oscope Research Group, Institute of Earth Physics and Space Science, Sopron, Hungary
  • 2Institute of Earth Physics and Space Science, Eötvös Loránd Research Network, Sopron, Hungary
  • 3Lithosphere Fluid Research Lab (LRG), Eötvös Loránd University, Budapest, Hungary
  • 4Institute of Geological Sciences, Polish Academy of Sciences, Wroclaw, Poland
  • 5Departamento de Investigación y Prospectiva Geocientífica, Instituto Geológico y Minero de España, Madrid, Spain
  • 6Instituto Andaluz de Ciencias de la Tierra, CSIC-UGR, Armilla, Spain

The Bakony-Balaton Highland Volcanic Field (BBHVF), where Neogene alkali basalts and their pyroclasts host a great number of upper mantle xenoliths, is situated in the western part of the Pannonian Basin. One of the barely investigated xenolith localities of the BBHVF is Mindszentkálla. In the BBHVF, most of the xenoliths have lherzolitic modal composition, however, the Mindszentkálla locality is dominated by harzburgites. In addition to the homogeneous coarse-grained harzburgite xenoliths, we collected composite and multiple composite (with more than two different domains) xenoliths that represent small-scale heterogeneities. Harzburgite, interpreted as the host rock, is crosscut by dunitic, orthopyroxenitic, apatite-bearing websteritic, and amphibole-phlogopite-bearing veins.

To understand the evolution of the conspicuously complex mantle beneath Mindszentkálla, in situ major and trace element analyses were carried out on all rock-forming minerals. The major element chemistry of silicate minerals in the harzburgite wall rock and dunite veins show lower basaltic element (Fe, Mn, Ti, Na) contents with respect to the orthopyroxenitic and websteritic veins. The rare earth elements display flat or spoon-shaped patterns in the harzburgitic clinopyroxenes, whereas the websteritic clinopyroxenes and the amphiboles of the amphibole-phlogopite vein are enriched in light rare earth elements.

The observed textural and geochemical features indicate that the Mindszentkálla xenoliths could have gone through significant mineralogical and compositional modifications in at least two events. During the first event, the lherzolitic mantle was metasomatized most likely by a silica-rich melt, which could have resulted in orthopyroxene-rich peridotitic lithology. The metasomatizing Si-rich melt is likely related to a former subduction event.

The second metasomatic event led to the formation of dunite, orthopyroxenite, apatite-bearing websterite, and amphibole-phlogopite-bearing veins. These lithologies are likely the products of interactions between volatile-enriched, asthenosphere-derived basaltic melts and the peridotite wall rock, or they represent the high-pressure crystallization of such melts. The ascent of these mafic melts may have happened shortly before the xenolith entrapment during the Neogene basaltic volcanism.

How to cite: Patkó, L., Kovács, Z., Liptai, N., Aradi, L. E., Berkesi, M., Ciazela, J., Hidas, K., Garrido, C. J., and Kovács, I. J.: Deciphering multiple metasomatism beneath Mindszentkálla (Bakony-Balaton Highland Volcanic Field, western Pannonian Basin) revealed by upper mantle peridotite xenoliths, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4679,, 2022.