EGU22-3733, updated on 27 Mar 2022
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Basaltic rocks from the Vardar ophiolite (North Macedonia): new insights on the metasomatism of sub-arc upper mantle using geochemical and stable isotope data

Valentina Brombin1, Edoardo Barbero1, Emilio Saccani1, Nicola Precisvalle1, Sonja Lepitkova2, Ivica Milevski3, Igor Ristovski4, Igor Milcov4, Gorgi Dimov5, Costanza Bonadiman1, and Gianluca Bianchini1
Valentina Brombin et al.
  • 1University of Ferrara, Physics and Earth Sciences, Ferrara, Italy (
  • 2Department for Petrology, Mineralogy and Geochemistry, Goce Delcev University of Štip, Republic of Macedonia
  • 3Department of Geography, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University in Skopje, Republic of Macedonia
  • 4GAYA-CER Non-Governmental Organization, Skopje, Republic of Macedonia
  • 5Faculty of Natural and Technical Sciences, Goce Delčev University, Štip, Republic of Macedonia

In the upper mantle, volatiles control its composition, partial melting conditions, as well as the ascent rate of the formed melts. As consequence, volatile composition of the mantle is, in turn, recorded in the melts and, therefore, in the erupted basaltic rocks. Despite their importance, origin, budget, and fluxes of the volatiles in the upper mantle are poorly constrained. It is well known that the main input of mantle volatiles, such as carbon (C) and sulphur (S), represents components released from the subducting slab, e.g., oceanic rocks and sediments, whose have characteristic isotopic signatures. In this view, studies of isotopic ratios of volatiles of subduction-related magmatic rocks could be used to identify the chemical components released by the subducting slab metasomatizing the upper mantle. To confirm this hypothesis, we investigated the major and trace element composition, as well as the C and S elemental contents and isotopic ratios of subvolcanic and volcanic rocks of the Vardar ophiolites of North Macedonia, which represent remnants of the Mesozoic Tethyan oceanic lithosphere formed in supra-subduction zone tectonic settings.

The ophiolites were sampled at Lipkovo and Demir Kapija localities, in the northern and southern part of North Macedonia, respectively. Based on whole-rock major and trace element composition, two main groups of rocks can be distinguished: i) Group 1 rocks, which are subalkaline basalts with backarc affinity and ii) Group 2 rocks, which are calc-alkaline basalts with arc affinity. The petrogenetic modelling based on trace and Rare Earth Elements, indicates that Group 1 mantle sources were affected by limited metasomatic processes by slab-released components, in particular aqueous fluids and sediment melts, whereas the Group 2 mantle sources were strongly metasomatized by sediment melts and adakitic melts. Accordingly, the Group 1 rocks exhibit C-enriched and S-depleted isotopic signature, indicating a minor involvement of melts from the subducting sediments. On the other hand, the C-depleted and S-enriched isotopic signatures of the Group 2 rocks suggest a major involvement of melts derived from the subducting sediments rich in organic matter and sulphate phases Therefore, both geochemical and isotopic data of the subvolcanic and volcanic samples of the North Macedonia ophiolites show that the sub-arc mantle sources are more affected by slab-released fluids than those of the backarc basin, which are more distal from the trench. Thus, combining the geochemical and isotopic data of subvolcanic and volcanic samples of complex geological framework can contribute to reconstruct the geodynamic scenarios, such as that of the Vardar ophiolites in the Dinaric-Hellenic belt. In addition, this approach may be useful to better understand the global geodynamic cycles of volatiles reconstructing their origin, budget, and isotopic composition, and understand the impacts on climate and environment from local to global scale.

How to cite: Brombin, V., Barbero, E., Saccani, E., Precisvalle, N., Lepitkova, S., Milevski, I., Ristovski, I., Milcov, I., Dimov, G., Bonadiman, C., and Bianchini, G.: Basaltic rocks from the Vardar ophiolite (North Macedonia): new insights on the metasomatism of sub-arc upper mantle using geochemical and stable isotope data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3733,, 2022.