Carbonatite-melilitite-phosphate immiscible melts from the aragonite stability field entrained from the mantle by a Pliocene basalt

Abstract A plagioclase megacryst containing composite crystal-glass inclusions was ejected in a Pliocene basaltic diatreme the Carpathian back-arc basin (Pannonian Basin). The grew from phonolitic melt, relics of which are preserved inclusions. Most pristine melt has undergone substantial compositional resetting by interaction with several batches low-viscosity carbonated, P-rich melilitite infiltrated and largely replaced original inclusion content. also caused partial resorption host crystallisation new calcic forming stringers palisades. carbonatite exsolved later crystallised to aragonite at ~ 800 °C 1.9 GPa. phosphate fraction solidified as CO 3 2− -rich A-B type apatite. At very late evolutionary stage, K- Si-rich fluids potassic silicic alteration glass along cracks interfaces between carbonate globules temperatures below 680 °C. oxygen isotope composition (6.2 ‰ V-SMOW; Vienna Standard Mean Ocean Water) 87 Sr/ 86 Sr ratio carbonates (0.7034) consistent mantle-derived melt. ratios (0.7047–0.7051) interstitial associated syenite xenoliths indicate metasomatised mantle source contaminated radiogenic crustal material or altered marine carbonate. O-isotope carbonates, 22.7 ± 0.6 V-SMOW calcite 23.6 0.7 aragonite, sedimentary precursor. Contrasting δ 13 C values calcite, -12.7 0.5 V-PDB (Vienna PeeDee Belemnite), (-4.6 V-PDB) low-temperature modification assisted $$\delta$$ δ C-depleted 2 preservation primary magmatic aragonite. microstructural geochemical evidence points towards heterogeneous silicate-carbonate fractions generated during metasomatism melting supra-subduction wedge.