The Mt Vulture volcanic complex (Italy): Evidence for distinct parental magmas and for residual melts with melilite

New data of mineral compositions, whole-rock major and trace element contents are presented for lava flows and dykes of Mt, Vulture volcano (southeastern Roman Magmatic Province). The dominant rock series ranges from basanite, through tephrite and foidite, to phonolite. Diopsidic to Fe-salitic (hedenbergitic) clinopyroxene is the major phenocryst phase, and shows a very strong Ti- and Al-enrichment trend (up to 5 wt% TiO2 and 12 wt% Al2O3). Phonolites have Fe-rich pyroxenes low in Ti and Al, as a consequence of fractionation of Ti-magnetite and/or melanite garnet. Feldspar ranges in composition from bytownite to Ba- and Sr-rich anorthoclase (up to 7 wt% BaO and 4 wt% SrO); the latter is present in the groundmass of mafic and intermediate rocks. Phonolites are characterized by anorthoclase and sanidine with Ba-rich cores, and with Ba-depleted rims. Subordinate melilite-bearing rocks are also present, and are characterized by melilite with a very large compositional variation, Ca-rich nepheline (up to 8 wt% CaO) and lack of feldspar and amphibole. Some of them also show calcite-rich ocellar structures, possibly due to liquid immiscibility. They have also major and trace element contents different from those of the feldspar-bearing rocks. This all indicates distinct parental magmas for feldspar-bearing and melilite-bearing rocks. These latter were likely generated by differentiation processes starting from olivine- and melilite-bearing ultramafic parental magmas. Mineral compositions and suitable phase diagrams indicate that the Melfi hauynophyre, which is the most MgO-poor melilite-bearing rock of Mt. Vulture, is close to a residual melt analogous to phonolite, but in petrogenetic systems with melilite and without feldspar. The high- to very high-titanium content of most of the ferromagnesian phases, despite a relatively low TiO2 of primitive Mt. Vulture rocks, is absent in other rocks of similar degree of evolution in the Roman Province. It resembles that found in anorogenic magmas aad gives further indications for a within-prate signature in this particular volcanic complex.