Recycled oceanic crust, with or without sediment, is often invoked as a source component of continental and oceanic alkaline magmas to account for their trace-element and isotopic characteristics. Alternatively, these features have been attributed to sources containing veined, metasomatized lithosphere. In melting experiments on natural amphibole-rich veins at 1.5 gigapascals, we found that par...

The Bikilal layered gabbro-complex is composed of zones/layers of olivine/ pyroxene gabbro and hornblende gabbro. Within the hornblende gabbro, repeated lens-like thin and elongated bodies of hornblendite are found intimately associated with massive and disseminated ilmenite-magnetite bodies, in places with apatite. Petrological examination of the hornblende gabbro shows 50-55% hornblende, 40-4...

Amphibolite blocks from an Archaean (2.9 Ga) trondhjemite-agmatite complex in the Lewisian at Gruinard Bay have a varied trace element and R E E content. Whilst some of the variability is attributable to element mobility during high-grade metamorphism and subsequent trondhjemite magmatism, it is for the main part considered to be a primary feature of the amphibolites. The observed trace element...

Abstract We present a new experimental dataset for reaction experiments between natural amphibole-clinopyroxene metasomes (hornblendite) and synthetic lherzolite that produced Na-rich alkaline melts. Experiments were conducted at 1, 3 4 GPa 1000–1300 °C. The generated melts range from foidite over basanite to phonotephrite. At 1 1000 1100 °C amphibole decompression-breakdown products generate p...

Strongly SiO2-undersaturated alkalic rocks (Mg# > 50, SiO2 ≤ 45 wt%, Na2O + K2O ≥ 3 wt%) occur in three early-stage (Sarnu-Dandali, Mundwara, Bhuj) and one late-stage (Murud-Janjira) rift-associated volcanic complexes the Cretaceous-Paleogene Deccan Traps flood basalt province of India. Thermobarometry based on clinopyroxene-liquid equilibrium suggests that they mostly crystallized beneath Moho...

Archean Quartzose Rocks at Akilia, Greenland Fedo and Whitehouse (1) presented data to support their hypothesis that granulite grade quartz magnetite rocks on the island of Akilia, southwest Greenland—which are conformably interposed with pyroxenite and hornblendite units that date from before 3830 million years ago (Ma) (2–4)—had a metasomatic ultramafic igneous origin. They offered that inter...

Abstract Cu-Ni-Co-PGE mineralization occurs at Haidbachgraben in the Early Palaeozoic, Subpenninic Hollersbach Complex of Central Tauern Window, Austria. Massive sulfide ore formed from melt segregated silicate during intrusion pyroxenite into magmatic rocks an MORB-type environment. Relics minerals include chromian spinel and polyphase droplets composed pyrrhotite, chalcopyrite pentlandite pre...