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6919726 
Journal Article 
Origin of mafic and ultramafic cumulates from the Ditrău Alkaline Massif, Romania 
Pál-Molnár, E; Batki, A; Almási, E; Kiss, B; Upton, BGJ; Markl, G; Odling, N; Harangi, S; , 
2015 
1 
Lithos
ISSN: 0024-4937 
ELSEVIER SCIENCE BV 
AMSTERDAM 
239 
1-18 
WOS:000366770700001 
Mafic-ultramafic cumulates enclosed in gabbroic-dioritic rocks form part of the Mesozoic Ditrau Alkaline Massif in the Eastern Carpathians, Romania. The poikilitic olivine- and pyroxene-rich and nearly mono mineralic hornblendite rocks display typical cumulate textures with early crystallised olivine (Fo(75-73)), diopside and augite. In the early stages of their genesis the amphibole was intercumulus whilst in later stages it acquired cumulus status as the fractionating magma evolved. Using major and trace element compositions of minerals and whole-rock samples the origin of these cumulates is determined and the parental magma composition and depth of emplacement are calculated.Cumulus clinopyroxene has more primitive composition than intercumulus amphibole suggesting closed system fractionation for the evolution of poikilitic olivine- and pyroxene-rich cumulates. The evolution of the amphibole-rich mesocumulates is more clearly the result of closed system crystallisation dominated by the precipitation of clinopyroxene and amphibole cumulus crystals.Lamprophyre dykes of the Ditrau Alkaline Massif are proposed to reflect multiple basanitic parental magma batches from which the cumulus olivine and clinopyroxene crystallised. Relative to these dykes the calculated equilibrium melts for intercumulus amphibole in the cumulates was more primitive whilst that for the cumulus amphibole was more evolved. The calculated crystallisation temperature and pressure of similar to 1000-1050 degrees C and similar to 0.7 GPa, based on the composition of the amphiboles, indicate crystallisation at lower crustal depths. Rare earth element compositions are consistent with an intra-plate tectonic setting. (C) 2015 Elsevier B.V. All rights reserved. 
Mafic-ultramafic cumulate; Laser ablation; Thermobarometry; Intra-plate magmatism; Ditrau Alkaline Massif