Authors:Zsófia Pálos, István János Kovács, Dávid Karátson, Tamás Biró, Judit Sándorné Kovács, Éva Bertalan, Anikó Besnyi, György Falus, Tamás Fancsik, Martina Tribus, László Előd Aradi, Csaba Szabó and Viktor Wesztergom
NAMs in volcanic rocks
Before summarizing the case study results, it is worth reviewing the outcomes of similar studies targeting feldspar and clinopyroxene phenocrysts in different volcanic rocks. The main aim of this section is to give a
Up to 26 trace elements were determined in 9 different samples of plagioclase, orthopyroxene, clinopyroxene and magnetite
and the host pyroclastic matrix material using instrumental neutron activation analysis. Mineral to whole-rock partition coefficients
were reported and interrelationships between chemical composition and crystal structure of the minerals were discussed, especially
in the case of REE in plagioclase.
Authors:Z. Homonnay, E. Kuzmann, A. Vértes, I. Kubovics, K. Sólymos and Cs. Szabó
Mössbauer spectroscopy was used to study phlogopites from ultramafic xenoliths derived from alkali mafic rocks of the Transdanubian Midmountains. On the basis of evaluation of the Mössbauer spectra the following iron sites were identified /using the nomenclature published by Dyar1/ in the samples:
Quantitative analysis of all of the iron sites was performed. The Fe2+/Fe3+ ratio was found to be 3.33 for the sample for phlogopite xenolith and 2.05 for the sample from clinopyroxene-phlogopitite xenolith. There are evidences, that Fe3+ can occupy tetrahedral positions in upper mantle phlogopite, even if Si+Al>8. Our data suggest MARID+ glimmerite origin of micas.
Authors:Robab Hajialioghli, Mohssen Moazzen and Ralf Milke
The Kaleybar nepheline syenite intrusion forms the largest silica undersaturated alkaline exposure in northwestern Iran. It consists of various rock types ranging from nepheline syenite to nepheline diorite that were emplaced during Eocene-Oligocene times, corresponding to the Alpine orogeny. The essential rock-forming minerals in nepheline syenite are plagioclase, K-feldspar, nepheline and amphibole. Clinopyroxene is the dominant phase in nepheline diorites. Titanian garnet occurs as an uncommon accessory phase forming reddish to deep brown individual grains.
Chemically it is intermediate between Ti-andradite (67 to 78 mole %) and grossular (21 to 33 mole %) with TiO2 contents ranging from 1.5 to 5.0 wt %. Stoichiometry and R-mode factor analysis on garnet chemistry show that the dominant exchange vectors are Si-Ti and Al-Fe substitutions in the tetrahedral and octahedral crystal sites, respectively. A magmatic origin of the investigated Ti-garnet is suggested on the basis of mineralogical criteria and chemical properties.
of the undepleted peridotites has also been used to estimate the chemical composition of Earth’s primitive mantle ( Jagoutz et al. 1979 ; McDonough and Sun 1995 ). Mineralogically, undepleted lherzolites are rich in clinopyroxene and spinel, whereas
Authors:I. Oláh, Zs. Bendő, Gy. Szakmány, V. Szilágyi and B. Péterdi
Dobosi 1989 = G. Dobosi : Clinopyroxene zoning pattern in the young alkali basalts of Hungary and their petrogenetic significance. Contributions to Mineralogy and Petrology 101 (1989) 112–121.