Authors:Elemér Pál-Molnár, Gyöngyi Lelkes-Felvári, Anikó Batki, and Raffaele Sassi
Core samples of metamorphic rocks from the Sarkadkeresztúr Basement High (Békés-Codru Unit, Tisza Mega-unit) were examined, consisting mainly of two-feldspar augengneiss, garnet-andalusite-staurolite-bearing micaschist and paragneiss. The protolith of the plagioclase-microcline-augengneiss was found to be S-type granite (syenogranite) of unknown age. According to the major element analyses the protoliths of the studied metagranitoids of this basement can be classified as a syenogranite of metaluminous and peraluminous character displaying subalkaline affinity and a calcic granitic composition. The REE patterns are characterized by a slight enrichment of the light REEs and negative Eu and Yb anomalies. On the basis of discrimination diagrams for major and trace elements, the studied rocks were formed in a syn-collisional (continent-continent collision zone) tectonic environment. The low-pressure amphibolite facies metamorphism, which affected this basement, can be assigned to the Variscan.
The Dinaridic Alpine ophiolites can be divided into two groups: 1) those of the Jurassic Dinaride Ophiolite Zone (DOZ) and 2) those of the Cretaceous-Early Paleogene (?) Sava-Vardar Zone (SVZ). However, geologically and petrologically they have so far been treated as a whole, and their geotectonic setting has not been reliably established. We have investigated ophiolite terranes from both regions in order to determine their tectonic setting. Our comparison is based on trace element data and characteristic elemental ratios correlated with ophiolite settings in recent oceans. We show that the DOZ tectonite peridotites are enriched in LREE and have high Ti/V ratios (up to 23), whereas the SVZ mantle rocks are LREE-depleted and have low Ti/V ratios (1-4). The DOZ cumulate gabbros and peridotites are characterized by increased Ni content and high Ba/Sr ratio, positive Eu anomalies and lower Cr# of spinels, comparable with MORB cumulates. The SVZ cumulates do not show a positive Eu anomaly and are characterized by higher concentrations of V, Zr and Y, and higher K/Nb, Ti/Zr, Zr/Sm ratios, which correlate with those from some recent back-arc settings. Essential differences between DOZ and SVZ basaltic rocks are as follows: high-Ti vs. low-Ti ophiolites: Ti/V = 20-50 vs. <20; higher Mg#, Ni, Cr, Nb and Ta vs. higher Rb and Ba; elemental ratios of Sr/Zr, Ti/Zr, Y/Nb, Zr/Nb, Th/Nb, Th/Ta, La/Nb, La/Ta and Sm/Hf are similar to those from recent back-arc settings. These geochemical data confirm the earlier geologic model of Pamić et al. (2002). These contrasting geochemical signatures are the result of different geochemical processes taking place in two different settings: a) MORB along an accretionary plate margin underlain by oceanic upper mantle, and b) BARB along a supra-subduction zone characterized by an obducting upper mantle wedge underlain by subducted oceanic crust, which was a source of fluids.
Authors:Vladimir Naumov, Vladimir Kovalenker, Gheorghe Damian, Sergei Abramov, Maria Tolstykh, Vsevolod Prokofiev, Floarea Damian, and Ioan Seghedi
Crystal inclusions (plagioclase, biotite, magnetite) and melt inclusions were studied in minerals of the Laleaua Albă dacite (Baia Sprie, Romania). Electron microprobe analysis of 29 melt inclusions in the plagioclase, K-feldspar, and quartz confirm that crystallization of these minerals took place from typical silicic melts enriched in potassium relative to sodium (K2O/Na2O = 1.5). The sum of the petrogenic components is 92–99 wt%. This points to a possible change in water content from 8 to 1 wt% during crystallization of phenocrysts. According to ion microprobe analysis of 11 melt inclusions, the minimum water content is 0.5 wt%, and the maximum water content is 6.1 wt%. The presence of high-density water fluid segregation in one of the melt inclusions suggests that the primary water content in the melt could reach 8.4 wt%. Ion microprobe data revealed a high concentration of Cu (up to 1260 ppm) as well as higher U content (from 5.0 to 14.3 ppm; average 11.5 ppm) in some melt inclusions as compared to the average U contents in silicic melts (2.7 ppm in island-arc settings and 7.9 ppm in continental rift settings). Chondrite-normalized trace-element patterns in melt inclusions suggest a complex genesis of the studied magmatic melts. Contents of some elements (for instance Sr and Ba) are close to those in island-arc melts, while others (for instance Th, U, and Eu) resemble those in melts of continental settings.
Authors:Máté Krisztián Kardos and Adrienne Clement
century, as well as the introduction of the Water Framework Directive (WFD) with Hungary joining the EU in 2004, interrupted this progressive process. While WQ monitoring traditionally concentrated on the most important lakes and larger streams along with
Authors:Máté Krisztián Kardos and Adrienne Clement
were introduced in 1983 and 1994 ( Szabó 2008 ; Kerekes-Steindl 2016 ). The economic situation in the early 21 st century, as well as the introduction of the Water Framework Directive (WFD) with Hungary joining the EU in 2004, interrupted this