Alexandru Szakács

Neogene-Quaternary Volcanic forms in the Carpathian-Pannonian Region: a review

Neogene to Quaternary volcanic/magmatic activity in the Carpathian-Pannonian Region (CPR) occurred between 21 and 0.1 Ma with a distinct migration in time from west to east. It shows a diverse compositional variation in response to a complex interplay of subduction with rollback, back-arc extension, collision, slab break-off, delamination, strike-slip tectonics and microplate rotations, as well as in response to further evolution of magmas in the crustal environment by processes of differentiation, crustal contamination, anatexis and magma mixing. Since most of the primary volcanic forms have been affected by erosion, especially in areas of post-volcanic uplift, based on the level of erosion we distinguish: (1) areas eroded to the basement level, where paleovolcanic reconstruction is not possible; (2) deeply eroded volcanic forms with secondary morphology and possible paleovolcanic reconstruction; (3) eroded volcanic forms with remnants of original morphology preserved; and (4) the least eroded volcanic forms with original morphology quite well preserved. The large variety of volcanic forms present in the area can be grouped in a) monogenetic volcanoes and b) polygenetic volcanoes and their subsurface/intrusive counterparts that belong to various rock series found in the CPR such as calc-alkaline magmatic rock-types (felsic, intermediate and mafic varieties) and alkalic types including K-alkalic, shoshonitic, ultrapotassic and Na-alkalic. The following volcanic/subvolcanic forms have been identified: (i) domes, shield volcanoes, effusive cones, pyroclastic cones, stratovolcanoes and calderas with associated intrusive bodies for intermediate and basic calclkaline volcanism; (ii) domes, calderas and ignimbrite/ash-flow fields for felsic calc-alkaline volcanism and (iii) dome flows, shield volcanoes, maars, tuffcone/tuff-rings, scoria-cones with or without related lava flow/field and their erosional or subsurface forms (necks/ plugs, dykes, shallow intrusions, diatreme, lava lake) for various types of K- and Na-alkalic and ultra-potassic magmatism. Finally, we provide a summary of the eruptive history and distribution of volcanic forms in the CPR using several sub-region schemes.

On the age of the Dej Tuff, Transylvanian Basin (Romania)

On the age of the Dej Tuff, Transylvanian Basin (Romania) The Dej Tuff is an important stratigraphic marker in the Transylvanian Basin. However, its Early Badenian age is known only on biostratigraphical grounds so far. A number of radiometric dating techniques including K-Ar, Ar-Ar and fission-track have been used in order to constrain more precisely its age, allowing the calibration of the Transylvanian Basins evolutionary models. Although individual dating methods could not provide a unique, reliable and accurate radiometric age, comparison and evaluation of multiple methods gives 14.8-15.1 Ma as the most likely formation age of the Dej Tuff.

Probing tectonic processes with space geodesy in the south Carpathians: insights from archive SAR data

The Carpathian bend is amongst the tectonically most active areas in Europe where intraplate subduction triggers sub-crustal earthquakes releasing significant amount of seismic energy in a well-defined seismic zone. To constrain the deep processes by exploiting their linkage to the surface processes an accurate knowledge of surface deformations is required. Detection of small-magnitude tectonic processes with high reliability is a challenge in which the recent space geodetic techniques may bright a breakthrough. In this study we used the archive ENVISAT data set of the European Space Agency to investigate the feasibility limit of detecting crustal deformations in the region of the south Carpathian bend, where past geodetic observations failed to unravel the tectonic processes with high details. Despite the inherent limitations of radar interferometry our results show that coherent velocity field can be estimated with a magnitude of few mm/year. The vertical displacement field suggests subsidence in the Brasov basin which is in agreement with former studies, however radar interferometry can provide a more detailed picture.

The Campanian Ignimbrite tephra layer - a regional stratigraphic marker for the MIS 3 loess deposits of Romania

Loess deposits are widespread in Romania and many open profiles are found along the river valleys crossing the southern plains of the country, and these records are important resources for understanding paleoclimate dynamics and the Paleolithic cultural dispersal at the continental scale. However, loess deposits show significant lateral compositional variations, which bring about regional stratigraphic uncertainties, especially when site-to-site correlations still rely mainly on stratigraphic relationships, and only a handful of profiles having been investigated with more precise dating methods