Istvan Kovacs

Institute of Earth Physics and Space Science · Lithosphere physics

The Earth has distinctive convective behaviour, described by the plate tectonics model, in which lateral motion of the oceanic lithosphere of basaltic crust and peridotitic uppermost mantle is decoupled from the underlying mechanically weaker upper mantle (asthenosphere). The reason for differentiation at the lithosphere-asthenosphere boundary is c...

Several explanations have been proposed for variation in geophysical properties and depths for the lithosphere–asthenosphere boundary (LAB) and mid-lithospheric discontinuities (MLD). Here, we investigate the proposal that the dehydration solidus of pargasitic amphibole-bearing upper mantle with very low bulk water (hundreds ppm) may be one of the...

We present a new model for the formation of Plio-Pleistocene alkaline basalts in the central part of the Carpathian-Pannonian region (CPR). Based on the structural hydroxyl content of clinopyroxene megacrysts, the 'water' content of their host basalts is 2.0-2.5 wt.%, typical for island arc basalts. Likewise, the source region of the host basalts i...

Incorporation of hydrogen as structural hydroxyl (commonly referred to as water) in nominally anhydrous mantle minerals is known for the ‘hydrolytic weakening’ effect, which decreases the strength and electrical resistivity of the rock. Recent models have provided means of calculating rheological properties from geochemical data of upper mantle xen...

Apart from the lithosphere-asthenosphere boundary (LAB), mid-lithospheric discontinuities (MLDs) in thick and old continental lithospheres appear to play an important role in global plate tectonics. Initiation of intra-continental subduction, delamination of the lower continental lithospheric mantle and removal of cratonic roots are likely to occur...

Urbanization has resulted in the widespread development of built-up areas, often without considering the local geology and geomorphology. To improve risk assessments related to landslides, it is essential to determine the physical and chemical properties of sediments. The aim of this study is to exemplify an already mobilized and reworked layer bas...

Some studies have used physical techniques for the assessment of bone structure and composition. However, very few studies applied multiple techniques, such as those described below, at the same time. The aim of our study was to determine the chemical and mineralogical/organic composition of bovine tibial bone samples using geophysical/geochemical...

Nominally anhydrous mantle minerals (olivine, pyroxenes, garnets, etc.) in 11 peridotite xenoliths from four different uneconomic and economic Kaapvaal Craton kimberlite pipes (Matsoku, Thaba Putsoa, Pipe200 and Bultfontein) have been investigated using Fourier transform infrared spectroscopy (FTIR). Allxenoliths contain accessories of garnet, diop...

The Pipe 200 kimberlite in northern Lesotho on the southeast margin of the Kaapvaal Craton is a diamond-poor deposit despite its proximity to economically viable kimberlites like the Liqhobong kimberlite. We study harzburgite xenoliths' mineral composition, geochemistry, and pressure–temperature evolution to understand factors influencing diamond d...

The transition area between the Pannonian Basin and the East Carpathians is the subject of considerable tectonic research in Central Europe because of its geological diversity, especially for Lithosphere–Asthenosphere Boundary determinations. The major objective of this study is to investigate the Earth’s lithospheric structure and in particular to...

The Pannonian Basin is one of the best natural laboratories in the world to study the lithospheric response to continental extension and subsequent tectonic inversion. Here we address the topic of lithospheric structure by a combined geochemical and magnetotelluric analysis, which has been carried out in the framework of the Pannon LitH2Oscope proj...

This paper presents the results from a geographic information systems (GIS) workflow, which was used to analyze the spatial distribution and temporal evolution of volcanoes in the Mio-Pleistocene monogenetic Bakony-Balaton Highland Volcanic Field (BBHVF), located in the Pannonian Basin, Hungary. Volcanism occurred during the tectonic inversion in a...

Understanding the formation, migration and emanation of deep CO2, H2O and noble gases (He–Ne) in deepseated deformation settings is crucial to understand the complex relationship between deep-originated fluids and lithospheric deformation. To gain a better insight into these phenomena, we studied the origin of H2O, CO2 and noble gases of gas-rich s...

Bevezető Valahányszor erős, esetenként anyagi károkat vagy éppen emberáldozatokat is okozó földrengésről ad híreket a mé-dia, és a jelenséggel foglalkozó szakemberek a riporterek kereszttüzébe kerülnek, változatlanul feltevődik a föld-rengések előrejelzése lehetőségének a kérdése. 2023 első felében térségünkben-februárban a dél-Romániai Olté-niában...

The lithosphere‐asthenosphere boundary and mid‐lithospheric discontinuities are primary attributes of the upper mantle. The Pannonian region is an extensional sedimentary basin enclosed by collisional orogens. Here, we estimate the negative phase depth of S‐to‐P receiver functions to image the lithospheric thickness and other discontinuities with h...

The surface extrusion of rhyolite lava is linked with a complex edifice morphology and texturally diverse internal structure. The rarely exposed basal flow/dome zones provide a textural record of the mechanical and thermal stress between the overlying lava and existing topography. The Lebuj flow (Tokaj Mountains, Hungary) developed in a Miocene cal...

Debate on the future eruptive capability of Ciomadul (Csomád) volcano in the East Carpathians, Romania, has recently gained a new impetus and prompted wide media attention. A tentative of numerical thermal modelling claimed that the amount of magma currently present beneath the volcano is of 20-58 km3 in volume. However, these results can be challe...

Understanding the interactions between surface and deep Earth processes is important for research in many diverse scientific areas including climate, environment, energy, georesources and biosphere. The TOPO-EUROPE initiative of the International Lithosphere Program serves as a pan-European platform for integrated surface and deep Earth sciences, s...

Amphiboles in the upper mantle (most frequently pargasitic in composition) have recently gained attention due to their role in the water budget and potential control on the rheology and physical discontinuity layers of the mantle. Although nominally anhydrous minerals are often analyzed with Fourier-transform infrared (FTIR) spectroscopy, amphibole...

Many vertical seismic velocity anomalies observed below different parts of the Eurasian plate are rooted in the transition zone between the upper and lower mantle (410–660 km), forming so-called secondary plumes. These anomalies are interpreted as the result of thermal effects of large-scale thermal upwelling (primary plume) in the lower mantle or...

Information on seismic anisotropy in the Earth's mantle can be obtained from (1) shear-wave splitting analyses which allow to distinguish single or multi-layered anisotropy and delay time of the fast and slow polarized wave can indicate its thickness, and (2) studying mantle peridotites where seismic properties can be inferred from lattice preferre...

Single-lithology and composite xenoliths from Mindszentkálla (Bakony-Balaton Highland Volcanic Field) in the Carpathian-Pannonian region record geochemical evolution of the subcontinental lithospheric mantle. The dominant single-lithology xenoliths are orthopyroxene-rich (22 vol% on average) harzburgites. Three composite xenoliths contain either tw...

Information on mantle anisotropy can be obtained from methods such as studying the lattice-preferred orientation (LPO) in mantle peridotites, or conducting shear-wave splitting (SKS) analyses which allow to determine whether it is a single or multi-layered anisotropy and the delay time of the fast and slow polarized wave can indicate the thickness....

Structural hydroxyl content of volcanic quartz phenocrysts was investigated with unpolarized Fourier-transform infrared spectroscopy. The phenocrysts originated from five pyroclastic fallout deposits from the Bükk Foreland Volcanic Area (BFVA), Hungary, and two from the AD 1314 Kaharoa eruption (KH eruption), Okataina Volcanic Complex (Taupo Volcan...

Physical-chemical controls of continental magmatism evolution remain enigmatic. Of prime and controversial nature is the temporal transition from calc-alkaline magmas to alkali basalts, correlated with a switch in tectonic regime from extension to compression. We perform 1D thermo-kinematic modelling to analyze the evolution of the thermo-rheologic...

Sulfides from lherzolite and wehrlite xenoliths from the Nógrád-Gömör Volcanic Field (NGVF), located in the Northern Pannonian Basin, were studied to understand the behavior of chalcophile and siderophile elements during mafic melt – peridotite interaction. We applied in situ methods to analyze the major and trace elements, as well as Fe isotope co...

MMC. Supplementary material includes additional text (Supplementary Methods), table (Supplementary Table 1), and figures (Supplementary Figs. 1-7).

Detailed investigation of a Lower Miocene Plinian pyroclastic sequence that crops out in the Bükk Foreland Volcanic Area (BFVA) in Northern Hungary is presented here. The studied eruptive products are part of a ca. 50 metres thick pyroclastic succession comprising of a basal ignimbrite that is covered by stratified pyroclastic unit including a topm...

The aim of this study was to establish a 3D shear-wave velocity model of the transition zone between the Eastern Alps and the Pannonian basin by means of ambient noise tomography. Datasets from permanent networks as well as past and recently deployed temporary networks of broadband seismic stations have been processed. Empirical Green's functions w...

Although many different mechanisms for subduction initiation have been proposed, only few of them are viable in terms of consistency with observations and reproducibility in numerical experiments. In particular, it has recently been demonstrated that intra‐oceanic subduction triggered by an upwelling mantle plume could greatly contribute to the ons...

Long period magnetotelluric (MT) data were collected at 14 locations along a ~50 km long NNW-SSE profile in the Nógrád-Gömör Volcanic Field (NGVF), which is one of the five mantle xenolith bearing Neogene alkali basalt locations in the Carpathian-Pannonian region. As a result, a low resistivity anomaly (<10 Ωm) was observed approximately at 30–60 k...

The Styrian Basin is located at the westernmost part of the Carpathian-Pannonian region, in the transition zone between the Pannonian Basin and the Eastern Alps. The lithospheric mantle beneath the Styrian Basin (SB) was sampled by Plio-Pleistocene alkali basalts, which brought mantle xenoliths to the surface. Mantle xenoliths from the SB are mostl...

A Csillagászati és Földtudományi Kutatóközpont Geodéziai és Geofizikai Intézet szeizmológiai obszervatóriuma 2012-ben vette fel Kövesligethy Radó nevét. Az azóta eltelt évek során az általa működtetett hálózat jelentős fejlődésen ment keresztül. 2019-ben az állomások száma negyvenegyre nőtt, az ország egészét tekintve ilyen sűrűségű hálózat még nem...

The East Carpathian volcanic range experienced an along-arc, Late Miocene to Quaternary migration of eruptive activity during its ~11 Ma-long activity. Here, a novel and complex methodology is presented that yields new geochronological and geomorphological constraints on the evolution of the 20 volcanic edifices. New unspiked KAr ages either constr...

A Middle Miocene, ~8 m thick pyroclastic succession, reported from the Bükk Foreland Volcanic Area (BFVA) in Northern Hungary (Central Europe) specified here as the Jató Member, was produced by silicic phreatomagmatism (Phreatoplinian sensu lato). Two well-preserved outcrops ~8 km apart and inferred to be within ~10–50 km from source represent the...

The Optically Stimulated Luminescence (OSL) dating started in 2004 in the Geological Institute of Hungary, then continued in the successor Geological and Geophysical Institute of Hungary, and the Mining and Geological Survey of Hungary. Our OSL ages have contributed to the reconstructions of palaeohydrography and palaeomorphology as well as the tim...

By studying mantle xenoliths we can obtain direct information about the chemical and physical state of the lithospheric mantle. With this information, some important geophysical properties (e.g. seismic velocity, conductivity and effective viscosity) can be calculated, which provide a tool to better understand the evolution of the studied region. I...

Clinopyroxene-enriched upper mantle xenoliths classified as wehrlites are common (~20% of all xenoliths) in the central part of the Nógrád-Gömör Volcanic Field (NGVF), situated in the northern margin of the Pannonian Basin in northern Hungary and southern Slovakia. In this study, we thoroughly investigated 12 wehrlite xenoliths, two from each wehrl...

of the long term data taking, related to one of the proposed next generation ground-based gravitational detector’s location is presented here. Results of seismic and infrasound noise, electromagnetic attenuation and cosmic muon radiation measurements are reported in the underground Matra Gravitational and Geophysical Laboratory near Gyöngyösoroszi,...

The Pannonian region is a back-arc basin located within the arcuate Alpine–Carpathian mountain chain in central Europe. Beneath the basin both the crust and the lithosphere have smaller thickness than the continental average. During the last few decades several studies have been born to explain the formation of the Pannonian Basin but several key q...

This study analyzes the microstructures and deformational characteristics of spinel peridotite xenoliths from the Nógrád‐Gömör Volcanic Field (NGVF), located on the northern margin of a young extensional basin presently affected by compression. The xenoliths show a wide range of microstructures, bearing the imprints of heterogeneous deformation and...

The past decade has seen a great number of studies dealing with magmatic water contents and how these could be retrieved by the nominally anhydrous minerals' (NAMs) trace structural hydroxyl (water) contents. Constraints have been made to magmatic hygrometry with clinopyroxene and plagioclase. Although results suggest that the method is more flexib...

The structural hydroxyl content of the nominally anhydrous minerals (olivine and pyroxenes) in the upper mantle is among the important attributes that influence the physical and chemical features of the upper mantle. In this study, we provide detailed Fourier-transform infrared (FTIR) data on 63 petrographically and geochemically well-defined upper...

of the long term data taking, related to one of the proposed next generation ground-based gravitational detector's location is presented here. Results of seismic and infrasound noise, electromagnetic attenuation and cosmic muon radiation measurements are reported in the underground Matra Gravitational and Geophysical Laboratory near Gy\"ongy\"osoro...

Appreciated attempts have been devoted to use a simple unpolarized infrared analysis on unoriented anisotropic crystals of nominally anhydrous minerals to determine the content of H-species, rather than using the more demanding polarized techniques which determine by experimental work of both polarized and unpolarized analyses. In this study, we pr...

The Nógrád-Gömör Volcanic Field (NGVF) is located in the northern part of the Pannonian Basin, and is one of the five xenolith-bearing alkali basalt occurrences in the region. In NGVF, a lherzolite and a wehrlite series were distinguished based on petrographic and geochemical investigations. The lherzolites represent precursors for the metasomatic...

The aim is to give an overview on how geochemical and petrological data, obtained from upper mantle xenoliths, could be utilized to provide information on the geophysical properties of the upper mantle at their origin. First we demonstrate how a tentative lithospheric column may be constructed based on the equilibrium temperature of upper mantle xe...

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...

A gyengített teljes reflexiós Fourier transzformációs infravörös spektroszkópia (ATR FTIR) mennyiségi eredményeinek értelmezése általában nehéz és az adatok mélyebb áttekintéséhez különböző adatfeldolgozási módszereket kell alkalmazni. Ezeknek a módszereknek alkalmasnak kell lenniük a nagyméretű többdimenziós adatkészletek kezelésére és ezzel együt...

This study investigates the phase and melting relations of nominally ‘dry’ residual eclogites (Res2 and Res3), with varying bulk CaO/Na2O ratios (4 and 12, respectively), from ~160 (5 GPa) to ~90 km (3 GPa) depth. Garnet, clinopyroxene and minor quartz/coesite are subsolidus phases in both compositions. In contrast to Res2, in Res3, the proportions...

Three spinel lherzolite xenoliths from Mt. Quincan (Queensland, northeastern Australia) were studied with special attention to their enclosed fluid inclusions. The xenoliths are deformed, have porphyroclastic textures and overall show very similar petrographic features. The only significant difference is manifested in the abundance of fluid inclusi...

In the last few decades dense large-scale seismic networks showed their importance in studying the structure of the lithosphere and the upper mantle. The better understanding of the Apennines–Alps–Carpathian–Dinarides system is the main target of the AlpArray European international initiative in which more than 50 institutes are involved. The core...

The Mecsekalja Zone is a strike-slip fault zone that plays an essential role in the structural framework of South Transdanubia. The metamorphic and deformation history of the crystalline basement of the Mecsekalja Zone has been determined thus far based exclusively on a few surface outcrops and near-surface samples. The Szentlőrinc-1 (Sztl-1) well...