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Zilahi-Sebess L.,Magyar Allami Eotvos Lorand Geofizikai Intezet | Zilahi-Sebess L.,Geo Log Kft
Magyar Geofizika | Year: 2010

The actuality of the topic is given by the main target of geological investigations at Bátaapáti on the area designed for disposing low and intermediate level radioactive waste, i.e. by the Mórágy granite which is also a fractured rock with secondary porosity. Because of that, a better understanding of fracture systems and a more effective characterisation of the rock itself has a great importance also in the environmental protection. During the investigations since 1996, many well logging measurements and core analyses were carried out in this area. It has been an excellent opportunity to learn more about fractured rocks in general too, because in the hydrocarbon exploration such kind of rocks occur only in great depths in the basements and the oil industry is interested only in their altered crust, which might be a possible reservoir. Before the Bátapáti project, at the previous structural geological borehole investigations, the geophysical parameters were outweighed by core analysis. It has to be noted that fractured reservoirs increasingly significant in hydrocarbon exploration can be better understood by the help of the results of recent investigations made on altered zones of near-surface crystalline rocks. The most important feature of the seismically hard crystalline rocks is the fracture porosity because it directly affects both the hydrogeological and geomechanical properties of the rock. The pore space of rocks with secondary porosity is more irregular and that is why it cannot be so easily caracterized than that of the clastic sedimentary rocks with primary intergranular porosity. Probably, because the accumulated knowledge on the porosity and permeability in case of fractured rocks with secondary porosity is less than that in case of sedimentary rocks. In this paper we discuss the influence of fracture properties of fractured rocks on the physical parameters - first of all on specific electrical resistivity and sonic wave propagation. The main features of fracture systems and geomechanical properties were obtained from BHTV measurements, measurements of full acoustic waveform and from core samples. © 2010 Magyar Geofizikusok Egyesülete.

Kiss J.,Magyar Allami Eotvos Lorand Geofizikai Intezet | Pracser E.,Magyar Allami Eotvos Lorand Geofizikai Intezet | Szarka L.,MTA Geodeziai es Geofizikai Kutatointezet | Adam A,MTA Geodeziai es Geofizikai Kutatointezet
Magyar Geofizika | Year: 2010

In an earlier paper we suggested a possible additional source of geomagnetic and crustal conductivity anomalies: the socalled second-order magnetic phase transition in the Earth's crust, namely a significant enhancement of the magnetic susceptibility near the Curie (Néel) depth. Some geomagnetic anomalies of unknown origin can be easily explained by this phenomenon. In this paper we summarize the one- and two-dimensional magnetotelluric signatures due to a thin but very high-permeability body at mid-crustal depths. The magnitude of the anomaly due to a high-permeability layer is comparable to that due to a high-conductivity layer, with opposite sign. Wherever the classical magnetotelluric interpretation produces an unrealistic high-resistivity and extremely thick layer, and the nearby geomagnetic anomalies have a spatial wavelength indicating the same depth as the depth of the high resistivity layer, the second-order magnetic phase transition might be also considered as a possible explanation. Although it has been still questionable whether this phenomenon exists in the Earth's crust, some recent solid state physics laboratory results make it more and more probable that the magnetic phase transition might be a potential source of various geophysical crustal anomalies. © 2010 Magyar Geofizikusok Egyesülete.

Szamosfalvi A.,Magyar Allami Eotvos Lorand Geofizikai Intezet | Falus G.,Magyar Allami Eotvos Lorand Geofizikai Intezet | Juhasz G.,Magyar Olaj Es Gazipari Nyrt.
Magyar Geofizika | Year: 2011

The increasing emission of greenhouse gases especially carbon dioxide imposes a significant climatic issue. Adequate alternative solutions have to be found on a limited time frame in order to answer the arising problems. One of the solutions that may effectively reduce and hinder greenhouse gas emissions is carbon dioxide capture and geological sequestration. This complex technology has the advantage of producing radical emission reductions in adequately short time, without the necessity of drastically restructuring energy production. Depleted hydrocarbon reservoirs, although available, represent only limited storage potential. Whereas, thick groundwater storing hydrodinamically closed geological formations, namely saline reservoirs, as potential storage objects, are far more abundant and We have studied the potential rock formations considering the basic criteria for storing carbon dioxide in saline reservoirs. Our preliminary results show that several geological formations exist in Hungary which fulfil the discussed requirements. Among these formations we have selected the Szolnok Formation of s.l. Pannonian age, being one of the most appropriate formations for long term safety, to demonstrate the steps of 3 different approaches to estimate storage capacity.

Balla Z.,Magyar Allami Foldtani Intezet | Martonne Szalay E.,Magyar Allami Eotvos Lorand Geofizikai Intezet | Gulacsi Z.,Magyar Allami Eotvos Lorand Geofizikai Intezet
Foldtani Kozlony | Year: 2011

The palaeomagnetic results obtained from a collection of new samples taken from South Transdanubia partly confirmed earlier interpretations, but also presented the opportunity for further development of the earlier picture. In this process new support was given to the following statements: -Palaeomagnetic directions for the "Lower Cretaceous" subvolcanic bodies are much more consistent with no tilt correction than with it. Hence, they are obviously younger than the mid-Cretaceous folding. The Mórágy dykes cut crystalline rocks and their directions are ab ovo without any correction. These directions are consistent and fit well the declination trend of the Mecsek rocks. -On the basis of geological observations from the Villány Hills the folding took place after the Albian. Therefore, the subvolcanic activity could not have taken place in the Early Cretaceous. Regional considerations fix this magmatism at the beginning of the Late Cretaceous. Palaeomagnetic directions from the Lower Cretaceous effusives, after tilt correction, correspond to those from the sediments; thus they are older than the folding. Since the effusive and subvolcanic activities are separated by the mid-Cretaceous folding, they cannot be the products of the same magmatism. -Palaeomagnetic directions of the Mecsek and Mórágy subvolcanic bodies imply two significant rotations. The older of these moved in an anti-clockwise direction and started after the Albian. The younger rotation was clockwise and commenced after the intrusion of the Miocene Komló Andesite. The declinations which are observable in the presentday position are resultants of the two opposite rotations. In the earlier interpretation, the older rotation was conceived as a simple, significant, ≈90° rotation. The increased number of data made it possible to further develop this concept, given that the available data set points to a gradual change from ≈0° till ≈90°. In other words, most of the subvolcanic bodies were intruded during the rotation towards the west, not after it. This is because their present-day declination is less than the maximum eastern declinaton (≈90°), which is displayed by the Komló Andesite. The smeared distribution of the declinations makes it possible to determine the succession of the intrusive bodies: the oldest of these are the ones with the minimum declination; the youngest are represented by those with the maximum eastern declination. The newly-obtained palaeomagnetic direction from the Máriagyu{double acute}d (Villány Hills) dyke does not show any evidence of rotation. This direction is clearly younger than the folding. This circumstance constrains the relation between the Máriagyu{double acute}d dyke and the Mecsek and Mórágy subvolcanic bodies - i.e. the former is either older than the Mecsek and Mórágy rocks or synchronous with the oldest of them. From the above results the following palaeotectonic conclusions can be drawn: -After the mid-Cretaceous folding, South Transdanubia (and probably of the whole of the Tisza Unit) rotated towards the west relative to Europe (supposedly in Late Cretaceous). This rotation took place during the subvolcanic activity in the Mecsek-Mórágy area. -The magmatism which fixed the rotation should be incorporated into the palaeotectonic syntheses. In the last two decades the rotation has been accepted in the framework of these syntheses but without taking into account the Late Cretaceous alkali rift magmatism which actually dates this rotation. -The post-subduction origin of the lamprophyric magmatism of the Villány Hills should be integrated into one extensional palaeotectonic model. An explanation should be found for the existence of two different types of the upper mantle in two magmatic areas. These areas are situated at a distance (30 km) from each other; this is several times smaller than the supposed depth of the magma generation.

Kovacs I.,Magyar Allami Eotvos Lorand Geofizikai Intezet | Kovacs I.,Eotvos Lorand University | Falus G.,Magyar Allami Eotvos Lorand Geofizikai Intezet | Falus G.,Eotvos Lorand University | And 8 more authors.
Magyar Geofizika | Year: 2011

We review deformation patterns in mantle xenoliths from the central part of the Carpathian-Pannonian Region (CPR) and, in combination with seismic shear wave splitting data, attempt to define patterns of upper mantle anisotropy. Our interpretations from both lines of evidence support a model for east-west oriented asthenospheric flow, decoupled (at least in part) from the overlying lithosphere. Mantle flow fields resulting from Tertiary indentation of Europe by the Adriatic micro-plate and the resulting Alpine orogen may thus have been an important factor in driving the eastward extrusion of lithospheric blocks in the CPR accompanied by lithospheric extension, rapid 'rollback' of the Carpathian subduction system, and it's diachrounous collision with the European craton. According to this model, eastward asthenospheric flow would add signifi- cantly to the effects of slab rollback and gravitational instability. Thus, opening of the Pannonian Basin, rather than being exclusively driven by 'slab pull' and gravitational instability, could have been resulted, at least in part, from mantle flow associated with the Adria-European collision and ensuing Alpine orogeny.

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