The basement rocks, Neogene sediments and Quaternary alluvial deposits in the Abu Dabbab area, Eastern Desert of Egypt, are deformed by N-S, NE-SW, NW-SE and E-W trending faults. Complex cross-cutting relationships show a complicated history of initiation and reactivation of these faults. The recent fault scarps demonstrate different morphologies, modes of formation and relative ages. Recurrent, step and successively reactivated faulting was likely responsible for the exhumation and neo-formation of the fault scarps. Capture, deep incision, offset and reversal in flow direction of streams are the main drainage modifications induced by active faults. The concealed and active faults are associated with high drainage density anomalies. Segmentation phenomenon is common for all fault trends. Microearthquakes are concentrated at the intersection zones of faults and caused by upper crustal strike-slip, oblique-slip, reverse and normal faults. The paleostresses are not consistent with the present-day stress fields. The present-day NE-SW extension across the Red Sea combined with a local multidirectional tension led to reactivation of old faults and initiation of new fault trends.
The Greater Caucasus evolved in the Jurassic as a large elongated back-arc basin on the northern periphery of the Neo-Tethys Ocean. The semi-quantitative analysis of proportions between marine and continental facies for each of 67 time slices produced a detailed curve depicting transgressive and regressive episodes. Five remarkable peaks on this curve are interpreted as the maximum flooding surfaces (MFSs). They are established at the Sinemurian/Pliensbachian boundary (MFS1), in the upper Pliensbachian (MFS2), the lower Aalenian (MFS3), the upper Bajocian (MFS4) and the lower Tithonian (MFS5). All surfaces except for MFS4 occur within typical MFS-marking layers. The Jurassic MFSs of the Greater Caucasus Basin do not match transgression peaks of the 1st-order cycles of Western Europe and the MFSs of Arabia. Their correspondence to the global eustatic peaks also remains uncertain. The most unexpected event is found in MFS3, which occurs at a time of prominent global sea-level fall. Errors in constraints and interpretations as well as influences of regional tectonic activity explain a specificity of the regional MFSs. The use of the regional Jurassic MFSs from the Greater Caucasus Basin for correlation purposes, therefore, appears doubtful.
More than 5000 high precision seismic phases of 560 selected aftershocks (
≥ 2.0) of the January 26, 2001 Bhuj earthquake (
7.7) in western India are used for joint determination of the hypocentral parameters and for 3D inversion of P-wave velocity and
structures in the source area. The aftershocks are located with an average rms of 0.19 s, and average error estimates of latitude, longitude and depth are 1.2, 1.1 and 2.3 km respectively. Most of the aftershocks occurred in an area 70 × 35 sq km; the intense activity was observed at a depth range 12–37 km. A bimodal distribution of aftershocks indicates that the main shock rupture propagated in upward and downward directions. Further, the best located aftershocks show two trends, one in northeast, parallel to Anjar Rapar Lineament, and the other in northwest parallel to the Bhachau Lineament. Fault-plane solutions of the northeast trending aftershocks indicate reverse faulting with left-lateral strike-slip component. These solutions are comparable with the main shock solution. The northwest trending aftershocks, on the other hand, show reverse faulting with right-lateral strike-slip motion. The estimated velocity structure indicates that the source zone of the Bhuj earthquake has a number of blocks showing lateral heterogeneities in P-and S-wave velocities. A block having higher P-and S-wave velocities appears to have uplift relative to its surroundings. The mainshock occurred at the boundary between the high
uplifted block and the adjacent low
block. Gravity observations support our 3D inversion results. This high velocity block is surrounded by rocks of higher
or lower rigidity, which possibly acted as a barrier zone.
While the cadastral and topographic maps tie to the classical reference systems and frames, there will be need to know the relation between the classical and GPS-based networks in a particular country. In this study we discuss the scale factor and azimuth discrepancies between the Hungarian first order triangulation and the national GPS network emphasising their practical significance.The comparison of traditional and GPS derived slope and geodesic distances as well as the comparison of the different azimuths make possible the estimation of the scale and orientation differences of the two systems without the knowledge of height and geoid information which may contain additional errors, too.The estimated −4.34 mm/km mean value reflects the significant scale difference, which is similar to the values derived in neighbour countries. The −2.51 arcsec mean azimuth difference reflects the orientation of the two system.
This paper investigates the effect of electrode positioning errors on the inverted pseudosection. Instead of random spacing errors (as usually assumed in geoelectrics) we exactly measured this effect among field conditions. In the field, in spite of the greatest possible care, the electrode positions contain some inaccuracy: either in case of dense undergrowth, or varied topography, or very rocky field. In all these cases, it is not possible to put the electrodes in their theoretical position. As a consequence, the position data will contain some error. The inaccuracies were exactly determined by using a laser distance meter. The geometrical data from real field conditions and by using Wenner-
, pole-dipole and pole-pole arrays were then considered over homogeneous half space.As we have found, the positioning errors can be regarded as insignificant, even in case of relatively uncomfortable field conditions. However, in case of very rocky surface the distortions are more significant, but it is still possible to make some corrections: either by neglecting a few electrode positions with the greatest positioning error, or to minimize the inline errors, even on the price that offline deviations are high.
Authors:S. Dahy, G. Hassib, Abdel-Monem Mohamed and A. Hassoup
Suddenly, Aswan Seismic Network detected and observed a number of events beside Aswan city. The magnitude of these events ranged from 0.9 to 2.6. These events were considered very important events because they were located not far from the Aswan High Dam. The main purpose of this work is to investigate and identification of these events using different seismic methods. Small earthquakes and explosions have the same flat and displacement spectrum for short-period P waves and discrimination of small events rests on detection and location. The final result appears that the source of these events is not an artificial type.
Authors:A. Ádám, F. Kohlbeck, A. Novák and L. Szarka
In the continuation of the CELEBRATION-007 deep seismic profile from Hungary to Austria a series of deep magnetotelluric soundings has been carried out, using the instruments (from GFZ MT instrument pool). In spite of the high noise level, the relatively good imaging of the structure of the sedimentary Graz Basin and possibly fluid filled conducting fractures in the resistive rock matrix of the Eastern Alps have been indicated. They might be potential source of geodynamics (earthquakes?).
Intense magnetic storms are dominantly caused by the interplanetary manifestations of fast coronal mass ejections (CMEs); and are in two forms: the sheath region and the CME ejecta itself; both involving an intense and long duration southward interplanetary magnetic field component
. A study of the storm events which were divided into two parts of ‘intense’ −250 nT ≤ peak
< −100 nT) and ‘very intense’ (peak
< −250 nT) magnetic activities, each having four storm days spanning between 1976 and 2002 shows that an appreciable southward turning of
for a value >10 nT and long duration (>3 hour) would always cause a depression in the
magnitude, signifying an intense storm. The study reveals that ‘very intense’ storms are more likely to experience shock in the interplanetary magnetic field region faster than ‘intense’ storms with a plasma flow speed >400 km/s. This is because
plots shows that activity of storm sudden commencement (SSC) is not noticeable until about 7 hours to storm day under ‘intense’ storms, whereas, it is as much as 12 hours to storm day for ‘very intense’ activities.The
plots also shows that
southward orientation magnitude on the average for ‘very intense’ storms is not beyond −10 nT before the beginning of geomagnetic activity; with a northward orientation occurring less often with a magnitude less than 10 nT. However, a northward directed
appears more often before storm event in the case of ‘very intense’ storms with a magnitude that could be as high as 15 nT on the average and a southward orientation value not exceeding −10 nT. It was further observed from the
plot that ‘intense’ storms recover faster than the ‘very intense’ ones.
Contemporary geodetic measurement systems offer possibilities to measure movements and deformations of objects in all details. As such they give the opportunity to fulfil the trends in engineering surveying which intend to determine not only the geometrical changes of an object but above all to describe the kinematic and dynamic of the changes in space and time as subject of influencing forces. On the assumption that the kinematic process is observed with only one measurement system there is no redundancy of the measurements. For evaluation of the unknown system state and its statistics in real time, other methods such as filters have to be used instead of classical geodetic adjustment.The objective of the article is to introduce the Kalman filter as an alternative method for estimation of kinematic geodetic measurements. On the basis of kinematic process simulation the discretized continuous white noise acceleration model is given in detail. The kinematic process is captured with motorized electronic tachymeter, which enables automatic tracking of reflector and measuring. In the numerical example the importance of initial filter parameters definition, with the emphasis on defining the process noise, is given. In future work appropriate calibration system with known trajectory and velocity of the motion should be used for the evaluation of the mathematical model. Such system would assure independent measure of certainty. It will also be possible to test the instrument’s efficiency for kinematic measurements in dependence of measured values and velocity.
The mechanical behavior of the Buda Marl lies between those of rock and soil; it is therefore appropriate to define it as both weak rock and strong soil: some marl types behave like a weak rock and others like soil. In such cases the strength parameters of the material can be determined by rock mechanical or soil mechanical laboratory investigations. Often a problem occurs when the material cannot be assigned to either of these classes, in which case neither the commonly-used rock mechanical nor the soil mechanical tools are applicable to define the strength properties of the material. In this case the mechanical parameters of the material can only be estimated in an empirical fashion. The goal of this paper is to demonstrate the rock mechanical properties of the marl, using an empirical method, which can be use to determine the physical properties of a material that is neither rock nor soil.
Jordan is situated on the northwestern side of the Arabian Plate, along the eastern flank of the ancient Tethys Ocean on the western side of the Dead Sea Transform. The country hosts huge phosphate deposits. The deposits at Eshidiya are comprised of overburden, four phosphate beds (A0, Al, A2 and A3), a coquina/marl waste bed, and two silicified phosphate chert interwaste beds. Eshidiya ore beds are treated separately through beneficiation and upgrading, as they produce products of different grade; they are subdivided into three classes. A 65% TCP (tricalcium phosphate) sub-commercial product is also produced. The detrimental impurities are considered to be among the lowest in the world. Chemical analyses of major oxides, organic matter and some traces in the product, which indicate almost similar chemical signature, are discussed herein.
Authors:Tamás Bodoky, Márta Kis, István Kummer, Károly Posgay, László Sõrés and György Don
A more or less circular high-amplitude telluric conductivity anomaly is located at Magyarmecske, in southwestern Hungary. The authors collected and reinvestigated all available geophysical data previously measured in the area; based on this information it was concluded that the conductivity anomaly may well be explained as a buried impact crater. It is assumed that when the impact occurred, the target area was covered by a thick, coal-bearing Carboniferous sedimentary sequence. The projectile created a complex impact crater in these deposits, of a diameter of approximately 6–8 km. In the neighborhood of the crater the coal was modified by the impact's heat and pressure. Later the impact structure was partly eroded, partly deformed by younger tectonic movements, and covered by Neogene sediments of strongly variable thickness.
A fine-grained and a medium-grained oolitic limestone of Miocene age were studied on ashlars of monuments in Budapest. The studied buildings are located in a polluted urban environment. The surface alteration is characterized by the presence of white (thin and thick) and black (laminar and framboidal) weathering crusts. Flaking, scaling and blistering are common crust detachment forms. Crust detachment is followed by rapid surface loss in the form of granular disintegration or of secondary crusts stabilizing the stone surface. Non-destructive in situ mechanical tests such as Schmidt hammer rebound and Duroscope clearly document the presence of thin and thick weathering crusts, and the degradation of underlying fine-and medium-grained limestone. Crust formation is associated with a textural change, since precipitation of pore-occluding calcite and gypsum and reduction of porosity in the crust zone has been recorded. Crust detachment is attributed to the crystallization pressure of air pollution-related gypsum, to freeze/thaw cycles, and to differences in mechanical properties of crust and host rock.
The Jabal Hamra (538 Ma) and Jabal Abu ad Dud plutons in northeast Saudi Arabia are epizonal bodies consisting of alkali feldspar granite and alkali feldspar syenite. Fracture-controlled zones of highly altered granites are recorded along the margins of the plutons. The granites intrude metamorphosed volcano-sedimentary successions of the Matran Formation. The rocks of the two plutons are chemically indistinguishable. They are characterized by above-average Th, Nb, Y, Ta, Hf and Zr, very low CaO, TiO2, MgO, FeO and MnO, and by high contents of rare earth elements (REE). Tectonic discrimination diagrams suggest an intra-plate environment, with many geochemical and mineralogical features resembling post-orogenic A-type granites. Numerous local and regional geologic constraints indicate that the plutons were intruded in an extension-related setting following the cessation of Neoproterozoic arc-related magmatism. Geochemical data are consistent with their derivation by partial melting of depleted crust followed by fractional crystallization of feldspars, ferromagnesian minerals and REE-rich accessory phases. The radiogenic isotope data [eNd (T) values are +3.5 to +4.2] indicate that the granite magma was generated from a ‘juvenile’ source, which is typical of the rocks making up most of the Arabian-Nubian Shield. Rare-metal mineralization is associated with the fracture-controlled alteration zones that occur at Jabal Al Hamra and Jabal Abu ad Dud. The altered rocks are characterized by higher TiO2, Fe2O3, SiO2 and lower Al2O3, CaO, Na2O, than the unaltered rocks. They show high and wide range in the total REE contents (804–15579 ppm), Ta (6–194 ppm), Nb (51–3483 ppm), Hf (13–368 ppm), Zr (394–14887 ppm), Th (16–572 ppm) and U (4–143 ppm). Field observations and further petrographic and chemical studies suggest that the altered rocks and the rare metal enrichment are the products of hydrothermal-metasomatic alteration of the quartz alkali feldspar syenite and the alkali feldspar granite. The rare-metal enrichment was explained by orthomagmatic fluid transport of these elements as fluoride complexes, and their subsequent deposition as a result of mixing with externally derived Fe-rich fluids.
The spatially restricted Early Valanginian iron ore (limonite) and manganese deposit at Zengõvárkony (Mecsek Mts, southern Hungary) contains a rich, strongly limonitized, remarkably large-sized (specimens are 30–70% larger than those at their type localities) brachiopod-dominated (mainly Lacunosella and Nucleata) megafauna and a diverse crustacean microfauna, which indicates a shallow, nutrient-rich environment possibly linked to an uplifted block, and/or a hydrothermal vent.
Authors:Balázs Vásárhelyi, László Kovács and Ágnes Váró
Fissuring of rocks is frequently of greater importance in practical rock engineering operations than the strength of the intact rock. In practice boreholes are usually analyzed by the RQD method. The limitation of this method has been discussed by several authors: for example, for RQD = 0 % [that is, where the joint intercept (distance between joints in the cores) is 10 cm or less], or RQD = 100%, the RQD provides no information on the core pieces themselves. It does not matter whether the discarded pieces are soil or fresh rock pieces up to 10 cm in length. In early 2003, more than 3,000 meter-long boreholes were analyzed in parallel with two different methods: traditional RQD, and Hansági's C (or Kiruna) Method. According to the results, in the case of a very good or very poor core, the C method shows the jointing patterns better than the widely-used RQD method. The goal of this paper is to present the C method and its advandages/disadvandages. Linear regression was found for the values between 10% < RQD < 90%, but the C value is much more sensitive than the RQD. The classification of the boreholes according to C method is also presented.
The Kiscell Clay is the most frequently-occurring rock type of Budapest, especially on the Buda side of the Danube. It occurs near the surface as well as at great depth; for the purposes of this study the upper, approximately 35 meters of the unit was investigated. The results of previous laboratory analyses were collected and more than 2000 test results evaluated. Physical properties such as plasticity index, density, void ratio, and coefficient of compressibility were tested and the results statistically analyzed. Correlation between different properties is shown in graphic form, and equations are proposed to describe the various coefficients.
Three types of porous limestone from Sóskút quarry and two limestone types obtained directly from Matthias Church of Budapest (both in Hungary) were used to test the performance of five stone consolidants. The quarry specimens were treated under laboratory conditions by saturation. Three types of silicic acid ester, an aliphatic uretan resin and a polymethyl methacrylate were applied to the stone. Physical parameters such as density, porosity, ultrasonic sound velocity and Duroscope rebound value were measured on untreated and treated samples. The absorption rate of different consolidants was also detected. The physical properties of untreated and treated specimens were compared in order to analyze the performance of the consolidants. Duroscope tests have shown that after consolidation there is an increase in surface strength.
Authors:Stephen Fityus, Ákos Török and John Gibson
This paper presents a case study to illustrate the role played by geologic structures in the design and construction of major transportation infrastructure, in a setting of moderately deformed Paleozoic sedimentary rocks in eastern Australia. It describes a complex development of folding, faulting and jointing that has resulted in significant inclination of beds, juxtaposition of strata and affected the weathering characteristics of a wide range of rock types. The sequence, which displays an upward transition from marine to terrestrial sediments, comprises an interbedded succession of conglomerate, sandstone, shale and erratic volcanics and crystal tuff. Unfavorable relationships between major excavation faces, inclined beds and jointing have resulted in problems with the stability of road cuttings. Also, the presence of faults and dykes at various scales has had a significant effect on weathering and rock strength. The paper demonstrates the importance of the choice of alignment at design stage, and how a basis of good structural interpretation and geologic mapping can be used to avoid problems during construction and issues with ongoing maintenance.
In June 2003 Hungary accepted the European Standard for Aggregates for Railway Ballast (MSZ EN 13450: 2003). The European norm, compared with the Hungarian Standard, also includes a new examination method called the micro-Deval method for railway ballast aggregates, which was previously not used in Hungary. This paper presents the test results of aggregates for railway ballast-producing quarries, according to newly accepted Standard. The test materials consist of andesite, basalt, dolomite and limestone. The results cover a significant range. The study was aimed at finding a relation between the testing methods, in order to reduce the testing procedure; however, no clear relationship was found.
A new water balance calculation has been worked out that considers the effect of urbanization. This calculation method was applied to evaluate the water balance of the historic center of Budapest, the Buda Castle Hill, where an intensive network of cellars is found. The method, a combination of hydrogeologic tests and field measurements, was also tested in other Hungarian cities where underground structures are common, such as Eger, Pécs and Veszprém.
The calculation considers both natural and anthropogenic water sources. Beside the commonly-used natural factors such as precipitation, evaporation, runoff, infiltration, etc. it also employs input parameters such as broken pipelines and sewer systems. The water losses of these waterworks significantly influence the natural water balance and provide additional and very often significant water input into the water system. The new method is of great importance in designing and planning remedial actions for historic cities, where the built environment, cellars and natural caves are endangered by infiltrating water. Another feedback of the method is the application of the results in the long-term planning strategy of public works supplying or using water (water works, sewer system and energy sector).
Magnetotelluric method (MT) offers opportunity to detect crustal fluids along faults due to their high conductivity anomaly. Supposing that fluids deposited minerals in the conductive fractures (faults, dykes) decreasing the resistivity, the high seismicity in the area can be explained by the presence of these fluids. MT measurements were carried out in the period range 0.001–420 s crossing the Kalabsha fault (Aswan, Egypt) and Remiremont fault (Southern Vosges, France). In these work we detect geoelectrical resistivity anomalies of the Earth’s crust and link them to local seismic activity. Seismic events having magnitude (M<5) are found along fault zones in Kalabsha and Remiremont. The goals of our measurements are various. We would like to determine the precise location of the active faults, to study the connection of the Remiremont and Kalabsha seismicity to the MT resistivity structures, and to support the idea of the influence of the fluid-bearing conducting faults in the Remiremont and Kalabsha areas to the earthquake. These applications afford the unusual opportunity to study the percolation of water into the faults system and its effect on the seismicity, to reveal geological structures and the stress field covered by thin Quaternary formations. Data are analysed by 2D simultaneous inversion of both polarizations. The resulting models are compared with the local seismicity map. Our MT model reveals the conductive signature of the fault, as well as geological and tectonic stresses prevailing in active regions.
Some interpolation and smoothing techniques have been analyzed for velocity and acceleration determination from kinematic LEO (Low-Earth Orbiter) orbits. Tests were performed on a simulated GOCE orbit and on a kinematic CHAMP orbit as well.
Three major domal structures are trending northeast-southwest directions prevailed at El-Hasana area, northern part of Sinai Peninsula. These structures and their altered rock constituents attracted us to study these formations from geophysical view. The main target of this work is to establish the relation between these structures and Syrian Arc Tectonic System (SATS) prevailed at the studied area. The investigations were carried out using land magnetic survey, aeromagnetic, gravity and laboratory measurements.An intensive analysis using tectonic trend analysis and, 3D Euler deconvolution with different coefficients were applied to the potential field data. Also, cross-sections Euler deconvolution, Werner deconvolution and radial power spectrum have been applied. The results illustrate that most prevailed tectonics that could forming these anticlines are trending at N 35°–65° E direction which related to the Syrian tectonics (SATS) direction. The depth to the basement rocks ranges between 2 km at the southern parts to 2.3 km at the northern parts of the studied area.The magnetic susceptibility map was constructed using laboratory measurements for more than 120 collected rock samples along the surveyed area. The average values range between 0.7 × 10
to 1 × 10
SI for limestone samples, whereas the sandstone varies between 1 × 10
to 1.5 × 10
SI unit. The results show that the magnetic values are higher for the rock samples picked along the anticlinal structures.
The problem of handling outliers in a deformation monitoring network is of special importance, because the existence of outliers may lead to false deformation parameters. One of the approaches to detect the outliers is to use robust estimators. In this case the network points are computed by such a robust method, implying that the adjustment result is resisting systematic observation errors, and, in particular, it is insensitive to gross errors and even blunders. Since there are different approaches to robust estimation, the resulting estimated networks may differ. In this article, different robust estimation methods, such as the M-estimation of Huber, the “Danish”, and the
-norm estimation methods, are reviewed and compared with the standard least squares method to view their potentials to detect outliers in the Tehran Milad tower deformation network. The numerical studies show that the
-norm is able to detect and down-weight the outliers best, so it is selected as the favourable approach, but there is a lack of uniqueness. For comparison, Baarda’s method “data snooping” can achieve similar results when the outlier magnitude of an outlier is large enough to be detected; but robust methods are faster than the sequential data snooping process.
Ground based observations of the “Széchenyi István” Geophysical Observatory of the Hungarian Academy of Sciences (Nagycenk) offer a unique opportunity for investigation of the complex processes of Earth’s environment and of its effect on radio wave propagation. High temporal resolution recording of variations of the geomagnetic field, vertical incidence sounding of the ionosphere and observation of whistlers enable determination of plasma density profiles in the inner magnetosphere (plasmasphere) and their changes. Study of ionospheric processes and their effects in the upper atmosphere (thermosphere) is supported by a permanent GPS station. Both DC and AC fields of lightning discharges are also recorded in the Observatory. Measurement of the DC field is related to the atmospheric electric circuit, where the global thunderstorm activity is the generator and fine weather areas play the role of loading. Loading of the atmospheric electric field depends on rate of ionization, ionization being caused by galactic cosmic rays. However, galactic cosmic rays are modulated by solar activity. Similarly amplitude of Schumann resonances depend on thunderstorm activity and its distance from the recording site. Resonance frequencies occurring at wave-lengths approximating dimensions of the Earth-ionosphere waveguide are affected by conductivity variations of the upper boundary of the cavity resonator and thus, by changes of thickness of the cavity resonator.
During the last ten years there were systematic works carried out in Croatia on the realisation and implementation of the new height system. The results of these works, based on the analysis and completely new processing of the existing archive data of geometric levelling measurements, are the basis for the introduction of the new Croatian height system into official usage. As the introduction of the new height system has direct impact on the changes of national control network benchmark heights, it is necessary to determine and investigate the changes and relations between the “old” and “new” heights of benchmarks. For this purpose, the benchmark heights in the national geometric levelling control networks have been compared and analysed at the north-western part of the territory of the Republic of Croatia chosen to be representative test area. Comparison results are achieved and presented in this paper.
Authors:P. Varga, Z. Bus, B. Süle, A. Schreider, C. Bizouard, D. Gambis and C. Denis
In its first part this work focuses on connection of length of day (LOD) with centered and eccentric geomagnetic dipole fields described with the use of Gaussian coefficients derived from global geomagnetic observations is discussed for the epoch 1900–2000. The statistical comparison of temporal variation of earth magnetic and astronomical data shows close correlation of geomagnetic dipole momentum
and ΔLOD. It should be mentioned that the time-correlation is closer when the centred geomagnetic dipole is used for statistical modelling. In the same time no relation was found between ΔLOD and the orientation variations of the geomagnetic dipole.In the second part of present study the connection of geomagnetic field and the LOD is investigated in geological time-scale. A significant ΔLOD was found which coincides in time with the geomagnetic Mesozoic low. The reason of this coincidence is enigmatic.
Authors:Emő Márton, Davor Pavelić, Bruno Tomljenović, Péter Márton and Radovan Avanić
This paper summarizes the paleomagnetic results that have
been obtained for the Neogene of the Croatian part of the Pannonian Basin since
1995. The paleomagnetic investigations were carried out almost exclusively on
sediments, which were deposited in widely differing environments. Most of the
paleomagnetic directions can be considered as of pre-folding age, but some were
clearly acquired diagenetically or even after deformation. This means that any
future magnetostratigraphic study in the southern Pannonian Basin must be
carried out with utmost care. Fortunately, the tectonic interpretation of the
data is favorably affected by the fact that magnetizations of pre and
post-folding ages show the same angles of declinations. They suggest that the entire
Croatian part of the Pannonian Basin rotated counterclockwise, by about 30°,
after the Early Pontian and before the Holocene. It is also remarkable that
Ottnangian data from the Slavonian Mts do not indicate a Tisia-type clockwise
rotation during the mid-Miocene.
In this article the approximating solution of electrical logging direct problem is presented which is applicable in the case of different continuous radial resistivity profiles. The Green function of the direct problem is derived in the environments mentioned above for different electrode radii, which is the basic function in the apparent resistivity calculation of various electrical sondes. The results also could be the useful for the resistivity profile inversion, and sensitivity analysis.
A network of fluxgate magnetometers was operated over Garhwal Lesser Himalaya Seismic Belt (GLHSB) in Uttarkashi area during 1987–1990. This study delineated a narrow conductive zone south of MCT and named as Garhwal Lesser Himalaya Conductivity Anomaly (GLHCA). Pseudo-sections of |
| for a traverse across GLHCA implicate that the top of the anomaly is within 10 km depth and mostly of 2D nature. The tectonic formation associated with the anomaly is found to be polarization sensitive and the polarization characteristics show that the anomaly is not parallel to Main Central Thrust (MCT) but inclined by about 10°–30° in anti clockwise direction. The frequency and polarization characteristics of the induction response of GLHCA are discussed in this paper.
In this article, we propose a technique for the precise cleaning of the gravity anomaly database based on the cross validation approach. The terrestrial gravity anomalies were compared versus a global geopotential model and take into account the effect of topography in this comparison. The efficiency of the cross-validation technique is illustrated in outlier detection as well as in choosing the proper gridding technique as a case study in construction of the Iranian new gravity database. In order to reduce the effect of topography and the discretisation error, a special interpolation scheme is used for gridding of the free-air gravity anomalies. The final grid file was created based on the Kriging method with 80″ × 90″ block resolution. The overall accuracy for the new Iranian gravity database is estimated in the order of 10 mGal.
In the seismic source zone of Bánát more than 600 earthquakes are known since 1773 among them six events with magnitude of 5.0–5.7 measured on the surface magnitude scale. The macroseismic reinterpretation of the April 2, 1901 earthquake yields epicentral intensity of VII on the European Macroseismic Scale, and a focal depth value of 12 km. Based on empirical relations the maximum rupture area is estimated as 50–55 km
and the maximum displacement along the fault is about 16 cm in the Bánát seismic zone due to the
= 5.7 event occurred on July 12, 1991. The average recurrence that we may expect an earthquake of
≥ 3.4 every 1 year, an earthquake of
≥ 4.3 every 10 years and an earthquake of
≥ 5.3 every 100 years in the studied source zone. The probabilistic seismic hazard assessment predicts 1.3–2.1 m/sec
peak ground accelerations, and 6.7–7.3 maximum (theoretical) earthquake intensity values with 10% chance of exceedance for an exposure time of 100 years in the region.
The Carpathian Basin is situated in the territory between the Mediterranean area, which is seismically one of the active regions and the Carpathian Mountains belt. The temporal variation of seismicity is investigated on the example of three seismo-tectonically different regions: the Carpathian Basin, the Vrancea region and the Dinarides. The seismicity is analyzed since 1900 in order to investigate the existence of diurnal periodicities using hodographs. There are two different diurnal distributions opposing each other: maximum early morning dominates until the year 1963, followed by a period of time when earthquakes seem to occur more often around 13h local time mainly concerning the weak
< 3.2 events. The midday maximum in the number of minor events may be caused by the inclusion of quarry blasts, but the diurnal geomagnetic variations correlate well with diurnal changes in earthquake activity. Duma and Rhuzin (2003) suppose that the current vortices induced by Sq variations in the lithospheric layer, flowing across the horizontal component of the geomagnetic field generate a torque which can be added to the tectonic loading stress (which have a maximum about noon) and may help trigger instability in a fault approaching the failure threshold.The spatial and temporal fractal structures of earthquakes were analyzed using the box counting method. The regions were divided into different size
of a square box and were counted the minimum number
) of boxes necessary to cover all the data. The recurrence times of earthquakes are shown to be a clustering process and are much higher in the Carpathian Basin. The earthquakes in these regions have self-similar structures. The slope of log
function for Carpathian Basin breaks at about 20 km, which divides the range into two bands. This breaking at about 20 km maybe connected to the intrinsic weakness of the Carpathian Basin lithosphere.
Authors:V. Silbergleit, S. Gigola and C. D’Attellis
We perform two statistical studies of monthly mean sunspots one of them by considering the Daubechies 4-wavelet analysis and the other one by using the multiple linear regression method. We found that the Hurst’s parameters of the fractional Brownian motion is equal to = 0.98 manifesting the long memory of the data set. The proposed second method is used for solar cycles 16 and 23 and the results are remarkably good in comparison to the predictions made by solar dynamo and precursor methods. A weak correlation is found among the maximum amplitude of a cycle and the other ones related to the prior seven and twelve cycles. An early prediction of the maximum smoothed international sunspot number for cycles 24 and 25 are 128 and 161, respectively.
There are different criteria for designing a geodetic network in an optimal way. An optimum network can be regarded as a network having high precision, reliability and low cost. Accordingly, corresponding to these criteria different single-objective models can be defined. Each one can be subjected to two other criteria as constraints. Sometimes the constraints can be contradictory so that some of the constraints are violated. In this contribution, these models are mathematically reviewed. It is numerically shown how to prepare these mathematical models for optimization process through a simulated network. We found that the reliability model yields small position changes between those obtained using precision respectively. Elimination of some observations may happen using precision and cost model while the reliability model tries to save number of observations. In our numerical studies, no contradictions can be seen in reliability model and this model seems to be more suitable for designing of the geodetic and deformation networks.
Authors:V. Singh, D. Shanker, H. Singh and M. Banerjee
Seismically Kutch peninsula is very active. The distribution of seismicity in Peninsular Shield region from 1902 to 2001 show 12 earthquakes of
≥ 6. The energy ratio from Kutch basin to Deccan trap is 20:1 and from trap to rest of the shield is 5:1. The last one hundred years seismicity data show Kutch basin is seismically more active than Deccan trap and the rest of the Peninsular Shield. The maximum magnitude of earthquake in the Kutch region is 7.7. The generations of large earthquakes in the region are difficult to explain, as plate boundary does not exist. In order to understand the physical processes that are taking place in the region to generate such large events the detailed analyses of geophysical and geological data have been examined in the light of development of rift, subsidence of basin, vertical tectonics and recent geophysical findings. In such regions, petrologic model can provide better explanation for release of fluid that generates large earthquakes, sprouting of sands, liquefaction, and large number of aftershocks activities and direction of stresses for aftershock sequences. The presence of magma in the Kutch upper mantle could be derived from various geological (subsidence of basin, development of rift faults) and geophysical observations (high heat flow over Cambay region, prominent positive Bouguer gravity anomalies and low shear velocity in the upper mantle). The inspection of seismological data shows all the medium size to large earthquake have occurred in shear zone of large gravity gradients or along the four major faults of the region. In view of geological and geophysical observations, petrologic model is proposed for generation of earthquakes in the region. The number of aftershocks and direction of stresses in the focal region of aftershocks would depend on the direction of movement of fluid incursion in the focal region after the occurrence of the main events. The recent Bhuj earthquake also shows more than 3000 aftershocks from Jan 29 to April 15, 2001. The expanding swarm activity in the focal region and the direction of stresses derived from first motion data of aftershocks for focal depths 2 to 8 km, 8 to 25 km, and 25 to 38 km supports the proposed model. Also, shear wave tomography studies in this region have revealed low shear wave velocity in the upper mantle of Cambay from shallow depth to 200 km depth showing high temperature zone. The analyses reveal the presence of conducting fluid in the focal zone, which is the main cause for generation of medium size to large earthquake in the region.
Authors:Tamás Budai, János Haas, Harald Lobitzer, Olga Piros and Attila Vörös
The Middle Triassic
Wetterstein Limestone was investigated on the Feuerkogel, in the eastern
Höllengebirge area, Austria. Cephalopod-bearing coquina interbeds consisting
predominantly of orthocone cephalopods were found within the dasycladacean
inner platform lagoon facies. Based on sedimentological studies the coquina
beds are interpreted as storm accumulations. Dasycladacean biostratigraphic
data permit assigning the studied succession to the Late Anisian-Early Ladinian
interval. Ammonites of age-diagnostic value found in the coquina horizon
suggest the Avisianum Subzone of the Reitzi Zone that corresponds to the upper
part of the Anisian.
The results of seven
Ar analyses and two K/Ar analyses of mineral
separates of metamorphic rocks from the Transdanubian part (west of the Danube
River) of the Tisza Mega-Unit is presented, and a review of the
geochronological data available in the literature is given. Investigated rocks
come from boreholes and include amphibolite facies rocks, mainly containing
garnet, staurolite, kyanite, andalusite and sillimanite as index minerals. The
investigated area covers 120 × 85 km in Transdanubia, including all tectonic
units distinguished by previous authors. The
spectra of the muscovites yielded fairly well-established plateau ages ranging
from 307 Ma-312 Ma in all units. Similar muscovite Ar/Ar cooling ages of ca 310
Ma were obtained from other parts of Tisza Mega-unit east of the Danube, e.g.
from the kyanite-sillimanite-bearing metapelites of the Villány-Bihar Subunit
(Great Plain; Lelkes-Felvári et al. 2003).
In the Gerecse Mts,
Jurassic successions built of sedimentary rocks characteristic of the
peri-Mediterranean region are found. The lower part of the Toarcian stage,
largely representing the "Ammonitico Rosso marl" facies, contains
very diverse and abundant ammonite faunas. Bed-by-bed sampling of four sections
carried out during the late seventies and early eighties of the last century
has resulted in the collection of more than 15 000 specimens, the bulk of them
belonging to the orders Phylloceratina and Lytoceratina. Due to the presence of
very rare index forms of the suborder Ammonitina, the successions could be
fitted into the zonal scheme established for the NW European Toarcian. The aim
of the present paper is to provide information on the stratigraphic distribution
of Ammonitina in the Bifrons and Gradata Zones as well as to present a subzonal
subdivision of these beds.
Authors:Katalin Judik, Kadosa Balogh, Darko Tibljaš and Péter Árkai
K-Ar age data of
illite-K-white mica-rich, <2 µm grain size fraction samples were determined
on various lithotypes of the Paleozoic-Mesozoic, very low- to low-grade
metamorphic complex, the Jurassic ophiolitic mélange and the
Cretaceous-Paleocene sedimentary sequence of Mt. Medvednica, Croatia. K-Ar ages
of the high-temperature anchizonal-epizonal Paleozoic-Mesozoic complex scatter
around ca. 110 Ma for slates, phyllites and marbles with phyllite
intercalations, while they are significantly younger (ca. 80 Ma) for
metavolcanoclastic rocks that are devoid of detrital K-white mica. Beside the
Cretaceous (Alpine) K-Ar radiometric age data, no evidence of a possibly older,
Variscan metamorphic event was detected. In the Jurassic ophiolitic mélange and
the Cretaceous-Paleocene sequence the obtained mixed isotopic age data do not
provide reliable estimates for the age of the diagenetic alterations. In the
Paleozoic and Mesozoic formations from the Bükk, Szendrõ and Uppony Mts.
(NE Hungary) and in the Paleozoic rocks series from the Internal Dinarides,
similar Alpine (Cretaceous) K-Ar ages were determined. These data may suggest
metamorphic processes related to the subduction of the Dinaridic oceanic crust
beneath Eurasia accompanied by compressional crustal thickening.
The Sa'al Belt
comprises a variety of Late Proterozoic island-arc assemblages of metasediments
and metavolcanics. The metavolcanics are calc-alkaline to sub-alkaline rocks
with minor tholeiitic tendency, whereas the metasediments are originally
sediments that were shed from active volcanic islands. The belt is polydeformed
and regionally metamorphosed up to the greenschist facies, with late and
post-tectonic granitoid intrusions. Tectonically the Sa'al Belt evolved through
multiple phases of ductile and brittle deformation. The ductile deformation is
manifested in three folding generations and shear zones whereas the brittle
deformation is represented by thrusting and faulting. The first folding
generation (F1) is represented by intrafolial and drag folds that are
apparently coeval with thrusting, and show vergence more or less parallel to
that of thrusts. Thrusting took place in a convergent environment within and
along the contact between different metavolcanics and metasediments. The
highest principal stress is horizontal, oriented N50°W, and the relative
transport direction is to SE toward the foreland. A second fold generation (F2)
overprinted the first folding with widely-spread kink folds and kink bands. All
criteria indicate the prevalence of a NW-SE-oriented simple shear regime that
was associated with slip essentially parallel to banding. The third folding
generation (F3) has a slip nature and has overprinted both F1 and F2, producing
sub-vertical NW-SE-trending S3-surfaces, meaning that the highest principal
stress orientation rotated towards NE-SW. Dynamic analysis of the fabrics
within the extensive subvertical E-W-trending ductile shear zones indicates
that they are produced by a subhorizontal highest principal stress oriented
S47°E. Moreover, shear sense indicators display a simple shear with dextral
sense of movement. Two conjugate shear planes are the main elements of the
brittle deformation. The first is a left-lateral strike-slip fault set trending
N to NNE, and the second a right-lateral strike-slip fault set trending NW.
These conjugate shear planes were formed with subhorizontal highest principal
stress oriented N25°W.
evolution of various volcanic areas in Hungary has been determined by (a) the
original volcanic succession and related, primary landforms and (b) the
subsequent postvolcanic tectonism and erosion. This overview presents some
details of these processes through selected relief types from the Miocene
volcanic mountains of Hungary: the High Börzsöny erosional caldera rim, the
Rocks of Vadálló-kövek, the Dobogókõ Ridge, the Danube Bend area, and
the badlands and fairy chimneys of the southern foreland of the Bükk Mts, by
showing different volcanic relief types, and postvolcanic tectonic,
paleogeographic and erosional history. In the Quaternary, the tectonic
transformation of these and other volcanic areas has been highly variable; in
contrast, erosional processes of the Quaternary, i.e. pedimentation, loess and
other eolian sedimentation, derasion, periglacial relief formation, and channel
erosion, have affected almost all areas in Hungary; hence types and rates of
erosion can be well constrained.
encountered Upper Cretaceous (Santonian) Iharkút terrestrial vertebrate
locality has yielded several vertebrate taxa since its discovery. Scincomorphan
lizards are also represented in this fauna by several jaw fragments. The most
abundant of these is represented by seven dentary fragments and an
indeterminate jaw fragment with characteristic teeth. The hypertrophied
splenial, the heterodont dentition, the cementum deposition at the bases of the
teeth, and the large subcircular resorption pits assign this type to the family
Teiidae. The dentition is composed of conical, monocuspid teeth in the mesial
region and transversely widened bicuspid teeth in the distal region. This
morphology is well known in members of the subfamily Polyglyphanodontinae.
Based on their dental morphology the Iharkút finds can be easily assigned to
the genus Bicuspidon. This genus is known from two species, B. numerosus Nydam
et Cifelli 2002 from the Albian-Cenomanian of Utah (North America) and B.
hatzegiensis Folie et Codrea 2005 from the Maastrichtian of the Hat¸eg Basin
(Transylvania, eastern Europe). The Hungarian specimens differ from Bicuspidon
numerosus in that the latter has bicuspid teeth in the distal part of the tooth
row, in contrast to the Hungarian species, which has two monocuspid teeth in
the distal region, one equal to the size of the preceding teeth, and one less
than half the size of the former one. The presence of monocuspid teeth at the
end of the tooth row resembles B. hatzegiensis, but since the very end of the
tooth row of the latter is not known it is not possible to determine if B.
hatzegiensis also has two monocuspid teeth distally. Thus it is not impossible
that the Hungarian specimens represent a new species, but at present the lack
of necessary information allows its determination only as Bicuspidon aff.
Authors:Anita Jávor, Zuárd Ditrói-Puskás and Gábor Dobosi
The newly discovered
crustal xenoliths from Miocene andesites in the Mátra Mts (Northeast Hungary)
were classified into three petrographic types. Type 1 is a garnetiferous,
plagioclase-rich cumulate rock, presumed to originate from the felsic portion
of the nearby Szarvaskõ-Darnó mafic igneous complex. The almandine-rich
garnet has been inferred to be of granulite facies origin. Garnet -
orthopyroxene geothermobarometry on the orthopyroxene - plagioclase corona
structure around it indicates a later high temperature (800-950 °C) low
pressure (3-4 kbar) retrogression event. Type 2 is also plagioclase-rich
cumulate rock with contact metamorphic assemblage containing spinel, corundum
and andalusite, which crystallized in the course of dehydration reactions of
biotite and/or smectite in hornblende hornfels to sanidinite facies conditions.
Type 3 is microsyenite, which contains abundant anorthoclase and minor amount
of Na- and K-rich kaersutitic-barkevikitic amphibole.
succession of Gorski Kotar reveals the typical sedimentary signature of the
inner Adriatic Carbonate Platform realm. On the basis of its facies
characteristics eleven informal lithofacies units can be distinguished. By
origin, they are grouped into three depositional settings that alternated over
the spacious Adriatic platform area during the Jurassic. These are: (1)
subtidal below fair-weather wave-base to higher-energy subtidal above
fair-weather wave-base, (2) subtidal below fair-weather wave-base with episodic
higher-energy influences and (3) peritidal. The alternation of depositional
settings reflects periods of intensive, large-scale regional tectonic movements
during the geodynamic evolution of the western Neo-Tethys region, such as the
opening/closing of the Dinaridic branch of the Neo-Tethys and opening of the
A Jurassic marginal
depositional system of the Adriatic carbonate platform was analyzed in order to
determine its depositional architecture and major depositional controls. Based
on their facies characteristics, seven lithofacies units have been
distinguished, which constitute four paleoenvironmental associations: top of
the platform (shallow subtidal below and above the fair-weather wave-base),
upper foreslope, toe-of-slope and basin. The environmental changes are
interpreted to be related to tectonic activity as a consequence of regional
extensional movements, connected with the opening of the Dinaridic branch of
the Neo-Tethys. These extensional movements resulted in multi-stage drowning of
the northeastern part of the Adriatic carbonate platform, leading to its gradual
back-stepping and accordingly the expansion of the pelagic basin. The
interpretation presented here can serve as a useful model for re-evaluating
previously analyzed sections of the Adriatic Carbonate Platform margin.