Paleomagnetic and AMS properties of a 100m long core drilled from Miocene lake sediments in the Turiec basin

A 100 m long core was drilled from the Late Miocene deepwater lake sediments of the Turiec Basin for sedimentological, paleontological and magnetostratigraphic study. For the latter, 79 samples were selected, packed in folia and kept refrigerated till the laboratory measurements started. The samples were not oriented azimuthally, neither with respect to each other, except five pairs from a depth 36, 51, 69, 85, 97 m, which served to check the degree of consistency of the paleomagnetic signal. For the test several specimens were drilled from each of the 10 samples, NRM and AMS measured, and stepwise thermal demagnetization accompanied by susceptibility monitoring carried out till the NRM signal was lost. This invariably happened by 400 °C, while the susceptibility, after a considerable decrease started to increase dramatically at this temperature. All these features pointed to magnetic iron sulphide, probably greigite, as the carrier of the NRM. Both the paleomagnetic signal and the AMS fabrics revealed a high degree of consistency. Following the test experiments a large number of core segments were subjected to similar treatment. In some of them thin intercalation of silty and sandy material indicated the bedding dip in a range from 8° to 15° in the otherwise homogenous deepwater grey carbonatic clay. The dip direction and angle showed fairly good agreement with the magnetic foliation plane, thus the latter can be a proxy for the former, when silty intercalations are lacking. By reorienting the cores with respect to each other azimuthally (Fig.1.) and eventually to the dip direction observed nearby surface outcrops, we are hoping to define a paleomagnetic direction for the locality of the drill core. Concerning magnetic polarity, the majority of the so far studied cores have normal magnetization, with indication of two short reversals in the uppermost 20 m. As the study is not yet finished, the so far unexplored segments may modify the polarity pattern

First magnetic measurements on PM10 filters from two stations in Serbia and comparison of the results with those from nine Hungarian stations

We are presenting the results of magnetic susceptibility measurements carried out on PM10 filters collected at two stations in Serbia from July 1st to 31st October 2011 and compare them with those from 9 stations in Hungary, located at different settings and monitoring PM10 derived from different anthropogenic sources. As the vast majority of the magnetic grains in PM10 are derived from anthropogenic sources, it stands to reason to say that variations in magnetic susceptibility are more closely related to pollution than the mass of the dust. Comparison between susceptibilities measured on filters from Hungarian and Serbian stations (Novi Sad and Veliko Gradište) reveals that the latter are polluted similarly to Győr, a Hungarian town with fairly heavy traffic. The difference, however, is that in Győr, Sundays are less polluted than weekdays, while in the Serbian towns such trend is not observable (reason can be no camion stop). Miskolc, an industrial town with heavy traffic in NE Hungary shows twice as high susceptibilities as the previously mentioned locations, while the rest of the Hungarian stations investigated are just moderately polluted (values are only somewhat higher than those for a background station)

Transport of Pollutants around a High Building: Integrated Magnetic, Mineralogical and Geochemical Study

We studied the degree and distribution of traffic induced pollution at a 40 m high building at the side of a major road in Budapest by making magnetic, mineralogical and geochemical analysis on settled dust samples collected at different levels and at the front and back sides of the building. We observed strong seasonal dependence of the amounts of anthropogenic pollutants, which were highest during summer. This season was also characterized by strong vertical variation of the amounts of dust, of the magnetic susceptibilities (reflecting best the traffic induced pollution) and of the concentrations of Pb. All these have maximum values at 9 m, on both sides of the building. The pattern of the distribution does not correspond to what is predicted by an air flow model published for high buildings with similar morphology and wind conditions

The comparison of anisotropy of magnetic remanence with the anisotropy of magnetic susceptibility of the Dukla nappe from the Outer Western Carpathians

The Carpathians belong to the European Alpine system, which was formed during the convergence and collision of the European and African plates. The Polish segment of the Western Outer Carpathians is a north-verging thrust-and-fold belt composed largely of Lower Cretaceous to lower Miocene flysch. The belt comprises five rootless nappes: Skole, Subsilesian, Silesian, Dukla and Magura nappes. This paper presents the results of anisotropy of magnetic susceptibility (AMS), anisotropy of magnetic remanence (Anisotropy of Anhysteric Remanent Magnetization, AARM) and isothermal remanent magnetization (IRM) studies performed both in Oligocene turbidite sequences in the frontal part of the Dukla nappe and in olistostrome complex of the Lipowica quarry, topping the Silesian nappe in front of the Dukla nappe. For the study 102 individually oriented cores were drilled at nine geographically distributed localities. At each locality claystones were sampled, except Lipowica quarry, where silt and sandstone were also drilled. The AMS measurements showed that, the magnetic fabrics were dominantly foliated, with a weak but in the most cases well defined lineations, which correlate to the local strikes. At four localities the AMS lineations are aligned with the general (NW-SE) tectonic trend of the unit. The samples from Lipowica quarry and three other localities exhibit different, but still horizontal AMS lineations. At locality 6, the AMS lineation is vertical. In this case the question was if this peculiarity is due to strong deformation or mineralogical reasons. Because of the relatively low susceptibilities (1-3*10-4 SI), paramagnetic minerals can be importantcontributors to the AMS fabric. In order to study the magnetic fabric of the ferromagnetic mineral, which, according to the IRM measurements, most probably magnetite, AARM measurements were carried out so far on the samples from three localities and compared with the AMS fabric. We observed that, the difference between the AMS and AARM lineations at locality 8 is small. At locality 6 the AARM fabric is “normal” and parallel to the main tectonic trend of the Dukla nappe, and so becomes the AMS fabric after thermal demagnetization at 460°C. We interpret these phenomena as related to the presence of siderite in the rock, which is a paramagnetic mineral, known for its ability of creating inverse fabric in sediments. Concerning locality 1, the directions of the AMS and AARM lineations are quite different in all three rock types studied, but none of them are aligned with the main tectonic trend of the Dukla nappe. The above results outline a really complicated picture of the deformation history of the Dukla nappe, where the documented or suspected presence of the olistoliths may explain the often occurring local anomalies. Further AARM measurements are planned in the near future in order to understand better the tectonics of the Dukla nappe

Pleistocene climate and environment reconstruction by the paleomagnetic study of a loess-paleosol sequence (Cérna Valley, Vértesacsa, Hungary)

Abstract Four paleosol layers indicating wet and moderate periods and five loess layers indicating dry and cold climate were separated by different methods. The following climate cycle model, based on the development of the sediment sequence created by the influence of climatic, geologic and geomorphologic phenomena, was established by detailed paleomagnetic studies (e.g. anisotropy of magnetic susceptibility (AMS), isothermal remanent magnetization (IRM), frequency dependence of magnetic susceptibility (κFD), etc.): –A well-foliated magnetic fabric predominantly built up by multi-domain ferromagnetic minerals (magnetite, maghemite) was developed during the semi-arid (350–400 mm/y) and cold loessification period of the Pleistocene. The magnetic fabric can reflect the direction of dust deposition and/or the paleoslope. –The accumulation period of dust was followed by the more humid (650 mm/y) pedogenic period indicated by the enrichment of superparamagnetic minerals and by the disturbed or inverse magnetic fabric developed during pedogenesis by different processes (e.g. leaching and/or bioturbation). –The third period following the pedogenic period is the humid erosional phase indicated by the finely layered reworked loess. The magnetic fabric built up by multi-domain ferro- and superparamagnetic minerals is characterized by better-aligned directions of principal susceptibilities than in the wind blown material. Sheet wash and other waterlogged surface processes appeared in the fabric of these layers. This process is possibly connected to sudden, rare yet significant events with high precipitation and absence of vegetation. –The cycle was closed by the beginning of the next dust accumulation period

The role of compressional tectonics, sedimentary transport and mineral composition on AMS and AARM fabrics. A case study of the flysch from the Dukla nappe, OuterWestern Carpatians, Poland

The Carpathians belong to the European Alpine system. The Polish segment of the Western Outer Carpathians is a north-verging thrust-and-fold belt composed largely of Lower Cretaceous to Lower Miocene flysch. The belt comprises the Skole, Subsilesian, Silesian, Dukla and Magura rootless nappes. Anisotropy studies were carried out both in Oligocene turbidite sequences of the Dukla nappe and in the olistostrome of the Lipowica quarry. For the study 102 individually oriented cores were drilled at nine geographically distributed localities. At each locality mudstones/claystones were sampled, except Lipowica quarry, where silt and sandstone were also drilled. Because of the relatively low susceptibilities (1-3*10-4 SI), paramagnetic minerals can be important contributors to the AMS fabric. AMS and AARM measurements were carried out and the fabrics were compared. Despite of the weak AMS lineations, the mean lineation direction is well defined in all cases on site/locality level. With one exception where the lineation is perpendicular to the bedding plane (due to the presence of siderite), the AMS lineations can be interpreted as due to compressional tectonics. Concerning the AARM lineations they are highly scattered in the sandstone, show a tendency for alignment in the silt and some of the mudstone/claystone sites, and are well clustered in the other cases. The AARM lineations for four localities correlate to the AMS, and the local strike. The AARM lineation of the siderite bearing rock is also sub-parallel to the local strike. In the remaining cases the AARM linations are suspected to be related to sedimentary transport. Due to the lack of solemarks at most localities this will be investigated systematically with photo-statistical grain shape analysis in oriented thin sections. X-ray diffraction measurements also will be carried out to identify the paramagnetic contributors to the AMS. Acknowledgments: This work was partly financed by the Hungarian Research Fund (OTKA) project no. K105245 and from a joint project of the Academies of Science of Poland and Hungary

Determining clast and magnetic fabric of a subaqueous lahar deposit as a tool for reconstructing paleoflow directions and emplacement processes.

Flow-related fabric of a subaqueously emplaced laharic deposit (Rám Hill Pumiceous Sandstone) were investigated around the middle Miocene Keserűs Hill lava dome group (northern Hungary). A twofold methodology, consisting of image analyis on rock surfaces and low-field anisotropy of magnetic susceptibility (AMS), was used to determine large-scale flow paths and emplacement processes. In addition, comparative measurements of magnetic anisotropy were performed by using an MFK1-FA multifunction kappabridge with 3D rotator (Studynka et al. 2014) at Agico, Inc. (Brno, Czech Republic). The results indicate a very good agreement between the azimuths of a-axis of the most elongated clasts from image analysis and the orientation of K1 susceptibilities from the measurements of the two laboratories. This agreement of fabric direction obtained by the two different methods allows to draw the following implications: 1) Fabric direction-derived large-scale flow paths show a near-radial pattern around the proposed eruption centre (Karátson et al. 2007) of the Keserűs Hill lava dome group (Fig. 1). Thus, our new data on paleoflow directions quantitatively confirm the former, one central vent-dominated volcano-structural reconstruction which was proposed on the basis of facies analysis. 2) Aggradation from multiple lahar pulses is presumable due to the vertical variation of shear direction within the exposures

Reconstruction of early phase deformations by integrated magnetic and mesotectonic data evaluation

Markers of brittle faulting are widely used for recovering past deformation phases. Rocks often have oriented magnetic fabrics, which can be interpreted as connected to ductile deformation before cementation of the sediment. This paper reports a novel statistical procedure for simultaneous evaluation of AMS (Anisotropy of Magnetic Susceptibility) and fault-slip data.The new method analyzes the AMS data, without linearization techniques, so that weak AMS lineation and rotational AMS can be assessed that are beyond the scope of classical methods. This idea is extended to the evaluation of fault-slip data. While the traditional assumptions of stress inversion are not rejected, the method recovers the stress field via statistical hypothesis testing. In addition it provides statistical information needed for the combined evaluation of the AMS and the mesotectonic (0.1 to 10m) data. In the combined evaluation a statistical test is carried out that helps to decide if the AMS lineation and the mesotectonic markers (in case of repeated deformation of the oldest set of markers) were formed in the same or different deformation phases. If this condition is met, the combined evaluation can improve the precision of the reconstruction. When the two data sets do not have a common solution for the direction of the extension, the deformational origin of the AMS is questionable. In this case the orientation of the stress field responsible for the AMS lineation might be different from that which caused the brittle deformation. Although most of the examples demonstrate the reconstruction of weak deformations in sediments, the new method is readily applicable to investigate the ductile-brittle transition of any rock formation as long as AMS and fault-slip data are available

Paleomagnetic and magnetic anisotropy results from Miocene Sediments of Central and Western Serbia

In this paper we are presenting a combined paleomagnetic and magnetic susceptibility anisotropy study carried out on 133 independently oriented samples collected from 11 geographically distributed localities (Fig. 1). The samples were drilled and oriented in situ from clay rich lake sediments of pre-Late Badenian and Pannonian-Pontian age and from Early-Mid Badenian marine clay. The principal aims were to find out if the area studied was involved in large scale displacement during or after the time covered by the samples and if the sediments were affected by ductile deformation during young tectonic movements

An integrated magnetic susceptibility anisotropy (AMS) and structural geological study on Cenozoic clay rich sediments from the Transdanubian Range

Systematic structural and anisotropy of magnetic susceptibility (AMS) measurements were carried out on Cenozoic clay rich deposits from the Transdanubian Range, central part of the Alcapa Unit. The aim was to improve the knowledge on the Neogene tectonic evolution of the area and on the connection of the stress field and the magnetic fabric of the sediments. The measurements of AMS revealed dominant foliation with weak lineation for Middle Eocene-Lower Miocene sediments. The directions of AMS lineation are aligned either with the direction of NNE-SSW extension of a strike slip phase (30–19 Ma) or with the direction of NE-SW extension of the main rifting phase of the Pannonian Basin (19–14 Ma). The studied Late Miocene sediments have foliated AMS fabric, maximum and intermediate AMS directions are intermixed, and the AMS fabrics do not show any sign of tectonic deformation. In contrast, joints and faults were observed in the same rocks. Detailed structural analysis shows two extensional phases between ca. 10-4 Ma, with E-W to WNW-ESE and with NW-SE extension, respectively and the youngest neotectonic strike-slip phase. The contrast between the presence of markers of brittle deformation and the absence of tectonically induced AMS lineation is striking, since the same types of sediments in the South Pannonian basin show just the opposite. The explanation may be that northward moving and CCW rotating Adria caused strong compression in the southern Pannonian basin, resulting in ductile deformation of the clay-rich sediments and systematic reorganization of AMS texture while in our study area sediments of similar character and age were at a larger distance from the strongly deforming basin part