Interaction between a Late Miocene andesitic dyke swarm and wet sediment in the Szoros Valley, Eastern Borsod Basin, Northeast Hungary

Magma/wet sediment interaction (e.g. autobrecciation, magma-sediment mingling, hyaloclastite and peperite-forming, etc.) is a common phenomenon, where hot magma intrudes into unconsolidated or poorly consolidated water saturated sediment. In the Eastern Borsod Basin (NE-Hungary) relatively small (2–30 m) subvolcanic bodies, sills and dykes with contact lithofacies zones were found generated by mechanical stress and quenching of the magma, and interacting with unconsolidated wet andesitic lapilli-tuff and tuff-breccia. Close to the contact between sediment and intrusions, thermal and mechanical effects may occur in the host sediment. Hydrothermal alteration and stratification of the host sediment were developed only locally along the contact zone, probably due to the paleo-hydrogeologic and paleo-rheological inhomogeneities of the lapilli-tuff–tuff-breccia deposits. Processes of magma/wet sediment interaction may be difficult to recognize because of limited exposure and/or certain similarities of the brecciated intrusions to the characteristics of the host sediment; hence detailed field work (geologic mapping or profiling) was required to demonstrate the subvolcanic origin of the brecciated andesite bodies

Determining the anisotropy of the hydraulic conductivity on sand samples

One of the most important properties of porous media is the so-called hydraulic conductivity. Hydraulic conductivity determinations are important for resolving hydrogeological problems, management and protection of groundwater resources, soil mechanics, geotechnics and environmental geology projects. In fact the hydraulic conductivity is a site specific parameter, which horizontal, vertical changes and directional dependence could have an affect significantly on the prediction of hydrodynamic, geotechnical or transport models. This paper present a comparison of hydraulic conductivity K values of unconsolidated fluvial sand samples collected at two sandpits near Nagykereki in the Berettyó–Körös region. The aim was to investigate whether anisotropy or with other words, directional dependence of hydraulic conductivity may occur or not. The K values were determined using laboratory permeameter as well as were calculated using empirical formulas of Beyer, Hazen and Zamarin. Undisturbed samples were taken from five directions: vertical, horizontal parallel and horizontal perpendicular to flow, and parallel and vertical to stratification and the hydraulic conductivity measurement was carried out using Eijkelkamp laboratory permeameter. After the measurement the undisturbed sand samples were dried and a mixed. With these new samples the measurement was repeated. For this study site it was found that definite hydraulic conductivity anisotropy cannot be observed, however small scale effects of stratification were detected. Hydraulic calculation methods based on grain-size distribution data cannot be applied to demonstrate anisotropy. The hydraulic calculations using Hazen and Beyer methods yielded almost the same values that were measured in laboratory on the samples with mixed stratification. Despite the fact that with the Zamarin calculation we got much smaller values they can be compared to the values of the natural stratification

Determining the anisotropoy of the hydraulic conductiviy on sand samples

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Szekunder karbonátok mennyisége és vertikális eloszlása tokaji talajszelvényekben

The forms and stocks of secondary carbonate accumulations and the distribution of secondary carbonate content were investigated in 20 soil profiles from Nagy-hegy, Tokaj. The secondary carbonate content varied to a great extent under different lithological conditions. The frequency of carbonate crusts coating the coarse fragments to a thickness of 1–7 mm was especially conspicuous. In selected profiles the amount of secondary carbonates was analysed separately for three carbonate pools: in the fine earth (−2) in the separate fractions of the fine earth, the skeletal fraction and the carbonate crusts and concentrations. The values obtained for the distinct soil horizons were then summed for the whole profile above the continuous hard rock. The loess deposits can be regarded as the primary source of calcium carbonate, but many types of secondary carbonate accumulations occurred in places where the loess deposits were completely eroded or the original surface of the soil was only preserved on terraces with retaining walls. The results suggest that the highest accumulation of calcium carbonate occurs in profiles where loess, redeposited loess or colluvial deposit covers weathered volcanic rocks (pyroxene dacite), resulting in lithological discontinuity. The carbonate crusts consisted of 55–96 % (m/m) CaCO3, and the coarse fraction (dacite boulders and blocks) also had a higher calcium carbonate content (5–10 % m/m) than the non-weathered pyroxene dacite. The calcium carbonate stocks in Calcic accumulation horizons proved to be 2.5 times higher than in the overlying soil horizons. The accumulation forms of carbonates in the soil profiles and the lack of loess deposits on the top of the soil profiles suggest that the calcium carbonate was accumulated in the transitional zone between the loess and the weathered volcanic rocks. This appears to have taken place under humid climatic conditions, unlike the recent climate, and can thus be regarded at least partially as the result of paleoecological processes

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A plutonista és neptunista iskolák hosszú ideig lezáratlan szakmai vitája óta eltelt több mint két évszázad alatt a magmás kőzettannal és vulkanológiával kapcsolatos tudásunk rendkívüli mértékben gyarapodott. Az egyre kifinomultabb műszeres vizsgálati módszerek alkalmazása, a recens folyamatok tudományos igényű megfigyelése, a laboratóriumi kísérletek eredményeinek felhasználása lehetővé tették a vulkáni kőzetek leírásán túl az azokat létrehozó vulkáni működés sajátos folyamatainak egyre mélyebb szintű ismeretét is. Általánosan elfogadott tény, hogy korszerű vulkanológia nem képzelhető el más tudományterületek (pl. geokémia, szedimentológia, szerkezeti földtan stb.) ismeretanyagának adaptálása nélkül, ami szükségessé teszi ezek eredményeinek nyomonkövetését, esetenként pedig vizsgálati módszereik vulkanológiai célú alkalmazását. Különösen igaz ez abban az esetben, ha a vulkáni képződényeket, valamint az azokat létrehozó folyamatokat ősföldrajzi környezetbe ágyazva szemléljük, kiterjesztve ezáltal vizsgálatainkat a különböző vulkáni- és vulkanoszediment fáciestársulások térbeli és genetikai összefüggéseire is. A fenti gondolatmenet szellemében készült disszertációban is e komplex értelmezés- és személetmódot igyekeztünk alkalmazni egy a hazai viszonylatban kevésbé kutatott ÉK-magyarországi terület, az ÉK-i Bükk-előtér vagy más néven Tardonaidombság példáján. A még hallgatóként elkezdett földtani térképező munka alapozta meg a kezdetben csak kisebb területi egységekre, később a Tardonai-dombság egészére kiterjesztett vulkanológiai vizsgálatainkat