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- Author or Editor: Rózsa Péter x
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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 mm), in carbonate crusts and other concentrations, and in the skeletal part of the soils (dominantly dacite blocks and boulders). In one profile a calculation was made of the calcium carbonate stocks (in kg m−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.
Quartz grains from the Ries impact structure containing shock-induced microstructures were investigated using Scanning Electron Microscopy in cathodoluminescence (SEM-CL), secondary electron (SEM-SE) and back-scattered electron (SEM-BSE) modes as well as Mott–Seitz analysis. The purpose of this study is to evaluate the mechanism by which CL detects Planar Deformation Features (PDFs) in quartz, which is one of the most important indicators of shock metamorphism in rock-forming minerals. PDFs are micron-scale features not easily identified using optical microscopy or scanning electron microscopy. The CL spectrum of PDFs in quartz that has suffered relatively high shock pressure shows no or a relatively weak emission band at around 385 nm, whereas an emission band with a maximum near 650 nm is observed independent of shock pressure. Thus, the ~385 nm intensity in shocked quartz demonstrates a tendency to decrease with increasing shock metamorphic stage, whereas the 650 nm band remains fairly constant. The result indicates that the emission band at 385 nm is related to the deformed structure of quartz as PDFs.
Obsidian samples from different localities of various geologic settings (Armenia, Hungary, Iceland, Mexico, Slovakia and Turkey) were analyzed by particle induced gamma-ray emission (PIGE) technique and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Samples from Mexico and Iceland show higher alkali and REE content as well as higher Nb and Ta abundances than the other samples. Discrimination diagrams show samples from Mexico and Iceland to belong to WPG. The position of the samples from the Tokaj Mts is also definite, and it corresponds to the expectation (VAG or VAG+syn-COLG fields). Using a Li-B diagram the obsidian samples can be distinguished according to their geographic distribution. By means of a Ce-Ti diagram, obsidian from the Tokaj Mts can be divided into three groups that may correspond to the archeometrical C2E, C2T and C1 groups. Phenocrysts in the obsidian samples from the Tokaj Mts, and the Aragats Mts (Armenia) were detected and analyzed by micro-PIXE (proton induced X-ray emission) method. In this way silicate minerals (zircon, pyroxene, biotite, plagioclase feldspars), ore minerals (chalcopyrite, pyrrhotite, pyrite), and other non-silicate mineral (anhydrite) were identified.
Impact material, especially magnetizable tiny grains (spherules, globules and platelets) of Barringer Meteor Crater (Arizona) was studied by combined nuclear analytical techniques. The samples were analyzed first by micro-proton-induced X-ray emission (PIXE) and deuteron-induced gamma-ray emission (DIGE) methods. In this way it was possible to determine the distribution of elements down to carbon. Using micro-synchrotron radiation X-ray fluorescence technique (SRXRF) we could determine medium and high atomic number trace elements such as the platinum-group metals. Our methodological developments made it possible for the first time to carry out quantitative analysis for more than 40 elements, providing new perspectives for the interpretation of the impact materials. Various compositions of the findings around the Barringer Crater were compared to analytical data of similar objects found in Carpathian Basin to elucidate their origin. This paper summarizes the more important results obtained by using ion beam microanalytical techniques.
