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    Wyświetlanie 1-6 z 6
    Tytuł:
    Reconstruction of palaeoclimatic changes in Central Europe between 10 and 200 thousand years BP, based on analysis of growth frequency of speleothems
    Autorzy:
    Hercman, Helena
    Powiązania:
    https://bibliotekanauki.pl/articles/2026763.pdf
    Data publikacji:
    2000
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    U-series dating
    speleothems
    palaeoclimatology
    speleothem growth frequency
    Opis:
    The present study is an attempt to utilise the uranium-thorium dates ofspeleothems as a source ofpalaeoclimatic data. The clue is that the changing climate influenced intensity of speleothem deposition, which is reflected in clustering of U-Series dates of speleothems in certain time intervals. This work discusses and improves various methods of combined presentation of dates, with a special attention to the presentation in form of growth frequency ('pdf) curves. Using the 'bootstrap' method the confidence intervals of the 'pdf' curves could be determined. Also the algorithm, originally developed to determine parameters of arbitrarily chosen maxima in the curve, has been modified. Due to that an assessment of number of maxima has been possible. This method enables objective distinction of phases of speleothem growth, which cannot be done 'by eye' when the 'pdf' curve is smooth. The statistical tests show that the reliable 'pdf' curve should contain more than 150 dates. Basing on 308 U-series dates of cave speleothems from southern Poland and other regions of central Europe, the growth frequency curves for the Carpathians and Uplands have been constructed. Comparison of phases of speleothem growth, distinguished by various authors for several regions of Europe, indicates that the climatic changes were synchronous over the whole region. However, different shapes of the 'pdf' curves reflect increasing continuity ofspeleothem growth in the N-S transect southwards. This may be connected with the N-S climatic gradient in Europe. Using the 'pdf' curves from caves of Tatra and Low Tatra Mountains the most probable timing of development phases ofmountain glaciers has been delimited.
    Źródło:
    Studia Quaternaria; 2000, 17; 35-70
    1641-5558
    2300-0384
    Pojawia się w:
    Studia Quaternaria
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Cryogenic carbonates and cryogenic speleothem damage in the Za Hájovnou Cave (Javoříčko Karst, Czech Republic)
    Autorzy:
    Žak, K.
    Lipták, V.
    Filippi, M.
    Orvošová, M.
    Hercman, H.
    Matouškova, Š.
    Powiązania:
    https://bibliotekanauki.pl/articles/2060084.pdf
    Data publikacji:
    2018
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    cryogenic cave carbonates
    speleothem damage
    Javoříčko Karst
    U-series dating
    Opis:
    A new locality of coarse-grained cryogenic cave carbonates has been found in the Za Hájovnou Cave in Javoříčko Karst in Central Moravia, Czech Republic. Crystals and crystal aggregates, usually up to 15 mm in size, form typical loose accumulations on the surface of large fallen limestone blocks and clays covering the bottoms of several cave chambers distant from the cave entrance. The cryogenic origin of the carbonates is supported by their mode of occurrence, specific crystal and aggregate morphology, and C and O stable isotope data. U-series dating of one sample of cryogenic carbonate (age 29.5 ±0.1 ka) indicated that a period of karst water freezing occurred in marine isotope stage (MIS) 3, within the Weichselian. The cave also hosts numerous examples of speleothem damage. As shown in this paper, some of these are clearly connected with freezing conditions and cave ice action.
    Źródło:
    Geological Quarterly; 2018, 62, 4; 829--839
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    New isotopic data on karst development in the northern Kraków-Wieluń Upland (southern Poland)
    Autorzy:
    Hercman, H.
    Gąiorowski, M.
    Sujka, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/191296.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    Kraków-Wieluń Upland
    caves
    speleothems
    U-series dating
    karst development
    Opis:
    The Kraków-Wieluñ Upland is one of the major palaeokarst regions in Poland. However, the stages of karst development in this area are neither well documented nor reconstructed. A series of samples from a new location in the vicinity of Raciszyn was analysed. On the basis of the results of U-series dating, four phases of speleothem deposition were distinguished: (1) older than 600 ka, (2) from more than 600 ka to 290 ka, (3) around 150 ka, and the youngest (4), younger than 3 ka. On the basis of all geochronological data from the region, eight stages of karst development were described. The structure of the oldest speleothems indicates even more stages of deposition and erosion that cannot be recognized using the 230Th/234U dating method. These results indicate that the initial creation of empty spaces in the limestone took place in pre-Pleistocene time. After 600 ka ago, climatic conditions were stable for more than 300 ka, allowing the continuous deposition of speleothems. Several episodes of erosion, deposition of clastic sediments and speleothem growth during the Middle and Early Pleistocene were described. This variability of the sedimentation regime clearly reflects climate changes during that period.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2016, 86, 4; 429-436
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Record of the Pleistocene at karst sites of the Świętokrzyskie (Holy Cross) Mountains region – a review
    Autorzy:
    Urban, Jan
    Hercman, Helena
    Ochman, Katarzyna
    Kasza, Andrzej
    Powiązania:
    https://bibliotekanauki.pl/articles/2025126.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    karst sites
    caves
    U-series dating
    Pleistocene
    Świętokrzyskie (Holy Cross) Mountains
    Opis:
    The objective of this paper is a review of data on reconstruction of the Pleistocene palaeogeography (environment) and stratigraphy based on studies of karst sites in the Świętokrzyskie (Holy Cross) Mountains. Although the number of known Pleistocene karst sites in this region is small, the investigations of them have played a crucial role in a research of the Pleistocene. The study of the Kozi Grzbiet site provided the first evidences for new climatostratigraphy and classification of glaciations in Poland. The explanation of genesis of cryogenic calcite crystals discovered in Chelosiowa Jama-Jaskinia Jaworznicka cave system started a new direction of palaeoenvironmental reconstructions of the last glacial period. Kadzielnia palaeontological site was one of the first Early Pleistocene fossil assemblages in karst studied in Poland, whereas Raj cave provided abundant palaeontological and archaeological material from the Last Glacial. Other sites are of less scientific importance, however some of them can be used in education and popularisation of geosciences. Small number of already studied sites does not exclude discoveries of next sites of high scientific importance.
    Źródło:
    Studia Quaternaria; 2019, 36; 87-108
    1641-5558
    2300-0384
    Pojawia się w:
    Studia Quaternaria
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pleistocene speleothem fracturing in the Western Carpathian orogenic foreland : A case study from transtensional setting at the eastern margin of the Bohemian Massif
    Autorzy:
    Babek, O.
    Briestenský, M.
    Přecechtělová, G.
    Štěpančíková, P.
    Hellstrom, J. C.
    Drysdale, R. N.
    Powiązania:
    https://bibliotekanauki.pl/articles/2059654.pdf
    Data publikacji:
    2015
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    speleothems
    U/Th series dating
    palaeoseismicity
    Pleistocene
    Bohemian Massif
    Western Carpathians
    Opis:
    We studied speleothem-fracturing styles and their tectonic context in three cave systems situated in the eastern Bohemian Massif, close to the Western Carpathians orogenic front: the Za hájovnou, Javoříčko, and Mladeč caves. The morphology of the speleothems in particularly thin stalactites, and supporting evidence from the cave interior, indicates a tectonic origin of the breakage. U/Th series dating of the stalactites, supported by Optically Stimulated Luminiscence (OSL) and 14C dating of soft sediments indicate that most of the fracturing occurred in the Upper Pleistocene, with the last fracturing events corresponding to MIS6 and MIS5 stages. OSL dating of faulted soft-sediment infill may even indicate that latest Pleistocene to Early Holocene tectonic events occurred in the Mladeč Cave. The speleothem fracturing is discussed in the regional context of the seismically active Nysa-Morava Zone situated at the junction between the Bohemian Massif (Elbe Fault Zone) and the Western Carpathians. This study provides the first evidence of palaeoseismicity from the subsurface and the oldest dated palaeoseismicity from the contact between the Western Carpathians and the Bohemian Massif.
    Źródło:
    Geological Quarterly; 2015, 59, 3; 491--506
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evolution of the Bystrej Valley caves (Tatra Mts, Poland) based on corrosive forms, clastic deposits and U-series speleothem dating
    Autorzy:
    Kicińska, D.
    Hercman, H.
    Najdek, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/191650.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    cave evolution
    scallops
    heavy minerals
    U-series speleothem dating
    palaeohydrology
    Tatra Mts.
    Opis:
    The origin and age of cave deposits, as well as palaeogeographical changes in the Bystrej catchment during the last ca. 250 ka, were reconstructed in Magurska, Kasprowa Niżnia, Goryczkowa, Kalacka and Bystrej caves (the Bystrej Valley). The reconstruction is based on the study of corrosive forms, heavy mineral analyses and U-series dating of speleothems. Two generations of palaeoflows were distinguished by observations of scallops and heavy mineral analyses. In the older stage, now abandoned caves drained massifs surrounding the Bystrej Valley and part of an adjacent valley. The direction of palaeoflow changed as a result of the water capture after Kasprowa Niżnia Cave came into being. In the later stages, the evolution of cave systems was controlled by glaciation-deglaciation cycles. Probably at this time, some caves located in the lowest parts of the massifs also started to be formed. U-series speleothem dating allows the determination of five phases of speleothem deposition: ca. 220–150 ka, ca. 135–105 ka, ca. 95–70 ka, ca. 40–23 ka and during the Holocene.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2017, 87, 1; 101-119
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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