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Uranium and polonium activities in karst water of the Niedźwiedzia Cave system (Sudety Mts.)

Gąsiorowski Michał, Hercman Helena, Sekudewicz Ilona, Mulczyk Anna

Annales Societatis Geologorum Poloniae

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2020

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Vol. 90, No. 4

505--512

EN

Polonium and uranium activities were measured in surface and karst water in the Kleśnica Stream catchment and the Niedźwiedzia Cave system (Sudety Mts., South-West Poland). The highest polonium concentration was recorded in surface water during flood events and in a sinter pool, located close to the touristic trail inside the cave. It points to a detrital source of the polonium and its transport in water absorbed by the clay fraction. Uranium activity increases downstream in the surface water of the Kleśnica Stream, indicating significant input of 234U and 238U from an area of outcropping marble. Water, autochthonous in the marble, that originated from precipitation and infiltration directly into the cave system is characterized by low uranium content. However, the uranium activity increases with the time of water percolation in the soil and epikarst zone and is higher at the lower cave level than at the upper and middle levels. Po and U activities were used as tracers for the area of water recharge and the mode of circulation. The results point to atmospheric precipitation as the almost exclusive source of water at the upper and middle cave levels, while water at the active level of the cave is a mixture of precipitation, infiltrating directly from the area above the cave passages, and horizontal flow, originating out of the marble outcrop.

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Record of the Pleistocene at karst sites of the Świętokrzyskie (Holy Cross) Mountains region – a review

Urban Jan, Hercman Helena, Ochman Katarzyna, Kasza Andrzej

Studia Quaternaria

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2019

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Vol. 36, Nr 2

87--108

EN

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.

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Carbon isotopes in wood combustion/pyrolysis products: experimental and molecular simulation approaches

Hercman Helena, Szczerba Marek, Zawidzki Paweł, Trojan Agata

Geochronometria

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2019

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Vol. 46, no. 1

111--124

EN

A series of laboratory experiments was performed to determine the carbon stable isotopic composition of different combustion/pyrolysis (B/P) products. Variation in the δ13C values of the products was observed, up to 4‰. The differences in the carbon isotopic compositions of the B/P products were dependent on temperature, time and wood type. Comparison of the results for fresh and fossil oak wood suggested that the δ13C differences were the effect of selective decomposition of some wood components during the fossilization process. The temperature dependence of the carbon isotopic composition was linked to variation in the carbon isotopic composition of the main wood components, which each had different levels of thermal stability. Isotopes exchange reactions in between different products can be also considered as possible source of variation of δ13C on temperature. Both these hypotheses were supported by molecular simulations of cellulose and lignin B/P. The results confirm that B/P should be treated as a continuous process, where the results depend on the degree of process development. Natural burning processes are dynamic and burning conditions change rapidly and it is necessary to take care when using combustion products as a paleoenvironmental proxy or as an isotopic characteristic for the identification of source material.

4

A continuous stable isotope record of last interglacial age from the Bulgarian Cave Orlova Chuka

Pawlak Jacek, Błaszczyk Marcin, Hercman Helena, Matoušková Šárka

Geochronometria

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2019

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Vol. 46, no. 1

87--101

EN

Recent research shows that the last interglacial climate was more unstable in comparison to Holocene. Lack of suitable dating techniques and precisely defined absolute age benchmarks is one from main problems for present LIG studies. Therefore many of LIG chronologies base on indirect dating techniques like record alignment strategies. In this context, speleothems are valuable paleoclimate archives because of their capability to be dated by U-series method. In Europe LIG speleothem records are known mostly from western and central part of the continent. In this paper we present a 1,650 mm long stalagmite (ocz-6) from Bulgarian Cave Orlova Chuka. The ocz-6 stalagmite records the period of time ca. 129–112 ka. Ocz-6 stalagmite was analyzed in terms of stable isotopic composition of calcite and trace elements content. All analyzed geochemical proxies point to dynamic changes in the environment during the Last Interglacial time. At the time of interglacial development (129–126.5 ka), ocz-6 records shows systematic change in proportion of moisture delivered from Atlantic source and other sources. The beginning of last interglacial optimum is connected with a rapid change to more humid and warm conditions. During interglacial demise local climate become more dependent from regional settings.

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Dating of the Holstejnskä Cave deposits and their role in the reconstruction of semiblind Holśtejn Valley Cenozoic history (Czech Republic)

Kadlec Jaroslav, Hercman Helena, Nowicki Tomasz, Głazek Jerzy, Vit Jan, Śroubek Pavel, Diehl Jimmy F., Granger Darryl

Geologos

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2000

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Vol. 5

57--64

EN

Large sections in cave deposits are exposed in the Holśtejnska Cave in the Moravian Karst (Czech Republic). The study of the genesis and age of these cave deposits poses a clue to the reconstruction of this cave system and of local paleohydrographic history. The time of deposition was determined by U-series dating of speleothems, 10Be and 26Al dating of quartz pebbles, radiocarbon dating of charcoal, measurement of paleomagnetic record in both clastic sediments and speleothems and by archeological evidence.