Maria Łanczont

New exposure of loess deposits in Boyanychi (Ukraine) — Results of thermoluminescence analyses

The loess site at Boynychi (the Volyn Upland) is of essential importance for the stratigraphy of Middle and Upper Pleistocene in Central Europe. The profile was recently dated by Fedorowicz and Prylypko in 2007 (parallel dating), and by Kusiak in 2009. The Upper Vistulian loesses are much thicker in the exposure from 2009 than in the earlier examined one (2007). The list of results obtained in the Gdańsk, Kiev and Lublin laboratories, respectively, can be divided in two. The first group contains the results obtained for the Horohiv and Korshiv pedocomplexes and for the loess from the penultimate glacial, which separates these pedocomplexes. The results from all laboratories are very similar and rather well describe the real age of dated deposits. The second group contains the widely differing results of dating of the Vistulian loesses. The TL ages obtained by Fedorowicz and Prylypko are considerably older than those obtained by Kusiak in the new exposure. The latter ones excellently correspond to the geologic-stratigraphic interpretation of the profile. Two incompatible series of TL dating results indicate that local variability of loess accumulation conditions in different stages of their formation may have resulted in incomplete luminescence zeroing of mineral material before deposition.

Mesopleistocene loess deposits in the Mamalyha 2 profile of Ukraine — interlaboratory comparison of the thermoluminescence dating results

The history of the interlaboratory comparison of TL dating results in Poland started in the 1980s. At that time the Lublin, Warsaw and Silesian laboratories made the first attempts at TL dating of the same loess samples from the Odonów profile. However, the cooperation ceased for many years due to great differences in the obtained TL age estimates. The next interlaboratory comparisons were made in the years 2000–2009 for the loess samples from several Polish (Dybawka, Tarnawce, Dankowice, Biały Kościół) and Ukrainian (Boyanychi, Halych, Velykyj Hlybochok, Yezupil) profiles. Most of the compared dates, obtained for the loess deposits from the Upper Pleistocene and younger part of the Middle Pleistocene, were consistent. This encouraged us to undertake the Gdańsk-Lublin interlaboratory cooperation in dating of 200-700 ka old loess deposits. Nine samples were taken from the Ukrainian profile Mamalyha 2 in 2009 for this purpose. The TL dating results indicate that comparable dates are obtained in two laboratories for loess deposits younger than 300 ka BP. The TL signal obtained in the Gdańsk laboratory for the samples older than 300 ka BP was saturated so such samples should not be dated by the multi-aliquot regeneration method. The results obtained in the Lublin laboratory for these deposits (489–682 ka) confirm that it is possible to date loess deposits older than 500 ka. It probably results from the use of total-bleach method with preheating at 160°C for the equivalent dose determination.

TL Ages of Loesses from the Last Two Glacials in Se Poland

TL Ages of Loesses from the Last Two Glacials in Se Poland Loesses cover a large area in SE Poland so their exploration is an important part of the palaeogeographical studies on Pleistocene. The research involves stratigraphic problems. At present, luminescence dating provides the greatest number of chronostratigraphic data concerning loesses. In this work we report TL ages of loesses from the last two glacial cycles in SE Poland, obtained in the TL Laboratory of the Department of Physical Geography and Palaeogeography, Maria Curie-Skłodowska University in Lublin after 1993. Samples for TL dating were collected in 11 loess profiles (2-9 samples in each site) in order to obtain additional information for stratigraphic interpretations deduced from paleopedological, lithological, structural, and other data. Basing on the comparison of 54 TL ages, we can determine age intervals, in which the dating results of similar values assemble, and then get general information about the periods of intensified Aeolian accumulation related to defined stratigraphic units. The TL ages of all samples were obtained using the total-bleach method (TB) for the determination of the equivalent dose.

PROBLEMS OF TL DATING OF THE MESOPLEISTOCENE LOESS DEPOSITS IN THE PODILLYA AND POKUTTYA REGIONS (UKRAINE)

In many papers different authors was described problem of systematic underestimation of TL ages for sediments older then 100 ka. We presented the results which probably are not significantly rejuvenated. This is another example of the TL dates made in Lublin laboratory which are likely in agreement with the stratigraphic interpretation. In 2002 Kusiak et al. published the TL ages ranging from 200 to 800 ka for the Zahvizdja loess profile in Ukraine. These first promising results of TL dating of so old deposits encouraged us to undertake further studies. In next years were discovered other Ukrainian loess profiles with the Middle and Lower Pleistocene deposits, among others in the Skala Podils’ka, Mamalyha and Vendychany sites. The thermoluminescence dating made for these profiles in the Lublin laboratory gave the next, after Zahvizdja, series of 15 TL ages ranging from 200 to 700 ka. This way we confirmed the possibility of TL dating of the deposits older than 400 ka BP.

The results of thermoluminescence dating in the Halych IIC (Ukraine) profile as the expression of the conditions of mineral material deposition

Many studies conducted in the last few years in Poland indicate that the results of thermoluminescence dating of loess are reliable and correspond well to their geological ages. They can form the basis for determination of the chronology of changes of palaeoenvironmental conditions. In this paper we report dating results from the Halych IIC profile (Halych Prydnistrov’ja region, Ukraine). Thermoluminescence dating of this profile gives new information about the influence of local conditions on the results of TL analysis. As much as 75% of the obtained results are distinctly overestimated, even by several hundred per cent, that is untypical of regional loess profiles. However, in the Halych Prydnistrov’ja region it is the second loess site in which such incompatibility of the expected age and thermoluminescence age is found. This fact indicates how this region is unique among the loess areas of SE Poland and NW Ukraine in respect of the conditions of mineral material transport and deposition. Further investigations are necessary to identify the reasons for regular overestimating of the TL results obtained for loess deposits of the Halych Prydnistrov’ja region.