Volume 27 (2007): Issue -1 (June 2007)

The new version of a double-vacuum crucible for fusion of small samples of refractory minerals has been described recently by Halas (2006). This novel type of high temperature crucible was further improved in the following important points: (1) The expensive material, tantalum, was replaced by much cheaper molybdenum which also appears to be significantly less corrosive in the presence of hot boron nitride ceramic used as the insulator, and (2) a versatile temperature controller was assembled from commercially available components.

The Strzegom-Sobótka Variscan Massif (Fore-Sudetic Block, NE Bohemian Massif) consists of various post-kinematic Variscan granitoids emplaced into Palaeozoic low grade metamorphic rocks. Biotite from five samples representing the hornblende-biotite monzogranite, biotite monzogranite and biotite granodiorite has been dated using the K-Ar method for two size-fractions (0.25-0.35 and 0.35-0.5 mm). Finer fractions show more intense chloritization and therefore the results for them were rejected in further discussion. Coarser fractions with higher potassium content were accepted as yielding a maximum estimate approaching the true K-Ar biotite cooling ages. The results are clustered in two groups. The older age group (308.8±4.6 Ma and 305.5±4.3 Ma) comprises results obtained from the biotite granodiorites. They are generally consistent with the zircon crystallization age of 308.4±1.7 Ma reported by Turniak et al. (2005) and imply rapid cooling of the biotite granodiorite from magmatic temperatures down to the closure temperature of K-Ar isotopic system in biotite. The younger group is defined by 291.0±4.4 Ma and 298.7±5.2 Ma ages for the hornblende-biotite monzogranite and 294.2±4.3 Ma age for the biotite monzogranite. In the absence of precise U-Pb or Pb-Pb zircon data further geochronological studies are needed to decipher precisely the cooling history of the monzogranites.

This study presents the results of radiometric K-Ar measurements on separated amphiboles from the andesite of the Dubie complex dyke. The data obtained cover the period of (291.3 ± 6.4) Ma, which corresponds to Carboniferous-Permian transition. The age is contemporaneous to the rhyodacitic and basaltoid volcanism of the Kraków region.

In the Outer Carpathians in Barnasiówka radiolarian shale formation, there is an intercalation underlied by bentonite. There were found very rare elements and minerals in this intercalation. It was recognized that this horizon has been filled with products of a big object collision with Earth. The age of the manganese-iron intercalation was determined by potassium-argon (K-Ar) dating of illites to be (89.3±1.2) Ma. Similar age, (85.2±0.6) Ma, was found for the post-impact glass from the Boltysh crater in Ukraine. It was concluded that the formation of this intercalation was synchronous with the Boltysh crater formation at the Cenomanian/Turonian boundary. The research for the K-Ar age of the crater creation in Logoisk (Belarus) established its formation to (124.2±1.2) Ma ago.

A newly acquired mass spectrometer MI 1201 by the Mass Spectrometry Laboratory will be adapted to determine rhenium and osmium isotope concentrations using negative thermal ionization mass spectrometry (NTIMS). We describe the principle of the Re-Os dating technique and the thermal ionization phenomena which lead to high precision isotope analysis on NTIMS.

The author collected 26 samples from six loess profiles located in Poland and Ukraine and 16 samples from three galcigenic profiles in Lithuania. TL and OSL dates were obtained for the samples. The TL dates were calculated in the Gdańsk University laboratory and the OSL dates were obtained by the Institute of Physics Laboratory at the Silesian Technical University. The dating results were referred to the OSL = f(TL) chart. In respect of luminescent dating results, the Upper Vistulian loess shows a high similarity of TL and OSL dates. It means that loess formation took place in conditions conductive to ensure that solar radiation the grains were exposed to reduce the energy accumulated in them. The TL dates of Middle and Upper Vistulian loess are slightly older than the OSL dates. The largest discrepancies were found in soil sample dates. The analysis of glacigenic profile dates is not unambiguous. The fact that the TL dates are older than the OSL dates may mean that during deposition the conditions were not sufficiently conductive to reduce the energy stored earlier in the grains examined with the TL method. This time could have been sufficient to reduce the energy examined with the OSL method.

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.

Distinctly diverse results of TL dating are obtained for the deposits with similar lithofacial features but filling morphologically differentiated karst palaeoforms (dolines, pipes, pockets). The infillings of dolines and pipes are mostly of the Saalian age. Based on sedimentological analysis, their formation conditions are related to sub- or/and terminoglacial environment. The age obtained for all infillings of pockets is underestimated in comparison with lithostratigraphic data. A close genetic relationship between these forms and periglacial conditions seems to indicate that the reduction of TL signal is mostly influenced by the disintegration of grains resulted from the repeated freezing and thawing of glaciogenic deposits. A considerable influence of frost weathering on the decrease of thermoluminescence intensity of mineral grains is indirectly confirmed by the results of experimental investigations consisting in the repeated TL measurements of pockets' infillings after successive freeze-thaw cycles.

In this paper, a lithological study taking into account trace metals of the profundal sediments from Słupiańska Bay in Wigry Lake is presented. A profile 5.26 m long has sandy muds at the bottom and moving upwards layers of calcareous gyttja, lacustrine chalk, and again calcareous gyttja are present. The profile is continuous, typical for the sediments of NE Poland formed from Allerøde to recent time. The results of the lithological analysis were correlated with results of high-resolution seismic survey. The results together with radiocarbon dating are part of interdisciplinary complex research comprising paleobiological study of pollen, Cladocera, diatom successions and human activity, which will be published in successive papers.

The Late Glacial and Holocene development of vegetation in the vicinity of the Wigry Lake is reconstructed using pollen analysis. The Late Glacial sediments include the Allerød and Younger Dryas chronozones. The Holocene section is complete. Pollen data combined with archaeological evidence and radiocarbon dating permit the recognition and characterisation of human influence on the local plant cover caused by settlers of Mesolithic and Neolithic cultures, by west Balts, by Grand Dukes of Lithuania and by Cameldolites order. On the basis of pollen analysis the development of aquatic and mire vegetation in the Wigry Lake is described.

Environmental changes in Wigry Lake during the Late Glacial and Holocene were studied on the basis of subfossil Cladocera analysis. Cladocera are present in a long core WZS/03 (Słupiańska Bay), and a surface sediments. The sediment contains remains of twenty-seven species belonging to 5 families. Species composition of plankton and the variability in the frequency of specimens of Cladocera made possible to distinguish five phases of their development, which well correlated with palynological phases. The correlation proves that the biological development of Wigry Lake was determined mainly by climatic changes. During the history of the lake, planktonic forms were dominant and represented by Bosminidae. It indicates that the lake was (excluding the initial part) deep and oligo- or mesotrophic. The mesotrophic state has been noted during the Atlantic chronozone and temporary. Taking into consideration the size and the depth as well as the rare human population around the lake it can be stated that the trophy rise was the result of the warm climate. It is also possible that during the last few decades the natural and anthropogenic factors could add. Probably mild winters, warm and long summers, increased tourists number were partly responsible for changes of water state.