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Optically stimulated luminescence techniques applied to the dating of the fall of meteorites in Morasko

Moska P., Stankowski W., Poręba G.

Geochronometria

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2018

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Vol. 45, no. 1

74--81

EN

Geological materials used for luminescence dating and associated with the fall of meteorites on the Earth’s surface are extremely rare. The Morasko region has gained fame over the past 100 years because of a cosmic catastrophe which took place there. After thousands of years, the remains of a large metal meteorite which fell in this area have been found. In this article, we would like to state whether it is possible, using luminescence methods, to determine the moment when the iron meteorite fell on the surface of the Earth. The material which was analysed consisted of meteorite crust layers – melt/fusion and “semi melt/fusion”, including sintered ones, along with the sediments surrounding the meteorite. The final results are connected with four objects of different sizes (large ones and small shrapnel – 261 kg, 34 kg, 970 g and 690 g). The obtained results show a large discrepancy, which is most likely associated with the problem of resetting the luminescence signal of the tested materials.

2

Luminescence chronostratigraphy for the loess deposits in Złota, Poland

Moska P., Adamiec G., Jary Z., Bluszcz A., Poręba G., Piotrowska N., Krawczyk M., Skurzyński J.

Geochronometria

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2018

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Vol. 45, no. 1

44--55

EN

Loess formations in Poland display a close relationship with cooling and warming trends of the Northern Hemisphere during the Pleistocene. Loess sequences sensitively record regional palaeoclimatic and palaeoecological changes. The Złota loess profile (21°39’E, 50°39’N) provides a unique opportunity to reconstruct climate conditions in the past in this part of Poland. This continuous sequence of loess and palaeosol deposits allows to distinguish between warmer and more humid climate which is favourable for soil development and much colder and dry periods which are conducive to loess accumulation. The silty and sandy aeolian material originates mainly from weathered rock surfaces affected by frost shattering or from glaciofluvial/fluvial deposits of river flood plains. In Poland, loess and loess-like formations occur in the southern part of the country, mostly in the south polish uplands, i.e. in the Lublin, Sandomierz, and Cracow Uplands. We used different techniques to establish a chronological framework for this site. 21 samples for luminescence dating were collected from the investigated loess profile in Złota. Infrared post-IR IRSL dating method was applied to the polymineral fine grains (4–11µm). The dating results are accompanied by detailed analyses of the geochemical composition, organic carbon and carbonate. Also, analysis of magnetic susceptibility and grain-size distribution were investigated. Based on such a large stratigraphic dataset an age-depth model using OxCal has also been constructed for this site.

3

Impact of sand extraction from the bottom of the southern Baltic Sea on the relief and sediments of the seabed

Uścinowicz S., Jegliński W., Miotk-Szpiganowicz G., Nowak J., Pączek U., Przezdziecki P., Szefler K., Poręba G.

Oceanologia

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2014

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No. 56 (4)

857--880

EN

Investigations of the geological structure and seabed dynamics as well as the morphological and sedimentological effects of sand extraction generated by different mining techniques were carried out in Polish waters of the Baltic Sea, NW of the Gulf of Gdańsk, at a water depth of 15-17 m. Three research cruises took place: just before, directly after and 11 months after dredging operations. Seismoacoustic profiling, a multibeam echosounder, a side-scan sonar, a 3 m vibro-corer and a box-corer were used during the research cruises. The grain size distribution and 137Cs content of the sand samples were determined. Marine shells were dated by the AMS14C technique and pollen analyses were carried out on samples of muddy sands lying below the marine sand. A 2 to 4.5 m thick layer of marine sands lies on the boulder till and locally on late Pleistocene ice margin lake deposits. The 137Cs content indicates that the 0.4-0.8 m thick sand layer is mobile during storms. After the dredging operations, four pits with diameters from 80 to 120 m, depths from 3 to 4.5 m and slopes with gradients up to 30-55° were measured. Several smaller irregularly shaped pits and double furrows 30-150 m in length and 0.3-0.5 m in depth were found. The sonar mosaic also shows a 50-100 m buffer zone of fine sand around the pits which flowed over the dredger's side with water and settled on the bottom. During one year after the dredging operation the furrows generated by trailer suction hopper dredging as well as the fine sand cover around the pits disappeared completely. The four post-dredging pits left by stationary suction dredging were shallower by 2-2.5 m, their diameters increased by 40-50 m, the gradient of the slopes was reduced by up to 5-10°, and the total volume was only about 3.5% smaller than directly after dredging.

4

Combined IRSL/OSL dating on fine grains from Lake Baikal sediments

Moska P., Poręba G., Bluszcz A., Wiszniowska A.

Geochronometria

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2008

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Vol. 31

39-43

EN

In this work we present luminescence dating results obtained for samples taken from a gravity core of sediments of the Lake Baikal. The initial attempts to date coarse quartz grains failed because such grains were very sparse and dim. Fine grain quartz was also relatively dim and only IRSL signal from fine grain polymineral fraction was sufficient to obtain absorbed dose estimates. We made the measurements on 6-12 µm fraction extracted by differential precipitation in a water column. Samples were collected from the sediment depth range between 80-750 cm which, basing on paleomagnetic data, were expected to cover the period up to ca. 150 ka. The equivalent absorbed doses measured by means of OSL grow with depth down to 350 cm where they reach about 100-120 Gy and then apparently saturate. For the depth range 80-350 cm IRSL ages also grow almost linearly from 11 to 50 ka. Calibrated radiocarbon ages obtained for micro samples of pollen from the same site yielded an average sedimentation rate of 6.86±0.21 cm/ka for the period between 15-1 ka BP. This is in good agreement with the sedimentation rate deduced from IRSL dating (6.15±0.55).

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On the contribution of radioactive fallout isotopes to the total dose rate in dating of young sediments

Poręba G., Moska P., Bluszcz A.

Geochronometria

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2006

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Vol. 25

47-50

EN

Palaeodosimetric methods of dating, especially the OSL method, are now capable of dating very recent sediments, that if formed within the last 100 years, experienced a contribution to the absorbed dose from the fallout radioisotopes, the contribution that forms a significant portion of the total absorbed dose. The paper presents results of calculations of this contribution from the radioisotopes other than 137Cs and finds it of approximately the same magnitude as dose received from 137Cs alone, meaning that it should be taken into account in the case of high precision dating of recently formed sediments.

6

Gamma spectrometry for OSL and TL dating of loess deposits at Dybawka and Tarnawce (SE Poland)

Poręba G., Fedorowicz S.

Geochronometria

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2005

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Vol. 24

27-32

EN

This article presents a comparison of results from the activity measurements of loess samples obtained with two methods in two laboratories. The methods are semiconductor gamma radiation spectrometry and gamma radiation scintillation spectrometry. Various measurement geometries and various sets of radioactivity standards were applied. Samples were collected from two loess profiles, namely Dybawka and Tarnawce. The results of activity measurements for natural radioisotopes of uranium, thorium and potassium obtained in the Gliwice and Gdańsk laboratories are in good agreement. Additionally, the activity of 235U was measured in the analysed samples.

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Isotopic investigations of uppermost sediments from Lake Wigry (NE Poland) and its environment

Pawlyta J., Pazdur A., Piotrowska N., Poręba G., Sikorski J., Szczepanek M., Król K., Rutkowski J., Hałas S.

Geochronometria

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2004

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Vol. 23

71-78

EN

This paper presents the results of the first isotopic investigations of sediments recovered from Lake Wigry (NE-Poland). In the spring/summer 2002 few sediment cores, plant samples and water profiles were collected specially for isotopic investigations. We obtained 210Pb activity profiles, 137Cs activity profiles and 14C activity/age profiles. Apparent ages of carbonate fraction for all sediment cores were determined. Sedimentation rates for collected cores were estimated using 14C dating method. In addition oxygen isotopic ratios of the water profiles, carbon stable isotopes ratio of collected sediment cores were determined.

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Concentration and vertical distribution of 137Cs in agricultural and undisturbed soils from Chechło and Czarnocin areas

Poręba G., Bluszcz A., Śnieszko Z.

Geochronometria

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2003

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Vol. 22

67-72

EN

This paper presents the results of measurements of 137Cs in soil profiles which were sampled in the Chechło and Zalesie areas, on the Proboszczowicka Highland, Poland, May 2002. Samples were collected from four soil profiles, three of them were taken on the cultivated field and one on the undisturbed field. The vertical distribution of 137Cs in collected profiles and the 137Cs inventory for all locations have been determined. The pH of soils (in distilled H2O and KCl solution) and the organic matter content of soil samples were also measured. Caesium concentration ranged from 0.0 to 15.37 Bq/kg and from 0.0 to 101.61 Bq/kg in soils from cultivated and undisturbed sites, respectively. The measured 137Cs deposition has been compared with the nuclear weapon tests caesium fallout. The obtained results show that the Chernobyl 137Cs fallout had relatively large contribution to total 137Cs deposition in the study areas.