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Radiocarbon dating of organic-rich deposits: Difficulties of paleogeographical interpretations in highlands of Russian Altai

Nepop R.K., Agatova A.R., Bronnikova M.A., Zazovskaya E.P., Ovchinnikov I.YU., Moska P.

Geochronometria

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2020

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Vol. 47, no.1

138--153

EN

The high mountainous southeastern part of Russian Altai is characterized by complicated sedimentation history. As a result of tectonic movements, Paleogene, Neogene, and even more old Carboniferous and Jurassic organicrich deposits had been partly uplifted and exhumed on the ridge’s slopes, where during the Pleistocene, they were affected by various exogenous processes including glaciation, glacio-fluvial erosion, winnowing activity of ice-dammed lakes, sliding during lake-draining events, followed by further intensive Holocene erosion, pedogenesis, and permafrost formation/degradation. Remobilized ancient organic matter had been involved into geomorphic and pedogenesis processes and affected the results of radiocarbon dating. Numerous radiocarbon ages obtained revealed several typical problems in interpretation of dating results, which was confirmed by multidisciplinary investigations of associated sediments in a wider regional context. This article presents a discussion on obtained apparent radiocarbon dates of organic material from ten sections of the SE Altai. In addition to radiocarbon analysis, in each case multidisciplinary study was carried out in order to properly interpret obtained dates, as well as to explain the inability of directly using apparent 14C ages as a geochronological basis for paleogeographical reconstruction. The analysis presented is of vital importance for establishing the chronology of formation of large ice-dammed lakes and their cataclysmic draining; revealing chronology and paleoenvironmental conditions of pedogenesis in the highlands of the SE Altai; and estimating the range and magnitude of the tectonically driven topography rebuilding in the post-Neogene time.

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Luminescence dating of the Volochysk section : a key Podolian loess site (Ukraine)

Fedorowicz S., Łanczont M., Mroczek P., Bogucki A., Standzikowski K., Moska P., Kusiak J., Bluszcz A.

Geological Quarterly

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2018

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Vol. 62, No. 3

729--744

EN

The Volochysk site belongs to important and unique loess sites in the Podolia Upland (W Ukraine) because it contains relatively well-developed loess deposits representing the last and penultimate glacial cycles. This loess-palaeosol sequence consists of pedocomplex S1 (MIS 5) developed on loess L2, and loess L1 (MIS 4-2) with the palaeosols of lower, interstadial rank. In this sequence, different periglacial structures were found, including the largest ones of ice-wedge cast type. Different quartz and polymineral fractions separated from the samples collected in the Volochysk site were dated using luminescence methods (SAR OSL, post-IR IRSL and TL) in three Polish luminescence laboratories in Gdańsk, Gliwice and Lublin. In total, 69 luminescence dating results were obtained for 18 samples. The methodological and research aims were to carry out mutual verification of the obtained dating results as well as to analyse and interpret the differences between them, and to determine the age of distinguished deposit layers and the period of cryogenic activities. The luminescence dates of the sediments, which were deposited during MIS 2, 3 and 4, corresponded fairly well to the ages attributed to these stages. They also indicate the age of periglacial phenomena. However, the TL dates were generally older than the OSL ones, especially those obtained for the sediments deposited during MIS 5 and 6. The results of the research of the Volochysk sequence were compared with those obtained in past years for the loess deposits of the Volhynian Upland (north of Podolia) during similar inter-laboratory analyses conducted to determine their age. The results of OSL datings of the older deposits (MIS 5 and MIS 6) are underestimated irrespective of the used method, and the type (quartz, polymineral) and size of grains. Numerous attempts were made to explain this phenomenon, which, however, give no answer. It was only found that this underestimation corresponded to the equivalent dose value of ~150 Gy.

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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.

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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.

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The Epigravettian and the Magdalenian in Poland: New chronological data and an old problem

Wiśniewski A., Połtowicz-Bobak M., Bobak D., Jary Z., Moska P.

Geochronometria

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2017

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Vol. 44, no. 1

16--29

EN

The aim of the paper is to present a new chronological model of recolonisation of the area located north of the Sudetes and the Carpathians after Late Glacial Maximum (LGM). Until recently, it was believed that reoccupation of these areas occurred only due to the Magdalenian people. New chronometric data (radiocarbon and optoluminescence ones) coming from the Magdalenian and Epigravettian sites together with the application of Bayesian modelling of new records allowed us to present another model. In the light of the new research, it seems that the groups classified as the Epigravettian and Magdalenian could have coexisted at the same time in the same areas. The new model states that it is possible to assume coexistence of these groups during the period of 2300 years between 16500 and 14200 years BP.

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OSL chronostratigraphy for loess deposits from Tyszowce – Poland

Moska P., Adamiec G., Jary Z., Bluszcz A.

Geochronometria

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2017

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Vol. 44, no. 1

307--318

EN

The presented work concerns a loess profile located in Tyszowce, in the eastern part of Poland on the Volyn Upland, close to the Ukrainian border. The investigated loess formation is well preserved and is characterised by clear stratigraphic units providing an opportunity to refine the loess chronostratigraphy in Poland. In the paper, we present luminescence ages of loess from the last glacial cycle in SE Poland (up to about 100 ka) together with seven radiocarbon ages. Twenty-one samples were collected and dated using infrared (post-IR IRSL) and blue light stimulated luminescence dating. Two fractions were used, namely polymineral fine grains (4–11 μm) and medium sized quartz grains (45–63 μm). The obtained luminescence ages show very good agreement of both methods in relation to loess deposits, however for the fossil soil units the post-IR IRSL method yields older ages. Radiocarbon dates also confirm luminescence chronostratigraphy for younger units. Moreover, the luminescence results are supported by detailed analyses of grain size distribution, carbonate content and magnetic susceptibility variations allowing to create a comprehensive picture of chronological evolution of this site.

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Optical dating and sedimentary record from the terrace depositional profile of the Warta River (Central Poland)

Dzieduszyńska D., Petera-Zganiacz J., Twardy J., Kittel P., Moska P., Adamiec G.

Geochronometria

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2014

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Vol. 41, no. 4

361--368

EN

Results of OSL dating and sedimentary studies from the profile of the low alluvial terrace of the middle Warta River are presented. The samples were dated using the single-aliquot regenera-tive method. Dating was used to establish a timing of the Weichselian Late Glacial events in the river valley environment. Stable conditions on the floodplain are expressed by the deposition of organic-rich series radiocarbon dated at 12 900-12 600 cal BP and 11 600-10 770 cal BP. Samples for OSL dating were collected from the mineral material deposited during the intensification of flood events during the Weichselian decline. The results obtained for the alluvia range from 12.78 ± 0.62 ka b2k to 14.33 ± 0.74 ka b2k. Sedimentological criteria allowed to distinguish between particular flood events. Overestimation of OSL ages is probably a result of rapidity of environmental changes in that time.

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OSL dating and lithological characteristics of loess deposits from Biały Kościół

Moska P., Adamiec G., Jary Z.

Geochronometria

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2011

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Vol. 38, no. 2

162-171

EN

Absolute dating using luminescence methods is widely applicable in geology, geomor-phology, palaeogeography and in archaeology in establishing ages of sediments and archaeological artefacts. By creating absolute time scales for different events in the history of Earth scientists are able to reconstruct changes in climate and environment in the past, and the history of colonization and development of culture. Grain size is the most important loess lithologic property. Grain size composition depends mainly on factors connected with depositional processes (i.e. variety of source areas, distance from source areas, frequency and intensity of dust transporting winds). The influence of post depositional processes on changes in grain size composition seems to be of less importance with the exceptions for warm and long periods of intensive pedogenesis, which are favorable for formation of clay minerals. Therefore the grain size differentiation within thick loess sections may be used as a proxy record of climate changes during loess cover development. Here we present results for 12 samples dated at the profile at Biały Kościół. Obtained OSL results in some cases are quite different as compared with the OSL and TL dates obtained during last 10 years by other authors and presented in previous publications relating to this loess profile.

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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.

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The Influence of cesium activity on the annual dose for OSL dating

Moska P., Poręba G. J., Bluszcz A.

Geochronometria

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2004

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Vol. 23

15-19

EN

Introduction of single aliquot protocols dramatically improved the accuracy of absorbed dose measurements, so now dating of very recent events, which ages are of the order of tens of years or even single years, becomes possible. The overall accuracy of the OSL age is now limited by the correct assignment of the dose rate. Certain types of recent sediments may contain fall-out radioisotopes that increase the average annual dose. In this paper we demonstrate that the contribution from fall-out radioactivity may be significant and the way to take it into account by using a modified age equation.