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1
Content available The crust structure of the Morasko meteorite – a preliminary hypothesis
Stankowski W. T. J.
Geologos
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2017
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Vol. 23, No. 1
53--56
EN
A small piece of the Morasko meteorite, weighing 970 g, yields traces of its journey through the Earth’s atmosphere and of its impact into a mineral substrate, such as reflected in the meteorite’s crust. This is seen in the crust structure in the form of sintered as well as fusion and semi-fusion layers for which ablative niches are optimum sites. Subsequent weathering processes have resulted in significant mineralogical changes in the crusts. The meteorite crusts originated during polygenetic processes.
2
Content available Dating the Morasko meteorite fall by natural thermoluminescence of the fusion crust
Fedorowicz S., Stankowski W. T. J.
Geologos
|
2016
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Vol. 22, No. 3
251--258
EN
The date of fall of the Morasko iron meteorite was determined by means of thermoluminescence measurements of the fusion crust and related local materials. Three small pieces, commonly referred to as ‘shrapnel’, were used. The results obtained are 4.5–5.0 ka, which is in good agreement with previous estimates of 4–6 ka on the basis of radiometric, dosimetric and palynological methods.
3
Content available The extraterrestrial matter falls in west-central Poland (Great Poland Lowland); historical and geological data
Stankowski W. T. J.
Acta Geologica Polonica
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2015
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Vol. 65, no. 2
263--268
EN
Direct and indirect evidence of falls of extraterrestrial matter in west-central Poland (Great Poland Lowland) is proved historically and environmentally. The chronological list of such events has historical (documents, medieval paintings, newspaper reports), geological and morphological documentation. The most important are the environmental sites of Morasko/Oborniki, Przełazy and Jankowo Dolne, where metallic meteorites were recognized. These meteorite falls represent a series of cosmic events: the Morasko fall was c. 5000 years BP, the Przełazy fall was c. 10000 years BP, and the age of the Jankowo Dolne fall is not fully documented.
4
Content available remote Dating of the reo site (Island of Saaremaa, Estonia) with silicate and iron microspherules points to an exact age of the fall of the Kaali meteorite
Moora T., Raukas A., Stankowski W. T. J.
Geochronometria
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2012
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Vol. 39, no. 4
262-267
EN
Pollen analyses and radiocarbon dates from the bottom sediments in the Kaali main crater suggested that the crater group is at least 4000-5000 years old. Investigations of silicate impact micro-spherules in surrounding mires (Raukas et al. 1995) put the age about 7500-7600 yr BP. Recently we found both silicate and iron microspherules from organic sediments below well-dated beach ridge in Reo site what supports the conclusions that the most realistic age of the Kaali craters is 7600š50 14C BP (8335-8537 cal BP) and the meteorite fall was from SSE to NNW.
5
Content available remote Luminescence and radiocarbon dating as tools for the recognition of extraterrestrial impacts
Stankowski W. T. J.
Geochronometria
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2011
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Vol. 38, no. 1
54-54
EN
Extraterrestrial events and the extraterrestrial origin of both material and impact forms were recognized in the Morasko, Kaali and Przełazy shallow geological profiles by means of luminescence and radiocarbon dating as well as the frequency of magnetic spherules. The obtained results provide a promising tool for proving theat extraterrestrial events affected characteristic lithological and morphological environmental features.
6
Content available remote Chronology of the last deglaciation in the south-eastern Baltic Region on the basis of recent OSL dates
Raukas A., Stankowski W. T. J., Zelčs V., Šinkunas P.
Geochronometria
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2010
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Vol. 36
47-54
EN
The study of the deglaciation chronology in the south-eastern Baltic Region belonging to the outer zone of the last Pleistocene glaciation has a long history. The Finnish investigator H. Hausen (1913) who worked in the north-western portion of the East-European Plain at the beginning of the 20th century was the first to attempt a reconstruction of the course of glacial retreat during the last glaciation. At that time investigators had no physical dating methods and the time scale based on varvometric method, introduced by the Swedish geologist G. de Geer (1912) who divided the deglaciation history of Scandinavia into Daniglacial, Gotiglacial and Finiglacial, each of which had different palaeoglaciological conditions. During last decades different dating methods, including 14C, ESR, luminescence methods and 10Be techniques have been used, but they could not help essentially improve the existing stratigraphical charts and many problems of topical interest in the history of deglaciation have not been solved yet. During last years the first two authors have studied the suitability of OSL method for the geochronological purposes, paying the most attention to the waterlaid sediments. In the first step they have found the most promising genetical varieties of glaciofluvial sediments (glaciofluvial deltas and sandurs) and in this paper they widened the study area to all three Baltic states with close cooperation with Latvian and Lithuanian colleagues. The obtained results demonstrated, that not all mineral grains in the uppermost glaciofluvial and glaciolacustrine sediments were fully bleached during the last deglaciation. Probably the older sediments also influenced to the luminescence results. It means, that stratigraphic conclusions based on single dates or their small sets are inadmissible and in each case luminiscence dating requires a verification using other methods.
7
Content available remote Luminescence dating of the Morasko (Poland), Kaali, Ilumetsa and Tsoorikmäe (Estonia) meteorite craters
Stankowski W. T. J., Raukas A., Bluszcz A., Fedorowicz S.
Geochronometria
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2007
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Vol. 28
25-29
EN
The TL dating of sinter crust of Morasko meteorites proves that the extraterrestrial matter fell about 5000 yr BP. Similar data were obtained for the Kaali impact. The OSL analyses show incomplete bleaching of old rock material especially in the Estonian craters. Almost all data obtained for the immediate impact area indicate ages younger than the Quaternary morphogenesis. The method used seems promising for determining the age of impacts and the origin of small depressions of unknown genesis.
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