Nowe dane luminescencyjne wieku impaktów w Morasku oraz Kaali

• Authors: Wojciech Stankowski

Title variants

EN

The new luminescence data of the Morasko and Kaali impacts

• Languages of publication: PL

Abstracts

EN

The identified features of the shells/skins which have developed around the four big Morasko meteorites found in 2006 year, indicate the existence of shock pressure and high temperature in the immediate vicinity of the falling lumps. This was also the moment when zeroing of the luminescence occurred. The results obtained for the dating of the meteorite shells/skins using the TL technique prove the age of luminescence zeroing about 5000 to 6000 years ago. TL dating of meteorite shells/skins was preceded by OSL measurements in the mineral sediments situated in the beds of Morasko hollows A and B, directly below the organic filling sediment. The Morasko crater A mineral bottom is constituted by deformed sediments from the Neogene “Poznań series”. In the crater B mineral bottom the glacial sediments exists – not younger than the “Poznań phase” of last Scandinavian glaciation. The theoretical youngest age all of these sediments is 17000-18000 years BP. The OSL results obtained into 101 measured portions of mineral material from the hollows, prove its rejuvenation. There are many indices <5000 years (13%) and in between 5000-10000 years (30%), totally 43%. Data from TL and OSL measurements for the area of the Morasko Meteorite Reserve are an indicator of the luminescence zeroing (both the shells/skins of meteorites and depressions bottom sediments), occurring around 5000 years ago. In Morasko area a local grouped fall of extraterrestrial material as well as craters creation took place. The Estonian Kaali main crater and surrounding small craters were examined too. The TL data from the material of main crater rim, the material from inside slope of crater 1 and the powered Silurian dolomites at the bottom of crater 4, gave a similar results – 5000-6000 years BP. Also older data (up to 11500 years BP) were obtained in the mixture of Quaternary and Silurian dolomite detritus of the inside slope crater 1 and at the rim top of crater 2/8.
The OSL data have given the similar results. The comparative study to the Ilumetsa and Tsõõrikmäe relatively small craters were performed. The Devonian sandstones exist there beneath the local features and sediments of Quaternary age. The measurement results of OSL technique do not evidence so clear data as in Kaali site. Only few indicators were young (<4500 year BP). Most of data seems to be under influence of not complete bleaching of old rocks luminescence signal. The attempt of the TL and OSL measurements to impact time establish lead to the following conclusion: a) explosive – “high energetic” events to be effective of full zeroing luminescence and impact time establish, b) the striking – “low energetic” events are less effective in bleaching luminescence and impact time establish.

Keywords

EN

Kaali impact; Morasko impact; luminescence data; meteorites

Discipline

• GEOPHYSICS: GEOPHYSICS

• Publisher: Polskie Towarzystwo Meteorytowe
• Journal: Acta Societatis Metheoriticae Polonorum
• Year: 2009
• Volume: 1
• Pages: 123-128

Contributors

author

Wojciech Stankowski

• Uniwersytet im. A. Mickiewicza, Instytut Geologii, Poznań

References

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• Document Type: article