Wyniki wyszukiwania - Biblioteka Nauki

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Dokumentacja znalezisk meteorytu Morasko w latach 2011–2014 : problemy metodyczne i uzyskane efekty

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Nowak M. , Muszyński A.

Przegląd Geologiczny

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2020

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tom Vol. 68, nr 12

879--885

EN

The Morasko meteorite is currently one of the biggest tourist attractions of the city of Poznań. In this paper we present the stages of creating documentation for finds of individual fragments of the Morasko meteorite, conducted at the Institute of Geology, Adam Mickiewicz University, in 2011-2014. During the initial period of documentary work, the focus was mainly on the compilation of topographic maps prepared by various authors to create one collective map of finds. ESRI (ArcGIS) software was used to prepare the documentation. The main problem at the initial stage of documentation was the coordination of source data prepared on topographic bases developed in various reference systems (PUWG 65, PUWG 92, tourist map without any system). During the years 2012-2014, topographic data were successively supplemented with new finds, resulting in a database comprising a total of 1413 items - containing coordinates, data on individual finders, masses (given as a range or as specific data in grams), depths at which meteorites rested, and, in some cases, special features (so-called shrapnel). The obtained documentation is a unique source of data on most of the fragments of the Morasko meteorite. It remains debatable whether the collected information is sufficient to calculate a reliable meteorite strewn field.

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Shock veins in the Sahara 02500 ordinary chondrite

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Owocki K. , Muszyński A.

Geologos

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2012

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tom Vol. 18, No. 2

111--118

EN

A specimen of the Sahara 02500 ordinary chondrite contains shock-produced veins consisting of recrystallised fine-grained pyroxenes that include small droplets of Ni-rich metal. Non-melted olivines and pyroxenes show planar deformations filled by shock-melted and -polluted metal and troilite. Shock-melted feldspathic glass is present close to the shock veins. Geothermometric estimations indicate that the meteorite locally experienced moderate shock metamorphism with a minimum local peak temperature above 1400ºC, resulting in partial melting of Ca-poor pyroxene and full melting of feldspars, metal and sulphides. The mineral assemblage in the shock veins suggests a pressure during melt recrystallisation below 10 GPa.

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Stanisław Lorenc (1943–2020) : geolog, rektor, podróżnik

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Biernacka J. , Muszyński A.

Przegląd Geologiczny

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2020

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tom Vol. 68, Nr 8

628--635

EN

Professor Stanislaw Lorenc (1943-2020) was a distinguished Polish geologist and Rector (President) of Adam Mickiewicz University in Poznań (2002-2008). He graduated from the University of Wroclaw, where he obtained MSc and PhD degrees, and completed his Habilitation thesis. Stanislaw Lorenc studied sedimentary rocks, primarily carbonates. He examined Upper Permian (Zechstein) carbonate and sulphate rocks of western Poland, and Cambrian metacarbonates of the Kaczawa Mountains. In 1988, Stanislaw Lorenc moved to Poznań, where, after the reactivation of geological studies at the University, he co-organized the Institute of Geology. He participated in many scientific marine cruises in the southern Pacific and the South China Sea, and taught marine geology at the University of Poznań. He was also engaged in the studies on geohazards and promoted research on tsunami sediments. Stanislaw Lorenc was an advocate of Polish-German scientific cooperation.

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Meteoryty, kratery uderzeniowe i inne ślady kosmicznej katastrofy w rejonie Moraska pod Poznaniem

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Szczuciński W. , Muszyński A.

Przegląd Geologiczny

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2020

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tom Vol. 68, Nr 8

637--644

EN

About 5,000 years ago near Morasko (the district of the present-day city of Poznań, western Poland) the largest known iron meteorite shower in Central Europe took place. The evidence of that impact, documented so far, comprises numerous iron meteorite fragments distributed over an area of approximately 3 km2 and at least six meteorite impact craters with a maximum diameter of about 100 m. The present paper reviews the most recent findings related to the meteorite, craters, processes of their formation, as well as the environmental effects of the impact in the Morasko area. The most important findings, reported in this review cover: 1) the recognition of two new minerals in the meteorite: moraskoite and czochralskiite; 2) the identification and detailed analysis of the ejecta layer around the craters and underlying paleosoil providing evidence for the mid-Holocene age of the impact; 3) the numerical modelling constraining the range of likely physical properties of the impactor, e.g. the diameter of the projectile forming the largest crater and its landing velocity (c. 1.5 m and 10km/s, respectively);4) the studies of the nearby lake and peat deposits revealing restricted environmental effects of the impact. The Morasko craters field is currently one of the best-studied examples of small/moderate-sized meteorite impact in unconsolidated sediments.

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Black sand properties in beach-dune system, Patea Beach, North Island, New Zealand

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Dłużewski M. , Hilton M. , Muszyński A. , Rotnicka J. , Woronko B.

Geological Quarterly

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2021

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tom Vol. 65, No. 3

art. no. 35

EN

The study focuses on sand grain properties in different parts of a beach-dune system built entirely of heavy mineral particles. These properties are related to: (1) resistance of particular minerals to weathering and abrasion, (2) hydraulic sorting in the swash zone, and (3) aeolian sorting during grain transport inland from the upper beach. The main waterlain and windlain sand properties depend on settling velocity which results from grain density (reflecting grain mineralogy), size, shape and roundness. The study was performed on the beach and dunes at Patea on the west coast of the North Island of New Zealand, which are comprised of heavy minerals assemblage containing a ferromagnetic (dominated by titanomagnetite) and non-ferromagnetic (mainly pyroxene and amphibole) fractions. The result demonstrates that three zones of different sand properties can be distinguished: (1) a lower swash zone dominated by non-ferromagnetic, larger and more angular particles which are carried back from the upper swash zone down the foreshore by the backwash; (2) an uppermost swash zone and beach with almost 100% of ferromagnetic, smaller and more rounded particles deposited at the back of the beach by the uprush, which during high tide and storms can reach the cliff toe, and can be reworked by wind; and (3) a climbing dune composed of a more poorly sorted mixture of non- and ferromagnetic particles. In terms of both mineralogy and grain size and shape, the dune sand is less uniform than the beach sand. Aeolian segregation resulted here in sand textural features opposite to those found in dune sands composed of light minerals. The results highlight the density-dependent variability of grain size and shape of beach-dune deposits consisting of only heavy minerals, and broaden our understanding of mechanisms of sedimentary processes which is particularly important when reconstructing older sedimentary successions.

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Zastosowanie metod instrumentalnych w badaniach meteorytu Morasko

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Muszyński A. , Runka T. , Gołębiewska B. , Michalska D. , Karwowski Ł.

Przegląd Geologiczny

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2019

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tom Vol. 67, nr 3

156--158

EN

Since its discovery, the Morasko meteorite has been the subject of many studies. Among the publications summarising the mineralogical and geochemical characteristics of the Morasko meteorite, two monographs are worth mentioning by: Dominik (1976) and Muszyński et al. (2012), in which the essentialfeatures of the Morasko meteorite were presented. Since the first piece of the Morasko meteorite was to be explored, the analysis of mineral composition has been conducted with more and more specialised and sophisticated instrumental methods. As it is well known, the Morasko meteorite is classified into the group of iron meteorites IAB MG, and consists mainly of the crystalline Fe-Ni alloy in the form of two minerals: kamacite and taenite, accompanied by tetrataenite. A commonly found structure of the mineral composition of the Morasko meteorite, as regards other iron meteorites, are graphite-troilite nodules, which contain silicate and phosphate minerals. This paper presents a review ofresearch on the mineralogy and geochemistry of the Morasko meteorite, where a number of instrumental tests have been used, from microscopic observations to microchemical semiquantitative analyses using scanning electron microscopy (SEM-EDS), microchemical quantitative analyses using an electron microprobe (WDS), to the structural methods applying Raman spectroscopy. The results of microscopic, microchemical and microstructural investigations, which have included the outer layer of the meteorite known as a fusion crust, have been presented against the petrographic composition of the meteorite. Besides, the type of sediment attached to the outer meteorite layer was examined. The research, conducted on two dozen meteorite fragments, allowed distinguishing two different zones concerning mineralogy and geochemistry, and to determine microstructural changes within them, most probably created in the processes related to the moment of the meteorite impact.