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Geochemical characteristics of spherules from the Pivdenna kimberlite pipe, East Azov region (Ukraine) : implications for their sources and origin

Yatsenko Ivan, Poberezhskyy Andriy, Stupka Oksana, Bekesha Serhii

Geological Quarterly

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2023

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Vol. 67, No. 1

art. no. 6

EN

The composition of spherules and particles of native metals from the Pivdenna kimberlite pipe, Ukraine, was studied using the SEM/EDS method. Three varieties of spherules have been distinguished: titanium-manganese-iron-silicate (TMIS) spherules, Ca-rich silicate spherules, and magnetite-wustite-iron (MW-I) spherules. TMIS spherules are composed of homogeneous glass, some having a native iron core. Large TMIS spherules may contain a crystalline phase with needle-like armalcolite. Ca-rich silicate spherules can be subdivided into two subtypes: calcium-silicate (CS) spherules where SiO2 and CaO are the dominant constituents, and calcium-iron-silicate (CIS) spherules with significant FeO content. CS spherules may contain a core consisting of native phases (Fe, Fe-Si, and Mn-Si-Fe). Native metal particles are represented by native Cu and native Zn. The spherule varieties from the Pivdenna pipe are similar to those from other kimberlite pipes in the world. We infer that the formation of spherules occurred in gas-melt streams, separately from the kimberlites, and propose a model for the formation of the most common variety of spherules (TMIS and MW-I varieties) in the region of the core-mantle boundary (CMB). First, a melt of the Fe-Ti-Mn-Si-O system was formed in ultra-low-velocity zones (ULVZ) as a result of thermochemical reactions (reduction) between the molten core and solid oxide-silicate rocks. The melt then migrates to shallower levels, where a decrease in temperature initiates oxidation with the formation of SiO2-TiO2-FeO-MnO-Fe0 melt, i.e. parent melt of TMIS and MW-I spherules. We interpret the formation of native metals in kimberlites as a result of the decomposition of nitrides, which came from the Earth’s core via intratelluric flows.

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Materia magnetyczna na granicach stratygraficznych fanerozoiku

Zalewski F.

Prace Naukowe Instytutu Nafty i Gazu

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2016

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nr 209 wyd. konferencyjne

119--122

EN

Today, the origin of spherules (spheroids) is attributed to two sources: anthropogenic (industrial) and/or cosmic. Anthropogenic spherules are produced in an industrial processes such as metallurgy, welding, grinding. Before the rise of industry and the use of iron tools we can find only spherules of cosmic origin deposited in the sediments. Spherules of cosmic origin fall to the surface of the Earth all the time [2]. They are a product of the process of ablation and combustion of meteoroids and cosmic dust during their fall through the Earth’s atmosphere, leaving behind a bolid trail [8]. Another natural source of origin of these objects are explosions. After passage of an extra-terrestrial body through the atmosphere, it hits the surface of the planet causing explosions. A big part of rock from the ground and extra-terrestrial matter evaporates during those explosions. The rest of the ejected material falls on the surface of the planet in the form of lumps, spherules, breccia, etc., covering a large area around the epicentre of the outbreak, or the entire planet. It forms a thin layer of molten post-explosive residue, which with the passing time – measured in geological terms – is covered with subsequent layers of sediment and becomes a timestamp in these sediments. Concentration of this type of material indicates a regional or global catastrophe caused by falling of objects of cosmic origin on Earth. One of these events was a meteorite fall in the area of the Yucatan Peninsula. This event caused an effect of nuclear winter and extinction of a large number of species of plants and animals, which left a layer of sediment enriched in iridium around the globe. This layer containing iridium and spherules is considered a typical strato border between the Cretaceous and Paleogene (K-T boundary) sediments, dating back to 66 million years [1, 11]. Tests to detect the magnetic spherules and matter on the borders of lithostratigraphic have been taken in the course of shale gas explorations in Poland. Previous research of laboratory samples from five wells indicate that material of the cosmic origin in the form of spherules and magnetic material is present in a large number of geological period borders, epochs and some stratigraphic formations. These results, combined with literature reports [5, 9] indicate the prevalence of the magnetic matter and spherules on the lithostratigraphic borders, which in turn creates the possibility of using the presence of that matter to a faster (compared to the current methods) and more precise determination of the relevant, lithostratigraphic borders.

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Materiał magnetyczny w próbkach soli z wysadów solnych Góra i Wapno

Jaworska J.

Przegląd Solny

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2015

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T. 11

78--82

PL

W próbkach soli cechsztyńskich zebranych z trzech fragmentów dostępnych rdzeni, pochodzących z dwóch wysadów solnych Góra i Wapno, wśród materiału rezydualnego, wyseparowano materiał charakteryzujący się wysoką magnetycznością. Analizom poddano dwa zebrane typy tego materiału, tj. sferule (sferulki) – kuliste, metaliczne formy oraz nieregularne ziarna. Łącznie przebadano 13 ziaren. Wielkość ziaren obu typów mieściła się w granicach 70-400 μm. Głównym składnikiem chemicznym sferul i ziaren nieregularnych jest tlenek żelaza, którego udział w próbkach wynosi od 70 do 100%. Geneza tego materiału magnetycznego nie jest jednoznacznie określona; mogą one mieć pochodzenie kosmiczne lub antropogeniczne.

EN

The Zechstein salt samples were collected from three fragments of cores, drilled from the Góra and Wapno salt domes. After the residual material had been separated, formations displaying high magnetism were found. Two types of such formations were subjected to analysis: round, metallic spherules and irregular particles. In total, 13 items were examined. The sizes of both types of the material ranged from 70 to 400 μm. Iron oxide was found to be the main chemical component of both spherules and irregular particles. Its proportion ranged from 70 to 100% in the samples. The origin of those magnetic materials has not been clearly determined. It can be either extraterrestrial or anthropogenic.

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Materia pozaziemska w otoczeniu kraterów meteorytowych Kaali (Estonia)

Uścinowicz Grzegorz

Geologos

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2008

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Vol. 14, No. 2

211--219

PL

Kratery meteorytowe Kaali (wyspa Saaremaa, Estonia) stanowią unikatowe miejsce w Europie, nie tylko ze względu na wyjątkową formę wykształcenia, ale także dostępność do badań metalicznej materii pozaziemskiej. Podczas badań terenowych prowadzonych w maju 2004 roku autor zgromadził próbki osadów, które posłużyły do badań drobnej frakcji materii magnetycznej występującej w obrębie kraterów meteorytowych Kaali. Na podstawie morfologii, cech powierzchni i składu chemicznego wyselekcjonowanych ziaren magnetycznych wyróżniono cztery grupy materii: (1) kosmiczne kulki zbudowane z tlenku żelaza, zawierające nikiel, (2) kulki węglowe, które wstępnie zaklasyfikowano jako antropogeniczne, (3) kulki krzemianowe interpretowane jako zestalone krople wymieszanej materii ziemskiej i pozaziemskiej, i (4) płytki zbudowane z tlenku żelaza, pozbawione niklu, które zinterpretowano jako zwietrzałe pozostałości materii pozaziemskiej. Opis morfometryczny kraterów Kaali został sporządzony na podstawie danych literaturowych oraz wizji lokalnej przeprowadzonej przez autora.

EN

The Kaali meteorite crater field is a unique place in Europe, not only because of its morphology but also because of the presence of large amounts of extraterrestrial material. During field work in May 2004, samples were collected at this site with the objective to study magnetic fines. Based on morphology, surface features and chemical composition of the selected magnetic material, four groups of spherules and plates were distinguished: (1) Ni-bearing Fe-oxide spherules of cosmic origin, (2) carbon spherules tentatively classified as anthropogenic, (3) silicate spherules interpreted as solidified droplets of mixed terrestrial and extraterrestrial matter, and (4) Ni-free Fe-oxide plates interpreted as weathered remnants of extraterrestrial material. The Kaali crater site is described morphologically on the basis of literature and the author’s own observations.

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Study of meteoritic matter for precise regional stratigraphy

Raukas Anto

Geologos

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2000

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Vol. 5

77--86

EN

New physical and isotope-geochemical methods and improvement of old classical methods have considerably enlarged our knowledge not only of the physical age of the deposits but also of the palaeogeographic situation in the past. During the last hundred years, microscopic glassy and ferrous spheroids of different origin have often been found in various geological formations. In 1996, IGCP project 384 “Impact and Extraterrestrial Spherules: New Tools for Global Correlation” with a duration of five years (1996-2000) was launched. Estonia with its two well-known astroblems (Kardla, Neugrund) and three groups of Holocene craters (Kaali, Ilumetsa, Tsoorikmae) serves as a key region for this kind of studies. The concentration of magnetite-silicate microimpactites in certain layers of peat in the surroundings of the Kaali and Ilumetsa craters suggests that the Holocene impact events can be precisely dated on the basis of l4C dates and pollen evidence, and serve as good regional chronostratigraphical markers. The age of the Kaali craters is approximately 7500 and Ilumetsa craters about 6600 years BP.