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Wstępna charakterystyka geochemiczna amfibolitów i skał ultramaficznych terranu West Ny-Friesland, północny Spitsbergen

Bazarnik Jakub, Barker Abigail, Majka Jarosław, Kośmińska Karolina, Elvevold Synnøve, Bazarnik Mirosława

Przegląd Geologiczny

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2021

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Vol. 69, nr 7

406--410

EN

The metamorphic Atomfjella Complex of the West Ny-Friesland Terrane, which belongs to the Eastern Basement Svalbard Province, is composed of four nappes, namely Dirksodden, Nordbreen, Rekvika and Finlandveggen. All these nappescomprise a granitic gneiss basement associated with a metasedimentary cover, both cut by numerous mafic dykes. At the top of the Atomfjella Complex, close to the boundary with the Mosselhalvaya Group (Nordaustlandet terrane), the lenses of ultramafic rocks also occur. Some authors suggested that they provide evidence for the presence ofa deeply rooted, large-scale tectonic boundary between the West Ny-Friesland and Nordaustlandet terranes. The performed geochemical characterization of amphibolites and ultramafic rocks showed that nearly all major elements (except Si and Fe) as well as LILE, have wide compositional ranges and no obvious trends (Bazarnik, Majka, 2021). It is conceivable that the Caledonian metamorphism may have affected K, Na and P, as well as LILE, and caused scatter of Al, Ti, Ca and Fe, and likely Si. The trace and REE elements plots are characterized mainly by trends that probably express the original magmatic processes. However, the elements that clearly deviate from these trends are disturbed due to either metamorphism or crustal assimilation. According to the Th/Yb vs Nb/Yb relationship, the studied rocks indicate generally low influence of crustal contamination, with only 3 samples in the field of MORB-OIB array (Fig. 4B). Besides the higher content of Mgandsome other minor differences in chemical composition, the ultramafic rocks exhibit trends similar to that of amphibolites. Based on this aforementioned similarity and the confirmed influence of the Caledonian metamorphism on both groups of rocks, we speculate about the common history of both groups of rocks. Moreover, thank sto the identification of metamorphic alterations in ultramafic rocks, it was proved that these rocks must be pre-Caledonian and, in turn, older than the alleged terrane boundary. Thus, the ultramafic bodies located close to the top of the Atomfjella Complex cannot mark the large terrane boundary and do not provide any evidence of a deeply rooted tectonic zone, but merely the result of ascension from deeper levels of the mantle.

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Niekonwencjonalne wykorzystanie amfibolitów dolnośląskich

Lubas M., Wyszomirski P.

Materiały Ceramiczne

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2009

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T. 61, nr 1

31-35

PL

Jak dotąd, amfibolity dolnośląskie ze złóż w Wieściszowicach i Ogorzelcu stosowane są wyłącznie dla celów budownictwa drogowego. W niniejszej pracy surowce te wykorzystano do otrzymania szkieł glinokrzemianowych i przeprowadzenia ich charakterystyki. Temperatury topienia badanych amfibolitów są stosunkowo niskie (ok. 1230°C - Wieściszowice, 1210°C - Ogorzelec), a lepkość uzyskanych stopów - korzystna (ok. 2,4 Pa.s w temperaturze 1400°C). Wygrzewanie szkieł w temperaturach 800 - 1100°C wskazuje na ich stosunkowo wysoką zdolność krystalizacyjną. Powstałe fazy krystaliczne reprezentowane są głównie przez spinele (magnetyt i/lub tytanomagnetyt) oraz pirokseny. Uzyskane wyniki sugerują możliwość wykorzystania badanych amfibolitów do produkcji tworzyw szklano-krystalicznych. Wytwarzanie z nich włóknistych materiałów izolacyjnych jest też możliwe, co jednak wymaga modyfikacji ich składu chemicznego.

EN

Up to now, Lower Silesian amphibolites from Wieściszowice and Ogorzelec deposits are applied only as crushed aggregates for the road construction. This paper presents the results of studies of aluminosilicate glasses obtained by melting these raw materials. The studied amphibolites have rather Iow melting temperatures (ca. 1230°C - Wieściszowice, 1210°C - Ogorzelec) and their viscosity is advantageous (ca. 2,4 Pa.s at 1400°C). An annealing of glasses at the temperature range of 800- 1100°C indicates their relatively high crystallization ability. It was found that the crystalline phases are mainly represented by magnetite and hematite as well as by pyroxenes. The results suggest the application of amphibolite glasses for the production of glass-ceramics wares. The manufacturing of fibrous insulating materials from these glasses is also possible but it requires the modification of their chemical composition.

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The petrology and geochemistry of mantle-derived basic and ultrabasic rocks from the Szklary massif in the Fore-Sudetic Block (SW Poland)

Gunia P.

Geologia Sudetica

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2000

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Vol. 33, nr 2

71-83

EN

This paper presents the results of petrological investigations of rocks from the Szklary serpentinite massif in the eastern margin of the Góry Sowie Block. Among the weakly serpentinised ultrabasites present, harzburgites, lherzolites and pyroxenites have been distinguished. Small enclaves of metabasites within the serpentinites represent low-Ti varieties and - like rodingites - they developed from initial gabbroides or picrites. They reveal a characteristic depletion in incompatible elements. This feature is reminiscent of high-Mg (boninite) basic magmas formed in island arc or back-arc basin environments. Plagiogranites, present within the serpentinites, most probably represent trondhjemites - more acid derivates formed during the fractional crystallisation of the same initial basic magma. On the basis of the petrological investigation results, the hypothesis was put forward that - with regard to their initial composition - the ultrabasites of the Szklary massif may represent heterogeneous spinel residual peridotites impregnated with pyroxenite veins. Enclaves of metabasites and plagiogranites, having the properties of mafic cumulates and/or fractional differentiates, may reflect a stage of further magmatic processes which took place in a zone of lithospheric plate convergence.