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Internal structure of the buried Suwałki Anorthosite Massif (East European Craton, NE Poland) based on borehole, magnetic and gravity data combined with new petrological results

Petecki Zdzisław, Wiszniewska Janina

Geological Quarterly

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2021

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Vol. 65, No. 1

art. no. 4

EN

Advanced magnetic and gravity data analysis has been used to acquire geophysical constraints providing new insights into the geological structure of the Suwałki Anorthosite Massif (SAM). The large negative magnetic anomaly of the SAM anorthosite intrusion is a result of the negative inclination of remanent magnetization, directed antiparallel to the present Earth’s magnetic field. Several filtering processes were applied to the magnetic and gravity maps to better understand the subsurface geology of the SAM area. The geological analysis of residual magnetic and gravity anomaly maps reveals the presence of different rock units, reflecting variation in petrological composition of the crystalline basement rocks. The 2-D modelling of magnetic and gravity data delineate the location and extent of the anorthosite-norite massif. The data is consistent with a thick upper crustal body with density 2690 kg/m3, low susceptibility (0.005 SI) and natural remanent magnetization (1.95 A/m), having inclination of I = –68°, and declination of D = –177°. The rocks bordering the central anorthosite body consist of norite and gabbronorite, granodiorite, diorite and charnockite. These main crystalline basement crustal units are shown more precisely on a new geological map of the SAM.

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Wstępne rozpoznanie obwódek cyrkonowo-hafnowych wokół minerałów kruszcowych w złożach Fe-Ti-V w suwalskim masywie anortozytowym (północno-wschodnia Polska)

Ruszkowski M., Wiszniewska J.

Przegląd Geologiczny

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2018

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Vol. 66, nr 2

107--110

EN

Zirconium-hafnium rims were discovered and described for the first time within the Suwalki Anorthosite Massif (SAM). They are observed at boundaries of Fe-Ti oxides ilmenite, hematitoilmenite and titanomagnetite with plagioclases. The most frequent forms reach 80-250 μm in length and 4-30 μm in width. These are narrow rims covering even up to 70% ore mineral grains. The most spectacular forms were "blown candle flame” structures. Their average width ranges from 20 to 45 μm and the length exceeds 350 μm in . Chemical composition analysis was carried out on the largest clusters of zircon crystals/rims which show high local enrichment in Hf (0.5-0.8% by weight). The boundaries of these crystals are cracked and blurry. This may suggest their participation in later fluids inflow processes within the rocks. The enrichment in hafnium content in zircon grains, is related to significant reduction in the amount of Th, U and Pb and increased amount- sof Ti and Fe in zircon rims. A large variety of forms and variability of their chemical composition point to a complex physical chemical orgin process.

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The deep-seated lowland relict permafrost from the Suwałki region (NE Poland) : analysis of conditions of its development and preservation

Szewczyk J.

Geological Quarterly

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2017

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Vol. 61, No. 4

845--858

EN

The Udryń PIG 1 research borehole drilled in northeastern Poland (54°14’49”N, 23°03’29”E, 223 m a.s.l.) revealed a permafrost layer, at least 93 m thick, within the sedimentary succession below a depth of 357 m. The base of the permafrost has not been reached at 450 m depth, where the drilling stopped, so its total present thickness remains unknown. The relict permafrost, unexpected in this part of Central Europe, is in the ice-water transition phase at a temperature slightly below the 0°C. Analysis of geophysical and hydrogeological data indicates the possibility of preserving the permafrost in the central part of sedimentary cover of the Suwałki Anorthosite Massif over an area of probably 50 km2. Preliminary results of geothermal modelling indicate maximum palaeothickness of permafrost at the end of the Last Glacial Maximum of probably ~600 m. The development of such a thick permafrost results both from a very low average annual temperature in the Weichselian Glaciation and a very low terrestrial heat flow density. It is very probable that similar zones of deep relict permafrost occurrences, undetected so far, may exist in other areas of the Precambrian Platform not only in Poland, but also in the neighbouring countries.

4

Mezoproterozoiczne złoże rud tytanomagnetytowych w suwalskim masywie anortozytowym i jego środowisko geologiczne

Wiszniewska J., Petecki Z.

Górnictwo Odkrywkowe

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2014

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R. 55, nr 2-3

44-51

PL

Rudonośny suwalski masyw anortozytowy (SAM) razem z anortozytowym masywem Kętrzyna i norytową intruzją Sep, występują w obrębie 200 km długości magmowego terenu zwanego kompleksem mazurskim (NE Polska). Rozciągający się pasmowo w kierunku W-E proterozoiczny kompleks mazurski jest zbudowany z różnorodnych skał o składzie od kwaśnych przez pośrednie do zasadowych. Kwarcowe monzonity i granodioryty są najbardziej rozpowszechnionym typem skał w obrębie facji. Kompleks mazurski przecina kilka kompleksów metamorficznej facji granulitowej i amfibolitowej np. kompleks pomorski, dobrzyński, ciechanowski i mazowiecki. Złoża rud Fe-Ti-(V) w anortozytowym masywie suwalskim zostały odkryte we wczesnych latach 60-tych XX wieku, pod miąższym nadkładem fanerozoicznych skał osadowych w obrębie małych dodatnich anomalii magnetycznych, w rejonie Krzemionki, Udryna, Jeleniewa i Jeziora Okrągłego. Złoża te zostały udokumentowane przy pomocy ok. 100 głębokich otworom wiertniczych, do głębokości 2300 m, a zasoby oszacowane w kat. C1 i C2 na ok. 1,5 mld ton rudy tytanomagnetytowej z wanadem, głównie w polu rudnym Krzemionka i Udryn.

EN

The ore-bearing Suwałki Anorthosite Massif (SAM) together with the Kętrzyn Anorthosite Massif and Sejny norite intrusion are located within 200 km long magmatic terrane called Mazury Complex (NE Poland). The beltiform Proterozoic Mazury Complex is made up of a variety of rocks from felsic and intermidiate to the basic ones. The quartz monzonites and granodiorites are the most widespread rock type within the suite. The belt crosscuts several metamorphic granulite and amphibolite fades units, including Pomorian, Dobrzyń, Ciechanów and Mazovian. Large Fe-Ti-(V) ore deposits of Krzemionka, Udryń, Jeleniewo and Jezioro Okragle have been discovered in early 60-ties, within the small positive magnetic anomalies in the Suwałki Massif and evaluated down to the depth of 2300 m by over 100 boreholes yielding of about 1.5 bilion tons of economic reserves, mostly at Krzemionka and Udryn ore fields.

5

Strontium isotope ratios and REE geochemistry in the Suwałki anorthosites, NE Poland

Wiszniewska J.

Geological Quarterly

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2000

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Vol. 44, Nr 2

183-186

EN

Strontium isotope ratios for 14 samples of anorthositic rocks in the Suwałki Anorthosite Massif (SAM) range from 0.704875 to 0.705772. The same isotopic ratios calculated for 1.5 Ga (the U-Pb zircon age of the rapakivi-like granites from adjacent Mazury Complex) range from 0.704583 to 0.705483. The corresponding eSr1500 values for the same rocks range from 25.5 to 39.0. The pronounced Eu anomaly which characterises the REE distribution in the anorthosite plagioclase is consistent with early crystallization from basic magma.