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Gierałtów versus Śnieżnik gneisses - what is the real difference?

Redlińska-Marczyńska Aleksandra

Geologos

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2011

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Vol. 17, No. 2

71--96

EN

Structural and petrographic study applied to the gneisses from the eastern part of the Orlica-Śnieżnik Dome, indicate that two different types of gneiss are present. The Śnieżnik gneisses are porphyrithic granites, constricted and sheared into L-S tectonites, most commonly with augens; the Gierałtów gneisses are sheared migmatites, porphyroblastic gneisses and banded gneisses, with two sets of metamorphic foliation, intrafolial folds and lensoid leucosome aggregates or metamorphic porphyroblasts. Both lithologies were later zonally sheared and transformed into more or less deformationally advanced mylonites, difficult to be distinguished from one of the two types. Identification of the Śnieżnik and Gierałtów gneisses is possible only between zones of the late (Variscan) shearing, in which the original, pre-kinematic structures are preserved.

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Late-orogenic magmatism in the Central European Variscides: SHRIMP U-Pb zircon age constraints from the Żeleźniak intrusion, Kaczawa Mountains, West Sudetes

Wachowiak K., Armstrong R., Kryza R., Muszyński A.

Geologia Sudetica

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2008

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Vol. 40

1-18

EN

We present new U-Pb isotope data obtained using the sensitive high mass-resolution ion microprobe (SHRIMP) technique on zircon crystals from the Żeleźniak subvolcanic intrusion in the Kaczawa Mountains, West Sudetes, SW Poland. The intrusion comprises shallow-level unmetamorphosed and undeformed fine-grained rhyolites, rhyodacites, and trachyandesites and deep-level medium-grained monzogranites and granodiorites. The surrounding country rocks, thought to be fragments of a Variscan accretionary prism, are blueschist- to subsequent greenschist facies metavolcanic and metasedimentary rocks of the Kaczawa Complex. The Żeleźniak intrusion has been correlated with other late- to post-tectonic Variscan volcanic and plutonic bodies in the region, such as the Karkonosze Granite, but the scarcity and often problematic quality of age constraints and of geochemical data have made such correlations speculative. Our new SHRIMP zircon ages of ~315-316 Ma from the Żeleźniak intrusion probably corresponds to the main magmatic stage. However, a younger age of ~269 Ma, derived from some zircon rims, is more difficult to interpret but might reflect either a much younger igneous event or a hydrothermal episode. The new date of ~315-316 Ma for the undeformed Żeleźniak intrusion also provides an upper age limit for deeper-level tectonic and metamorphic processes in the Kaczawa accretionary prism. Furthermore, the new SHRIMP zircon ages are among the oldest obtained from the volcanic rocks within the Variscan Belt in Central Europe and may correspond to the final stages of the exhumation of the blueschist facies rocks in this part of the orogen.

3

A new Lower Coniacian fauna from the Jerzmanice Zdrój region of the North Sudetic Basin, SW Poland

Chrząstek A.

Geologia Sudetica

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2008

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Vol. 40

33-50

EN

This paper describes and interprets a newly discovered Lower Coniacian (lower Upper Cretaceous) macro- and micro- fossil fauna (vertebrate and invertebrate remains) from sedimentary rocks of the Jerzmanice Zdrój region of the North Sudetic Basin of SW Poland. Several inoceramid bivalve taxa that previously were only known from other parts of the North Sudetic Basin were recovered from light grey, marly sandstones of Early Coniacian age. A fragment of ammonite was also discovered, as was a shark's tooth from the family Cretoxyrhinidae: this may be Cretoxyrhina mantelli Agassiz, 1843, a species not hitherto known from the Lower Coniacian (Emscherian sensu Scupin (1912-13)) of the North Sudetic Basin. Abundant foraminifers were observed in thin sections. The newly discovered inoceramid bivalves - Cremnoceramus deformis erectus Meek, 1877, Cremnoceramus waltersdorfensis waltersdorfensis Andert, 1911 and Inoceramus lusatiae Andert, 1911 - fit into the current biostratigraphic scheme for the region. The inoceramids can all be assigned to the Cremnoceramus deformis erectus Zone, which correlates with the Gavelinella moniliformis foraminiferal Zone and thereby confirms an Early Coniacian age. The Turonian-Coniacian boundary in the North Sudetic Basin can now be placed between the respective inoceramid zones of Inoceramus costellatus Woods, 1912 (actually Mytiloides costellatus Woods, 1912) and Inoceramus schloenbachi Böhm, 1911 (actually Cremnoceramus crassus crassus Petrascheck, 1903). The macrofossils found in the Jerzmanice section suggest that the host sediments were laid down in a Late Cretaceous epicontinental basin, under the North Sudetic Sea, that had deepened during the Early Coniacian. This interpretation agrees with the global bathymetric curve for the Late Cretaceous in Europe.

4

Occurrence of sulphides in Sowia Dolina near Karpacz (SW Poland) - en example of ore mineralization in the contact aureole of the Karkonosze granite

Mochnacka Ksenia, Oberc-Dziedzic Teresa, Mayer Wojciech, Pieczka Adam, Góralski Michał

Mineralogia

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2007

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Vol. 38, iss. 2

185--207

EN

The authors studied the poorly-known, uneconomic sulphide mineralization site in Sowia Dolina near Karpacz. Host rocks are hornfelses of the Velká Úpa schist series, which belongs to the Izera-Kowary Unit. Ore minerals assemblage includes: pyrrhotite, pyrite, chalcopyrite, arsenopyrite, sphalerite, galena and marcasite, accompanied by ilmenite and rutile. The oldest sulphide is high-temperature pyrrhotite crystallized at about 600°C, which is in good agreement with the temperature range of contact metamorphic conditions, revealed by muscovitesillimanite transformation. Low-temperature pyrrhotite and other sulphides formed at about 390°C (arsenopyrite geothermometer) down to 265°C (pyrrhotite geothermometer), whereas fluid inclusions studies of vein quartz demonstrated the temperature range 380-150°C. Mineralization in Sowia Dolina is similar to other ore hydrothermal deposits known from the proximal or distal contact zone of the Karkonosze granite.

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Hornfelsy Sowiej Doliny należą do jednostki izersko-kowarskiej i są częścią serii łupkowej grupy Velkej Úpy, przeobrażonej na kontakcie z waryscyjskim granitem Karkonoszy. W Sowiej Dolinie istnieją ślady dawnych robót górniczych, wyloty sztolni i hałdy, na których znaleźć można okazy z mineralizacją siarczków. Okruszcowane hornfelsy odznaczają się dobrze zachowaną foliacją i lineacją. Przejawem metamorfizmu kontaktowego są poligonalne zarysy ziaren kwarcu oraz rozpad muskowitu na sillimanit, zgodnie z reakcją: muskowit + kwarc = Al2SiO5 + K-skaleń + H2O, która oznacza warunki metamorfizmu wysokiego stopnia i osiągnięcie temperatury powyżej 600°C, a także krystalizacja andaluzytu i kordierytu, całkowicie zamienionego w pinit. Efektem zmian kontaktowych jest również powstanie pseudomorfoz po granacie. Najbogatsze skupienia minerałów kruszcowych stwierdzone zostały w hornfelsach wzbogaconych w kwarc lub przecinanych żyłkami kwarcowo-skaleniowymi. Dominującym minerałem rudnym jest pirotyn, rzadziej pojawia się piryt. Minerały te tworzą masywne skupienia kilkucentymetrowej miąższości, niekiedy także żyłki lub struktury rozproszone. W mniejszych ilościach występują: chalkopiryt, galena, sfaleryt, arsenopiryt, bornit, markasyt oraz minerały Ti. Sukcesja minerałów kruszcowych została określona na podstawie przerostów mineralnych (tab. 2). Najstarsze minerały, ilmenit i rutyl, są związane przypuszczalnie z metamorfizmem regionalnym. Po minerałach Ti krystalizował pirotyn. Młodszy od niego jest chalkopiryt, którego starsza generacja tworzy zrosty z pirotynem, następna natomiast występuje jako odmieszania w sfalerycie. Po pirotynie i starszym chalkopirycie, w tym samym czasie powstawały sfaleryt, arsenopiryt i galena. Markasyt jest minerałem wtórnym, tworzącym się w początkowych stadiach procesu wietrzenia rud na hałdzie. Następstwo siarczków potwierdziła interpretacja geotermometryczna wyników analiz chemicznych w mikroobszarze. Wykazała ona, że temperatury powstawania pirotynu wahały się w zakresie temperatur 630–265°C, a arsenopiryt krystalizował w temperaturze około 390°C. Temperatury powstawania kwarcu żyłowego oznaczone za pomocą inkluzji ciekło- -gazowych mieszczą się w zakresie temperatur 380–150°C. Porównanie obserwacji mikroskopowych rud z danymi chemicznymi i petrologicznymi pozwala na sugestię, że procesy metamorfizmu kontaktowego w temperaturach około 600°C odpowiadają krystalizacji wysokotemperaturowego pirotynu, natomiast pozostałe siarczki i kwarc żyłowy tworzyły się w procesach hydrotermalnych niższych temperatur, aż do około 150°C.

5

Offshore to onshore transition in the Upper Viséan paleontological record from the Paprotnia section (Bardo Mts., West Sudetes)

Haydukiewicz J., Muszer J.

Geologia Sudetica

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2002

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Vol. 34

17-38

EN

This report provides detailed information on the taphocenosis succession from the Paprotnia series exposed in the western part of the Bardo Mts. (West Sudetes) and regarded as a temporal equivalent of the pelagic crenistria Limestone (cd III a, Upper Viséan). Five taphocoenoses have been recognised in the investigated section, which is composed of claystone and mudstone shales, greywackes and subordinately by carbonates. They differ mainly in terms of the relative frequency, size and state of preservation of specimens, and less in terms of their taxonomical composition. Changes in their vertical succession are coincidental with changes in the lithological record. Analyses of their taxonomical composition and various parameters of their paleontological record, reviewed herein, were used to estimate the paleoenvironment. Taphocoenosis I was deposited under low-energy conditions, probably in oxygen-deficient waters below the wave base. Taphocoenosis II was most likely accumulated in the environment located between the storm wave and fair weather wave bases, in oxygenated water. The fossils of assemblage III developed in a turbulent environment of well-oxygenated and relatively high-temperature shallow water. The organisms of taphocoenosis IV reflect renewed settling of the shallow seafloor during a short period of low energy conditions interrupted by the rapid delivery of a large quantity of terrigenic deposits. The uppermost part of the section, composed mainly of greywackes, which contain only the remains of terrestrial plants (taphocoenosis V) may suggest proximity to land. Both the paleontological and lithological features of the Paprotnia series indicate gradual environmental changes from offshore to onshore conditions. Consequently, the Paprotnia series represents the shallower facies equivalent of the pelagic crenistria Limestone, which is widespread in the Kulm facies of Variscan Europe

6

Middle ro early late Viséan onset of late orogenic sedimentation in the Intra-Sudetic Basin, West Sudetes: miospore evidence and tectonic

Turnau E., Żelaźniewicz A., Franke W.

Geologia Sudetica

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2002

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Vol. 34

9-16

EN

The Early Carboniferous fluvial and deltaic sequence of the Intra-Sudetic Basin remained undated until recently, except for a Late Viséan ammonoid fauna in its upper part. Current miospore data indicate that the oldest part of the sequence is not older than the mid Viséan Knoxisporites triradiatus-Knoxisporites stephanephorus biozone of the west European miospore division. This palynological age determination is consistent with the recently obtained Ar-Ar cooling ages of white micas from sheared metamorphic rocks at the NW margin of the basin. This suggests that the rapid late orogenic denudation of the northern and western flanks of the Intra-Sudetic Basin must have started at or shortly after c. 335 Ma.

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The Early palaeozoic intracontinental rifting and incipient oceanic lithosphere development in the central West Sudetes (NE Bohemian Massif): the geochemistry of metabasites of the East Krknoše (Karkonosze) Complex

Patočka F., Smulikowski W.

Geologia Sudetica

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2000

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Vol. 33, nr 1

1-15

EN

Low- to medium-grade metabasites are the most abundant metaigneous rocks in the Early Palaeozoic metavolcanic (ąmetasedimentary) East Krkonoše (Karkonosze) Complex located at the Czech/Polish border in the central West Sudetes (NE Bohemian Massif). These mafic rocks are interpreted as metamorphosed equivalents of basic magmatites - both volcanics (lavas and pyroclastics) and subvolcanic intrusives. The correlation of lithostratigraphic units defined in the Czech (southern) and Polish (central and northern) parts of the East Krkonoše Complex is based on a comparison of the geochemical characteristics and petrography of the (1) The greenschists to greenstones (associated with abundant felsic metavolcanics) of the Czech East Krkonoše Complex, which are finely interfingered with low-grade metasediments, are correlated with the amphibolites forming small- to medium-sized bodies in medium-grade metasediments of the Polish East Karkonosze Complex. Both the low- and medium-grade metabasites are interpreted as comprising a range of metamorphosed tholeiitic, transitional and alkaline WPBs. (2) The largest mafic rock suite, which dominates the Polish part of the East Krkonoše Complex, has a dismembered promontory along the eastern margin of the East Krkonoše Complex Czech component. Most of these mafic rocks (blueschists, greenschists, greenstones and amphibolites) correspond to N- and E-MORBs. The above groups of rocks are broadly coeval and geochronologically overlap the Cambrian/Ordovician boundary. The similarity in magmatic ages and the diversity in geochemical features suggest that the East Krkonoše Complex metabasites are evidence for intracontinental rift development and the subsequent generation of incipient oceanic basin lithosphere in the NE Bohemian Massif during the Early Palaeozoic. Provided that the East Krkonoše Complex metabasites can be matched with similar rock suites in the West and Central European Variscides, their magmatic origin may be related to the rifting of northern Gondwana and large-scale break-up at the beginning of the Palaeozoic.

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Orthogneisses and metapelites from a polyphase tectonic zone - mesostructural versus microstructural evidence: an example from the Czerniawa Zdrój section (Izera-Karkonosze Block, West Sudetes)

Czapliński W.

Geologia Sudetica

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1998

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Vol. 31, nr 1

93-104

EN

Within the gneisses of the northern part of the Izera-Karkonosze Block (West Sudetes), there are 4 belts of schistose rocks. The Stara Kamienica schist belt in the Czerniawa section consists of a sequence of orthogneisses deformed to various degree, occurring concordantly with metapelitic mica schists. Structural analysis of these rocks, including quartz c-axis analysis, allows four stages of deformation, common for both lithologies to be recognized. The quartz c-axis microfabrics are often incompatible with other elements of the structural record, which is interpreted as having resulted from multiple overprinting of older microfabrics by younger ones in a heterogeneous deformation regime. This heterogeneity concerns the geometry of the deformation as well as the mechanisms, which included subgrain-rotation recrystallization, grain-boundary migration, microfracturing and pressure-solution processes.