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Indications of HP events in the volcanosedimentary succession of the Orlica–Śnieżnik Dome, NE Bohemian Massif: data from a marble-amphibolite interface

Twyrdy M., Żelaźniewicz A.

Geological Quarterly

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2017

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Vol. 61, No. 2

435--449

EN

A volcanosedimentary succession of the Młynowiec-Stronie Group (MSG) in the Orlica–Śnieżnik Dome (OSD), the Sudetes, NE Bohemian Massif underwent multiple folding and shearing during the Variscan Orogeny. In the sheared domains, there are less deformed pods in which rocks preserve better records of metamorphic events prior to the regional temperature peak. In one such pod, near Gniewoszów on the western limb of the dome, marbles enclosed by massive amphibolites occur. In these rocks, zoned plagioclase with actinolite and epidote inclusions and zoned amphibole grains allowed recognition of three mineral assemblages and three P-T stages at: (1) 310°C/3–4 kbar, (2) 480–500°C/10.5 kbar, (3) 500–530°C/6–6.5 kbar, based on isopleth intersections and checked against conventional thermobarometry. These define a steep clockwise P-T path and a geothermal gradient of 17°C/km before peak conditions were attained, which suggests subduction of the metavolcano-sedimentary rocks (Stronie Formation of the MSG) on the western limb of the OSD, with a transient yet discrete higher pressure episode. Mineral relicts capable of demonstrating a higher pressure event are scarce in the supracrustal rocks of the dome, mainly because they became more thoroughly equilibrated and obliterated during the temperature peak at mid-amphibolite facies conditions and the subsequent ubiquitous greenschist facies overprint.

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An insight into a gneiss core of the Orlica–Śnieżnik Dome, NE Bohemian Massif : new structural and U-Pb zircon data

Redlińska-Marczyńska A., Żelaźniewicz A., Fanning C. M.

Geological Quarterly

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2016

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Vol. 60, No. 3

714--736

EN

The Orlica–Śnieżnik Dome in the Sudetes, the NE Bohemian Massif, embraces two formations of felsic gneisses of controversial origin and evolution. Our study shows that despite similar geochemical signatures, they carry systematic minor differences in mineral, isotope, zircon and geothermobarometric characteristics. Four variants of the Gierałtów gneisses include migmatites and have a longer structural history than the Śnieżnik augen orthogneisses. U-Pb SHRIMP analyses yielded U-Pb ages of ~500 Ma for cores and ~498 Ma for wide outer parts of zircon grains in the twice-folded Gierałtów gneisses, and an age of ~500 Ma for a discordant neosome vein. Neoproterozoic metasediments were among precursors of the lithologically diversified Gierałtów Gneiss Formation. First deformation, metamorphism, and migmatisation of these rocks occurred at 515–475 Ma and overlapped with the development and emplacement of a porphyritic S-type granite precursor to the Śnieżnik Gneiss Formation. The metagranite (= Śnieżnik augen orthogneiss) embraced migmatitic xenoliths. Zircon grains from such xenoliths revealed distorted and replaced cores which yielded U-Pb ages that dispersed around 507–487 Ma, whilst wide darker poorly zoned outgrowths yielded ages from ~343 Ma to ~325 Ma (mean ~340 Ma). These outgrowths were interpreted as a record of Carboniferous metamorphism assisted by rich Zr- and U-carrying fluids. The Variscan metamorphic overprint was heterogeneous, and variously affected rocks of the two gneiss formations.

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The Orlica–Śnieżnik Dome, the Sudetes, in 2002 and 12 years later

Żelaźniewicz A., Jastrzębski M., Redlińska-Marczyńska A., Szczepański J.

Geologia Sudetica

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2014

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Vol. 42

105--123

EN

During the 2002 meeting of Czech, Polish and Slovak tectonic community in Żelazno, the Sudetes, the Central European Tectonic Studies Group (CETeG) was established. 12 years ago, participants of the meeting made an excursion to the eastern part of the Orlica–Śnieżnik Dome (OSD), which was focused on a variety of gneisses with inserts of (U)HP eclogites and various enclaves. The 2014 meeting brought members of the CETeG to the OSD again and an accompanying field excursion was dedicated mainly to evolution of metasedimentary and metavolcanogenic rocks in the region. This paper is a short review of the results of the studies undertaken in the OSD by different research groups in the last 12 years. The review is set against a background of what we knew about the geology of the dome in 2002. A significant progress was made. P-T paths were determined for mica schists and marbles as well as for metarhyolites originated from the continental crust and metabasites derived from the mantle. New light was shed on the origin of various types gneisses in the OSD and their genetic and structural relationships. A plethora of isotopic studies helped to better constrain timing of igneous and metamorphic events in the Orlica–Śnieżnik complex. Ages clustered around 350–340 Ma are repeatedly obtained, yet scarcer older ages up to 390 Ma and their geological significance are open to debate. Tectonic evolution of the dome was revised and new geodynamic concepts were proposed. However the new data has created some new problems and some old problems are still to be resolved in the future.

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The CETeG 2014 excursion to crystalline basement of the Orlica–Śnieżnik Dome, the Sudetes

Żelaźniewicz A., Budzyń B, Ilnicki S., Jastrzębski M., Murtezi M, Redlińska-Marczyńska A., Stawikowski W., Szczepański J.

Geologia Sudetica

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2014

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Vol. 42

125--136

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Rocks deformed in the constrictional regime: L>S to L tectonites in the Orlica-Snieżnik Dome, the Sudetes, Poland

Żelaźniewicz A., Kromuszczyńska O, Biegała N

Geologia Sudetica

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2014

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Vol. 42

101--102

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Quartz c-axis fabrics in constrictionally strained orthogneisses: implications for the evolution of the Orlica-Śnieżnik Dome, the Sudetes, Poland

Żelaźniewicz A., Kromuszczyńska O., Biegała N.

Acta Geologica Polonica

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2013

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Vol. 63, no. 4

697--722

EN

The Orlica-Śnieżnik Dome (OSD), NE Bohemian Massif, contains in its core several gneiss variants with protoliths dated at ~500 Ma. In the western limb of the OSD, rodding augen gneisses (Spalona gneiss unit) are mainly L>S tectonites with a prominent stretching lineation. The few quartz LPO studies have produced somewhat discrepant results. Reexamination of these rocks revealed that texture formation was a protracted, multistage process that involved strain partitioning with changing strain rate and kinematics in a general shear regime at temperatures of the amphibolite facies (450–600°C). Quartz c-axis microfabrics show complex yet reproducible patterns that developed under the joint control of strain geometry and temperature; thus the LPOs are mixed features represented by pseudogirdle patterns. Domainal differences in quartz microfabrics (ribbons, tails, quartzo-feldspathic aggregate) are common in the Spalona orthogneisses but uncommon in the sheared migmatitic gneisses. In the latter rocks, the constrictional strain was imposed on the originally planar fabric defined by high-temperature migmatitic layering. The constrictional fabric of the Spalona gneisses may have developed in the hinge zones of kilometer-scale folds, where the elongation occurred parallel to the fold axes. Other occurrences of rodding gneisses throughout the Orlica-Śnieżnik Dome are thought to occupy similar structural positions, which would point to the significance of large-scale folds in the tectonic structure of the dome.

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Gneisses in the Orlica-Śnieżnik Dome, West Sudetes : a single batholitic protolith or a more complex origin?

Redlińska-Marczyńska A., Żelaźniewicz A.

Acta Geologica Polonica

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2011

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Vol. 61, no. 3

307-339

EN

Detailed structural and petrographic studies confirmed the presence of two major units of ca. 515-480 Ma gneisses in the Orlica-Śnieżnik Dome (NE Bohemian Massif) and enabled the distinction of two formations which differ in their mineral composition (modal and chemical) and structural records. An intrusive contact between rocks of the two formations was observed. The Gierałtów Gneiss Formation is composed of rocks having at least two sets of folded metamorphic foliations, with relics of compositional banding and records of early shearing prior to migmatization and metablastesis which produced quartzofeldspathic segregations (D1-D2 events). Such aggregates, even if isometric and shared (D3) may, but must not be mistaken for original augens (porphyroclasts in the original granite). Modal contents of the feldspars differ widely (20-40% of plagioclase feldspar, 16-40% of alkali feldspar) as well as their composition (Ab[0-90], An[6-38]); the biotites can be either poor or enormously enriched in Al (0.26-1.07 Al[^VI]). Such heterogeneities are consistent with the inferred metamorphic transformations of originally diversified sedimentary-volcanogenic protoliths. in contrast, the Śnieżnik Gneiss Formation is composed of metagranites, dynamically metamorphosed into the augen gneisses. They possess only one set of mylonitic foliation and one rodding lineation, both developed during a regional shear event (D3). Nearly equal modes of feldspars and quartz, uniform composition of plagioclase feldspar (An6-23) and a rather stable amount of Al (0.3-08 AlVi) in the biotites are indicative of homogenization of a granitic protolith. Anatectic provenance of the gneisses is evidenced by enclaves. Felsic microgranular enclaves are chilled fragments of the parental intrusion, while xenoliths and surmicaceous enclaves are akin to rocks of the Gierałtów Formation, thus the latter or equivalent rocks formed a migmatic envelope of the Śnieżnik granite pluton.

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Struktury hydratacyjne i deformacyjne w skałach czapy gipsowej wysadu solnego Dębiny w rowie Kleszczowa

Krzesińska A., Redlińska-Marczyńska A., Wilkosz P., Żelaźniewicz A.

Przegląd Geologiczny

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2010

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Vol. 58, nr 6

522-530

EN

The Dębina salt dome is situated in central part of the Tertiary Kleszczów Graben, central Poland. Cap rocks of the dome were characterized on the basis of analysis of core material from a well drilled in the northern part of that structure. The cap rock sequence may be subdivided into two parts. Its lower part with breciated structure represents residuum from dissolution of saline series whereas the upper comprises rocks developed by coalescence of shale cover with gypsum. Gypsum rocks of the cap form 6 lithotypes. In these lithotypes it is possible to distinguish: 1) recrystallizational structures developed during diagenesis and multiple hydration transformations, 2) structures developed in a local stress field related to displacements evoked by dissolution of the cap rocks and fluid circulation. Structures of the first type include microcrystalline gypsum with anhydrite relics and carbonate nodules, lenticular and acicular gypsum, porphyroblastic and even-grained gypsum as well as vein gypsum and first generation of stylolites. The other type of structures is represented by: gypsum showing shape fabrics and associated gypsum nodules, gypsum grains with geometry of -clasts, fibrous gypsum in pressure shadows, structures of the core-and-mantle type, subgrains developing in bigger crystals and second generation of stylolites and slickolites. Five sets of fractures were recorded. These fractures developed in the cape rocks under stress field with the vertical maximum stress axis and active shear planes. The normal faults of B, C and D sets could be formed during upward motion of the dome, its stagnation, or during gravitational collapse triggered by karst processes. Oblique striations on microfault B surfaces point to later reactivation under local normal-slip regime caused by ongoing subsidence of the cap rocks, or alternatively - a reactivation that occurred in response to external stress field which controlled evolution of the extensional Kleszczów Graben.

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More evidence on Neoproterozoic terranes in Southern Poland and southeastern Romania

Żelaźniewicz A., Buła Z., Fanning M., Seghedi A., Żaba J.

Geological Quarterly

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2009

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Vol. 53, No 1

93-124

EN

New geological, geochemical and U-Pb SHRIMP zircon age data brought more information about basement units in subsurface of Southern Poland and SE Romania, which allows to revise and refine some earlier models in the framework of the break-up of the Rodinia/Pannotia supercontinent. In the Brno Block, Moravia, and in the Upper Silesia Block, three different terranes formed the composite Brunovistulia Terrane. The Thaya Terrane (low eNd(T)) of Gondwana (Amazonia) descent collided obliquely at 640–620 Ma with the Slavkov Terrane (moderate eNd(T)) composed of amphibolite facies metasediments and arc-related, mostly unfoliated granitoids which intruded at 580–560 Ma. At that time, back-arc rifting separated the couple Thaya–Slavkov (inherited zircons: 1.01–1.2, 1.4–1.5, 1.65–1.8 Ga) that drifted away from Gondwana until collision around 560–550 Ma with the Rzeszotary Terrane, the Palaeoproterozoic (2.7–2.0 Ga) crustal sliver derived from Amazonia or West Africa. At least these three units composed Brunovistulia, which occurred at low latitudes in proximity to Baltica as shown by palaeomagnetic and palaeobiogeographic data. Then Brunovistulia was accreted to the thinned passive margin of Baltica around its Małopolska promontory/proximal terrane. A complex foreland flysch basin developed in front of the Slavkov–Rzeszotary suture and across the Rzeszotary–Baltica/Małopolska border. The further from the suture the less amount of the 640–550 Ma detrital zircons extracted from the Thaya–Slavkov hinterland and the smaller eNd(T) values. In West Małopolska, the flysch contains mainly Neoproterozoic zircons (720–550 Ma), whereas in East Małopolska 1.8–2.1 Ga and 2.5 Ga zircons dominate, which resembles nearby Baltica. The basin infill was multiphase folded and sheared; in Up per Silesia prior to deposition of the pre-Holmia Cambrian over step. In Małopolska, the folded flysch series formed a large-scale antiformal stack with thermal anticline in its core marked by low-grade metamorphic overprint. In Central Dobrogea, Moesia, Ediacaran flysch also contains mainly 700–575 Ma detrital zircons which link the source area, likely in South Dobrogea with ca. 560 Ma granitoids, rather close with Gondwana. However, fauna in Lower Cambrian overstep strata shows Baltican affinity. Such features resemble Upper Silesia, thus Brunovistulia might have extended beneath the Carpathians down to Moesia. The other part of South Dobrogea with Palaeoproterozoic ironstones resembles Ukrainian banded iron formation. If true, the Baltican sliver would be incorporated in Moesia. Such a possibility concurs with the provenance data from Ediacaran flysch of Central Dobrogea, which points to uplifted continental block as a source of derital material. Our study supports an earlier proposition that at the end of the Neoproterozoic a group of small terranes that included Brunovistulia, Moesia and Małopolska formed the Teisseyre-Tornquist Terrane As semblage (TTA). In our model, a characterisistic feature of the TTA was a mixture of crustal elements that were derived from both Gondwana and Baltica, which gave rise to mutual collisions of the elements prior to and concurrent with the docking to Baltica in latest Ediacaran times. The presence of extensive younger covers and complex Phanerozoic evolution of individual members of the TTA impede the recognition of their Neoproterozoic history.

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Refining the granite, gneiss and schist interrelationships within the Lusatian-Izera Massif, West Sudetes, using SHRIMP U-Pb zircon analyses and new geologic data

Żelaźniewicz A., Fanning C., M., Achramowicz S.

Geologia Sudetica

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2009

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Vol. 41

67-84

EN

The eastern part of the Lusatian-Izera Massif, West Sudetes, comprises different types of gneissose rocks, collectively known as the Izera gneisses, with a subordinate component of petrographically varied mica schists. Coarse-grained gneisses and their protoliths have been dated at 515-480 Ma, but the lack of age data for other rocks has impeded accounts of their mutual relationships and, thus, the region's geological evolution. This paper reports new sensitive high-mass resolution ion microprobe (SHRIMP) U-Pb zircon data, and some new field and petrographic observations, for three representative rock types: 1) the Złotniki schist (a fine-grained quartz-albite-chlorite-sericite-biotite schist); 2) a fine-grained gneiss that grades to 'porphyroblastic' granite and which occurs on the slopes of Mt. Stóg Izerski; 3) a leucogranite found just the south of the village of Kotlina. A volcanogenic intercalation in the Złotniki Lubańskie schists developed at 560 Ma and contained xenocrystic zircons that grew in the source at 620 Ma and 600-580 Ma. The schists are interpreted as the metamorphosed equivalent of the Lusatian greywackes, which were derived from a dissected arc and deposited in a convergent-margin basin along northern peri-Gondwana. The zircons from the fine-grained gneisses yielded four age groups: 515 +- 7 Ma, 500 +- 12 Ma, 487 +- 13 Ma and 471 +- 8 Ma. Similar age groups of zircons can also be found in the coarse-grained metagranites. Rifting of Gondwana during the mid-Cambrian-early Ordovician was a protracted thermal event lasting ~30-45 m.y., with episodic attenuation of the mainland crust every ~5-10 m.y. before continental fragments finally became separated. Each episode successively promoted an increased heat flux from the mantle that facilitated melting of the crust, causing metamorphism and fusion of the Precambrian Lusatian-Izera basement and a final phase of S-type felsic magmatism. The leucogranite sample yielded zircons in two age groups, 508 +-5 Ma and 483.1 +- 3.6 Ma, with low Th/U ratios, which is interpreted as a product of an anatectic melting at deeper crustal levels. These leucogranites are in close spatial relation with belts of mica schist, which could mean that these granites used some rheologically weak zones that were introduced into the Izera pluton where large fragments of country rocks were trapped within the ~500 Ma granites.

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Regionalizacja tektoniczna Polski-stan obecny i próba uporządkowania

Żelaźniewicz A.

Przegląd Geologiczny

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2008

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Vol. 56, nr 10

887-894

EN

A geological map shows an outcrop pattern of rock units (usually lithostratigraphic) which after having experienced more or less severe tectonic deformation have become structural parts of the solid earth crust. Thus, such a map along with a complementary cross section(s) depicts tectonic structure of a given region at appropriate scale. While speaking about geology of the region one has to identify tectonic units and their boundaries (i.e. deformational structures) on the map and distinguish them by applying proper tectonic terms. In any region, such terms should be accompanied by geographical names to allow for the distinction between particular, more local tectonic units. Once given name should not be changed or replaced by others without producing justified reasons for that. This is an essence of tectonic regionalization which is often misused in recent practice conducted in Poland. In consequence, some units are addressed by 3 or 4 different terms, not seldom with different genetic connotations, or refer to units without determined boundaries. Such an unwelcome practice should be abandoned as it produces serious confusions and misunderstandings among geologists and still more, which is even worse, among non-geologists. The geological structure of Poland requires presentation on two maps. One of them is to show the picture available after removing Cenozoic cover and the other showing the picture after removing Permo-Mesozoic strata. A brief glossary of tectonic terms recommended by the Committee for Geological Sciences PAS is attached.

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Regionalizacja tektoniczna Polski-Polska południowo-zachodnia

Żelaźniewicz A., Aleksandrowski P.

Przegląd Geologiczny

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2008

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Vol. 56, nr 10

904-911

EN

Geologically, southwestern Poland is located between the Upper Elbe Fault Zone on the SW and the Dolsk Fault Zone on the NE. It comprises two major crustal blocks: the Lower Silesian Block and the South Wielkopolska Block separated by the narrow Middle Odra Horst. The Lower Silesian Block is principally subdivided into the Fore-Sudetic Block and the Sudetic Block. These blocks are further subdivided into several smaller tectonic units. Their boundaries and main features are briefly characterized. It is proposed here to initiate a discussion on internally coherent tectonic subdivision of the region, principles of such subdivision and due revision of the hitherto used terminology. The discerned tectonic units generally do not coincide with physiogeographic subdivision, thus it is not recommended to confuse the geographic and geologic regionalization.

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A Carboniferous/Permian, calc-alkaline, I-type granodiorite from the Małopolska Block, Southern Poland: implications from geo chemi cal and U-Pb zircon age data

Żelaźniewicz A., Pańczyk M., Nawrocki J., Fanning M.

Geological Quarterly

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2008

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Vol. 52, No 4

301-301

EN

A granodiorite from bore hole WB-102A in the Dol ina Będkowska, the Małopolska Block (MB), South ern Po land, yielded a mean U-Pb zir con age of 300 š3 Ma with SHRIMP II. No in her ited older com po nent was de tected. Geo chemically, it is a K-rich, I-type, calc-al ka line granodiorite with su pra-subduction char ac ter is tics (neg a tive Nb and Ti anom a lies). Silicic ig ne ous rocks are abun dant at the MB mar gin along the Kraków-Lubliniec Fault Zone (KLFZ) across which it ad joins to the Up per Silesian Block (USB) where such rocks are scarce. Both blocks be long to the Variscan fore land. Gra nitic rocks can not, how ever, gen er ate at fore land set tings. Thus, the hy poth e sis is put for ward that the par ent melt for the silicic rocks was de rived from the thick ened lower crust of the Variscan orogenic belt ow ing to extensional de com pres sion melt ing, and trans ported away to wards pul-apart open ings de vel oped along the crustal-scale fault zone (KLFZ) that un der went a com plex strike-slip his tory around the Car bon if er ous/Perm ian bound ary.

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Syntectonic Lower Ordovician migmatite and post-tectonic Upper Viséan syenite in the western limb of the Orlica-Śnieżnik Dome, West Sudetes: U-Pb SHRIMP data from zircons

Żelaźniewicz A., Nowak I., Larionov A.N., Presnyakov S.

Geologia Sudetica

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2006

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Vol. 38

63-80

EN

In the Orlica-Śnieżnik Dome, the West Sudetes, metagranites of 515-480 Ma age occur as coarse-grained augen gneisses (Śnieżnik type) in the middle of the dome, whereas fine-grained, often migmatitic gneisses (Gierałtów type) are located more externally. Both the origin and genetic relationships of the gneisses have been disputed for many years. In a quarry near Zdobnice, in the western part of the dome, migmatitic gneisses and a post-tectonic dyke of unfoliated biotite-hornblende high-K syenite occur. The migmatititc gneiss has mesosome with relic minerals, notably Ca-Fe garnet and pseudomorphs after Al2SiO5 polymorph (?), indicative of an early granulitic metamorphism at considerably high pressure and temperature. Retrogression at still high temperature of ~720-750°C under the upper amphibolite facies conditions was accompanied by migmatization which among others produced cross-cutting neosome veins of graphic granite. Zircons from the melt derived neosome and from the syenite dyke were analysed with SHRIMP II. The former yielded a concordia age of 485š12 Ma which is taken to constrain the waning stage of the Late Cambrian-Early Ordovician migmatization. Migmatitic gneisses may have represented a metasedimentary-metaigneous Neoproterozoic crust that underwent multistage metamorphism, granulite facies inclusive, and then yielded to extensive partial melting between 515 Ma and 480 Ma. Our new data shows that the migmatization in the Orlica-Śnieżnik Dome was concurrent with the intrusion of a granitic precursor of the augen gneisses and does not support the views that the migmatitic gneisses can be a derivative of the ~500 Ma granite. In the Late Cambrian-Early Ordovician, the porphyritic granite intruded in migmatitic country rocks which mantled the granitic core. Both lithologies were later ductilely sheared and deformed under lower conditions of the amphibolite and greenschist facies during the Variscan orogeny. Four zircon grains from the post-tectonic syenite dyke yielded a concordia age of 326š3 Ma, which is interpreted as the time of its intrusion. This constrains the ductile Variscan events in the studied region.

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Cadomian versus younger deformations in the basement of the Moravo-Silesian Variscides, East Sudetes, SW Poland: U-Pb SHRIMP and Rb-Sr age data

Żelaźniewicz A., Nowak I., Bachliński R., Larionov A.N., Sergeev S.A.

Geologia Sudetica

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2005

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Vol. 37

35-51

EN

U-Pb SHRIMP dating of zircons from a metapegmatite vein which cross-cuts amphibolite facies paragneisses confirms ~580 Ma magmatism in the basement of the northern part of the Moravo-Silesian Zone (Jeseníky Mts.). Structures older than the felsic vein set are interpreted as a record of the Cadomian orogeny. This has been represented by N-trending, W-vergent folds followed by a top-to-the east shearing that occurred at T = 600°C and P = 5 kbar in the Neoproterozoic. The subsequent tectonic overprint led to folding and shearing of the pegmatite, which took place at similar P-T conditions but was associated with top-to-the west kinematics and shortening at a high angle to the foliation. This event likely developed during early stages of Variscan convergence when the Moravo-Silesian crust (Brunovistulia) was subducted and forced down below the approaching upper plate composed of terranes of the Bohemian Massif. Alternatively, it may have occurred around 500 Ma, related to crustal extensional (break-up of Gondwana margins in Cambrian times). Although the first option is favoured, presumably the two may have actually happened. The last ductile deformation was a top-to-the-east younger shearing localized in zones of various widths, assigned to the Variscan collision and reverse movement of the basement rocks. The latter two events occurred at temperatures that allowed in the metapegmatite for the crystal plastic deformation of quartz grains from which the strain was removed by subsequent static recrystallization, and that were high enough to reset the Rb-Sr system in this rock. Consequently, the obtained Rb-Sr isochron age of 290 Ma is considered to reflect the time of uplift. Such late regional uplift is characteristic of the northern part of the Moravo-Silesian Zone, which is the footwall to the Moldanubian Thrust, which separates the Bohemian Massif terranes from the Brunovistulia terrane. It follows from this study that in the East Sudetes basement rocks, structures which are often classified as Variscan may in fact be Cadomian and that the Cadomian record in these rocks is richer than previously assumed.

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The Orava Deep Drilling Project and post-Palaeogene tectonics of the Northern Carpathians

Golonka J., Aleksandrowski P., Aubrecht R., Chowaniec J., Chrustek M., Cieszkowski M., Florek R., Gawęda A., Jarosiński M., Kępińska B., Krobicki M., Lefeld J., Lewandowski M., Marko F., Michalik J., Oszczypko N., Picha F., Potfaj M., Słaby E., Ślączka A., Stefaniuk M., Uchman A., Żelaźniewicz A.

Annales Societatis Geologorum Poloniae

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2005

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Vol. 75, No 3

211-248

EN

This paper presents an insight into the geology of the area surrounding the ODDP proposed drilling site, and the structural development of the Carpathians in post-Palaeogene times. Since the deep drilling is proposed to be located in the Orava region of the Northern Carpathians, on the Polish-Slovak border, the structure and origin of the Neogene Orava Basin is also addressed in the paper. The outline of geology of the Carpathian Mountains in Slovakia and Poland is presented. This outline includes the Inner Carpathian Tatra Mountains, the Inner Carpathian Palaeogene Basin, the Pieniny Klippen Belt, the Outer Carpathians, the deep structure below the Carpathian overthrust, the Orava Basin Neogene cover, the Neogene magmatism, faults and block rotations within the Inner and Outer Carpathians, and the Carpathian contemporary stress field. The outline of geology is accompanied by the results of the most recent magnetotelluric survey and the detailed description of the post-Palaeogene plate tectonics of the circum-Carpathian region. The oblique collision of the Alcapa terrane with the North European plate led to the development of the accretionary wedge of the Outer Carpathians and foreland basin. The northward movement of the Alpine segment of the Carpathian-Alpine orogen had been stopped due to its collision with the Bohemian Massif. At the same time, the extruded Carpatho/ Pannonian units were pushed to the open space, towards a bay of weak crust filled up by the Outer Carpathian flysch sediments. The separation of the Carpatho/Pannonian segment from the Alpine one and its propagation to the north was related to the development of the N-S dextral strike-slip faults. The formation of the West Carpathian thrusts was completed by the Miocene time. The thrust front was still progressing eastwards in the Eastern Carpathians. The Carpathian loop including the Pieniny Klippen Belt structure was formed. The Neogene evolution of the Carpathians resulted also in the formation of genetically different sedimentary basins. These basins were opened due to lithospheric extension, flexure, and strike-slip related processes. A possible asteno- sphere upwelling may have contributed to the origin of the Orava Basin, which represents a kind of a rift modified by strike-slip/pull-apart processes. In this way, a local extensional regime must have operated on a local scale in the Orava region, within the frame of an overall compressional stress field affecting the entire West Carpathians. Nevertheless, many questions remain open. Without additional direct geological data, which can be achieved only by deep drilling under the Orava Deep Drilling Project, these questions cannot be fully and properly answered.

PL

W grudniu 1999 Polska dołączyła do programu wierceń kontynentalnych - International Continental Scientific Drilling Program (ICDP). W ramach tego programu jest przygotowywany projekt głębokiego wiercenia w strefie kontaktu teranu Karpat wewnętrznych i płyty północnoeuropejskiej. Praca przedstawia zarys geologii Karpat na terenie Polski i Słowacji, ze szczególnym uwzględnieniem Tatr, paleogenu wewnątrzkarpackiego, pienińskiego pasa skałkowego, zachodnich Karpat zewnętrznych, podłoża nasunięcia karpackiego na południe od Krakowa, neogeńskiego wulkanizmu i budowy geologicznej niecki orawskiej. Wiercenie "Orawa" byłoby usytuowane w rejonie Jabłonki-Chyżnego na linii przekroju sejsmicznego CELEBRATION CEL01, jak również w niedalekim sąsiedztwie głębokiego przekroju geologicznego Kraków-Zakopane i na linii przekroju Andrychów-Chyżne. Przekroje Kraków--Zakopane i Andrychów-Chyżne wykorzystują szereg wierceń Państwowego Instytutu Geologicznego i PGNiG, a także badania sejsmiczne i magnetote-luryczne. Usytuowanie wiercenia w rejonie przygranicznym pozwoli na międzynarodową współpracę z geologami i geofizykami słowackimi. Wiercenie to ma na celu wyjaśnienie szeregu problemów badawczych. Jednym z nich jest zagadnienie młodych i współczesnych ruchów tektonicznych w Karpatach. Przez obszar karpacki przebiega granica europejskiego pola plam gorąca, wyznaczona neogeńskim wulkanizmem oraz rozkładem strumienia cieplnego. Na obszarze pomiędzy Górną Orawą a Górnym Śląskiem, linia graniczna łącząca neogeńskie wulkanity Zakarpacia z andezytami rejonu przypienińskiego i bazaltami Dolnego Śląska przecina skośnie nasunięcia jednostek fliszowych Karpat Zewnętrznych. Równocześnie w rejonie Orawy do pienińskiego pasa skałkowego skośnie dochodzi oś karpackiej, ujemnej anomalii grawimetrycznej, a podłoże skonsolidowane występuje na głębokości nie większej niż 6-9 km, a więc w zasięgu głębokiego wiercenia, co sugerują wyniki badań megnetotellurycznych (Żytko, 1999) i magnetycznych. Podniesienie to, przy generalnym zapadaniu podłoża platformy europejskiej pod Karpaty ku południowi, może bya spowodowane warunkami geotermicznymi, na skutek podnoszenia się astenosfery i występowania pióropuszy płaszcza. Pióropusze te mogą bya niezależne od karpackiej kompresji i subdukcji. Z piórpuszami tymi łączy się lokalna i regionalna ekstensja w warunkach megaregionalnej kompresji. Zjawiska tego rodzaju nie są jeszcze dokładnie poznane, aczkolwiek występują w kilku miejscach na świecie (np. Panteleria na Morzu Śródziemnym). Opracowanie zagadnienia roli pióropuszy płaszcza i określenie ich relacji do kolizji i subdukcji mają zasięg globalny, a ich wyjaśnienie w rejonie karpackim pozwoli na stworzenie uniwersalnego modelu ewolucji orogenów. Nie jest wykluczone, że mamy do czynienia z orogenezą "modyfikowaną" przez pióropusz płaszcza. Powstanie niecki Orawy i Podhala mogłoby więc mieć związek z riftingiem spowodowanym wpływem pióropuszy płaszcza na pograniczu dwóch płyt. Ryft ten jest obrzeżony między innymi wyniesieniami Babiej Góry i Orawskiej Magury. Z ryftem może być związany wulkanizm ukryty pod neogeńskimi utworami niecki orawskiej, a widoczny jako wysokooporowe ciała na profilach megnetotellurycznych. Tektonikę tego obszaru komplikuje występowanie uskoków przesuwczych o różnym przebiegu i orientacji i związane z nimi tworzenie się basenów międzyprzesuwczych typu pull-apart. Proponowane wiercenie przyczyniłoby się do uzyskania odpowiedzi na postawione wyżej problemy. Dla określenia dokładnej lokalizacji wiercenia i jego właściwej interpretacji geologicznej konieczne będzie wykonanie dodatkowych prac geofizycznych. Płytka sejsmika wyjaśniłaby zasięg utworów neogeńskich i pozycję pienińskiego pasa skałkowego pod utworami neogenu, zaś głęboka sejsmika, a zwłaszcza zdjęcie 3-D, przyczyni łaby się do lepszego rozpoznania tektoniki wgłębnej.

17

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.

18

Paleomagnetism and remagnetization of Upper Devonian synorogenic clastic sediments from the Pogorzała Formation (Świebodzice Depression, West Sudetes, Poland

Kądziołko-Hofmokl M., Jeleńska M., Aifa T., Edel J.B., Żelaźniewicz A.

Geologia Sudetica

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1999

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Vol. 32, nr 2

113-126

EN

The Upper Devonian highly polymict conglomerates (site 26) and sandstones with clasts (site 27) of the Pogorzała Formation in the synorogenic Świebodzice Depression, West Sudetes, are hydrothermally altered and show signs of penetration by mineralized fluids. Nearly all the magnetic minerals present (mainly Fe-oxides and pyrrhotite accompanied by Fe-hydroxides) are of secondary origin. Rocks from each site carry multicomponent natural remanence composed of Mesozoic/post-Mesozoic and Palaeozoic components. In the conglomerates (site 26) two Palaeozoic components, labelled P and C, occur in the matrix and pebbles, whereas in the sandstones with large clasts (site 27) only one Palaeozoic component labeled C1 occurs. This means that the results of the conglomerate test for both sites are negative and the studied rocks were remagnetized during several remagnetization episodes. The overprints present in site 26 closely fit the reference data for the Baltica Plate for the Early Permian component (P) and Viséan component (C). The overprint present in site 27 is slightly shifted from the Westphalian (C1) segment of the reference path. The P component is also close to the path of polar wander for Variscan Europe.

19

Granitoids of the Odra Fault Zone: late- to post-orogenic Variscan intrusions in the Saxothuringian Zone, SW Poland

Oberc-Dziedzic T., Żelaźniewicz A., Cwojdziński S.

Geologia Sudetica

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1999

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Vol. 32, nr 1

55-71

EN

There are 5 occurrences of granodioritic to monzogranitic rocks found subsurface along the Odra Fault Zone a Permo-Mesozoic horst defining the northeastern edge of the Bohemian Massif. These are generally unfoliated, I-type granitoids with low A/CNK and initial Sr/Sr ratios making them geochemically and petrographically akin to late- to post-kinematic Variscan granitoids of the West Sudetes, being closest to those of the eastern part of the Fore-Sudetic Block (Strzelin, Niemcza). They represent late/post-orogenic, collisional intrusives of Early-Late Carboniferous age which are widespread throughout the Saxothuringian and Moldanubian zones in the Bohemian Massif. The country rocks to the granitoids are mica schists and paragneisses attaining staurolite-grade. The granitoids lack evidence of ductile or brittle strike-slip movement of Late Carboniferous-Permian age along the Odra Fault Zone, which thus has to be taken as a dip-slip fault zone, rather than a late Variscan dextral strike-slip feature. Brittle to semi-brittle deformation of the Odra granitoids relates to the formation of the horst during Permo-Mesozoic times. A Silurian-Early Devonian magmatic arc of the Mid-German Crystalline Rise, identified further to the west in Germany, probably does not have an easterly prolongation into Poland because there is no evidence for arc-related magmatism of that age in the Sudetes and Fore-Sudetic Block.