The Saxothuringian Terrane defined in the western part of the Bohemian Massif is regarded to have easterly continuations in the Karkonosze–Izera Massif, the Kamieniec Ząbkowicki Belt and the Orlica–Śnieżnik Dome. All these units comprise Early Ordovician (~500 Ma) metagranites associated with mica schists. Even more to the east, ~500 Ma metagranites and metasedimentary rocks occur also in the Strzelin Massif of the East Sudetes, where they are known as the pale and dark Stachów gneisses, respectively. Altogether, these rocks form the Stachów Complex which was thrust on the Strzelin Complex of the Brunovistulicum Terrane during the Variscan Orogeny. The contribution presents lines of evidence for a Saxothuringian affinity of the Stachów Complex rocks: (1) the new SHRIMP U-Pb age data of zircons from both the pale and dark Stachów gneisses; (2) the indication that the zircon age spectra from the ~500 Ma granitoids and their accompanying metasedimentary rocks are similar to those found in other parts of the Sudetes; (3) the “Armorican” age pattern of inherited zircons of the pale Stachów gneisses, as also observed in the Saxothuringian Terrane; (4) the similarity of trace elements and Sm-Nd isotope data of the Stachów gneisses and correlative rocks from the Karkonosze–Izera Massif and the Orlica–Śnieżnik Dome.
South-west Poland (Silesia) is the region of dramatic history which has left significant heritage, comprising, e.g., numerous historical castles. In this paper, we describe selected castles in Lower Silesia, with special attention given to the usage of exotic (imported) decorative stone materials traded across Europe in various historical periods. Out of the total number of c. 100 historical castles and palaces in SW Poland, only three of them, i.e. Czocha, Ksi¹¿ and Moszna, have preserved significant amount of the original stone decoration. In Czocha Castel, apart from local stones, we have identified, e.g.: red and white, and grey limestones (from Belgium, Germany or Italy). In Ksi¹¿ Castle, the interiors have a great variety of exotic stone materials: travertine, marbles and limestones, e.g. Rosso di Francia, and many others, mostly from France and Italy. In Moszna Castle, representative rooms are adorned with “marbles”: Rosso di Verona, Giallo di Verona, Giallo Siena, Rosso di Francia, and serpentinites and ophicalcites (from Austria and Italy). Most of the exotic stones in the three castles studied were imported at the turn of the 19th–20th centuries and in the early 20th century, when the castles were largely reconstructed and redecorated.
New petrographic and geochemical data show some differences between Variscan Bt-Ms granites occurring either as small plutons or dykes in the Strzelin Massif (SW Poland). The granites of the Gromnik and Górka Sobocka plutons are rich in micas and crystallized from "wet" magmas; the granites in the dykes and in the Gębczyce pluton are mica-poorer and cordierite-bearing rocks, derived from “dryer” magmas. The lower initial eNd values in the Bt-Ms granites of the dykes, compared with those in the plutons, reflect a more "crustal" signature of the former, possibly due to local crustal assimilation, via AFC, shortly before emplacement. Much more radiogenic initial 87Sr/86Sr ratios in the dykes, up to 0.726, further suggest the involvement of extraneous, hydrous crustal fluids enriched in 87Sr during the evolution of late-stage magma derivatives. The new U-Pb SHRIMP zircon age of 296 ± 6 Ma for the Gębczyce Bt-Ms granite shows that this body belongs to the third stage of magmatism in the Strzelin Massif. The U-Pb SHRIMP zircon data for the Bt-Ms granite dykes provide ages similar to those of their host rocks: c. 295 Ma for the Gęsiniec tonalite and the enclosed Bt-Ms granite, and c. 285 Ma for the Strzelin biotite granite and its Bt-Ms granite dykes. These new data from peraluminous rock-types complement our previous studies focused on the tonalites, granodiorites and biotite granites, and shed light on the late-stage igneous evolution of the Strzelin Massif.
A 415 g single meteorite was purchased in 2010 by T. Jakubowski from a dealer in Morocco. The meteorite was isometric in shape, ca. 8 cm in size, with distinct regmaglypts on the original ablated surface, and covered mostly in primary crust with one broken surface. The weight of the sample studied was 69 g. The meteorite is composed of several types of chondrules including porphyritic-Ol-Px, barred-Ol, radial-Px, granular and cryptocrystalline with distinct and diffused (not sharp) boundaries, and opaque grains and aggregates, enclosed in a very fine-grained matrix. The average compositions of minerals are: olivine (both in chondrules and matrix) − Fo70.4Fa29.1Te0.5, pyroxenes, represented by Mg-Fe (Ca-poor) orthopyroxene (and minor clinopyroxene?) − En73.9Fs24.1Wo2.0, feldspars (small in the matrix and in barred chondrules), with An12-37, and Or~3-4, taenite − Fe 70.80, Ni 25.50 and Co 1.67 wt. %, troilite − Fe0.98S1.00, chromite (Fe2+ 0.96Mg0.12Mn0.01Zn0.01) (Cr1.52Al0.23Fe3+ 0.02Ti0.10Si0.02)O4; altered accessory minerals including apatite and iron-rich secondary phases have also been identified and analyzed. The meteorite is of petrologic type 5, as evidenced by the observed recrystallization of the matrix, relatively good preservation of the chondrule structures, homogeneous composition of olivine and pyroxene, and the presence of only secondary small feldspar grains. The shock stage, S2, is based on the presence of undulatory extinction and irregular fractures in olivine crystals. The weathering grade, W3, is confirmed by the observation that kamacite is totally altered into secondary iron phases, whereas Nirich taenite, and troilite are only partly weathered. The specimen shows many bulk- and mineral-chemical parameters corresponding, mostly, to the LL chondrite group (e.g., Fe/SiO2 0.49, SiO2/MgO 1.62, Fa in olivine 29.05). However, concentrations of several other elements, including REE, are not fully consistent with the average values for the LL ordinary chondrites. Apparently, the parent body of the studied NWA 7915 meteorite was depleted in Dy, Tm, and Yb, compared to typical LL-type ordinary chondrite parent bodies. Also, relatively high concentrations of other elements, including Ba and Sr, have been measured, which may result from terrestrial weathering in hot desert conditions. The meteorite has been classified as LL5 ordinary chondrite, S2, W3, and registered in the Meteoritical Society database as NWA 7915. The type specimen is deposited in the Mineralogical Museum of the University of Wrocław.
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Professor Józef Zwierzycki was born in1888in Krobia, a small town in Wielkopolska (Great Poland), then under Prussian domination. From 1909 till 1914, he studied mining engineering at the Mining Academy, and geology and palaeontology at the University of Berlin. After graduating and obtaining a doctorate degree in geology, he won the competition for a position of geologist in the Dutch Geological Survey in the Dutch East Indies. He left Europe just on the eve of the World War I. He worked on Java, Sumatra and New Guinea in very difficult field conditions, and his work included: geological and soil mapping, geological prospecting of mineral resources, studying unique palaeontological sites and many volcanoes. During 24 years of work on the Malay Archipelago, Józef Zwierzycki was employed as a "research-explorer", "inspector" and, finally, from 1933 till 1938, the Director of the entire Dutch Geological Survey in the Dutch East Indies. After being retired, he received the highest Dutch state award, the Cross of Oranje-Nassau Order for his scientific achievements and work in the Dutch East Indies. In 1938, Józef Zwierzycki, with all the family, returned to Poland. He got a new job in the Polish Geological Institute in Warsaw. After the outbreak of the World War II, he was responsible for securing the property, archives and collections of the Institute. Józef Zwierzycki was arrested and sent to Auschwitz in 1941. One year later, due to firm efforts made mainly by German geologists, he was released from Auschwitz and transported to Berlin, where as a prisoner, he worked for geological needs. In summer 1944, when he was escorted to the Carpathians, he made a bravura escape and hid in Kraków. With a help from his brother-in-low, Professor Kazimierz Maślankiewicz, he luckily hold out in the hiding place till the liberation of Kraków from German occupation. In May 1945, Józef Zwierzycki came to Wroclaw with a group of professors, mainly of Lvov University and Polytechnics, to secure the remnants of buildings and scientific collections of the high schools, left by Germans in the city. In the same year, he obtained a "habilitation" degree and in 1948 received the title of "ordinary professor". Józef Zwierzycki was an outstanding academic teacher with very wide geological knowledge and enormous professional experience, so he gave lectures in several subjects. The research interests of Professor Zwierzycki were, at that time, mainly connected with mineral deposits in SW Poland. Professor Zwierzycki prepared scientific background for prospection of copper deposits, and is considered as a co-discoverer of these deposits in Lower Silesia. Professor Józef Zwierzycki died in 1961. He is among the greatest Polish geologists of the 20th century.
PL
Profesor Józef Zwierzycki urodził się w 1888 roku w Krobi, małym wielkopolskim miasteczku, wówczas pod zaborem pruskim. W latach 1909-1914 studiował w Berlinie - górnictwo na Akademii Górniczej oraz geologię z paleontologią na uniwersytecie. Po uzyskaniu stopnia inżyniera górnika i doktoratu z geologii wygrał konkurs na posadę geologa-eksploratora w Holenderskiej Służbie Geologicznej w Indiach Holenderskich (dzisiejsza Indonezja), dokąd wyjechał w przededniu wybuchu I wojny światowej. Pracował w bardzo trudnych warunkach terenowych na Jawie, Sumatrze i Nowej Gwinei, sporządzając mapy geologiczne i glebowe, poszukując bogactw mineralnych, badając unikalne stanowiska paleontologiczne oraz liczne wulkany. W czasie 24 lat pracy na Archipelagu Malajskim był geologiem-eksploratorem, inspektorem, a w latach 1933-1938 Dyrektorem całej Holenderskiej Służby Geologicznej w Indiach Holenderskich. Po przejściu na emeryturę, za zasługi dla geologii Holandii, otrzymał najwyższe odznaczenie holenderskie, Order Oranje Nassau. W 1938 roku wrócił wraz z rodziną do Polski i podjął pracę w Państwowym Instytucie Geologicznym w Warszawie. Po wybuchu II wojny światowej pełnił obowiązki dyrektora Instytutu i ratował mienie, archiwa i zbiory geologiczne. W 1941 roku został aresztowany i osadzony w Auschwitz, skąd ponad rok później został zwolniony dzięki wstawiennictwu m.in. geologów niemieckich. Następnie przez dwa kolejne lata przymusowo pracował na rzecz geologii w Berlinie. 1 sierpnia 1944 roku zbiegł eskortującym go żołnierzom w Krakowie i w ukryciu, zorganizowanym przez swojego szwagra - profesora Kazimierza Maślankiewicza, dotrwał do zakończenia wojny. W maju 1945 r. przyjechał do Wrocławia w grupie lwowskich profesorów by zorganizować polskie szkolnictwo wyższe i zabezpieczyć poniemieckie zbiory naukowe. W tym samym roku zrobił habilitację, a w 1948 został profesorem zwyczajnym. Profesor Zwierzycki był wybitnym nauczycielem akademickim, który dzięki bardzo szerokiej wiedzy prowadził wykłady z wielu przedmiotów geologicznych. Powojenne badania naukowe Profesora Zwierzyckiego wiążą się głównie z tematyką złóż surowców mineralnych Dolnego Śląska. Wyznaczył podstawy teoretyczne poszukiwań złóż rud miedzi w południowo-zachodniej Polsce i w związku z tym jest uznany za współodkrywcę złóż miedzi na monoklinie przedsudeckiej. Profesor Józef Zwierzycki, który zmarł w 1961 roku, należy do grona największych polskich geologów XX wieku.
Petrological data and recently published U/Pb zircon SHRIMP ages reveal a protracted Variscan magmatic evolution in the Strzelin Massif (SW Poland), with three main stages of granitoid plutonism: 1 – tonalitic I, 2 – granodioritic and 3 – tonalitic II/granitic. The granitoids of the second and third stages form the Strzelin intrusion that is composed of three varieties: medium-grained biotite granite, fine-grained biotite granite and fine-grained biotite-muscovite granite. New SHRIMP data show that the medium-grained and fine-grained biotite granites comprise different zircon populations that reflect complex and prolonged plutonic processes. Two distinct magmatic events seem to be represented by well-defined zircon populations with apparent 206Pb/238U ages of 303 ± 2 Ma in the medium-grained biotite granite, and 283 ± 8 Ma in the fine-grained biotite granite. These dates, however, do not necessarily reflect the true magmatic ages, possibly being “rejuvenated” by radiogenic lead loss in zircons (impossible to resolve based on routine SHRIMP data). Based on field evidence, the third variety, the biotite-muscovite granite, postdates both types of biotite granites. The petrographic and geochemical features, including Nd isotope signature, along with various zircon inheritance patterns and ages, suggest that the parental magmas of the three granites originated from different crustal sources and were emplaced during three successive magmatic pulses.
The Gęsiniec composite intrusion in the northern part of the Strzelin Massif (Fore-Sudetic Block, SW Poland) was formed in the course of three late Variscan magmatic episodes: tonalitic I, granodioritic, and tonalitic II/granitic. The age of the Gęsiniec tonalite, 295 š3 Ma, is the same as that of another tonalite body in the southern part of the Strzelin Massif, the Kalinka tonalite. The younger biotite-muscovite (Bt-Ms) granite, in a dyke cutting the Gęsiniec tonalite, has an indistinguishable isotopic age of 295 š5 Ma; it contains, however, inherited zircons with ages between ca. 1.5 Ga to 374 Ma, similar to zircon ages from surrounding gneisses. This suggests that the magmatic protolith of gneisses and the magma of the Bt-Ms granite could have come from similar sources, or that the magma of the Bt-Ms granite was contaminated by the gneisses. Both the tonalite and Bt-Ma granite represent a late stage of the granitoid magmatism in the eastern part of the Variscan orogen.
Rhyodacite sheets (the Sady Górne Rhyodacites) in the lowermost part of the Permo-Carboniferous Intra-Sudetic Basin molasse fill have been mapped as intrusives but, later on, based on ambiguous field and petrographic evidence, reinterpreted as lower Carboniferous lavas and tuffs; if so, they would mark the earliest episode of late-orogenic volcanism in the Intra-Sudetic Basin and in the whole Sudetes region in SW Poland. However, re-examination of field relationships and new observations are consistent with an intrusive emplacement of the rhyodacites as conformable to semiconformable, simple to composite sheets. SHRIMP zircon study indicates that the rhyodacites contain rare inherited zircons of ca. 560 Ma, and ca. 470 Ma (or slightly older), and a main population of zircons with an average concordia age of 306.1 š2.8 Ma. This latter age documents the emplacement of the rhyodacites during a mid/late late Carboniferous (Westphalian) stage of volcanism in the Intra-Sudetic Basin in the Central European Variscides. This post-orogenic volcanism was possibly initiated several million years later than previously assumed, and could have comprised a few pulses over a relatively prolonged time span of millions of years.
The Central-Sudetic ophiolites comprise mafic-ultramafic complexes around the E and S edges of the Góry Sowie Massif in SW Poland and are recognized as fragments of Devonian (~400 Ma old) oceanic crust. They contain small rodingite bodies and tectonized granite dykes that potentially can highlight the igneous, metamorphic and structural development of the ophiolitic suites. The granite dykes have been tentatively correlated with the Variscan granitoids of the Strzegom-Sobótka Massif to the north. However, new U-Pb SHRIMP zircon data for granites from the serpentinite quarry at Jordanów show a concordia age of 337 š4 Ma for the main zircon population, and of 386 š10 Ma for minor inheritance. Thus, the age of the granite is considerably older than the ages of the Strzegom-Sobótka granitoids, dated at ~310-294 Ma. The granite dyke has a similar age as some other granitoids found near the ophiolitic fragments, e.g., the Niemcza granitoids to the south, dated at 338 +2/-3 Ma; these older granitoids all represents a relatively early stage of granitoid magmatism recorded in that part of the Variscan Orogen. The age of the granitoid dyke within serpentinites confirms that the Paleozoic ophiolites were incorporated into the continental crust already in early Visean times.
U-Pb SHRIMP ages of one granodiorite and two tonalite samples from the Strzelin Massif, northern part of Brunovistulicum, reveal three distinct stages of Carboniferrous-early Permian granitoid magmatism: tonalitic I - 324 Ma, granodioritic - 305 Ma and tonalitic II/granitic - 295 Ma. The first stage of magmatism coincided with the first migmatization event which took place shortly after the first deformation. The second stage of granitoid plutonism was coeval with the second migmatization event which produced abundant pegmatites. It took place after compressional phases of the second deformation and was related to decompression at the beginning of tectonic denudation. The third, most abundant stage of magmatism was connected with late extension in that part of the Variscan Orogen.
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Many basement units of the Variscan orogen that are exposed in the Sudetes, SW Poland, comprise widespread ~500 Ma orthogneisses and associated mica schists, the latter often of unknown age and derivation. Our new U-Pb sensitive high resolution ion microprobe (SHRIMP) zircon ages from two samples of the Izera metagranites, both around 503 Ma, are in a good agreement with the well established late Cambrian-early Ordovician magmatism in the West Sudetes. An Archean inherited zircon age of ~ 3.4 Ga is one of the oldest zircon ages reported so far from the Bohemian Massif. The orthogneisses of the Karkonosze-Izera Massif (KIM) have calculated TDM ages of between 1.50 and 1.93 Ga, but these ages are not necessarily evidence for a Mid-Proterozoic crustal derivation: more probably, they reflect the average of several detrital components mixed into the granitoid magma sources. In spite of likely age differences, the Lusatian greywackes, which outcrop to the west, and the mica schists of the KIM display similar geochemical characteristics, suggesting that both could have been derived from similar sources. However, the presence of lower Ordovician products of within-plate volcanism - intercalations of quartzofeldspathic rocks and amphibolites within the mica schists - supports an idea that the mica schist protoliths, derived mainly from crustal rocks, could have also contained an admixture of contemporaneous volcanic materials. The age spectra of inherited zircons from the KIM orthogneisses and their Nd-isotopic signatures are comparable to the Lusatian greywackes: this suggests that the Lusatian greywackes, or very similar rocks, could have been the source material for the granitic protoliths of the KIM orthogneisses.
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Recent geochronological studies, including sensitive high mass-resolution ion microprobe (SHRIMP) zircon dating, have helped to differentiate into specific age groups the various gneisses that occur within the basement units of the central-European Variscides. The Fore-Sudetic Block basement unit, for example, has been divided into two major gneiss groups of Neoproterozoic and Cambrian/Ordovician age, respectively. These two gneiss groups have been assigned to different tectonic units, themselves separated by a major tectonic boundary that is interpreted to be the northern continuation of the Moldanubian (Lugodanubian) Thrust. This thrust divides the main tectonostratigraphic units of the Bohemian Massif: the Moldanubian and Saxo-Thuringian units to the west, and the Moravo-Silesian unit to the east. This paper interprets new SHRIMP zircon data from the Nowolesie gneiss at Skalice (sample S6) and integrates the results with data from the Strzelin gneiss at Dębniki (sample S3), which is within the Strzelin Massif (E part of the Fore-Sudetic Block). Both the Nowolesie and Strzelin gneisses contain numerous inherited zircons within the age range of 1.5-2.0 Ga, indicating Meso- and Palaeoproterozoic sources for the zircons and suggesting that these zircons were recycled into younger units that subsequently underwent partial melting. The ages derived from samples S6 and S3, together with the absence of the Grenvillian ages (~1.3-0.9 Ga), suggest a West-African and/or Amazonian cratonic crust as the source for both the Nowolesie and Strzelin gneiss protoliths. The main zircon populations from both gneisses fall into two similar age groups: 602 +-7 Ma and 587 +- 4 Ma for the Nowolesie gneiss; 600 +-7 Ma and 568 +- 7 Ma for the Strzelin gneiss. These sets of Ediacaran (late Neoproterozoic) dates possibly reflect anatexis of the gneiss protoliths during the Cadomian orogeny.
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The Lower Carboniferous Paprotnia beds of the Bardo Structural Unit in the central Sudetes, composed predominantly of mudstones with Upper Viséan fossils, include several bentonite layers. The bentonites, composed mainly of kaolinite, illite/smectite and smectite, with minor amounts of quartz, calcite and iron hydroxides, also contain abundant zircons, the features of which indicate their volcanic derivation. The main population of the zircons yielded a SHRIMP U-Pb age of ~ 334 Ma corresponding with, and numerically constraining, the biostratigraphic data. The field evidence, biostrati- graphic and geochronological results, together with mineralogical data from the bentonites, indicate continental margin-type sedimentation and contemporaneous volcanic (andesitic-rhyolitic) activity in the neighbouring region during the ongoing Variscan orogeny in central Europe in Late Viséan times.
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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.
The structure and evolution of the Polish part of the Variscan Orogenic Belt is reviewed, based on published data and interpretations. The Sudetic segment of the Variscides, together with adjacent areas, experienced multi-stage accretion during successive collisional events that followed the closure of different segments of the Rheic Ocean. In SW Poland, Variscan tectono-stratigraphic units are tectonically juxtaposed and often bear record of contrasting exhumation/cooling paths, constrained by palaeontological and geochronological data. This points to the collage-type tectonics of this area. A three-partite subdivision of the Sudetes is proposed that reflects timing differences in deformation and exhumation of the respective segments. The Central,West and East Sudetes were deformed and amalgamated during the Middle/Late Devonian, at the turn from the Devonian to Carboniferous and during Early Carboniferous times, respectively. Problems in extending the classical tectono-stratigraphic zonation of the Variscides into the Sudetes are discussed and attributed to activity along Late Palaeozoic strike-slip faults and shear zones, disrupting and dispersing the initially more simply distributed tectono-stratigraphic units into the present-day structural mosaic. Relationships between the Variscan Externides and the foreland basin are explored. Sediments of the foreland basin locally onlap the external fold-and-thrust belt that had undergone an earliest Carboniferous partial tectono-thermal overprint. During the Late Carboniferous, the SW part of the foreland basin was heavily affected by thrusting and folding and incorporated into the Externides. DuringWestphalian C to Early Permian times, localized folding and thrusting affected the distal parts of the foreland basin, probably in response to dextral transpressional movements along NW–SE trending basement faults.
Published geochronological data, petrology, geochemistry and geological context of orthogneisses in the Strzelin and the Stachów complexes (NE-part of the Fore-Sudetic Block), together with structural observations help to locate the northern extension of the boundary between the East and West Sudetes within the poorly exposed NE margin of the Bohemian Massif. The Strzelin complex, in the east, comprises the Strzelin gneiss, with zircon ages of 600š7 and 568š7Ma, and the Nowolesie gneiss with a mean zircon age of 1020_ 1Ma. The Stachów complex to the west, which forms several tectonic klippen in the Strzelin Massif and in the Lipowe Hills Massif, contains the Gościęcice gneiss and pale Stachów gneiss, both yielding Late Cambrian zircon ages (~500š5 Ma). The orthogneisses in both complexes correspond to peraluminous S-type granites, but have different inherited zircon ages and display contrasting trace element characteristics, indicating different sources and petrogenetic histories. Based on the ages, petrology and overall geological context, the Strzelin orthogneiss is similar to the Keprník orthogneiss of the East Sudetes, whereas the orthogneisses of the Stachów complex correspond to rocks known from theWest Sudetes (e.g. the Izera and Śnieżnik orthogneisses). The Stachów and the Strzelin complexes are separated by the Strzelin Thrust, which may be interpreted as the northern extension of the boundary between the East and West Sudetes, i.e. part of the boundary between the Brunovistulian and Moldanubian terranes of the NE part of the Bohemian Massif.
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The Sudetes in the NE part of the Bohemian Massif stretch between the NW–SE-trending Odra Fault Zone and Elbe Fault Zone and represent a structural mosaic which was shaped, predominantly, during the Variscan orogeny. They are composed of various geological units, including basement units in which Neoproterozoic to Carboniferous rocks are exposed, and a post-orogenic cover of younger deposits. During the long history of geological research, the Sudetes have become a “type locality” for a range of important geological phenomena, such as granites and orthogneisses, ophiolites and (meta)volcanic sequences, granulites, eclogites and blueschists, nappe tectonics and terrane concepts. In spite of significant recent achievements, many key problems need further study, and a selection of them is proposed in this paper: (a) the presence of older, Neoproterozoic (Cadomian) rocks and their position within the Variscan collage, (b) the character and emplacement setting of Palaeozoic, pre-Variscan sedimentary successions and magmatic complexes (including ophiolites), (c) structural evolution, metamorphism (in particular HP/T grades) and exhumation of deeper crustal blocks during the Variscan orogeny, and (d) post-orogenic development. Future investigations would require an interdisciplinary approach, combining various geological disciplines: structural geology, petrology, geochemistry, geophysics and geochronology, and, also, multilateral interlaboratory cooperation.
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We report the first occurrence of diagenetic or low grade metamorphic monazite from the Palaeozoic mudrock successions of the Kaczawa Complex of the West Sudetes, Poland. Where observed in relation to the enclosing mudrock, this monazite comprises tiny irregular grains, less than 20 microns in diameter, intergrown with the surrounding matrix minerals. This monazite resembles previously described examples of diagenetic monazite from elsewhere in the world in mostly possessing low contents of Th and U but differs in forming much smaller grains, which show only slight zonation of rare earth elements (REEs). Some of the monazite grains studied also appear to have formed synchronously with the cleavage, perhaps a function of early deformation and fluid release in an accretionary prism environment. Relatively Th-rich cores, and an association with altered detrital biotite in some instances, suggests that at least some of the in situ monazite growth might have taken place as overgrowths on primary detrital monazite particles.
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The morphological features and typological distributions of zircon in the mylonites of the Niemcza Shear Zone (NZ) and in the gneisses and migmatites of the Góry Sowie Block (GSB), in the NE part of the Bohemian Massif, SW Poland, provide important petrogenetic indicators in the strongly deformed metamorphic rocks. The observed similarities between the zircon populations (combined with other field and petrographic evidence) strongly suggest that at least a part of the mylonites developed at the expense of rocks similar to the GSB gneisses and migmatites. The protoliths of the gneisses and migmatites (both in the GSB and within the NZ) were predominantly of sedimentary character, but the zircons suggest that crustal-type granites (in the case of the NZ gneiss and mylonite protoliths) and hybrid mantle/crustal-type granites (in the case of the GSB migmatite protoliths) could have been important sources for the original, mostly detrital (?) material. The large proportion of zircon grains in the NZ mylonites, showing effects of disintegration, can result from sedimentary abrasion of detrital material, and this apparently corroborates the hypotheses that a part of the NZ mylonites derived from protoliths other (more strongly reworked by sedimentary processes?) than those typical of the gneisses and migmatites of the GSB. However, there is also evidence that mylonitization could have influenced the morphometric features of the zircon crystals, generally increasing the proportion of fractured and broken crystals and, most spectacularly, reducing the mean size of the zircon grains in the mylonites. The controversy remains open and to find better constraints would require further detailed petrological studiem
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Analiza cech morfologicznych, analiza typologiczna metodą Pupina, oraz mikrosondowe badania chemiczne cyrkonów z łupków kwarcowo-skaleniowych oraz łupków łyszczykowych reprezentujących tzw. "formację łupków z Czarnowa" wskazują na urozmaicony charakter protolitów tych skał. Koncentraty cyrkonowe z pięciu różnych, wyselekcjonowanych próbek były poddane analizie typologicznej: trzy próbki z drobnoziarnistych łupków kwarcowo-skaleniowych z północnej części jednostki Czarnowa, dwie próbki z ciemniejszych i grubiej-ziarnistych łupków łyszczykowych z południowej części tej jednostki. Populacje cyrkonów ze wszystkich analizowanych próbek wykazują duże podobieństwo pod względem ogólnych cech morfologicznych. Znaczące różnice zostały jednak zaobserwowane przy analizie typologicznej: próbki łupków kwarcowo-skaleniowych zawierają cyrkony z dominacją słupa {100} i piramidy {101} (typy S24, S23, S19 oraz S18), podczas gdy w cyrkonach łupków łyszczykowych dominują formy {110} i {211}. Zmienność typologiczna odpowiada zmienności obserwowanej w chemicznej charakterystyce cyrkonów: badane ziarna z łupków łyszczykowych wykazują wyższą zawartość Hf, przeważnie z brzegami wzbogaconymi w Hf względem środka. Duża proporcja kryształów euhedralnych oraz generalny brak tzw. pozornego kąta wygaszania w cyrkonach z wszystkich próbek sugerują pierwotne magmowe źródło pochodzenia materiału tych skał. Lupki kwarcowo-skaleniowe z północy terenu prawdopodobnie reprezentują skały wulkanogeniczne, natomiast łupki łyszczykowe z części południowej zawierają cyrkony typowe dla granitoidów typu S lub dla materiału osadowego otrzymanego z tego typu magmowego protolitu.
EN
The quartzo=eldspathic rocks (so-called "leptynites ") and mica schists of the Czarnów unit in the eastern Karkonosze Complex (West Sudetes) exhibit problematic origin and age. They may represent felsic metavolcanics and metasediments of Neoproterozoic (?) age, and form apparently the country rocks of the Kowary orthogneiss that intruded at ca. 500 Ma ago. To highlight the problematic origin of the Czarnów schists, zircons from a set of representative samples of these rocks were studied. This study included description of morphological features, Pupin 's typological classification and electron-microprobe analyses. Zircon concentrates from 5 different rock samples were first studied using a typology method. Three samples come from fine-grained quartzo-feldspatic schists from the northern part of the Czarnów unit, whereas two samples from coarser-grained and darker mica schists in the southern part of the area. All the studied samples reveal zircon populations with many similarities in morphology. However, considerable differences are ascertained in typological analysis: samples from the quartzo-feldspatic schists have types with dominating {100} prism and {101} pyramide (types S24, S23, S19 and S18), whereas in those from the mica schists forms {110} and {211} prevail. This tvpological variation corresponds to differences observed in chemical characteristics of the zircons: the studied grains from the mica schists display higher Hfcontents, usually with rims richer in Hf The observed large proportion of idiomorphic crystals and a general lack of "apparent extinction angle " in all samples suggest their igneous origin. The quartzo-feldspathic schists of the northern area most probably represent acid volcanogenic rocks, whereas the mica schists in the southern part contain zircons ivpical of S-type granitoids or sedimentary material derived from such igneous protoliths.
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