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![Fig. 8. V-Ti/1000 diagram [47]. Symbols as in Fig. 4.](profile/Stanislaw-Mazur-3/publication/251631338/figure/fig5/AS:667832803135495@1536235156760/V-Ti-1000-diagram-47-Symbols-as-in-Fig-4_Q320.jpg)
The Kłodzko Metamorphic Complex (KMC) in the Central Sudetes is a composite outcrop of pre-Upper Devonian metasedimentary and metaigneous rocks, formed of several thrust units. The metaigneous rocks are geochemically diversified, and were interpreted to reflect a complex geodynamic setting of emplacement. The association of large amounts of felsic...
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The Paleozoic low-grade metamorphic rocks in Shipka Stara Planina Mountains (Fig. 1) comprise a major part of the pre-Mesozoic basement in this area. They have been an object of interest of quite a few studies (Kostov, 1949; Kalvacheva, Prokop, 1988; Yanev et al., 1995). Unsolved problems concerning their tectonic position, stratigraphy and deforma...
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... The Kłodzko Unit includes abundant calc-alkaline igneous rocks of Neoproterozoic and Cambrian age (Kryza et al. 2003;Mazur et al. 2004Mazur et al. , 2015 and has affinities to the Teplá-Barrandian Zone (Aleksandrowski and Mazur 2002;Mazur et al. 2006), particularly the Kralupy-Zbraslav Group that is the oldest part of the Teplá-Barrandian succession. Similar to large areas of the Teplá-Barrandian Zone, the Kłodzko Unit was involved in early Variscan deformation at the transition from the Middle to Late Devonian (Hladil et al. 1999) that emplaced the unit above the Nowa Ruda section of the Sudetic Ophiolite (Mazur et al. , 2015. ...
The NW Iberian Allochthon and the Teplá-Barrandian and Moldanubian zones represent the internal parts of the Variscan belt in their respective domains. A correlation based on the lithological association, protolith ages, metamorphic evolution, detrital zircon age spectra and tectonic setting is attempted between the NW Iberian Massif and SE Bohemian Massif in order to check whether they could have formed part of the same allochthonous stack. The Galicia-Trás-os-Montes Zone of the Iberian Massif and the internal zones of the Bohemian Massif include from bottom to top a Parautochthon and Lower Allochthon representing the outer edge of the northern Gondwana margin, an oceanic Middle Allochthon with Cambro-Ordovician and Early Devonian ophiolites and an Upper Allochthon interpreted as a peri-Gondwanan terrane. Early Variscan, subduction-related high-pressure metamorphism characterizes many of the allochthonous units, with ages younging from the structurally upper to the lower units from 400–385 Ma to 370–360 Ma, respectively. High- and ultrahigh-pressure metamorphism occurred also in the Saxothuringian Autochthon at 360–340 Ma, but not in the NW Iberian Autochthon. The different behavior of the Autochthon in the Iberian and Bohemian massifs accounts for their distinct evolutions from 360 Ma onward. We conclude that the Upper Allochthon was a unique peri-Gondwanan terrane, whereas the Middle Allochthon represents units of the same peri-Gondwanan ocean, opened at the Cambro-Ordovician boundary, and having recorded localized renewed activity in the Silurian–Early Devonian. No other oceans separated the Lower Allochthon, Parautochthon and Autochthon.
... (Kryza et al., 1996), the Orlica-Śnieżnik Dome (Kryza et al., 1996;Stawikowski, 2006), the Moldanubian Zone (Vrána, 1989;Kröner et al., 2000;Racek et al., 2006;Tajčmanová et al., 2006;Janoušek et al., 2007), the Kutná Hora Unit , LP granulites from the Moldanubian Zone (Tajčmanová et al., 2006), HP granulite clasts from the Culm deposits of the Moravo-Silesian Palaeozoic (Čopjaková et al., 2005). B: group II, HP mafic granulites from the Góry Sowie Massif (Kryza et al., 1996), the Orlica-Śnieżnik Dome (Kryza et al., 1996), the Moldanubian Zone (Kröner et al., 2000;Racek et al., 2008), pyriclasites from the S Bohemian Massif (Bues and Zulauf, 2000), amphibolites and metabasites from the Orlica-Śnieżnik Dome (Stawikowski, 2005), Moldanubian Zone (Janoušek et al., 2008), the Kłodzko Metamorphic Massif (Kryza et al., 2003), and Silesicum (Štipská et al., 2006), and eclogites from the Orlica-Śnieżnik Dome (Bakun-Czubarow and Kusy, 2001;Stawikowski, 2005), the Moldanubian Zone (O'Brien and Vrána, 1995;Racek et al., 2006), the Kutná Hora Unit (Faryad, 2009), and Silesicum (Štipská et al., 2006). C: group III, gneiss and migmatites from the Góry Sowie Massif (Budzyń et al., 2004), the Orlica-Śnieżnik Dome (Stawikowski, 2005;Redlińska-Marczyńska, 2011), the Moldanubian Zone (Vrána and Bártek, 2005;Racek et al., 2006), mica schists from the Orlica Śnieżnik Dome (Jastrzębski, 2009), the Staré Město Belt (Jastrzębski, 2012), Silesicum (Štipská et al., 2006), and the Moldanubian Zone (Racek et al., 2006). ...
... In the Sudetes, however, there are also rare metabasites of largely MORB-type but with supra-subduction zone affinities ( Kryza et al., 2003). With an established late Neoproterozoic age, they corroborate evidence from other parts of the Bohemian Massif of subduction of an oceanic-type domain beneath the active Gondwanan margin (Mazur et al., 2004 and references therein). ...
Metamorphosed during the Variscan orogeny, sediments of the ca. 560 Ma Młynowiec Formation and ca. 530 Ma Stronie Formation in the Bystrzyckie and Orlickie Mountains (Central Sudetes, Poland) contain metabasites with a range of basaltic compositions. Immobile trace element and Nd isotope features allow distinction of dominant, either E-MORB-like (Group 1: Zr/Nb 9–20, εNd530 +2.6 to +6.7) or mildly enriched N-MORB-like tholeiites (Group 2: Zr/Nb 21–27, εNd530 +0.2 to +6.7), and scarce but genetically important OIB-like alkaline (Group 3: Zr/Nb 5, εNd530 +2.2) or depleted tholeiitic rocks (Group 4: Zr/Nb 67, εNd530 +7.9). Neither the radiogenic age nor age relationships between these four groups are known. However, field evidence suggests that the metabasites are younger than the Młynowiec Formation and that their emplacement must have been coeval with the accumulation of the Stronie Formation sediments. The OIB affinity of Group 3 is interpreted to reflect an enriched mantle (EM)-type asthenopheric source whilst the groups of tholeiitic rocks indicate involvement of depleted (locally slightly residual) MORB-type mantle (DMM). Several geochemical signatures, the decoupling between Nd isotope and trace element characteristics, and melting models indicate variable enrichment of the DMM-like source, here ascribed to asthenosphere-derived OIB-like melts (Group 1 and 2) and a contribution from a supra-subduction zone (Group 2 and 4). Based on contrasting back-arc basin (BAB)- and within-plate-like affinities of the metabasites, and on petrogenetic constraints from the spatially related infill of the Stronie Formation rift basin, the studied magmatic episode is suggested be related to cessation of the supra-subduction zone activity, presumably induced by ridge-trench collision. This event might have led to slab break-off, the development of a transform plate boundary, opening of a slab window and upward migration of sub-slab enriched asthenosphere. Decompression melting of the upwelling asthenosphere could then have produced OIB-like melts which segregated and infiltrated into the mantle of the former subduction zone, with randomly distributed slab-derived components. In an extensional regime, magmas generated at shallow levels from heterogeneous mantle regions were emplaced within sedimentary rocks of the overlying rift basin. The vestiges of subduction-related processes and within-plate style of mantle enrichment suggest that the metabasites could be related to final stages of the Cadomian orogeny and incipient Early Palaeozoic rifting of Gondwana that heralded the opening of the Rheic Ocean.
... 1.0 Ga sub-continental lithospheric mantle (Murphy and Dostal, 2007;Murphy et al., 2010), whereas felsic magmas were mainly formed by anatexis of Neoproterozoic or Mesoproterozoic basement (e.g. Pin and Marini, 1993;Kryza and Pin, 1997;Kryza et al., 2003;Sanchez-Garcia et al., 2003;Murphy et al., 2006b;Kryza et al., 2003). ...
... 1.0 Ga sub-continental lithospheric mantle (Murphy and Dostal, 2007;Murphy et al., 2010), whereas felsic magmas were mainly formed by anatexis of Neoproterozoic or Mesoproterozoic basement (e.g. Pin and Marini, 1993;Kryza and Pin, 1997;Kryza et al., 2003;Sanchez-Garcia et al., 2003;Murphy et al., 2006b;Kryza et al., 2003). ...
We discuss the potential geodynamic connections between Paleozoic arc development along the flanks of the interior (e.g. the Iapetus and Rheic) oceans and the exterior Paleopacific Ocean. Paleozoic arcs in the Iapetus and Rheic oceanic realms are preserved in the Appalachian–Caledonide and Variscan orogens, and in the Paleopacific Ocean realm they are preserved in the Terra Australis Orogen. Potential geodynamic connections are suggested by paleocontinental reconstructions showing Cambrian–Early Ordovician contraction of the exterior ocean as the interior oceans expanded, and subsequent Paleozoic expansion of the exterior oceans while the interior oceans contracted. Subduction initiated in the eastern segment of Iapetus at ca. 515 Ma and Early to Middle Ordovician orogenesis along the flanks of this ocean is highlighted by arc–continent collisions and ophiolite obductions. Over a similar time interval, subduction and orogenesis took place in the exterior ocean and included formation of the Macquarie arc in the Tasmanides of Eastern Australia and the Famatina arc and correlatives in the periphery of the proto-Andean margin of Gondwana. Major changes in the style of subduction (from retreating to advancing) in interior oceans occurred during the Silurian, following accretion of the peri-Gondwanan terranes and Baltica, and closure of the northeastern segment of Iapetus. During the same time interval, subduction in the Paleopacific Ocean was predominantly in a retreating mode, although intermittent episodes of contraction closed major marginal basins. In addition, however, there were major disturbances in the Earth tectonic systems during the Ordovician, including an unprecedented rise in marine life diversity, as well as significant fluctuations in sea level, atmospheric CO2, and 87Sr/86Sr and 13C in marine strata carbonates. Stable and radiogenic isotopic data provide evidence for the addition of abundant mantle-derived magma, fluids and large mineral deposits that have a significant mantle-derived component. When considered together, the coeval, profound changes in the style of tectonic activity and the disturbances recorded in Earth Systems are consistent with the emergence of a superplume during the Ordovician. We speculate that the emergence of a superplume triggered by slab avalanche events within the Iapetus and Paleopacific oceans was associated with the establishment of a new geoid high within the Paleopacific regime, the closure of the interior Rheic Ocean and the amalgamation of Laurussia and Gondwana, which was a key event in the Late Carboniferous amalgamation of Pangea.Graphical AbstractResearch Highlights►Geodynamic connections exist among Paleozoic arcs in interior and exterior oceans ►Changes in arc activity are coeval with disturbances in Earth Systems ►These changes may relate to the Ordovician emergence of a superplume
... Recent geochemical and Sm-Nd isotopic data indicate that the mafic magmas are continental, withinplate tholeiites that were derived from an enriched ca. 1.0 Ga subcontinental lithospheric mantle, whereas the felsic magmas were derived by the melting of Neoproterozoic or Mesoproterozoic basement (Kryza et al., 2003;Murphy et al., 2006b;. These traits suggest that the magmatism occurred along the Gondwanan margin and form part of a passive margin succession that developed as the Rheic Ocean opened by the drift of peri-Gondwanan terranes northward Nance et al., 2006). ...
... (e.g. Pin and Marini, 1993 ;Kryza and Pin, 1997 ;Kryza et al., 2003;Sánchez-García et al., 2003;Murphy et al., 2006b). Murphy et al. (2006a) relate this extension to slab pull associated with northwesterly-directed subduction along the Laurentian margin in a manner analogous to the rifting of the Cimmerian terranes and the opening of Neotethys in the Cenozoic (see Stampfli and Borel, 2002). ...
Differences in the origin and evolution of the Iapetan and Rheic oceans profoundly affected the development of the Ouachitan–Appalachian–Variscan orogen. The Iapetus Ocean was initiated in the Late Neoproterozoic–Early Cambrian by the separation of large continental landmasses (Laurentia, Baltica, Gondwana), whereas the Rheic Ocean originated in the Late Cambrian–Early Ordovician as the result of the separation of several ribbon continents, collectively termed peri-Gondwanan terranes, from the northern margin of Gondwana. Compared to the classic passive margin developed along the Laurentian margin of Iapetus, passive margin successions to the Rheic Ocean are more limited in extent.
... Sm-Nd isotopic values indicate that mafic rocks in this region were derived from a 1.0 Ga subcontinental lithospheric mantle source. In eastern Europe, the Klodsko Metamorphic Complex is an example of Neoproterozoic to Devonian metasedimentary rocks with bimodal magmatic rift-related suites of Cambro-Ordovician age developed in the northern margin of Gondwana (Kryza et al., 2003). Details of some other mafic complexes related to Rheic Ocean are given by Murphy et al. (in press), in which the authors identify a Late Cambrian-Early-Ordovician age for the birth of the Rheic Ocean along the northern margin of Gondwana: this would include the Acatlán Complex mafic rocks. ...
Ordovician igneous rocks in the western Acatlán Complex (Olinalá area) of southern Mexico include a bimodal igneous suite that intrudes quartzites and gneisses of the Zacango Unit, and all these rocks were polydeformed and metamorphosed in the amphibolite facies during the Devono-Carboniferous. The Ordovician igneous rocks consist of the penecontemporaneous amphibolites, megacrystic granitoids and leucogranite, the latter dated at ca. 464 Ma. Geochemical and Sm–Nd data indicate that the amphibolites have a differentiated tholeiitic signature, and that its mafic protoliths formed in an extensional setting transitional between within-plate and ocean floor. The amphibolites are variably contaminated by a Mesoproterozoic crustal source, inferred to be the Oaxacan basement exposed in the adjacent terrane. The most primitive samples have εNdt (t=465 Ma) values significantly below that of the contemporary depleted mantle and were probably derived from the sub-continental lithospheric mantle. The megacrystic granites were most probably derived by partial melting of an arc crustal source (similar to the Oaxacan Complex) and triggered by the ascent of mafic magma from the lithospheric mantle. Sm–Nd isotopic signatures suggest that metasedimentary rocks from Zacango Unit were derived from adjacent Oaxacan Complex. Trace elements relationships (e.g. La/Th vs. Hf) and REE patterns suggest provenance in felsic-intermediate igneous rocks with a calc-alkaline signature. The Ordovician bimodal magmatism is inferred to have resulted from rifting on the southern flank of the Rheic Ocean and is an expression of a major rifting event that occurred along much of the northern Gondwanan margin in the Ordovician.
... This complex is interpreted to preserve remnants of the northern Gondwanan margin that was telescoped during the Variscan orogeny (Cymerman et al. 1997). Kryza et al. (2003) identified two dominant Palaeozoic meta-igneous units within the KMC: ...
The Rheic Ocean formed during the Late Cambrian–Early Ordovician when
peri-Gondwanan terranes (e.g. Avalonia) drifted from the northern margin of Gondwana, and
was consumed during the collision between Laurussia and Gondwana and the amalgamation of
Pangaea. Several mafic complexes, from the Acatla´n Complex in Mexico to the Bohemian
Massif in eastern Europe, have been interpreted to represent vestiges of the Rheic Ocean. Most
of these complexes are either Late Cambrian–Early Ordovician or Late Palaeozoic in age. Late
Cambrian–Early Ordovician complexes are predominantly rift-related continental tholeiites,
derived from an enriched c. 1.0 Ga subcontinental lithospheric mantle, and are associated with
crustally-derived felsic volcanic rocks. These complexes are widespread and virtually coeval
along the length of the Gondwanan margin. They reflect magmatism that accompanied the early
stages of rifting and the formation of the Rheic Ocean, and they remained along the Gondwanan
margin to form part of a passive margin succession as Avalonia and other peri-Gondwanan terranes
drifted northward. True ophiolitic complexes of this age are rare, a notable exception occurring in
NW Iberia where they display ensimatic arc geochemical affinities. These complexes were thrust
over, or extruded into, the Gondwanan margin during the Late Devonian–Carboniferous collision
between Gondwana and Laurussia (Variscan orogeny). The Late Palaeozoic mafic complexes
(Devonian and Carboniferous) preserve many of the lithotectonic and/or chemical characteristics
of ophiolites. They are characterized by derivation from an anomalous mantle which displays timeintegrated
depletion in Nd relative to Sm. Devonian ophiolites pre-date closure of the Rheic Ocean.
Although their tectonic setting is controversial, there is a consensus that most of them reflect narrow
tracts of oceanic crust that originated along the Laurussian margin, but were thrust over Gondwana
during Variscan orogenesis. The relationship of the Carboniferous ophiolites to the Rheic Ocean
sensu stricto is unclear, but some of them apparently formed in a strike-slip regimes within a
collisional setting directly related to the final stages of the closure of the Rheic Ocean.
... At about the same time as these orogenic events, the Rheic Ocean formed as a result of the Late Cambrian–Early Ordovician drift of peri-Gondwanan terranes (including Ganderia-Avalonia and Carolinia) away from the northern Gondwanan margin, which preserves a ca. 500 Ma passive-margin assemblage and coeval voluminous bimodal magmatism in southern Mexico (Acatlán Complex; Nance et al., 2006), Britain, Iberia, and the Bohemian Massif (e.g., Sánchez-García et al., 2003; Kryza et al., 2003 ). An Early Ordovician breakup unconformity and widespread rift-related subsidence are indicated by the distribution of the Armorican Quartzite across much of mainland Europe (Quesada et al., 1991; Linnemann et al., 2004). ...
Geodynamic models for supercontinent assembly, whereby the dispersingcontinental fragments of a supercontinent break up and migratefrom geoid highs to reassemble at geoid lows, fail to accountfor the amalgamation of Pangea. Such models would predict thatthe oceans created by continental breakup in the early Paleozoic(e.g., Iapetus, Rheic) would have continued to expand as thecontinents migrated toward sites of mantle downwelling in thepaleo-Pacific, reassembling an extroverted supercontinent asthis ocean closed. Instead, Pangea assembled as a result ofthe closure of the younger Iapetus and Rheic Oceans. Geodynamiclinkages between these three oceans preserved in the rock recordsuggest that the reversal in continental motion may have coincidedwith the Ordovician emergence of a super-plume that produceda geoid high in the paleo-Pacific. If so, the top-down geodynamicsused to account for the breakup and dispersal of a supercontinentat ca. 600-540 Ma may have been overpowered by bottom-upgeodynamics during the amalgamation of Pangea.
... Only the structurally uppermost Ktodzko Fortress Unit contradicts this trend, revealing epidote-amphibolite facies metamorphism. The differences in the geochemical characteristics of the meta-igneous rocks suggest derivation of the individual units from various plate tectonic settings (Kryza et al. 2003). This conclusion is in accord with the contrasting protolith ages associated with different parts of the KMC. ...
The Kłodzko Metamorphic Complex comprises a number of thrust units, consisting of meth-igneous and metasedimentary rocks of the Variscan basement of the Sudetes, NE Bohemian Massif. The thrust sheet stack rests upon unmetamorphosed Nowa Ruda ophiolite and is unconformably overlain by Frasnian-Fammenian sediments. The studied rocks underwent six deformation events, scattered in time between the Middle Devonian and Late Carboniferous. The multiphase deformation produced a steep foliation that consistently trends WNW-ESE and a mineral lineation plunging to the ESE at a shallow to moderate angle. The results of the AMS study show that, despite the complex structural evolution, all the studied rocks bear a similar magnetic fabric mirroring the principal structural directions. This relationship between magnetic and structural fabrics is apparent in all tectonic units irrespective of the considerable variations in strain rate and metamorphic grade. This suggests a rather low dependence of magnetic anisotropy on the changing conditions and intensity of deformation.
... These occurrences are interpreted to represent Ordovician continental rifts, as well as Silurian and Devonian successions of oceanic basins. Interpretations that suggest the formation of these successions in an extensional setting were recently challenged by Kryza et al. (2003) , based on geochemical results from the Kłodzko Metamorphic Complex (KMC). The new data indicate that the majority of meta-igneous rocks in this area originated in a supra-subduction setting. ...
... 2. A mØlange body defining the Ła ˛czna unit (Mazur and Kryza 1999). 3. The Bierkowice unit, which is built up by mafic volcanic rocks with an intraplate geochemical signature (Nare ˛bski et al. 1988; Kryza et al. 2003). 4. The S ´ cinawka unit, which comprises a MORB-type gabbro (Kryza et al. 2003) 5. ...
... 3. The Bierkowice unit, which is built up by mafic volcanic rocks with an intraplate geochemical signature (Nare ˛bski et al. 1988; Kryza et al. 2003). 4. The S ´ cinawka unit, which comprises a MORB-type gabbro (Kryza et al. 2003) 5. The Orla-Gołogłowy unit, which consists of MORBtype gabbros and mafic volcanics (Kryza et al. 2003), deep marine sediments, felsic volcanics and granitoid intrusions. ...
The Kodzko Metamorphic Complex (KMC) in the Central Sudetes consists of meta-sedimentary and meta-igneous rocks metamorphosed under greenschist to amphibolite facies conditions. They are comprised in a number of separate tectonic units interpreted as thrust sheets. In contrast to other Lower Palaeozoic volcano-sedimentary successions in the Sudetes, the two uppermost units (the Orla-Googowy unit and the Kodzko Fortress unit) of the KMC contain meta-igneous rocks with supra-subduction zone affinities. The age of the KMC was previously assumed to be Early Palaeozoic–Devonian, based on biostratigraphic findings in the lowermost tectonic unit. Our geochronological study focused on the magmatic rocks from the two uppermost tectonic units, exposed in the SW part of the KMC. Two orthogneiss samples from the Orla-Googowy unit yielded ages of 500.43.1 and 500.24.9Ma, interpreted to indicate the crystallization age of the granitic precursors. A plagioclase gneiss from the same tectonic unit, intimately interlayered with metagabbro, provided an upper intercept age of 590.17.2Ma, which is interpreted as the time of igneous crystallization. From the topmost Kodzko Fortress unit, a metatuffite was studied, which contains a mixture of genetically different zircon grains. The youngest 207Pb/206Pb ages, which cluster at ca. 590-600Ma, are interpreted to indicate the maximum depositional age for this metasediment. The results of this study are in accord with a model that suggests a nappe structure for the KMC, with a Middle Devonian succession at the base and Upper Proterozoic units at structurally higher levels. It is suggested here that the KMC represents a composite tectonic suture that juxtaposes elements of pre-Variscan basement, intruded by the Lower Ordovician granite, against a Middle Palaeozoic passive margin succession. The new ages, combined with the overall geochemical variation in the KMC, indicate the existence of rock assemblages representing a Gondwana active margin. The recognition of Neoproterozoic subduction-related magmatism provides additional arguments for the hypothesis that equivalents of the Tepl-Barrandian domain are exposed in the Central Sudetes.
