Reconstruction of the mid-Devonian HP-HT metamorphic event in the Bohemian Massif (European Variscan belt)

Collett, Stephen; Schulmann, Karel; Deiller, Piérig; Štípská, Pavla; Peřestý, Vít; Ulrich, Marc; Jiang, Yingde; Marien, Luc de Hoÿm de; Míková, Jitka

doi:10.1016/j.gsf.2022.101374

Cited by 14 publications

(7 citation statements)

References 123 publications

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“…Consequently, if in the same Variscan internal zone, metabasalts have protolith ages on the one hand at 500 Ma and on the other hand at 470-450 Ma this means that they come from two different oceanic crusts, the youngest being the Rheic Ocean and the oldest the so-called Mirovoi or Ran Ocean, depending on the authors. It is significant to note that similar results were obtained in other segments of the northeastern Variscan belt with similar conclusions (Soejono et al, 2010;Collett et al, 2020Collett et al, , 2022.…”

Section: B-magmatic Protolith Ages and Geodynamic Consequencessupporting

confidence: 85%

Deciphering the nature and age of the protoliths and peakP−Tconditions in retrogressed mafic eclogites from the Maures-Tannneron Massif (SE France) and implications for the southern European Variscides

JOUFFRAY¹,

Lardeaux²,

Tabaud³

et al. 2023

BSGF - Earth Sci. Bull.

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We present new constraints on age, nature and tectonic setting of mafic eclogites protoliths from the Maures-Tanneron Massif, southern Variscan belt. Whole-rock major and trace elements geochemistry was combined with 206Pb/238U zircon dating to improve the understanding of this key-target of the European Southern Variscides. Geochemical data show that protoliths of the mafic eclogites are typical MORBs, while REE and HFSE patterns suggest an E-MORB affinity. However, the geochemical study shows several signs of crustal contamination, increasing with degree of retrogression. A comparison with Sardinian eclogites, which belong to the same Variscan micro-plate “MECS” (Maures-Estérel-Corsica-Sardinia), demonstrate that the eclogites included in migmatites, which is the case of the studied samples, are the most contaminated. Anyway, the Maures-Tanneron mafic eclogites represent the witness of oceanic basaltic crust. Zircon cores display homogeneous Th/U ratios (0.3-0.4), consistent with a magmatic origin, and define an age peak at ca. 500 Ma interpreted as the most plausible emplacement age of the basaltic protolith. This age suggests that this protolith was part of an oceanic floor older than the Rheic Ocean and located north of the Gondwana active continental margin as predicted by recent unified full plates reconstruction models. Although the eclogites studied are retrogressed the study of frozen mineral inclusions trapped in garnets combined with thermodynamic modelling yields a P-T range of 16.8-18.5 kbar for 630-660°C, coherent with standard subduction paleo-geotherm. These new data suggest that mafic eclogites recognized in the “MECS” Variscan micro-plate represent the closure of oceanic domains of different ages.

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Section: B-magmatic Protolith Ages and Geodynamic Consequencessupporting

confidence: 85%

Deciphering the nature and age of the protoliths and peakP−Tconditions in retrogressed mafic eclogites from the Maures-Tannneron Massif (SE France) and implications for the southern European Variscides

JOUFFRAY¹,

Lardeaux²,

Tabaud³

et al. 2023

BSGF - Earth Sci. Bull.

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“…This allows us to propose a new model for the development of the Cambro-Ordovician rocks cropping out in the eastern part of the Fore-Sudetic Block from the early Palaeozoic to the Carboniferous. The model is generally consistent with those proposed for other Late Neoproterozoic and Cambro-Ordovician sequences exposed in the Bohemian Massif (Jastrzębski et al 2017; Hajná et al 2018; Collett et al 2020; Soejono et al 2020; Collett et al 2022; Soejono et al 2022). Our data combined with already published results shed new light on the development of the passive Gondwana margin and the nature of the tectonic suture separating the Central and East Sudetes.…”

Section: Introductionsupporting

confidence: 88%

“…Some authors discussed the presence of the Rheic suture between the Central and East Sudetes (e.g. Mazur et al 2012; Jastrzębski et al 2013; Jastrzębski et al 2015; Oberc-Dziedzic et al 2018; Jastrzębski et al 2020; Śliwiński et al 2022), while others questioned its existence in this fragment of the Variscan belt of Europe (Soejono et al 2010; Collett et al 2021, 2022). Unfortunately, this fragment of the Variscan orogen is partly located on the Fore-Sudetic Block, where the metamorphic basement is mostly covered by Cenozoic sediments.…”

Section: Introductionmentioning

confidence: 99%

Provenance of the early Palaeozoic volcano-sedimentary successions from eastern part of the Central Sudetes: implications for the tectonic evolution of the NE Bohemian Massif

Szczepański,

Kaszuba,

Anczkiewicz

et al. 2023

Geol. Mag.

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The Kamieniec Metamorphic Belt (KMB) and the Doboszowice Metamorphic Complex (DMC) expose a fragment of the pre-Variscan volcano-sedimentary cover preserved in the Fore-Sudetic Block in the NE part of the Bohemian Massif. We present the age of detrital and magmatic zircon grains and the bulk rock chemical composition of rock samples from the KMB and the DMC to better understand the evolution of the early Palaeozoic Gondwana margin. The zircon age spectra were acquired by U–Pb LA–ICP–MS dating and represent two groups that differ by maximum depositional age (MDA). The paragneiss from the DMC displays the MDA at 456 Ma, whereas the mica shist from the KMB displays the MDA at 529 Ma. Older age peaks in both groups of samples are represented by the Neoproterozoic and less frequent the Paleoproterozoic and Archean. The data presented indicate that the rock successions were sourced from the Cadomian orogen and deposited in the basins that developed on the Gondwana margin. Our results support the suggestion that the crystalline basement in the eastern part of the Fore-Sudetic Block has an affinity to the Trans-Saharan Belt or West African Craton and was part of a Gondwana shelf. The final stage of evolution of the studied successions was related to the Variscan thermal overprint. Based on presented data, we support the idea that the suture separating the Brunovistulian domain from the rest of the Gondwana-derived terranes is not related to the closure of the Rheic Ocean and represents a local feature.

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“…The different architecture of the eastern part of the European Variscan belt is also supported by geophysical identification of two parallel and south‐dipping belts associated with dense bodies separating the Saxothuringian basement from the Teplá‐Barrandian Zone upper plate and the Central Armorican Domain from the French Massif Central (Schulmann et al., 2022; Figure 1). The structurally higher belt of reflectors is interpreted as a remnant of the Mid‐Variscan Ocean closed during Upper Devonian (Collett et al., 2022), while the structurally deeper reflectors are located above the high‐velocity and high‐density zone representing a deeply subducted continental margin of the Saxothruringian block beneath the Mid‐Variscan Allochthon during early Carboniferous (Konopásek et al., 2019). This deep continental subduction is associated with the development of the Saxothuringian orogenic wedge described here and is likely responsible for sub‐lithospheric relamination and early Carboniferous thickening of the Mid‐Variscan Allochthon followed by the formation of HP granulite diapirs described in the Moldanubian unit (Maierová et al., 2021).…”

Section: Discussionmentioning

confidence: 99%

“…The earliest stages of the Saxothuringian wedge indicate the development of an accretionary wedge during oceanic subduction. Its relics are preserved in the Mariánské Lázně Complex and Münchberg Klippe (Collett et al, 2018(Collett et al, , 2022Deiller et al, 2021;Scherer et al, 2000) located in the hanging wall of the later orogenic wedge (Münchberg Crystalline Complex in Figures 2a and 14c). These two complexes contain oceanic crust derived fragments that had been subducted to peak pressures at ∼390 Ma and later incorporated into the accretionary wedge and exhumed below the blocking temperatures of the argon system by ∼375 Ma (Collett et al, 2018;Dallmeyer & Urban, 1998).…”

Section: Assembly Of the Saxothuringian Orogenic Wedgementioning

confidence: 99%

Assembly of the Variscan Orogenic Wedge in the Bohemian Massif: Monazite U‐Pb Geochronology of the Tectonic Events Recorded in Saxothuringian Metasediments

et al. 2023

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The most spectacular manifestation of plate tectonics is the formation of orogenic belts. A popular geodynamic model explaining the formation of collisional orogens is the wedge model (e.g., Dahlen et al., 1984;Malavieille, 2010;Platt, 1986;Willett et al., 1993), originally applied to accretionary wedges formed above subducting plates. However, the geodynamic evolution of many collisional orogens involves the closure of oceanic domains followed by continental collision resulting in a protracted evolution and transition from accretionary to orogenic wedge systems. Such evolution then reflects the pre-collisional subduction of an oceanic lithosphere, the associated formation and exhumation of Ultra-High-Pressure (UHP) rocks and the subduction of buoyant crustal material (e.g., Beaumont et al., 1996;Burov et al., 2014;Sizova et al., 2014) leading to a complex polyphase structural and metamorphic record.European Variscides (Figure 1) are the major segment of a large orogenic system resulting from progressive closure of the Rheic Ocean which separated Gondwana and Laurussia. Despite the major along strike variations in orogenic architecture and provenience of individual tectono-metamorphic units (Martínez Catalán et al., 2020), the tectonic evolution and timing of major events could be successfully correlated (Catalan et al., 2021) between individual segments of the orogenic belt. The Erzgebirge Crystalline Complex, representing part of the Saxothuringian Domain in the Bohemian Massif, preserves numerous occurrences of eclogite-and blueschist-facies rocks with UHP relics pointing to a subduction environment in an orogenic wedge setting (e.g.,

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Reconstruction of the mid-Devonian HP-HT metamorphic event in the Bohemian Massif (European Variscan belt)

Cited by 14 publications

References 123 publications

Deciphering the nature and age of the protoliths and peakP−Tconditions in retrogressed mafic eclogites from the Maures-Tannneron Massif (SE France) and implications for the southern European Variscides

Deciphering the nature and age of the protoliths and peakP−Tconditions in retrogressed mafic eclogites from the Maures-Tannneron Massif (SE France) and implications for the southern European Variscides

Provenance of the early Palaeozoic volcano-sedimentary successions from eastern part of the Central Sudetes: implications for the tectonic evolution of the NE Bohemian Massif

Assembly of the Variscan Orogenic Wedge in the Bohemian Massif: Monazite U‐Pb Geochronology of the Tectonic Events Recorded in Saxothuringian Metasediments

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