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Palaeozoic amalgamation of Central Europe: An introduction and synthesis of new results from recent geological and geophysical investigations
Abstract and Figures
Multidisciplinary studies undertaken within the EU-funded PACE Network have permitted a new 3-D reassessment of the relationships between the principal crustal blocks abutting Baltica along the Trans-European Suture Zone ( TESZ ). The simplest model indicates that accretion was in three stages: end-Cambrian accretion of the Bruno-Silesian, Łysogóry and Małopolska terranes; late Ordovician accretion of Avalonia, and early Carboniferous accretion of the Armorican Terrane Assemblage ( ATA ), which had coalesced during Late Devonian — Early Carboniferous time. All these accreted blocks contain similar Neoproterozoic basement indicating a peri-Gondwanan origin: Palaeozoic plume-influenced metabasite geochemistry in the Bohemian Massif in turn may explain their progressive separation from Gondwana before their accretion to Baltica, although separation of the Bruno-Silesian and related blocks from Baltica during the Cambrian is contentious.
Inherited ages from both the Bruno-Silesian crustal block and Avalonia contain a 1.5 Ga ‘Rondonian’ component arguing for proximity to the Amazonian craton at the end of the Neoproterozoic: such a component is absent from Armorican terranes, which suggests that they have closer affinities with the West African craton.
Models showing the former locations of these terranes and the larger continents from which they rifted, or to which they became attached, must conform to the above constraints, as well as those provided by palaeomagnetic data. Hence, at the end of the Proterozoic and in the early Palaeozoic, these smaller terranes, some of which contain Neoproterozoic ophiolitic marginal basin and magmatic arc remnants, probably occurred within the end-Proterozoic supercontinent as part of a ‘Pacific-type’ margin, which became dismembered and relocated as the supercontinent fragmented.
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... Located in South Dobrudzha, NE Bulgaria, is the c. 500 km 2 Dobrudzha Basin. Concealed under a thick Mesozoic cover (Tenchov 2007), the basin evolved in the eastern part of the Moesian Platform, a peri-Gondwanian microplate of Avalonian affinity that, in the Late Devonian, accreted with the southern Laurussia margin (Yanev 2000;Winchester et al. 2002;Spahićand Gaudenyi 2019). Thus, before the Mesozoic strikeslip displacement related to the Alpine Orogeny, the Dobrudzha Basin was probably located east of the Upper Silesian Basin in the eastern extension of the Variscan Foreland as a part of the NVB (Banks and Robinson 1997;Kalvoda and Bábek 2010;Elter et al. 2020;Narkiewicz 2020). ...
... As a result, the precise Pennsylvanian position of peri-Gondwanian terranes, and, in turn, reliable palaeogeographical reconstruction of Pennsylvanian basins of the southern Variscan foreland, is often a matter of discussion (e.g. Yanev 2000;Winchester et al. 2002;Kalvoda and Bábek 2010;Kroner and Romer 2013;Domeier and Torsvik 2014). We focus only on the basins with an alternation of shallow-marine and non-marine strata indicative of a coastal setting in the reach of glacioeustatic controls, where a reliable biostratigraphic record exists. ...
In Europe, North Africa and Asia Minor, the remains of Pennsylvanian sedimentary basins bearing continental deposits either intimately mixed with shallow marine strata or deposited in exclusively continental settings are preserved. Long-lasting research on these basins allowed definition of regional stages and substages based on marine fauna and terrestrial flora, later extended by terrestrial and fresh-water faunal biostratigraphies. Glacioeustatically driven marine bands provide laterally widespread correlation markers, however, where such bands are missing only biostratigraphic control exists. Resolution of biostratigraphic zonations combined with gaps in sedimentary successions and variable quality of the fossil record throughout the basin fills do not allow in all cases the precise correlation among the Pennsylvanian basins in Europe and, in turn, the timing of tectonic, climatic and biotic events and thus an absolute complete understanding of response of terrestrial and fresh-water biota to climate changes across eastern tropical Pangea. Helpful are new radioisotopic ages of intercalated volcaniclastics, which reveal partial diachroneity of some widely used biostratigraphies. We attempt to present the current state of the art to stimulate further research to mitigate gaps in our knowledge.
... The overall geological architecture of the Moldanubian Zone ( Figure 1 (b)) results from the interplay of several geodynamic events (e.g. Brandmayer et al., 1995;Edel et al., 2003;Finger et al., 2007Finger et al., , 2022Kalvoda et al., 2008;Megerssa et al., 2022;Schulmann et al., 2009;Schulmann & Gayer, 2000;Verner et al., 2014;Winchester et al., 2002;Žák et al. 2011, 2019: (a) early subduction(s) followed by ∼E-W oriented continental collision and prograde MP/(U)HP metamorphism (ca. 380 to 346 Ma), (b) rapid exhumation of deep-seated rocks associated with an extensive HT/ MP(LP) isothermal overprint (ca. ...
The geological map of the Klenov Pluton (Moldanubian Batholith), and its 3D visualization, brings the new findings in the context of granite emplacement within late-Variscan settings. The Klenov Pluton has a peraluminous composition resulting from partial melting of metasedimentary sources and subsequent differentiation. The new ages 327.14 ± 0.21 Ma and 327.80 ± 0.37 Ma, reflect the narrow time-span of magma emplacement and cooling. The 327 Ma Klenov Pluton was emplaced syntectonically as a 'sheet-like' granite intrusion at depth ca. 10 kilometers during the later stages of the Pelhřimov Core Complex exhumation (at ca. 329 to 327 Ma) associated with ∼N-S oriented compression. Gravity modelling suggests that the Klenov Pluton has an asymmetric shape where its western flank is parallel to the ∼NW moderately dipping Pelhřimov Core Complex. The eastern margin of the Pluton is shallower and has been later modified by ∼SE-side-up normal faulting (Lodhéřov Fault Zone). ARTICLE HISTORY
... For this reason, it is not surprising that this admittedly enigmatic pre-Alpine area has often been omitted from the large-scale (European to global) palaeogeographical reconstructions, or figured in a simplistic way in them (e.g. see Tait et al. 2000;Winchester et al. 2002;Cocks 2004, 2017;Kroner and Romer 2013;Franke et al. 2017). ...
The Ordovician documented in south-eastern Europe reflects different sedimentary environments, from shallow water to basin, belonging to diverse palaeogeographical domains. Some of these geological sectors and their palaeontological content have been well described for a long time, like the Carnic Alps, that represent one of the most continuous Palaeozoic sequence in the world. For some other areas, the quality of the data is variable and the knowledge is less detailed, sometimes with lithostratigraphic units still to be formalized, also reflecting the fragmentary nature of the outcrops. The Ordovician stratigraphy of diverse successions of south-eastern Europe has been herein revised and integrated with new data in the attempt of detecting a global scenario for this critical time interval in the evolution of life.
The Moesian Platform represents a major tectonic unit of the foreland of the Carpathians and Balkans, spanning across the southern part of Romania and the northern part of Bulgaria. Although the Moesian Platform is considered to be a stable tectonic unit, it has played a significant role in the geological history of the region, influencing the development of the surrounding Carpathian and Balkan mountain ranges, making it an area of interest for studying tectonic history, geological structures, and landscape evolution. In the southern part of the Moesian Platform in Romania, delineated to the north and to the east by the steep slopes of the Argeş River valley and to the south by the steep slopes of the Danube River valley, an elevated and W–E promontory-looking geomorphological feature identified by the local inhabitants as “hill” is distinct from the neighbouring flat relief of the Romanian plain. This study is the result of a comprehensive investigation into the geomorphological features and neotectonic structures within this region. An intriguing outcrop displaying a filled fault, cutting and displacing the Quaternary sedimentary formations of the recently named Argeş Promontory, shed light on recent tectonic activities that have influenced the landscape. By integrating field observations, geological, and tectonic data, as well as satellite geodetic data, our results contribute to a better understanding of the study area’s regional geodynamics, emphasizing the significant role of tectonic activity in shaping the present-day landscape.
The Bohemian Massif in the eastern Variscan Orogen is the host of globally significant ultrahigh-pressure metamorphic rock suites that experienced enigmatic unroofing processes. In the eastern Bohemian Massif, the Moravosilesian Culm Basin (The Czech Republic) with ≤7.5 km thick Lower Carboniferous sili-
ciclastic turbidities has recorded crustal unroofing associated with the late Paleozoic amalgamation of Gondwana and Laurussia. This study presents data from sandstone petrography, heavy mineral assemblages, and detrital zircon U-Pb geochronology from Moravosilesian Culm sediments. Sandstone modal compositions imply continental/recycled orogen affinities. High-grade metamorphic lithic fragments and high garnet contents in upper Culm sediments indicate the exhumation of the middle to lower crustal materials, consistent with those of the Bohemian Massif. Detrital zircon U-Pb data constrain maximum depositional ages of sediments in the Drahany Upland to 335–326 Ma (late Viséan–middle Serpukhovian). Detrital, igneous and metamorphic zircon U-Pb data compiled from surrounding regions support that source regions for lower Culm sediments (Moldanubian Unit and Sudetes) remained the same. Whereas, upper Myslejovice sediments might have derived from exhumation and erosion of the root of the Moldanubian Unit and/or Moravosilesian Nappes. Rapid exhumation of the Moldanubian Unit within the Bohemian Massif during the deposition of upper Culm sediments is inferred.
The manuscript presents the current state and proposals for the management of the old granite, quartz, and serpentinite quarries located in the Ślęża Massif (SW Poland, 50°51′51.22″ N; 16°42′26.80″ E), an area entirely covered by forests and protected by various legal protection measures. The quarries are abandoned and subjected to intense natural plant succession, so they are disappearing from the landscape. Nine quarries were analyzed regarding their natural and landscape characteristics. Due to the variety of their sizes, specific locations, geological–topographical traits, and forest and site conditions, the quarries may be turned into tourist attractions enhancing the social function of forests while, at the same time, ensuring their protective functions. If properly managed, they may contribute to the multifaceted development of tourism, performing scientific-cognitive, educational, sports, or cultural functions, and, as a result, to a partial reduction in the tourist pressure on biotic and abiotic natural resources along the presently most frequently used routes. This paper attempts to present arguments indicating that a former mining working site may be a positive and attractive landscape element in harmony with the vegetation cover, beneficial for both nature and humans.
The Holy Cross Mountains (HCM) in Poland, is an isolated natural outcrop of Paleozoic rocks located within the Trans-European Suture Zone (TESZ), a tectonic collage of continental terranes adjacent to the Tornquist margin of the Baltica. This uniqueness made the HCM a target for paleogeographic research. Based on the facies differences, the HCM had been divided into two major units, the southern (the Kielce Unit) and northern (the Łysogóry Unit) part (SHCM and NHCM, respectively). Their position in relation to each other and the Baltica continent during Silurian times is still a matter of discussion, whether both parts of the HCM were separated terranes located along the Baltica margin or they shared in common paleogeographic history. Here, we present the results of comprehensive rock magnetic measurements applied as a tool to interpret paleoenvironmental conditions during deposition and burial and therefore allow discussion about the terranes’ relative position.
To recognize the magnetic mineral composition and texture of studied Silurian graptolitic shales several rock magnetic measurements were conducted including low-temperature Saturated Isothermal Remanent Magnetization (SIRM), thermal demagnetization of three-component IRM, and hysteresis measurements, as well as anisotropy of magnetic susceptibility (AMS). The sampled rocks come from both units of the HCM.
In all analyzed samples we found single domain (SD) stoichiometric magnetite of mostly diagenetic (i.e., postdepositional) origin and goethite resulting likely from weathering. In turn, detrital magnetite, even if observed in previously investigated Silurian rocks from the Baltica margin, was not identified in this study, what we attribute to dissolution during diagenesis in the deep-water environment. Solely in the NHCM, SD hematite and maghemite grains were observed, which we interpret as detrital in origin. These grains have been preserved in the suboxic environment of the NHCM sub-basin bottom waters due to their resistance to dissolution in marine waters. Considering the deposition conditions (oxygenation of the near-bottom zone) rather similar for both HCM parts, we associate the presence of aeolian hematite grains solely in the NHCM rocks with a more proximal position of the NHCM than the SHCM in relation to the Baltica continent during late Llandovery (Silurian). This conclusion agrees with some existing paleogeographic models.
In addition to petromagnetic studies focused on the analysis of ferromagnets, AMS measurements were also carried out. The results indicate that the magnetic susceptibility is mainly governed by paramagnetic minerals, mostly phyllosilicates with small ferromagnetic contributions. Oblate AMS ellipsoid and distinct bedding parallel foliation indicate prevailing sedimentary-compactional alignment. Observed magnetic lineation of tectonic origin resulting from weak strain is related presumably to Variscian deformations.
Ampferer-type subduction is a term that refers to the foundering of hyper-extended
continental or embryonic oceanic basins (i.e., ocean-continent transitions) at passive continental margins. The lithospheric mantle underlying these rift basins is mechanically weaker, less dense, and more fertile than the lithospheric mantle underlying bounded continents. Therefore, orogens resulting from the closure of a narrow, immature extensional system are essentially controlled by mechanical processes without significant thermal and lithologic changes. Self-consistent, spontaneous subduction initiation (SI) due to the density contrast between the lithosphere and the crust of ocean-continent transitions is unlikely to occur. Additional far-field external horizontal forces are generally required for the SI. When the lithosphere subducts, the upper crust or serpentinized mantle and sediments separate from the lower crust, which becomes accreted to the orogen, while the lower crust subducts into the asthenosphere. Subduction of the lower crust, which typically consists of dry lithologies, does not allow significant flux-melting within the mantle wedge, so arc magmatism does not occur. As a result of melting inhibition within the mantle wedge during Ampferer-type subduction zones, the mantle beneath the resulting orogenic belts is fertile and thus has a high potential for magma generation during a subsequent breakup (i.e., magma-rich collapse).
A Continent Revealed presents the findings of the European Geotraverse (EGT), - a unique study of the tectonic evolution of the continent of Europe, and the first comprehensive cross section of the continental lithosphere. A well-illustrated book and a set of maps and profiles have been put together by key workers in the EGT project to present the great wealth of information yielded by the project. The book outlines the scientific achievements of the European Geotraverse. It tells how the information now available is key evidence in the piecing together of the tectonic evolution of the European continent. The authors have reviewed the work of their colleagues to unravel the nature, evolution and dynamics of the European lithosphere. The stimulating study reveals much of the workings of the earth and the processes that shaped the continent of Europe as we see it today. The maps and profiles, along a 250 kilometre wide swath stretching 4600 kilometres from Scandinavia to the Mediterranean, form a three dimensional picture of the structure, properties and composition of the continental lithosphere of Europe in an atlas format. Many of the data are also presented on an accompanying compact disk. The book completes the boxed set, and is also available on its own in paperback. The EGT project has filled many gaps in our knowledge of the lithosphere, and is a celebration of coordination and communication across geographical borders and between disciplines. This book tells the story of international collaboration on an unprecedented scale, by several hundred geoscientists in a series of well-defined international projects.
This book presents the first systematic English review of the tectonostratigraphic evolution of the various regional tectonic elements which comprise the central European orogens. Recent political changes have permitted authors from all central European countries, to contribute to this work, thus providing access to previously unavailable material. Each major tectonic element is systematically described in terms of its stratigraphic, structural, igneous, metamorphic and economic evolution. Each section is thoroughly referenced, thus providing an invaluable introduction to the geological complexity of the region. Introductory chapters provide the required regional geophysical and tectonic overviews.
Diabase intrusion cropping out in the Bardo syncline (southern region of the Holy Cross Mts) was paleomagnetically investigated. Positive results of paleomagnetic fold test enabled to define the age of characteristic remanent magnetization as the late Ludlovian-early Gedinian. Geological evidences point to its late Ludlovian age. Paleomagnetic pole (Lat. = 12°S, Long.=340°E) fits well to the Ludlowian segment of the Baltic apparent polar wander path. Hence paleomagnetic data indicate that the Bardo area was located in the present position at the margin of the East European Platform as early as the latest Silurian. They do not support hypothesis about large-scale rotation of southern region of the Holy Cross Mts in the Variscan time.
