scholarly journals Structural pattern and emplacement mechanisms of the Krížna cover nappe (Central Western Carpathians)

2012 ◽  
Vol 63 (1) ◽  
pp. 13-32 ◽  
Author(s):  
Roberta Prokešová ◽  
Dušan Plašienka ◽  
Rastislav Milovský
Keyword(s):  
Driving Forces ◽  
Structural Evolution ◽  
Evolutionary Model ◽  
Structural Data ◽  
Western Carpathians ◽  
Low Grade ◽  
Structural Pattern ◽  
Thrust Tectonics ◽  
Central Western Carpathians ◽  
Nappe Emplacement

Structural pattern and emplacement mechanisms of the Krížna cover nappe (Central Western Carpathians)The Central Western Carpathians are characterized by both the thick- and thin-skinned thrust tectonics that originated during the Cretaceous. The Krížna Unit (Fatric Superunit) with a thickness of only a few km is the most widespread cover nappe system that completely overthrusts the Tatric basement/cover superunit over an area of about 12 thousands square km. In searching for a reliable model of its origin and emplacement, we have collected structural data throughout the nappe body from its hinterland backstop (Veporic Superunit) to its frontal parts. Fluid inclusion (FI) data from carbonate cataclastic rocks occurring at the nappe sole provided useful information about the p-T conditions during the nappe transport. The crucial phenomena considered for formulation of our evolutionary model are: (1) the nappe was derived from a broad rifted basinal area bounded by elevated domains; (2) the nappe body is composed of alternating, rheologically very variable sedimentary rock complexes, hence creating a mechanically stratified multilayer; (3) presence of soft strata serving as décollement horizons; (4) stress and strain gradients increasing towards the backstop; (5) progressive internal deformation at very low-grade conditions partitioned into several deformation stages reflecting varying external constraints for the nappe movement; (6) a very weak nappe sole formed by cataclasites indicating fluid-assisted nappe transport during all stages; (7) injection of hot overpressured fluids from external sources (deformed basement units) facilitating frontal ramp overthrusting under supralithostatic conditions. It was found that no simple mechanical model can be applied, but that all known principal emplacement mechanisms and driving forces temporarily participated in progressive structural evolution of the nappe. The rear compression operated during the early stages, when the sedimentary succession was detached, shortened and transported over the frontal ramp. Subsequently, gravity spreading and gliding governed the final nappe emplacement over the unconstrained basinal foreland.

scholarly journals Thermal evolution of the Malá Fatra Mountains (Central Western Carpathians): insights from zircon and apatite fission track thermochronology

2010 ◽  
Vol 61 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Martin Danišík ◽  
Milan Kohút ◽  
Igor Broska ◽  
Wolfgang Frisch
Keyword(s):  
Fission Track ◽  
Thermal Evolution ◽  
Western Carpathians ◽  
Low Grade ◽  
Apatite Fission Track ◽  
Metamorphic Overprint ◽  
Fission Track Thermochronology ◽  
Fast Cooling ◽  
Central Western Carpathians ◽  
Early Late

Thermal evolution of the Malá Fatra Mountains (Central Western Carpathians): insights from zircon and apatite fission track thermochronologyWe apply zircon and apatite fission track thermochronology (ZFT and AFT, respectively) to the Variscan crystal-line basement of the Malá Fatra Mts (Central Western Carpathians) in order to constrain the thermal history. The samples yielded three Early Cretaceous ZFT ages (143.7±9.6, 143.7±8.3, 135.3±6.9 Ma) and one Eocene age (45.2±2.1 Ma), proving that the basement was affected by a very low-grade Alpine metamorphic overprint. Although the precise timing and mechanisms of the overprint cannot be unequivocally resolved, we propose and discuss three alternative explanations: (i) a Jurassic/Cretaceous thermal event related to elevated heat flow associated with extensional tectonics, (ii) early Late Cretaceous thrusting and/or (iii) an Eocene orogeny. Thermal modelling of the AFT cooling ages (13.8±1.4 to 9.6±0.6 Ma) revealed fast cooling through the apatite partial annealing zone. The cooling is interpreted in terms of exhumation of the basement and creation of topographic relief, as corroborated by the sedimentary record in the surrounding Neogene depressions. Our AFT results significantly refine a general exhumation pattern of basement complexes in the Central Western Carpathians. A younging of AFT ages towards the orogenic front is evident, where all the external massifs located closest to the orogenic front (including Malá Fatra Mts) were exhumed after ~13 Ma from temperatures above ~120 °C.

scholarly journals Linkage of the Manín and Klape units with the Pieniny Klippen Belt and Central Western Carpathians: balancing the ambiguity

2019 ◽  
Vol 70 (1) ◽  
pp. 35-61 ◽  
Author(s):  
Dušan Plašienka
Keyword(s):  
Sedimentary Cover ◽  
Structural Data ◽  
Western Carpathians ◽  
Stress System ◽  
Accretionary Wedge ◽  
Short Term ◽  
Fault Structures ◽  
Pieniny Klippen Belt ◽  
Central Western Carpathians ◽  
Bottom To Top

Abstract The paper deals with the structure and evolution of the Pieniny Klippen Belt in its classic area in western Slovakia. The so-called Peri-Klippen Zone provides a transition from the Pieniny Klippen Belt s.s. built up by Jurassic to Eocene Oravic units (Šariš, Subpieniny and Pieniny from bottom to top) to the outer margin of the Central Western Carpathians composed of Triassic to mid-Cretaceous successions of the Fatric and Hronic cover nappe systems. The Peri-Klippen Zone attains a considerable width of 15 km in the Middle Váh River Valley, where it is composed of the supposedly Fatric Manín, Klape and Drietoma units, as well as their post-emplacement, Gosau-type sedimentary cover. All these units are tightly folded and imbricated. The complex sedimentary and structural rock records indicate the late Turonian emplacement of the frontal Fatric nappes in a position adjacent to or above the inner Oravic elements, whereby they became constituents of an accretionary wedge developing in response of subduction of the South Penninic– Vahic oceanic realm separating the Central Western Carpathians and the Oravic domain. Evolution of the wedge-top Gosau depressions and the trench-foredeep basins of the foreland Oravic area exhibit close mutual relationships controlled by the wedge dynamics. The kinematic and palaeostress analyses of fold and fault structures revealed only one dominating stress system coeval with development of the accretionary wedge, which is characterized by the generally NW–SE oriented main compression axis operating in a pure compressional to dextral transpressional regime, interrupted by short-term extensional events related to the wedge collapse stages. Younger, Miocene to Quaternary palaeostress fields correspond to those widely recorded in the entire Western Carpathians. Relying on the regional tectonostratigraphic and structural data, the problematic issues of the palaeogeographic settings of the Manín and Klape units, presumably affiliated with the Fatric cover nappe system, and of the provenance of numerous olistoliths occurring at different stratigraphic levels are then discussed in a broader context.

scholarly journals Structural evolution of the Turňa Unit constrained by fold and cleavage analyses and its consequences for the regional tectonic models of the Western Carpathians

2016 ◽  
Vol 67 (2) ◽  
pp. 179-195 ◽  
Author(s):  
Alexander Lačný ◽  
Dušan Plašienka ◽  
Rastislav Vojtko
Keyword(s):  
Large Scale ◽  
Structural Evolution ◽  
Lower Triassic ◽  
Geological Structure ◽  
Western Carpathians ◽  
Low Grade ◽  
Accretionary Wedge ◽  
Deformation Stage ◽  
Bedding Planes ◽  
Regional Tectonic

AbstractThe Turňa Unit (Turnaicum, Tornaicum) is one of the three nappe systems involved in the geological structure of the inner zones of the Western Carpathians. The unit is formed by a system of partial nappes and duplexes, which overlie the Meliata Unit s.l. and are overridden by the Silica Nappe. The Slovenská skala partial nappe in the investigated area includes clastic sediments of the mid-Carboniferous, Permian and Early Triassic age, followed by mostly deep-water Middle-Upper Triassic succession predominantly composed of carbonates. Structural analysis of cleavage planes and folds was carried out predominantly in the Lower Triassic Werfen Formation. The measured deformational structures are polygenetic and were principally formed in three successive deformation stages. The first deformation stage is represented by bedding-parallel, very low-grade metamorphic foliation that was related to nappe stacking and formation of the Mesozoic accretionary wedge during the latest Jurassic and earliest Cretaceous. The second deformation stage is represented by systems of open to closed, partly asymmetric folds with SW-NE oriented, steeply NW- or SE-dipping axial-plane cleavage. Regionally, the folded bedding planes are usually moderately SE-ward dipping, the NW-ward and subvertical dips are less common. The mesoscopic fold structures predominantly occur in the SW-NE trending anticlinal and synclinal hinge zones of large-scale folds. These structures evolved in a compressional tectonic regime with the NW-SE to N-S orientation of the maximum compressional axis. The third observed deformation stage was activated during ENE-WSW oriented shortening. This stage is chiefly represented by open, kink-type folds. Some inferences for regional structures and tectonic evolution of the area are discussed as well.

scholarly journals Formation of a Composite Albian–Eocene Orogenic Wedge in the Inner Western Carpathians: P–T Estimates and 40Ar/39Ar Geochronology from Structural Units

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 988
Author(s):  
Marián Putiš ◽  
Ondrej Nemec ◽  
Martin Danišík ◽  
Fred Jourdan ◽  
Ján Soták ◽  
...  
Keyword(s):  
Evolutionary Model ◽  
White Mica ◽  
Western Carpathians ◽  
Low Grade ◽  
Accretionary Wedge ◽  
Structural Units ◽  
Upper Carboniferous ◽  
The North ◽  
Orogenic Wedge ◽  
Pieniny Klippen Belt

The composite Albian–Eocene orogenic wedge of the northern part of the Inner Western Carpathians (IWC) comprises the European Variscan basement with the Upper Carboniferous–Triassic cover and the Jurassic to Upper Cretaceous sedimentary successions of a large oceanic–continental Atlantic (Alpine) Tethys basin system. This paper presents an updated evolutionary model for principal structural units of the orogenic wedge (i.e., Fatricum, Tatricum and Infratatricum) based on new and published white mica 40Ar/39Ar geochronology and P–T estimates by Perple_X modeling and geothermobarometry. The north-directed Cretaceous collision led to closure of the Jurassic–Early Cretaceous basins, and incorporation of their sedimentary infill and a thinned basement into the Albian–Cenomanian/Turonian accretionary wedge. During this compressional D1 stage, the subautochthonous Fatric structural units, including the present-day higher Infratatric nappes, achieved the metamorphic conditions of ca. 250–400 °C and 400–700 MPa. The collapse of the Albian–Cenomanian/Turonian wedge and contemporary southward Penninic oceanic subduction enhanced the extensional exhumation of the low-grade metamorphosed structural complexes (D2 stage) and the opening of a fore-arc basin. This basin hemipelagic Coniacian–Campanian Couches-Rouges type marls (C.R.) spread from the northern Tatric edge, throughout the Infratatric Belice Basin, up to the peri-Pieniny Klippen Belt Kysuca Basin, thus tracing the south-Penninic subduction. The ceasing subduction switched to the compressional regime recorded in the trench-like Belice “flysch” trough formation and the lower anchi-metamorphism of the C.R. at ca. 75–65 Ma (D3 stage). The Belice trough closure was followed by the thrusting of the exhumed low-grade metamorphosed higher Infratatric complexes and the anchi-metamorphosed C.R. over the frontal unmetamorphosed to lowest anchi-metamorphosed Upper Campanian–Maastrichtian “flysch” sediments at ca. 65–50 Ma (D4 stage). Phengite from the Infratatric marble sample SRB-1 and meta-marl sample HC-12 produced apparent 40Ar/39Ar step ages clustered around 90 Ma. A mixture interpretation of this age is consistent with the presence of an older metamorphic Ph1 related to the burial (D1) within the Albian–Cenomanian/Turonian accretionary wedge. On the contrary, a younger Ph2 is closely related to the late- to post-Campanian (D3) thrust fault formation over the C.R. Celadonite-enriched muscovite from the subautochthonous Fatric Zobor Nappe meta-quartzite sample ZI-3 yielded a mini-plateau age of 62.21 ± 0.31 Ma which coincides with the closing of the Infratatric foreland Belice “flysch” trough, the accretion of the Infratatricum to the Tatricum, and the formation of the rear subautochthonous Fatricum bivergent structure in the Eocene orogenic wedge.

scholarly journals Provenance of the Permian Malužiná Formation sandstones (Malé Karpaty Mountains, Western Carpathians): evidence of garnet and tourmaline mineral chemistry

2015 ◽  
Vol 66 (2) ◽  
pp. 83-97 ◽  
Author(s):  
Marek Vďačný ◽  
Peter Bačík
Keyword(s):  
Regional Metamorphism ◽  
Mineral Chemistry ◽  
Source Rocks ◽  
Granitic Rocks ◽  
Western Carpathians ◽  
Low Grade ◽  
Magmatic Rocks ◽  
Potential Source ◽  
Ophiolitic Rocks ◽  
Central Western Carpathians

Abstract The chemistry of detrital garnets (almandine; spessartine-, grossular-, and pyrope-rich almandine; andradite) and mostly dravitic tourmalines from three sandstone samples of the Permian Malužiná Formation in the northern part of the Malé Karpaty Mts (Western Carpathians, SW Slovakia) reveals a great variability of potential source rocks. They comprise (1) low-grade regionally metamorphosed rocks (metacherts, blue schists, metapelites and metapsammites), (2) contact-thermal metamorphic calcareous rocks (skarns or rodingites), (3) garnet-bearing mica schists and gneisses resulting from the regional metamorphism of argillaceous sediments, (4) amphibolites and metabasic sub-ophiolitic rocks, (5) granulites, (6) Li-poor granites and their associated pegmatites and aplites as well as (7) rhyolites. Consequently, the post-Variscan, rift-related sedimentary basin of the Malužiná Formation originated in the vicinity of a low- to high-grade crystalline basement with granitic rocks. Such lithological types of metamorphic and magmatic rocks are characteristic for the Variscan terranes of the Central Western Carpathians (Tatricum and Veporicum Superunits).

Low-grade metamorphism and accretion tectonics: Southern Uplands terrain, Scotland

1985 ◽  
Vol 49 (352) ◽  
pp. 335-344 ◽  
Author(s):  
A. E. S. Kemp ◽  
G. H. J. Oliver ◽  
J. R. Baldwin
Keyword(s):  
Subduction Zones ◽  
Structural Data ◽  
Low Grade ◽  
Structural Level ◽  
Concomitant Increase ◽  
Illite Crystallinity ◽  
Grade Metamorphism ◽  
Trench Slope ◽  
Reflectance Data ◽  
Trajectory Characteristic

AbstractPrevious studies of low-grade metamorphism in the Southern Uplands accretionary terrain indicated prehnite-pumpellyite facies/anchizone conditions developed throughout the area, except for local preservation of trench-slope sediments and an accreted seamount at zeolite facies/advanced diagenetic grade. New graptolite reflectance data are presented that show a general northward increase in temperature in the Southern Uplands. The results from two cross-strike traverses in the southern and central belts in contemporaneous sequences, using illite crystallinity, illite lateral spacing (bo) , and graptolite reflectance, indicate the development of systematic accretion-related low-grade metamorphism. Well-developed and constant anchizone conditions occur throughout the NE (Langholm) traverse, associated with common, F1 accretion-related folding and a regionally penetrative S1 cleavage. In the SW (Kirkcudbright) traverse, however, the youngest, last accreted packets are preserved at a transitional diagenetic stage and lack a penetrative S1 cleavage. Illite crystallinity, graptolite reflectance, and bo increase systematically northward through earlier accreted packets, reaching values of the NE traverse only at the northern end. The concomitant increase of bo with illite crystallinity suggests the relatively high P-low T trajectory characteristic of subduction zones. Integration of metamorphic and structural data relates increasing intensity of aceretion-related F1 folding, developmertt of S1 fabric, and onset of later fold phases to grade of metamorphism and structural level within the accretionary pile.

The geometry and structural evolution of a crustal-scale Caledonian fold complex: the Ballybofey Nappe, northwest Ireland

1994 ◽  
Vol 131 (4) ◽  
pp. 519-537 ◽  
Author(s):  
G. I. Alsop
Keyword(s):  
Structural Evolution ◽  
Sedimentary Facies ◽  
Crustal Thickening ◽  
Nappe Complex ◽  
Structural Regime ◽  
Gravity Driven ◽  
Facies Variation ◽  
Dominant Structure ◽  
Nappe Emplacement ◽  
Deformation Gradients

AbstractThe gross geometries exhibited by crustal-scale fold nappes are considered a consequence of both original stratigraphic relationships associated with sub-basin configuration, coupled with the nature of the structural regime and tectonic processes involved in the generation of the nappe pile. The Neo-Proterozoic Dalradian metasediments of northwestern Ireland provide a well-constrained and correlatable stratigraphy which defines a sequence of sub-reclined, tight-isoclinal Caledonian (c. 460 Ma) fold nappes. Within this fold complex, the dominant structure is the crustal-scale Ballybofey Nappe, which may be traced for 40 km along strike and is responsible for a regional (500 km2) stratigraphie inversion. The gentle, NE-plunging attitude of this fold results in a complete spectrum of tectonic levels and deformation gradients being exposed. Relatively low strains in the upper fold limb gradually increase down through the nappe, resulting in the generation of composite foliations and lineations and the development of a 10 km thick shear zone which culminates in a high strain basal detachment with underlying pre-Caledonian basement. The Ballybofey Nappe nucleated and propagated along a major zone of lateral sedimentary facies variation, coincident with the margin of a major Dalradian sub-basin. The large amplitude of the nappe is strongly influenced by the lateral heterogeneity within the metasedimentary sequence, and is associated with a minimum of 25–30 km ESE-directed translation concentrated within the overturned limb. Additional significant displacement is also focused along the basal décollement. Generation of the nappe complex resulted in significant crustal thickening and amphibolite facies metamorphism consistent with 15–18 km of burial, induced by a sequence of nappes propagating in the direction of overshear. The ESE-directed translation of the major fold nappes is away from the Caledonian foreland and a gravity-driven mechanism of nappe emplacement is suggested. Rigorous structural analysis within the cohesive stratigraphie framework enables relationships between the tectonic evolution and stratigraphic patterns to be distinguished, thus allowing models of fold nappe generation and mid-crustal deformation to be evaluated.

scholarly journals A Middle Triassic pachypleurosaur (Diapsida: Eosauropterygia) from a restricted carbonate ramp in the Western Carpathians (Gutenstein Formation, Fatric Unit): paleogeographic implications

2018 ◽  
Vol 69 (1) ◽  
pp. 3-16 ◽  
Author(s):  
Andrej Čerňanský ◽  
Nicole Klein ◽  
Ján Soták ◽  
Mário Olšavský ◽  
Juraj Šurka ◽  
...  
Keyword(s):  
Middle Triassic ◽  
Carbonate Platform ◽  
Small Body ◽  
Western Carpathians ◽  
Subtidal Zone ◽  
Postcranial Skeleton ◽  
Tatra Mountains ◽  
Carbonate Ramps ◽  
Shallow Subtidal ◽  
Central Western Carpathians

AbstractAn eosauropterygian skeleton found in the Middle Triassic (upper Anisian) Gutenstein Formation of the Fatric Unit (Demänovská dolina Valley, Low Tatra Mountains, Slovakia) represents the earliest known occurrence of marine tetrapods in the Western Carpathians. The specimen represents a partly articulated portion of the postcranial skeleton (nine dorsal vertebrae, coracoid, ribs, gastral ribs, pelvic girdle, femur and one zeugopodial element). It is assigned to the Pachypleurosauria, more precisely to theSerpianosaurus–Neusticosaurusclade based on the following combination of features: (1) small body size; (2) morphology of vertebrae, ribs and femur; (3) tripartite gastral ribs; and (4) microanatomy of the femur as revealed by μCT. Members of this clade were described from the epicontinental Germanic Basin and the Alpine Triassic (now southern Germany, Switzerland, Italy), and possibly from Spain. This finding shows that pachypleurosaur reptiles attained a broader geographical distribution during the Middle Triassic, with their geographical range reaching to the Central Western Carpathians. Pachypleurosaurs are often found in sediments formed in shallow, hypersaline carbonate-platform environments. The specimen found here occurs in a succession with vermicular limestones in a shallow subtidal zone and stromatolitic limestones in a peritidal zone, indicating that pachypleurosaurs inhabited hypersaline, restricted carbonate ramps in the Western Carpathians.

Late Carboniferous Schlingen in the Gotthard nappe (Central Alps) and their relation to the Variscan evolution

2021 ◽  
Author(s):  
Mario Buehler ◽  
Roger Zurbriggen ◽  
Alfons Berger ◽  
Marco Herwegh ◽  
Daniela Rubatto
Keyword(s):  
Shear Zone ◽  
Country Rock ◽  
Structural Evolution ◽  
Point Of View ◽  
Swiss Alps ◽  
Low Grade ◽  
Central Alps ◽  
Structural Investigations ◽  
Alpine Belt ◽  
Main Cluster

<p>Many pre‐Mesozoic basements of the Alpine belt contain kilometre‐scaled folds with steeply inclined axial planes and fold axes. Those structures are referred to as Schlingen folds. They deform polymetamorphic gneisses, often Late‐Ordovician metagranitoids and are cross‐cut themselves by Permian intrusions. However, the structural evolution of such Schlingen is still not completely understood and their geodynamic significance for the Variscan evolution is not clear. To close this gap, this study investigates in detail a well-preserved Schlingen structure in the Gotthard nappe (Central Swiss Alps). This Schlingen fold evolved by a combination of shearing and folding under amphibolite facies conditions. Detailed digital field mapping coupled with petrological and structural investigations reveal local synkinematic migmatisation in the fold hinges parallel to axial planes. U‐Pb dating of zircons separated from associated leucosomes reveal cores that record a detrital country rock age of 450 ± 3 Ma, and rims with a range of dates from 270 to 330 Ma. The main cluster defines an age of 316 ± 4 Ma. We ascribe this Late‐Carboniferous age to peak metamorphic conditions of the late‐Variscan Schlingen phase.</p><p>The pre-Schlingen structures are subdivided into three older deformation events, which are connected to the Cenerian and post-Cenerian deformations. In addition, until now unknown, post Schlingen-, but pre-Alpine transpressional deformation have been detected and described. This superimposed deformation produced locally a low-grade foliation and minor undulation of the Schlingen structures.</p><p>The detail data of the investigated fold structures are linked with already described Schlingen folds in the wider Alpine realm, which all are concentrated in the most southern parts of the Variscides. From a geodynamic point of view and based on the new tectono-metamorphic constraints, we propose Schlingen formation preceded and concurred the crustal-scale transpressional tectonics of the East Variscan Shear Zone. This scenario separates, at least in a structural sense, the Southern Variscides from more northern parts (also Gondwana derived) inside Pangea, where Schlingen folds are absent.</p>

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