scholarly journals Slab Break-offs in the Alpine Subduction Zone

2019 ◽  
Author(s):  
Emanuel D. Kästle ◽  
Claudio Rosenberg ◽  
Lapo Boschi ◽  
Nicolas Bellahsen ◽  
Thomas Meier ◽  
...  
Keyword(s):  
Body Wave ◽  
Eastern Alps ◽  
Central Alps ◽  
Slab Geometry ◽  
Tomographic Images ◽  
Velocity Anomaly ◽  
Tectonic Processes ◽  
The Alps ◽  
Geological Constraints ◽  
European Plate

Abstract. After the onset of plate collision in the Alps, tectonic processes are inferred to have changed dramatically in the Alps: European plate break-offs in various places of the Alpine arc, as well as a subduction polarity reversal in the eastern Alps have been proposed. We review body-wave tomographic studies, compare them to our surface-wave-derived model, and interpret them in terms of slab geometries. We infer that the shallow subducting portion of the European plate is likely detached under both the western and eastern (but not the central) Alps. The Alps-Dinarides transition may be explained by a combination of European and Adriatic subduction. This implies that the deep high-velocity anomaly (> 200 km depth) mapped by tomographers under the eastern Alps is a detached segment of the European plate. The shallower fast anomaly (100–200 km depth) can be ascribed to European or Adriatic subduction, or both. These findings are compared to previously proposed models for the eastern Alps in terms of slab geometry, but also integrated in a a new, alternative geodynamic scenario that best fits both tomographic images and geological constraints.

scholarly journals Slab Break-offs in the Alpine Subduction Zone

2019 ◽  
Author(s):  
Emanuel D. Kästle ◽  
Claudio Rosenberg ◽  
Lapo Boschi ◽  
Nicolas Bellahsen ◽  
Thomas Meier ◽  
...  
Keyword(s):  
Deep Structure ◽  
Body Wave ◽  
Eastern Alps ◽  
Central Alps ◽  
Slab Geometry ◽  
Tomographic Images ◽  
Velocity Anomaly ◽  
The Alps ◽  
Geological Constraints ◽  
European Plate

Abstract. After the onset of plate collision in the Alps, at 32–34 Ma, the deep structure of the orogen is inferred to have changed dramatically: European plate break-offs in various places of the Alpine arc, as well as a possible reversal of subduction polarity in the eastern Alps have been proposed. We review body-wave tomographic studies, compare them to our surface-wave-derived model for the uppermost 200 km, and reinterpret them in terms of slab geometries. We infer that the shallow subducting portion of the European plate is likely detached under both the western and eastern (but not the central) Alps. The Alps-Dinarides transition may be explained by a combination of European and Adriatic subduction. This would imply that the deep, high-velocity anomaly (> 200 km depth) mapped by tomographers under the eastern Alps is a detached segment of the European plate. The shallower fast anomaly (100–200 km depth) can be ascribed to European or Adriatic subduction, or both. These findings are compared to previously proposed models for the eastern Alps in terms of slab geometry, but also integrated in a new, alternative geodynamic scenario that best fits both tomographic images and geological constraints.

European-Adriatic plate collision in teleseismic tomography of the Eastern Alps

2021 ◽  
Author(s):  
Jaroslava Plomerova ◽  
Helena Zlebcikova ◽  
Gyorgy Hetenyi ◽  
Ludek Vecsey ◽  
Vladislav Babuska ◽  
...  
Keyword(s):  
Body Wave ◽  
Oceanic Lithosphere ◽  
Eastern Alps ◽  
Seismic Network ◽  
Quality Data ◽  
Seismic Velocities ◽  
Teleseismic Tomography ◽  
Adriatic Plate ◽  
The Alps ◽  
Mountain Belts

<p>We present potential scenarios of the European and Adriatic plates’ collision that formed the Alps and the neighbouring mountain belts. Our results are based on teleseismic body-wave data from the AlpArray-EASI complementary experiment (2014-2015, Hetényi et al., Tectonophysics 2018) and the AlpArray Seismic Network (Hetényi et al., Surv. Geophys. 2018).  Tomography of seismic velocities in the upper mantle along a ca. 200 km broad and 540 km long north-south transect images steady southward thickening of the lithosphere beneath the Bohemian Massif  and northward dipping East-Alpine lithospheric keel. Thanks to the dense spacing of the AlpArray Seismic Network stations and high-quality data, the high-resolution tomography resolves for the first time two sub-parallel down-going high-velocity heterogeneities beneath the Eastern Alps, instead of a single, thick anomaly. The southern heterogeneity, which we relate to the subducted Adriatic plate, is more distinct than the northern one, which loses its connection with the shallow parts. Moreover, amplitudes and size of this heterogeneity decrease in cross-sections perpendicular to the strike of the Alps when shifting towards the Central Alps. The presented collision scenarios consider the smaller northern heterogeneity as (1) a remnant of a delaminated early phase subduction of the European plate with the reversed polarity relative to that in the Western Alps, (2) a piece of continental and oceanic lithosphere together, or, (3) a fragment of a quite extended lithosphere margin foundering in a preceding phase of the Adriatic subduction.</p>

scholarly journals European tectosphere and slabs beneath the greater Alpine area – Interpretation of mantle structure in the Alps-Apennines-Pannonian region from teleseismic V<sub>p</sub> studies

2021 ◽  
Author(s):  
Mark Handy ◽  
Stefan Schmid ◽  
Marcel Paffrath ◽  
Wolfgang Friederich ◽  
Keyword(s):  
Pannonian Basin ◽  
Lower Boundary ◽  
Eastern Alps ◽  
P Wave ◽  
Moho Depth ◽  
Abrupt Decrease ◽  
Tauern Window ◽  
Lateral Extrusion ◽  
The Alps ◽  
European Plate

Abstract. Based on recent results of AlpArray, we propose a new model of Alpine collision that involves subduction and detachment of thick (180–200 km) European tectosphere. Our approach combines teleseismic P-wave tomography and existing Local Earthquake Tomography (LET) allowing us to image the Alpine slabs and their connections with the overlying orogenic crust at an unprecedented resolution. The images call into question the conventional notion that slabs comprise only seismically fast lithosphere and suggest that the mantle of the downgoing European Plate is heterogeneous, containing both positive and negative Vp anomalies of up to 5–6%. We interpret these as compositional rather than thermal anomalies, inherited from the Variscan and pre-Variscan orogenic cycles. They make up a kinematic entity referred to as tectosphere, which presently dips beneath the Alpine orogenic front. In contrast to the European Plate, the tectosphere of the Adriatic Plate is thinner (100–120 km) and has a lower boundary approximately at the interface between positive and negative Vp anomalies. Horizontal and vertical tomographic slices reveal that beneath the Central and Western Alps, the downgoing European tectospheric slab dips steeply to the S and SE and is only locally still attached to the Alpine crust. However, in the Eastern Alps and Carpathians, the European slab is completely detached from the orogenic crust and dips steeply to the N-NE. This along-strike change in attachment coincides with an abrupt decrease in Moho depth below the Tauern Window, the Moho being underlain by a pronounced negative Vp anomaly that reaches eastward into the Pannonian Basin area. This negative Vp anomaly is interpreted to represent hot upwelling asthenosphere that was instrumental in accommodating Neogene orogen-parallel lateral extrusion of the ALCAPA tectonic unit (upper plate crustal edifice of Alps and Carpathians) to the east. A European origin of the northward-dipping, detached slab segment beneath the Eastern Alps is likely since its imaged down-dip length (300–500 km) matches estimated Tertiary shortening in the Eastern Alps accommodated by south-dipping subduction of European tectosphere. A slab anomaly beneath the Dinarides is of Adriatic origin and dips to the northeast. There is no evidence that this slab dips beneath the Alps. The slab anomaly beneath the northern Apennines, also of Adriatic origin, hangs subvertically and is detached from the Apenninic orogenic crust and foreland. Except for its northernmost segment where it locally overlies the southern end of the European slab of the Alps, this slab is clearly separated from the latter by a broad zone of low Vp velocities located south of the Alpine slab beneath the Po Basin. Considered as a whole, the slabs of the Alpine chain are interpreted as attenuated, largely detached sheets of continental margin and Alpine Tethyan lithosphere that locally reach down to a slab graveyard in the Mantle Transition Zone (MTZ).

The Alpine Deep Structure from Surface Wave Tomography

2020 ◽  
Author(s):  
Thomas Meier ◽  
Amr El-Sharkawy ◽  
Sergei Lebedev
Keyword(s):  
Surface Wave ◽  
Phase Velocity ◽  
High Velocity ◽  
Deep Structure ◽  
Eastern Alps ◽  
Surface Wave Tomography ◽  
Mantle Lithosphere ◽  
Velocity Anomaly ◽  
Wave Tomography ◽  
The Alps

&lt;p&gt;Collisional tectonics of the Alps is driven by several slab segments. A detailed imaging of the lithosphere-asthenosphere system beneath the Alps is, however, challenging due to the relatively small size of the slab segments and the highly curved geometry of the Alps. Surface waves, due to their high sensitivity to variations in seismic velocities at lower crustal and upper mantle depth, are well suited to study the Alpine deep structure. New azimuthally anisotropic Rayleigh wave phase velocity maps are calculated from automated inter-station phase velocity measurements in a very broad period range (8 &amp;#8211; 350 s). The constructed local dispersion curves are then inverted individually for 1-D shear-wave velocity models using a new implementation of the stochastic Particle Swarm Optimization (PSO) inversion algorithm that enables the calculation of a high-resolution 3-D shear-wave velocity model from the crust down to 300 km beneath the Alps. In the Central Alps, a nearly vertical high velocity anomaly down to depth of 250 km is imaged and interpreted as subducting Eurasian mantle lithosphere. In contrast, low velocities in the Western Alps at depth of approximately 100 km and downwards are supporting the shallow slab break-off model. In the Eastern Alps, the presence of a vertically continuous high-velocity anomaly from 75 km to about 200 km depth beneath the northern Eurasian foreland and the almost continuous extension of a high-velocity anomaly from the Dinarides towards the Eastern Alps hint at a bivergent slab geometry beneath the Eastern Alps caused by subducting mantle lithosphere of both Eurasian and Adriatic origin. There is also evidence for subduction of Adriatic lithosphere to the east beneath the Pannonian Basin and the Dinarides down to a depth of about 150 km. Beneath the northern Apennines, the model indicates an attached Adriatic slab, whereas a slab window is found beneath the central Apennines. The results show that surface wave tomography can contribute to the imaging of complex slab geometries and slab segmentation in the Alpine region.&lt;/p&gt;

scholarly journals Local tectonic deformations measured by extensometer at the eastern foothills of the Alps at the Sopronbánfalva Geodynamic Observatory, Hungary

2019 ◽  
Vol 49 (3) ◽  
pp. 373-390
Author(s):  
Gyula Mentes ◽  
Márta Kiszely
Keyword(s):  
Strain Rate ◽  
Pannonian Basin ◽  
Compressive Strain ◽  
Local Strain ◽  
Eastern Alps ◽  
Local Deformation ◽  
Temporal And Spatial Distribution ◽  
Tectonic Processes ◽  
The Alps ◽  
Local Strain Rate

Abstract In Hungary, at the foot of the Eastern Alps, in the Sopronbánfalva Geodynamic Observatory (SGO), a quartz-tube extensometer has been used for recording the Earth’s tides and local tectonic deformations since 1991. The 27-year long strain record (1991–2017) shows a continuous compression of the rock with changing rate. The relations between the measured local deformation and present-day tectonics in the region of the observatory were investigated. The local strain rate variations were also compared with the temporal and spatial distribution as well as with the magnitudes of earthquakes occurred within 200 km from the observatory in two sectors around the azimuth of the extensometer (116°): 116°±15° and 296°±15°. Our investigations show that earthquakes can also influence the strain rate. Earthquakes to the west of SGO generally increase the compressive strain rate, while earthquakes in the Pannonian Basin, with some exceptions, have no significant effect on the local strain rate variations measured in the SGO. It has been found that the recorded compressive strain is in good accordance with the recent tectonic processes in the region of the SGO determined by Global Navigation Satellite System (GNSS) technology and geophysical measurements. From the results it can be concluded that the uplift of the Alps, tectonic processes in the East Alpine region and in the Pannonian Basin play the most important role in the changing local compressive strain rate.

Tomography image of double high-velocity heterogeneity beneath the Eastern Alps from the AlpArray data

2020 ◽  
Author(s):  
Jaroslava Plomerová ◽  
Helena Žlebčíková ◽  
György Hetényi ◽  
Luděk Vecsey ◽  
Vladislav Babuška ◽  
...  
Keyword(s):  
Bohemian Massif ◽  
High Velocity ◽  
Seismic Anisotropy ◽  
Body Wave ◽  
Eastern Alps ◽  
Quality Data ◽  
Seismic Velocities ◽  
Adriatic Plate ◽  
The Alps ◽  
Mountain Belts

&lt;p&gt;&lt;span&gt;Convergence between the European and African plates formed the Alps and the neighbouring mountain belts. We present results based on teleseismic body-wave data from the AlpArray-EASI complementary experiment (2014-2015, Het&amp;#233;nyi et al., Tectonophysics 2018) and the AlpArray Seismic Network (Het&amp;#233;nyi et al., Surv. Geophys. 2018). Tomography of seismic velocities in the upper mantle, as well as seismic anisotropy study along a ca. 200 km broad and 540 km long north-south transect (crossing the Bohemian Massif in the north, the East-Alpine root, and reaching the Adriatic Sea in the south), image the steeply northward dipping East-Alpine root, dominated by the Adriatic plate, steady southward thickening of the lithosphere beneath the Bohemian Massif and distinct regional variations of mantle lithosphere fabrics modelled in 3D. These characteristics imply complex, domain-like architecture of the collisional zone of the European/Adriatic plates beneath the Alps. Thanks to the close spacing of the AlpArray stations and high-quality data, the high-resolution tomography resolved for the first time two neighbouring&lt;/span&gt;&lt;span&gt; high-velocity northward-dipping heterogeneities &lt;/span&gt;&lt;span&gt;beneath the Eastern Alps, instead of one thick root of the lithosphere. The southern one, which we relate to the Adriatic plate, is more distinct, the northern one is less pronounced, it delaminates at ~100km depth and diminishes in direction toward the Central Alps. It may represent a remnant of an early phase subduction of the European plate with the switched polarity (relative to the polarity in the Western Alps), or a preceding phase of the Adriatic subduction.&lt;/span&gt;&lt;/p&gt;

Microseismicity in the Eastern Alps: Preliminary Results From the Swath-D Network

2021 ◽  
Author(s):  
Rens Hofman ◽  
Joern Kummerow ◽  
Simone Cesca ◽  
Joachim Wassermann ◽  
Thomas Plenefisch ◽  
...  
Keyword(s):  
Large Data ◽  
Eastern Alps ◽  
Detection Methods ◽  
Mountain Range ◽  
Network Methods ◽  
Data Volume ◽  
Geophysical Processes ◽  
The Alps ◽  
Mountain Belts ◽  
Surrounding Areas

&lt;p&gt;The AlpArray seismological experiment is an international and interdisciplinary project to advance our understanding of geophysical processes in the greater Alpine region. The heart of the project consists of a large seismological array that covers the mountain range and its surrounding areas. To understand how the Alps and their neighbouring mountain belts evolved through time, we can only study its current structure and processes. The Eastern Alps are of prime interest since they currently demonstrate the highest crustal deformation rates. A key question is how these surface processes are linked to deeper structures. The Swath-D network is an array of temporary seismological stations complementary to the AlpArray network located in the Eastern Alps. This creates a unique opportunity to investigate high resolution seismicity on a local scale.&lt;/p&gt;&lt;p&gt;In this study, a combination of waveform-based detection methods was used to find small earthquakes in the large data volume of the Swath-D network. Methods were developed to locate the seismic events using semi-automatic picks, and estimate event magnitudes. We present an overview of the methods and workflow, as well as a preliminary overview of the seismicity in the Eastern Alps.&lt;/p&gt;

Review of the Incurvaria vetulella species-group in the Alps (Lepidoptera: Incurvariidae)

1993 ◽  
Vol 24 (1) ◽  
pp. 109-120 ◽  
Author(s):  
Peter Huemer
Keyword(s):  
Eastern Alps ◽  
Species Group ◽  
Female Genitalia ◽  
Male And Female ◽  
The Alps ◽  
Southwestern Alps

AbstractHuemer, P.: Review of the Incurvaria vetulella species-group in the Alps (Lepidoptera: Incurvariidae). Ent. scand. 24: 109-120. Copenhagen, Denmark. April 1993. ISSN 0013-8711. The Incurvaria vetulella species-group in the Alps is defined and reviewed. The following species are recognized: vetulella (Zetterstedt, 1839) (eastern Alps), triglavensis Hauder, 1912 stat. n. (southeastern Alps) and ploessli sp. n. (southwestern Alps). All species are described and/or redefined and adults, male and female genitalia are illustrated. Furthermore, Scandinavian specimens of vetulella and circulella (Zetterstedt, 1839) are illustrated for comparison. The considerable external variation between various alpine populations of vetulella is discussed and regarded as infraspecific. A lectotype of triglavensis is designated.

scholarly journals Environmental factors as drivers for macroinvertebrate and diatom diversity in Alpine lakes: New insights from the Stelvio National Park (Italy)

2019 ◽  
Vol 78 (2) ◽  
Author(s):  
Angela Boggero ◽  
Silvia Zaupa ◽  
Simona Musazzi ◽  
Michela Rogora ◽  
Elzbieta Dumnicka ◽  
...  
Keyword(s):  
High Altitude ◽  
National Park ◽  
Geographical Area ◽  
National Research Council ◽  
Nutrient Content ◽  
Eastern Alps ◽  
High Elevation ◽  
Alpine Lakes ◽  
High Altitude Lakes ◽  
The Alps

Information on the biodiversity of high altitude lakes in the Stelvio National Park was scarce and fragmentary, in most cases limited to a few studies on a single biological issue. To fill this gap, a multidisciplinary research program was established in 2011 to investigate macroinvertebrates, diatoms, and water chemistry in 8 high altitude lakes within the boundaries of the Park (Rhaetian Alps, Eastern Alps). The results of this study were compared with data on biological assemblages and chemical parameters of Alpine lakes in the Pennine-Lepontine Alps (Western Alps), to evaluate the role of local drivers with respect to regional ones. This comparison was possible thanks to the adoption of standardized sampling methodologies developed since the ’90s by the National Research Council-Water Research Institute (Verbania), in collaboration with several European Research centers. Despite located in a restricted geographical area, the lakes of the Stelvio National Park showed a high variability of chemical composition, and of sensitivity to acidification, lower than that of the Pennine-Lepontine Alpine lakes. Macroinvertebrate and diatom taxa were ubiquitous and frequent along the Alps, and mainly represented by cold-stenothermal species. Richness, Shannon, Simpson, and Pielou indices applied to phyto- and zoobenthos highlighted significantly lower values in Stelvio National Park lakes than in those of Pennine-Lepontine for macroinvertebrates, while no significant differences were found for diatoms. Two groups of lakes were identified by Cluster Analysis, mainly on the basis of major ion concentrations. Canonical Correspondence Analysis showed that the macroinvertebrate assemblage of the lakes studied is driven mainly by altitude and lake surface, and, to a lesser extent, by nutrient content. On the contrary, pH and acid-related variables played a secondary role for diatoms, while nutrients and, more in general, ionic content had significant effects on their species composition. Overall, the results of this first investigation showed that the high elevation of these lakes affects their macroinvertebrate assemblages, while their diatom communities are comparable throughout the Alps.

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