Geodynamic evolution of an Alpine terrane—the Austroalpine basement to the south of the Tauern Window as a part of the Adriatic Plate (eastern Alps)

2008 ◽  
Vol 298 (1) ◽  
pp. 5-44 ◽  
Author(s):  
Bernhard Schulz ◽  
André Steenken ◽  
Siegfried Siegesmund
Keyword(s):  
Eastern Alps ◽  
The South ◽  
Geodynamic Evolution ◽  
Tauern Window ◽  
Adriatic Plate ◽  
Austroalpine Basement

scholarly journals Neogene kinematics of the Giudicarie Belt and eastern Southern Alpine orogenic front (Northern Italy)

2021 ◽  
Author(s):  
Vincent F. Verwater ◽  
Eline Le Breton ◽  
Mark R. Handy ◽  
Vincenzo Picotti ◽  
Azam Jozi Najafabadi ◽  
...  
Keyword(s):  
Cross Sections ◽  
Eastern Alps ◽  
Strike Slip ◽  
Fault System ◽  
Late Oligocene ◽  
Lateral Variation ◽  
Tectonic Structures ◽  
Tauern Window ◽  
Adriatic Plate ◽  
Lateral Extrusion

Abstract. Neogene indentation of the Adriatic plate into Europe led to major modifications of the Alpine orogenic structures and style of deformation in the Eastern Alps. Especially, the offset of the Periadriatic Fault by the Northern Giudicarie Fault marks the initiation of strike-slip faulting and lateral extrusion of the Eastern Alps. Questions remain on the exact role of this fault zone in changes of the Alpine orogen at depth. This necessitates quantitative analysis of the shortening, kinematics and depth of decoupling underneath the Northern Giudicarie Fault and associated fold-and thrust belt in the Southern Alps. Tectonic balancing of a network of seven cross sections through the Giudicarie Belt parallel to the local shortening direction reveals that it comprises two kinematic domains with different amounts and partly overlapping ages of shortening. These two domains are delimitated by the NW-SE oriented strike-slip Trento-Cles – Schio-Vicenza fault system, cross-cutting the Southern Alpine orogenic front in the south and merging with the Northern Giudicarie Fault in the north. The SW kinematic domain (Val Trompia sector) accommodated at least ~18 km of Late Oligocene to Early Miocene shortening. Since the Middle Miocene, the SW kinematic domain experienced a minimum of ~12–22 km shortening, whereas the NE kinematic domain underwent at least ~25–35 km shortening. Together, these domains contributed to an estimated ~53–75 km of sinistral strike-slip motion along the Northern Giudicarie Fault, implying that (most of) the offset of the Periadriatic Fault is due to Late Oligocene to Neogene indentation of the Adriatic plate into the Eastern Alps. Moreover, the faults linking the Giudicarie Belt with the Northern Giudicarie Fault reach ~15–20 km depth, indicating a thick-skinned tectonic style of deformation. These fault detachments may also connect at depth with a lower crustal Adriatic wedge that protruded north of the Periadriatic Fault and was responsible for N-S shortening and eastward escape of deeply exhumed units in the Tauern Window. Finally, the east-west lateral variation of shortening indicates internal deformation and lateral variation in strength of the Adriatic indenter, related to Permian – Mesozoic tectonic structures and paleogeographic domains.

Microstructures and mineral chemistry in amphibolites from the western Tauern Window (Eastern Alps), and P-T deformation paths of the Alpine greenschist-amphibolite facies metamorphism

1995 ◽  
Vol 59 (397) ◽  
pp. 641-659 ◽  
Author(s):  
Bernhard Schulz ◽  
Claude Triboulet ◽  
Claude Audren
Keyword(s):  
Mineral Chemistry ◽  
Eastern Alps ◽  
Amphibolite Facies ◽  
Tauern Window ◽  
Metamorphic History ◽  
Lithostratigraphic Units ◽  
Facies Metamorphism ◽  
Austroalpine Basement ◽  
T Deformation Paths ◽  
Extension Axis

AbstractAmphibolites in the Mesozoic part of the parautochthonous Lower Schieferhülle (LSH), the allochthonous Upper Schieferhülle (USH) and the overlying Austroalpine basement (AA) in and around the western Tauern Window (Eastern Alps) suffered a progressive Alpine deformation. Lineations and foliations L1-S1, L2-S2 defined by preferentially oriented (Na-Ca) amphiboles as well as F3 folds and further foliations Smyl and S4 in the metabasites are structures of successive deformational stages with a constant W-E main extension axis of strain. The (Na-Ca) amphiboles in assemblages with epidote, chlorite, albite/oligoclase and quartz are zoned with similar continuous zonation trends from early actinolite in the cores to magnesio-hornblende and tschermakitic hornblende, and from magnesio-hornblende to late actinolite in the rims in the three lithostratigraphic units. Geothermobarometry involving tremolite-edenite and (pargasite-hastingsite)-tremolite end-member equilibria in amphiboles allowed us to reconstruct prograde-retrograde P-T paths for the Alpine greenschist-amphibolite facies event. The paths passed P/Tmax at 6–7 kbar/600°C. Similar shapes of the paths in AA, USH and Mesozoic LSH indicate a common metamorphic history and a stacking of these units prior to or during the pre-Pmax evolution. Moderate P-T ratios are characteristic for the temperature-dominated compression paths and indicate continental collisional rather than subduction zone metamorphism. The middle to late Alpine greenschist-amphibolite facies event appears as an independent metamorphism along a complete P-T loop which may have followed an earlier and poorly documented high-pressure/low-temperature event.

P-T data of Ky-St-Grt gneisses hosting HP amphibolites and eclogites from the Austroalpine Polinik complex, Kreuzeck Mountains, Eastern Alps, Austria

2011 ◽  
Vol 3 (2) ◽  
Author(s):  
Martin Michálek ◽  
Marián Putiš ◽  
Christoph Hauzenberger
Keyword(s):  
High Pressure ◽  
Mineral Assemblage ◽  
Eastern Alps ◽  
Strike Slip ◽  
Slip Zone ◽  
Mineral Association ◽  
Lateral Strike Slip ◽  
Tauern Window ◽  
Austroalpine Basement ◽  
T Values

AbstractThis study focuses on metapelites of the Polinik complex in the Kreuzeck Mts. southeast of the Tauern Window, Eastern Alps, where kyanite — staurolite — garnet gneisses host eclogites and high pressure (HP) amphibolites of the Austroalpine basement. The stable mineral assemblage is garnet — staurolite — biotite — kyanite — quartz. Estimated metamorphic conditions from conventional geothermobarometry are 654±30 °C and 0.9±0.08 GPa, and Average P-T values calculated by THERMOCALC, are 665±15 °C at 0.77±0.09 GPa. Formation of the present mineral association in gneisses is related to the exhumation (D2) stage of hosted eclogites/HP amphibolites within a lateral strike-slip zone.

Time for a change of paradigm for Alpine subduction?

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

<p>The prevailing paradigm of mountain building in the Alps entails subduction of European continental lithosphere some 100km thick beneath the Adriatic plate. Based on recent results of AlpArray, we propose a new model that involves subduction and wholesale detachment of locally much thicker (200-240 km) European lithosphere. Our approach combines teleseismic P-wave tomography and existing Local Earthquake Tomography (LET) to image the Alpine slabs and their connections with the overlying orogenic crust at unprecedented resolution. The images call into question the simple notion that slabs comprise only seismically fast lithosphere and suggest that the mantle of the downgoing European plate is compositionally heterogeneous, containing both positive and negative seismic anomalies of up to 5%. We interpret these as compositional rather than thermal anomalies, inherited from the Paleozoic Variscan orogenic cycle and presently dipping beneath the Alpine orogenic front. In contrast to the European Plate, the lithosphere of the Adriatic Plate is thinner (100-120 km) and has a more poorly defined lower boundary approximately at the interface between positive and negative Vp anomalies.</p><p> </p><p>Horizontal and vertical tomographic slices reveal that beneath the Central and Western Alps, the downgoing European Plate dips steeply to the S and SE and is locally detached from the Alpine crust. However, in the Eastern Alps and Carpathians east of the central Tauern Window, the Alpine slab anomaly occupies the 150-400 km depth interval and dips steeply to the N-NE, having completely detached from the  Alpine orogenic crust. This along-strike change coincides with an abrupt eastward decrease in Moho depth (Kind et al., this session), the Moho being underlain by a pronounced negative Vp anomaly reaching 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 E.  An Adriatic origin of the northward-dipping, detached slab segment beneath the Eastern Alps is unlikely since its imaged down-dip length (200-300 km) matches estimated Tertiary shortening in the Eastern Alps accommodated by south-dipping subduction of European lithosphere, whereas shortening in the south-vergent eastern Southern Alps is only ≤ 70 km.</p><p> </p><p>A slab anomaly beneath the northernmost Dinarides, laterally adjoining the Eastern Alps, is missing. The slab anomaly beneath the northern Apennines, of Adriatic origin und dipping beneath the Tyrrhenian backarc, hangs subvertically and appears to be almost detached from the Apenninic orogenic crust. Except for its westernmost segment where it meets the Alpine slab, this slab is clearly separated from the latter by a broad extent of upwelling asthenosphere located south of the Alpine slabs beneath the Po Plain, i.e., just south of the Alpine subduction zone. Considered as a whole, the slabs beneath 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).</p>

scholarly journals Age constraints on the evolution of the Austroalpine basement to the south of the Tauern Window

2006 ◽  
Vol 96 (3) ◽  
pp. 415-432 ◽  
Author(s):  
Siegfried Siegesmund ◽  
Till Heinrichs ◽  
Rolf L. Romer ◽  
Daniel Doman
Keyword(s):  
The South ◽  
Tauern Window ◽  
Austroalpine Basement ◽  
Age Constraints

Mineral chemistry, geothermobarometry and pre-Alpine high-pressure metamorphism of eclogitic amphibolites and mica schists from the Schobergruppe, Austroalpine basement, Eastern Alps

1993 ◽  
Vol 57 (387) ◽  
pp. 189-202 ◽  
Author(s):  
Bernhard Schulz
Keyword(s):  
High Pressure ◽  
Mineral Chemistry ◽  
Eastern Alps ◽  
Upper Ordovician ◽  
Progressive Deformation ◽  
Tauern Window ◽  
High Pressure Metamorphism ◽  
Facies Metamorphism ◽  
Austroalpine Basement ◽  
T Path

AbstractAlternating eclogitic amphibolites, mica schists and orthogneisses in the Schobergruppe to the south of the Tauern Window suffered a post-Upper-Ordovician progressive deformation D1-D2which produced parallel planar-linear structures in all the rocks. Zoned garnets, preferentially oriented zoned clinopyroxenes (Jd 35-42%) and albite (An 7-9%) give evidence of high-pressure metamorphism (550-650°C 14-16 kbar) of the metabasites. Ca-amphiboles crystallized during subsequent decompression. In a kyanite-staurolite-garnet mica schist 300 metres below the metabasites, garnetbearing assemblages grew synchronous with the development of foliations S1and S2. Garnets are zoned with increasing XMgand decreasing-increasing-rcdecreasing Xcafrom cores to rims. Albitic plagioclase (An 1-3%) and micas are enclosed in garnet cores and rims, are in contact with garnet, and occur with garnet in microlithons. When these minerals are used for geothermobarometry, a prograde P-T evolution (460 to 680°C with coeval pressure variations which reach high-pressure conditions can be estimated. This suggests that garnet-plagioclase geobarometry with albitic plagioclase works in the relevant P-T field. Similar garnet zonation trends and a similarly shaped P-T path from mica schists of an adjacent region with late-Variscan cooling ages, points to an eady-Variscan age of the syn-D1-D2high-pressure and subsequent amphibolite-facies metamorphism.

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