A natural and controlled source seismic profile through the Eastern Alps: TRANSALP

Institut für Geowissenschaften, Universität Potsdam, POB 601553, 14415 Potsdam, Germany
Earth and Planetary Science Letters (Impact Factor: 4.73). 08/2004; 225(1):115-129. DOI: 10.1016/j.epsl.2004.05.040


The combined passive and active seismic TRANSALP experiment produced an unprecedented high-resolution crustal image of the Eastern Alps between Munich and Venice. The European and Adriatic Mohos (EM and AM, respectively) are clearly imaged with different seismic techniques: near-vertical incidence reflections and receiver functions (RFs). The European Moho dips gently southward from 35 km beneath the northern foreland to a maximum depth of 55 km beneath the central part of the Eastern Alps, whereas the Adriatic Moho is imaged primarily by receiver functions at a relatively constant depth of about 40 km. In both data sets, we have also detected first-order Alpine shear zones, such as the Helvetic detachment, Inntal fault and Sub-Tauern ramp in the north. Apart from the Valsugana thrust, receiver functions in the southern part of the Eastern Alps have also observed a north dipping interface, which may penetrate the entire Adriatic crust [Adriatic Crust Interface (ACI)]. Deep crustal seismicity may be related to the ACI. We interpret the ACI as the currently active retroshear zone in the doubly vergent Alpine collisional belt.

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Available from: Frank Scherbaum, Oct 09, 2015
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    • "It is imaged by the K-model as well, and furthermore, Dando (2010) delineated this slab by teleseismic tomography based on data from the CBP-project (Dando et al., 2011; Houseman et al., 2010). Additional support for the existence of high velocity mantle above the 410 km mantle discontinuity is supplied by receiver functions, which have piercing points in the area of the " deep slab " (Kummerow et al., 2004). The L-model does not extend as deep and far enough to the east to resolve this high velocity body. "
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    ABSTRACT: During the last two decades teleseismic studies yielded valuable information on the structure of the upper mantle below the Alpine–Mediterranean area. Subducted oceanic lithosphere forms a broad anomaly resting on but not penetrating the 670km discontinuity. More shallow slabs imaged below the Alpine arc are interpreted as subducted continental lower lithosphere. Substantial advances in our understanding of past and active tectonic processes have been achieved due to these results. However, important issues like the polarity of subduction under the Eastern Alps and the slab geometry at the transition to the Pannonian realm are still under debate. The ALPASS teleseismic experiment was designed to address these open questions.Teleseismic waveforms from 80 earthquakes recorded at 75 temporary and 79 permanent stations were collected during 2005 and 2006. From these data, a tomographic image of the upper mantle was generated between 60km and 500km depth. Crustal corrections, additional station terms, and ray bending caused by the velocity perturbations were considered. A steeply to vertically dipping “shallow slab” below the Eastern Alps is clearly resolved down to a depth of ~250km. It is interpreted as European lower lithosphere detached from the crust and subducted during post-collision convergence between Adria and Europe. Below the Pannonian realm low velocities or high mantle temperatures prevail down to ~300km depth, consistent with the concept of a Pannonian lithospheric fragment, which underwent strike–slip deformation relative to the European plate and extension during the post-collision phase of the Alpine orogeny. Between 350km and 400km depth, a “deep slab” extends from below the central Eastern Alps to under the Pannonian realm. It is interpreted as subducted lithosphere of the Alpine Tethys. At greater depth, there is a continuous transition to the high velocity anomaly above the 670km discontinuity.
    Tectonophysics 09/2011; 510(1):195-206. DOI:10.1016/j.tecto.2011.07.001 · 2.87 Impact Factor
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    • "Beneath the ''Transalp'' seismic profile in the Eastern Alps, the European Moho is imaged by both reflection seismic and receiver functions to dip gently southward, from a depth of 35 km beneath the northern foreland to a maximum depth of 55 km beneath the central part of the Eastern Alps. In contrast, the Adriatic Moho is imaged by the receiver function method to be at a relatively constant depth of about 40 km (Kummerow et al. 2004). A south-directed subduction of European lithosphere was also reconstructed for the entire Eastern Alps (Brückl et al. 2010), contrary to the northward subduction of the Adriatic plate beneath the European plate since late Oligocene to Miocene time as has been suggested (Schmid et al. 2004) based on mantle tomography (Lippitsch et al. 2003). "
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    ABSTRACT: Denudation rates from cosmogenic 10Be measured in quartz from recent river sediment have previously been used in the Central Alps to argue that rock uplift occurs through isostatic response to erosion in the absence of ongoing convergence. We present new basin-averaged denudation rates from large rivers in the Eastern and Southern European Alps together with a detailed topographic analysis in order to infer the forces driving erosion. Denudation rates in the Eastern and Southern Alps of 170–1,400mmky−1 are within a similar range to those in the Central Alps for similar lithologies. However, these denudation rates vary considerably with lithology, and their variability generally increases with steeper landscapes, where correlations with topographic metrics also become poorer. Tertiary igneous rocks are associated with steep hillslopes and channels and low denudation rates, whereas pre-Alpine gneisses usually exhibit steep hillslopes and higher denudation rates. Molasse, flysch, and schists display lower mean basin slopes and channel gradients, and, despite their high erodibility, low erosion rates. Exceptionally low denudation rates are also measured in Permian rhyolite, which has high mean basin slopes. We invoke geomorphic inheritance as a major factor controlling erosion, such that large erosive glaciers in the late Quaternary cold periods were more effective in priming landscapes in the Central Alps for erosion than in the interior Eastern Alps. However, the difference in tectonic evolution of the Eastern and Central Alps potentially adds to differences in their geomorphic response; their deep structures differ significantly and, unlike the Central Alps, the Eastern Alps are affected by ongoing tectonic influx due to the slow motion and rotation of Adria. The result is a complex pattern of high mountain erosion in the Eastern Alps, which has evolved from one confined to the narrow belt of the Tauern Window in late Tertiary time to one affecting the entire underthrust basement, orogenic lid, and parts of the Southern Alps today. KeywordsCosmogenic nuclides–Denudation rates–European Alps–Orogenic steady state
    International Journal of Earth Sciences 07/2011; 100(5):1163-1179. DOI:10.1007/s00531-010-0626-y · 2.09 Impact Factor
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    • "In Fig. 9, the velocity maps at 24 and 30 s still exhibit low velocities associated with the Alps and northern-central Apennines. The low velocities beneath the central Alps are probably related to the thick crust in this region, where the crust has been estimated to be about 50 km (Waldhauser et al. 2002; Kummerow et al. 2004; Li et al. 2007; Tesauro et al. 2008). The low-velocity anomalies "
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    ABSTRACT: We present the surface wave dispersion results of the application of the ambient noise method to broad-band data recorded at 114 stations from the Istituto Nazionale di Geofisica e Vulcanologia (INGV) national broad-band network, some stations of the Mediterranean Very Broadband Seismographic Network (MedNet) and of the Austrian Central Institute for Meteorology and Geodynamics (ZAMG). Vertical-component ambient noise data from 2005 October to 2007 March have been cross-correlated for station-pairs to estimate fundamental mode Rayleigh wave Green's functions. Cross-correlations are calculated in 1-hr segments, stacked over periods varying between 3 months and 1.5 yr. Rayleigh wave group dispersion curves at periods from 8 to 44 s were determined using the multiple-filter analysis technique. The study region was divided into a 0.2° × 0.2° grid to invert for group velocity distributions. Checkerboard tests were first carried out, and the lateral resolution was estimated to be about 0.6°. The resulting group velocity maps from 8 to 36 s show the significant difference of the crustal structure and good correlations with known geological and tectonic features in the study region. The Po Plain and the Southern Alps evidence lower group velocities due to soft alluvial deposits, and thick terrigenous sediments. Our results also clearly showed that the Tyrrhenian Sea is characterized with much higher velocities below 8 km than the Italian peninsula and the Adriatic Sea which indicates a thin oceanic crust beneath the Tyrrhenian Sea.
    Geophysical Journal International 03/2010; 180(3):1242-1252. DOI:10.1111/j.1365-246X.2009.04476.x · 2.56 Impact Factor
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