Mapping the Moho of the Western Alps by wide-angle reflection seismics

Hirm, A.; Nadir, S.; Thouvenot, François; Nicolich, R.; Pellis, G.; Scarascia, S.; Tabacco, I.; Castellano, F.; Merlanti, F.

doi:10.1016/0040-1951(89)90243-6

Cited by 32 publications

(7 citation statements)

References 6 publications

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“…Early CSS Moho mapping (e.g., Ansorge, ; Hirn et al, ; Miller et al, ) revealed a striking asymmetry of the crustal root and an apparent pronounced imbalance among topographic load, Moho depth, and Bouguer gravity in the Central and Western Alps (Kissling, ; Lyon‐Caen & Molnar, ), leading to the proposal of a lithosphere mantle slab load to achieve isostatic equilibrium (Holliger & Kissling, ; Zanolla et al, ). The presence of such a deep‐seated load has recently been confirmed through advances in seismic tomography technologies (Figure ).…”

Section: Geophysical Surveys Of Deep Crustal Levels Resulting In a Stmentioning

confidence: 99%

Rollback Orogeny Model for the Evolution of the Swiss Alps

2018

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The construction of the European Alps and the Himalayas has been related to the convergence and subsequent collision of two continental plates. Nearly all models of orogeny build on this concept, and all of them relate the stacking of nappes and the buildup of topography to compressional forces at work in response to the collision between two continental plates. For the central European Alps, however, these models fail to explain the first‐order observations of a mountain belt, which particularly includes the striking isostatic imbalance between the low surface topography and the thick crust beneath the Alps. Here we review and synthesize data on the geologic architecture of the central Alps, the chronology and pattern of crustal deformation, and information about the deep crustal structure derived from seismic tomography. Furthermore, we discuss the intrinsic and explicit assumptions in the kinematic models of Alpine evolution in the context of plate tectonic considerations. We combine these views with progress in understanding that has been gained through subduction and collision, isostatic mass and force balancing and with information that has been collected on the modern seismic regime. We conclude that a rollback orogeny model for the European plate offers the most suitable concept to explain the ensemble of surface and deep lithosphere observations. In this model gravity forces drive the evolution of the orogen and the construction of surface topography is accomplished without the requirement of a hard collision between two continents.

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Section: Geophysical Surveys Of Deep Crustal Levels Resulting In a Stmentioning

confidence: 99%

Rollback Orogeny Model for the Evolution of the Swiss Alps

2018

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“…The deep low-gravity and low-velocity anomalies can be interpreted as the deep crustal roots of the Alps, which have P-wave velocities lower than the surrounding mantle lithosphere. A thicker crust beneath the Alps has already been delineated by active seismic experiments and gravity modelling (Hirn et al 1989;Scarascia & Cassinis 1997).…”

Section: The Alpsmentioning

confidence: 99%

Crustal and uppermost mantle structure in Italy fron the inversion of P-wave arrival times: geodynamic impliations

Stefano

Chiarabba

Lucente

et al. 1999

Geophysical Journal International

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S U M M A RYIn this paper we present a 3-D image of the P-wave velocity structure in the crust and uppermost mantle beneath Italy, obtained by inverting P-wave arrival times of crustal earthquakes. We used about 48 000 arrival times at stations close to the epicentres (within 200 km) to mitigate the e¡ects of both reading errors and intrinsic complexity for long-distance ray paths due to the scale of heterogeneities in the Earth structure beneath Italy. Whereas two of the inverted layers (located in the lower crust and beneath the Moho) are well resolved by the data, the upper crustal layer has regions of relatively poor resolution beneath the central Apennines, due to the sparse station spacing. We made several attempts, varying the Moho geometry, to obtain reliable and stable results without introducing too complex and unconstrained a priori information. One of the most important results is the discovery of low-velocity anomalies at 38 km depth beneath the northern Apenninic and Calabrian arcs, which we interpret as subducted crustal material of the Adriatic and Ionian lithospheres. In the lower crust beneath the entire Apennines, a pronounced low-velocity belt is present, suggesting high temperatures in front of the bent Adriatic lithosphere. Based on our results and on those previously obtained from seismic tomography, we propose a model for the geodynamic evolution of the Apenninic system in which the present-day scenario re£ects lateral heterogeneities in the subducting Ionian (oceanic) and Adriatic (continental) lithosphere.

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“…Our processing of the wide‐angle reflection data is based on the principles of standard processing of CMP‐sorted reflection seismic data (e.g. Yilmaz, 2001; ECORS‐CROP Deep Seismic Sounding Group et al 1989) and transformation of trace amplitudes to complex amplitudes (Valasek et al 1991). We did not apply the STA/LTA algorithm since we are interested in the reflection band waveform not just in the onset of reflected energy.…”

Section: Stacking and Inversion Of Stacked Datamentioning

confidence: 99%

Application of stacking and inversion techniques to three-dimensional wide-angle reflection and refraction seismic data of the Eastern Alps

Behm¹,

Brückl²,

Chwatal³

et al. 2007

Geophysical Journal International

131

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SUMMARY We present new methods for the interpretation of 3‐D seismic wide‐angle reflection and refraction data with application to data acquired during the experiments CELEBRATION, 2000 and ALP 2002 in the area of the Eastern Alps and their transition to the surrounding tectonic provinces (Bohemian Massif, Carpathians, Pannonian domain, Dinarides). Data was acquired on a net of arbitrarily oriented seismic lines by simultaneous recording on all lines of seismic waves from the shots, which allows 2‐D and 3‐D interpretations. Much (80%) of the data set consists of crossline traces. Low signal to noise (S/N) ratio in the area of the young orogens decreases the quality of travel time picks. In these seismically heterogeneous areas it is difficult to assign clearly defined arrivals to the seismic phases, in particular on crossline record sections. In order to enhance the S/N ratio, signal detection and stacking techniques have been applied to enhance the Pg‐, Pn‐ and PmP phases. Further, inversion methods have been developed for the interpretation of WAR/R‐data, based on automated 1‐D inversion (Pg) and the application of the delay time concept (Pn). The results include a 3‐D velocity model of the crust based on Pg waves, time and depth maps of the Moho and a Pn‐velocity map. The models based on stacked data are robust and provide a larger coverage, than models based on travel time picks from single‐fold (unstacked) traces, but have relatively low resolution, especially near the surface. They were used as the basis for constructing models with improved resolution by the inversion of picks from single‐fold data. The results correlate well with geological structures and show new prominent features in the Eastern Alps area and their surrounds. The velocity distribution in the crust has strong lateral variations and the Moho in the investigation area appears to be fragmented into three parts.

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Mapping the Moho of the Western Alps by wide-angle reflection seismics

Cited by 32 publications

References 6 publications

Rollback Orogeny Model for the Evolution of the Swiss Alps

Rollback Orogeny Model for the Evolution of the Swiss Alps

Crustal and uppermost mantle structure in Italy fron the inversion of P-wave arrival times: geodynamic impliations

Application of stacking and inversion techniques to three-dimensional wide-angle reflection and refraction seismic data of the Eastern Alps

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