Slab geometry and upper mantle flow patterns in the Central Mediterranean from 3D anisotropic P-wave tomography

Rappisi, Francesco; VanderBeek, Brandon; Faccenda, Manuele; Morelli, A; Molinari, I

doi:10.1002/essoar.10510649.1

Cited by 3 publications

(6 citation statements)

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“…We exclude any potential change in European Moho attitude either due to European slab breakoff or European slab rollback after (U)HP rock exhumation. Recent tomography models of the Alpine region document in fact a continuous and undetached European slab beneath the Western Alps down to the mantle transition zone (e.g., Zhao et al, 2016b;Rappisi et al, 2022), whereas late-stage slab rollback would imply an additional exhumation event on the lower-plate side of the orogen, which is not observed (Malusà et al, 2015).…”

Section: Lateral Moho Variations and Relations With The Slab Structurementioning

confidence: 99%

Along-strike variations in the fossil subduction zone of the Western Alps revealed by the CIFALPS seismic experiments and their implications for exhumation of (ultra-) high-pressure rocks

Ambert

Malusà

Solarino

et al. 2022

Earth and Planetary Science Letters

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Section: Lateral Moho Variations and Relations With The Slab Structurementioning

confidence: 99%

Along-strike variations in the fossil subduction zone of the Western Alps revealed by the CIFALPS seismic experiments and their implications for exhumation of (ultra-) high-pressure rocks

Ambert

Malusà

Solarino

et al. 2022

Earth and Planetary Science Letters

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“…To resemble realistic conditions a first inversion was performed using delay times calculated through our Model CWM with the same distribution of sources (Supplementary Figure S2A) and receivers (Figure 2A), and the same regularization parameters as in the anisotropic tomography model of the Central Mediterranean by Rappisi et al (2022) (Test 1). For this first test normally distributed errors with a standard deviation of 450 ms was added to the seismic data.…”

Section: Starting Model Discretization and Regularizationmentioning

confidence: 99%

“…Following the workflow described in Section 2.3.1, we first inverted a set of time delays computed through Model CWM using the distribution of sources and receivers as in Rappisi et al (2022) (see Supplementary Figure S2A and Figure 2A; Test 1). We added random errors with a standard deviation of 450 ms to the data (i.e.…”

Section: Anisotropic Tomography Inversionsmentioning

confidence: 99%

“…On the contrary, Zhao et al (2016) document the lateral continuity of the European slab from the Western Alps to the Central Alps, and the downdip slab continuity beneath the Central Alps, ruling out the hypothesis of slab break-off to explain Cenozoic Alpine magmatism. The teleseismic P-wave tomography of Rappisi et al (2022), referred as model ani-NEWTON21, exhibits a continuous slab beneath the Alps, divided into an Eastern, Central, and Western segment characterised by changes in dip. Similarly, the extent of the Dinaric slab at ~30 Ma is largely debated.…”

Section: How Well Does Model Cwm Fit Seismological Observations?mentioning

confidence: 99%

“…After ~20 Myr (Figure 5D-F and Supplementary Figure S4) subducted lithospheric portions are found below the areas corresponding to the Alboran, Kabylides and Calabria-Apennine region where seismic tomographic methods have revealed several positive velocities anomalies (Spakman, 1991;Spakman et al, 1993;Wortel and Spakman, 2000;Gutscher et al, 2002;Piromallo and Morelli, 2003;Spakman and Wortel, 2004;Wortel et al, 2009;Bezada et al, 2013;Van der Meer et al, 2018). For example, Model CWM retrieves 1) the high-velocity body arranged horizontally over the 660 km discontinuity interpreted as the Ionian slab lying and broadening at the base of the upper mantle by P-wave tomographic models (Amato et al, 1993;Spakman et al, 1993;Selvaggi and Chiarabba, 1995;Lucente et al, 1999;Piromallo and Morelli, 2003;Spakman and Wortel, 2004;Van der Meer et al, 2018); 2) the portion of the slab under the Northern Apennines extending down to 150 km depth and from ~180 km down to about 660 km depth (Supplementary Figure S4B) (Spakman and Wortel, 2004;Giacomuzzi et al, 2012;El-Sharkawy et al, 2020) and 3) the Calabrian slab continuous from the surface down to a depth of 660 km (Giacomuzzi et al, 2012;Neri et al, 2012;Scarfì et al, 2018;Presti et al, 2019;El-Sharkawy et al, 2020;Rappisi et al, 2022); 4) the portion of slab imaged under the north African margin of Algeria, hanging down to ~150 km depth and from ~200 km joining to the Calabrian slab (Supplementary Figure S4B) Frontiers in Earth Science | www.frontiersin.org (Chertova et al, 2014;Van der Meer et al, 2018); 5)...…”

Section: How Well Does Model Cwm Fit Seismological Observations?mentioning

confidence: 99%

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Tomographic Image Interpretation and Central-Western Mediterranean-Like Upper Mantle Dynamics From Coupled Seismological and Geodynamic Modeling Approach

et al. 2022

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The Central-Western Mediterranean (CWM) is one of the most complex tectonic setting on Earth. Episodes of slab rollback, break-off and tearing, the opening of back-arc extensional basins (i.e., Liguro-Provencal, Alborean, Algerian and Tyrrhenian basins), the presence of large mountain ranges, active volcanoes and violent earthquakes have made the Mediterranean an ideal environment to study a wide range of geodynamic processes and an important target for seismological studies (e.g, seismic tomography). Here we build a geodynamic model which, although it does not reproduce its exact tectonic structure (e.g., due to the limits of the numerical method, approximations in the initial setup, etc), presents multiple and geometrically complex subduction systems analogous to those found in the CWM. The tectonic evolution of this model is estimated with petrological-thermo-mechanical 3D simulations, then, we dynamically compute the upper mantle fabrics and seismic anisotropy as a function of the strain history and local P-T conditions. After comparing the model with SKS splitting observations in order to quantify the discrepancies with the true Central-Western Mediterranean, we use the elastic tensors predicted for the modeled configuration to perform 3D P-wave anisotropic tomography by inverting synthetic P-wave delay times. Using the geodynamic model as reference, we evaluate the capabilities of a recently developed seismic tomography technique to recover the isotropic anomalies and anisotropy patterns related to a complex subduction environment in different conditions, such as poor data coverage and bad data quality. We observe that, although P-wave tomography still remains a powerful tool to investigate the upper mantle, the reliability of the retrieved structures strongly depends on data quality and data density. Furthermore, the recovered anisotropic patterns are consistent with those of the target model, but in general an underestimation of the anisotropy magnitude in the upper mantle is observed. In the light of future developments, our study suggests that by combining micro- and macro-scale geodynamic simulations and seismological modeling of seismic anisotropy it will be possible to reproduce, at least to a first order, the tectonic evolution of real study regions (e.g., the Mediterranean) thus providing fundamental constraints on the processes that have contributed in shaping their current geological scenario.

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Seismic Anisotropy Tomography and Mantle Dynamics

et al. 2023

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Seismic anisotropy tomography is the updated geophysical imaging technology that can reveal 3-D variations of both structural heterogeneity and seismic anisotropy, providing unique constraints on geodynamic processes in the Earth’s crust and mantle. Here we introduce recent advances in the theory and application of seismic anisotropy tomography, thanks to abundant and high-quality data sets recorded by dense seismic networks deployed in many regions in the past decades. Applications of the novel techniques led to new discoveries in the 3-D structure and dynamics of subduction zones and continental regions. The most significant findings are constraints on seismic anisotropy in the subducting slabs. Fast-velocity directions (FVDs) of azimuthal anisotropy in the slabs are generally trench-parallel, reflecting fossil lattice-preferred orientation of aligned anisotropic minerals and/or shape-preferred orientation due to transform faults produced at the mid-ocean ridge and intraslab hydrated faults formed at the outer-rise area near the oceanic trench. The slab deformation may play an important role in both mantle flow and intraslab fabric. Trench-parallel anisotropy in the forearc has been widely observed by shear-wave splitting measurements, which may result, at least partly, from the intraslab deformation due to outer-rise yielding of the incoming oceanic plate. In the mantle wedge beneath the volcanic front and back-arc areas, FVDs are trench-normal, reflecting subduction-driven corner flows. Trench-normal FVDs are also revealed in the subslab mantle, which may reflect asthenospheric shear deformation caused by the overlying slab subduction. Toroidal mantle flow is observed in and around a slab edge or slab window. Significant azimuthal and radial anisotropies occur in the big mantle wedge beneath East Asia, reflecting hot and wet upwelling flows as well as horizontal flows associated with deep subduction of the western Pacific plate and its stagnation in the mantle transition zone. The geodynamic processes in the big mantle wedge have caused craton destruction, back-arc spreading, and intraplate seismic and volcanic activities. Ductile flow in the middle-lower crust is clearly revealed as prominent seismic anisotropy beneath the Tibetan Plateau, which affects the generation of large crustal earthquakes and mountain buildings.

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Slab geometry and upper mantle flow patterns in the Central Mediterranean from 3D anisotropic P-wave tomography

Cited by 3 publications

References 0 publications

Along-strike variations in the fossil subduction zone of the Western Alps revealed by the CIFALPS seismic experiments and their implications for exhumation of (ultra-) high-pressure rocks

Along-strike variations in the fossil subduction zone of the Western Alps revealed by the CIFALPS seismic experiments and their implications for exhumation of (ultra-) high-pressure rocks

Tomographic Image Interpretation and Central-Western Mediterranean-Like Upper Mantle Dynamics From Coupled Seismological and Geodynamic Modeling Approach

Seismic Anisotropy Tomography and Mantle Dynamics

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