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1. Highlights on mantle deformation beneath the Western Alps with seismic anisotropy using CIFALPS2 data

Author

Pondrelli, S, Salimbeni, S, Confal, J, Malusa', M, Paul, A, Guillot, S, Solarino, S, Eva, E, Aubert, C, Zhao, L, Pondrelli, Silvia, Salimbeni, Simone, Confal, Judith M., Malusa' Marco Giovanni, Paul, Anne, Guillot, Stephane, Solarino, Stefano, Eva, Elena, Aubert, Coralie, Zhao, Liang, Pondrelli, S, Salimbeni, S, Confal, J, Malusa', M, Paul, A, Guillot, S, Solarino, S, Eva, E, Aubert, C, Zhao, L, Pondrelli, Silvia, Salimbeni, Simone, Confal, Judith M., Malusa' Marco Giovanni, Paul, Anne, Guillot, Stephane, Solarino, Stefano, Eva, Elena, Aubert, Coralie, and Zhao, Liang

Abstract

There are still open questions about the deep structure beneath the Western Alps. Seismic velocity tomographies show the European slab subducting beneath the Adria plate, but all these images did not clarify completely the possible presence of tears, slab windows, or detachments. Seismic anisotropy, considered an indicator of mantle deformation and studied using data recorded by dense networks, allows a better understanding of mantle flows in terms of location and orientation at depth. Using the large amount of shear wave-splitting and splitting-intensity measurements available in the Western Alps, collected through the CIFALPS2 temporary seismic network, together with already available data, some new patterns can be highlighted, and gaps left by previous studies can be filled. Instead of the typical seismic anisotropy pattern parallel to the entire arc of the Western Alps, this study supports the presence of a differential contribution along the belt that is only partly related to the European slab steepening. A nearly north-south anisotropy pattern beneath the external Western Alps, a direction that cuts the morphological features of the belt, is clearly found with the new CIFALPS2 measurements. It is, however, confirmed that the asthenospheric flow from central France towards the Tyrrhenian Sea is turning around the southern tip of the European slab.

Published
2024

2. The Deep Structure of the Alps based on the CIFALPS Seismic Experiment: A Synthesis

Author

Malusà, M, Guillot, S, Zhao, L, Paul, A, Solarino, S, Dumont, T, Schwartz, S, Aubert, C, Baccheschi, P, Eva, E, Lu, Y, Lyu, C, Pondrelli, S, Salimbeni, S, Sun, W, Yuan, H, Malusà, M. G., Guillot, S., Zhao, L., Paul, A., Solarino, S., Dumont, T., Schwartz, S., Aubert, C., Baccheschi, P., Eva, E., Lu, Y., Lyu, C., Pondrelli, S., Salimbeni, S., Sun, W., Yuan, H., Malusà, M, Guillot, S, Zhao, L, Paul, A, Solarino, S, Dumont, T, Schwartz, S, Aubert, C, Baccheschi, P, Eva, E, Lu, Y, Lyu, C, Pondrelli, S, Salimbeni, S, Sun, W, Yuan, H, Malusà, M. G., Guillot, S., Zhao, L., Paul, A., Solarino, S., Dumont, T., Schwartz, S., Aubert, C., Baccheschi, P., Eva, E., Lu, Y., Lyu, C., Pondrelli, S., Salimbeni, S., Sun, W., and Yuan, H.

Abstract

The European Alps are the site where classic geologic concepts such as nappe theory, continental subduction and slab breakoff have been first proposed. However, the deep tectonic structure of the Alps has long been poorly constrained by independent geophysical evidence. This review paper summarizes the main results of the CIFALPS passive seismic experiment, that was launched by Chinese, French and Italian scientists in the 2010s to provide new insights on the deep tectonic structure of the Alpine region. The application of a wide range of tomographic methods to the analysis of a single fossil subduction zone makes the CIFALPS experiment a potential reference case for the analysis of other orogenic belts. Major results include: (i) the first seismic evidence of European continental crust subducted into the Adriatic upper mantle, beneath the place where coesite was first recognized in continental (U)HP rocks in the Alps; (ii) evidence of a major involvement of the mantle wedge during (U)HP rock exhumation; (iii) evidence of a serpentinized plate interface favoring continental subduction; (iv) evidence of a continuous slab beneath the Western and Central Alps, ruling out the classic model of slab breakoff magmatism; (v) evidence of a polyphase development of anisotropic fabrics in the Alpine mantle, either representing active mantle flows or fossil fabrics inherited from previous rifting stages. Detection of these major tectonic features allows to propose interpretive geologic cross-sections at the scale of the lithosphere and upper mantle, providing a baseline for future analyses of active continental margins.

Published
2021

3. 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

Author

Paul, A, Malusa', M, Solarino, S, Salimbeni, S, Eva, E, Nouibat, A, Pondrelli, S, Aubert, C, Dumont, T, Guillot, S, Schwartz, S, Zhao, L, Paul, Anne, Malusa', Marco G., Solarino, Stefano, Salimbeni, Simone, Eva, Elena, Nouibat, Ahmed, Pondrelli, Silvia, Aubert, Coralie, Dumont, Thierry, Guillot, Stéphane, Schwartz, Stéphane, Zhao, Liang, Paul, A, Malusa', M, Solarino, S, Salimbeni, S, Eva, E, Nouibat, A, Pondrelli, S, Aubert, C, Dumont, T, Guillot, S, Schwartz, S, Zhao, L, Paul, Anne, Malusa', Marco G., Solarino, Stefano, Salimbeni, Simone, Eva, Elena, Nouibat, Ahmed, Pondrelli, Silvia, Aubert, Coralie, Dumont, Thierry, Guillot, Stéphane, Schwartz, Stéphane, and Zhao, Liang

Abstract

In complex plate-boundary settings, a reliable 3-D geophysical characterization of the deep tectonic structure is a fundamental starting point for a breakthrough in the analysis of processes controlling plate subduction and (U)HP rock exhumation. The Western Alps host one of the best-studied fossil subduction zones worldwide, with a well-defined deep structure in 2-D based on recent geophysical experiments. However, a full 3-D characterization of its deep tectonic structure is still lacking. Here we present a series of new receiver function cross-sections across the northern and southern Western Alps, validated and complemented by a S-wave velocity model from ambient-noise tomography that provides additional constraints between the profiles. We document a marked change in Moho attitude from the northern Western Alps, where the eastward-dipping European Moho reaches ∼45 km depth beneath the Gran Paradiso dome, to the southern Western Alps, where the European Moho reaches ∼70 km depth beneath the equivalent Dora-Maira dome. This change in Moho attitude takes place over a few tens of kilometers and was likely emphasized by deformation of the slab during subduction. The Western Alps subduction wedge is much thicker in the south than in the north, and the mantle-wedge rocks are deeply involved in orogeny exclusively in the south, where coesite is found in continental (U)HP rocks at several locations. Our detailed information on the 3-D structure of the subduction wedge provides first-order constraints for the next-generation of thermo-mechanical numerical models and may help explain the lateral variations in exhumation style revealed by the geologic record.

Published
2022

4. Receiver function mapping of the mantle transition zone beneath the Western Alps: New constraints on slab subduction and mantle upwelling

Author

Liu, D, Zhao, L, Paul, A, Yuan, H, Solarino, S, Aubert, C, Pondrelli, S, Salimbeni, S, Eva, E, Malusà, M, Guillot, S, Liu, Dongyang, Zhao, Liang, Paul, Anne, Yuan, Huaiyu, Solarino, Stefano, Aubert, Coralie, Pondrelli, Silvia, Salimbeni, Simone, Eva, Elena, Malusà, Marco Giovanni, Guillot, Stéphane, Liu, D, Zhao, L, Paul, A, Yuan, H, Solarino, S, Aubert, C, Pondrelli, S, Salimbeni, S, Eva, E, Malusà, M, Guillot, S, Liu, Dongyang, Zhao, Liang, Paul, Anne, Yuan, Huaiyu, Solarino, Stefano, Aubert, Coralie, Pondrelli, Silvia, Salimbeni, Simone, Eva, Elena, Malusà, Marco Giovanni, and Guillot, Stéphane

Abstract

To better constrain the deep structure and dynamics of the Western Alps, we studied the mantle transition zone (MTZ) structure using P-wave receiver functions (RFs). We obtained a total of 24904 RFs from 1182 events collected by 307 stations in the Western Alps. To illustrate the influence of the heterogeneity on the upper mantle velocity, we used both IASP91 and three-dimensional (3-D) velocity models to perform RF time-to-depth migration. We documented an MTZ thickening of about 40 km under the Western Alps and most of the Po Plain due to the uplift associated with the 410-km discontinuity and the depression associated with the 660-km discontinuity. Based upon the close spatial connection between the thickened MTZ and the location of the subducted slabs, we proposed that the thick MTZ was due to the subduction of the Alpine slab through the upper MTZ and the presence of remnants of subducted oceanic lithosphere in the MTZ. The uplift associated with the 410-km discontinuity provided independent evidence of the subduction depth of the Western Alps slab. In the Alpine foreland in eastern France, we observed localized arc-shaped thinning of the MTZ caused by a 12 km depression of the 410-km discontinuity, which has not been previously reported. This depression indicated a temperature increase of 120 K in the upper MTZ, and we proposed that it was caused by a small-scale mantle upwelling. Hardly any uplift of the 660 km discontinuity was observed, suggesting that the thermal anomaly was unlikely to be the result of a mantle plume. We observed that the thinning area of the MTZ corresponded to the area with the highest uplift rate in the Western Alps, which may have indicated that the temperature increase caused by the mantle upwelling contributed to the topographic uplift. (C) 2021 Elsevier B.V. All rights reserved.

Published
2022

5. Insights Into the Origin and Deformation Style of the Continental Moho: A Case-Study From the Western Alps (Italy)

Author

Salimbeni, S, Piana Agostinetti, N, Pondrelli, S, Salimbeni, S, Piana Agostinetti, N, and Pondrelli, S

Abstract

Several hypotheses on the origin of the continental Moho are still debated and multiple mechanisms may contribute to its formation. Here, we present quantitative estimation of the seismic properties and anisotropy of the crust-mantle transition in the Western Alps where an example of newly formed (proto)-continental Moho is unusually shallow. We make use of teleseismic P-to-S converted-waves recorded by stations deployed on top of the Ivrea Body (IB), a volume of possibly serpentinized mantle peridotite below exhumed (ultra-)high pressure crustal rocks. The IB has been mapped by gravity, magnetic, active and passive seismic surveys suggesting an extremely shallow Moho. We demonstrate that the P-to-S converted waves propagating through this region display coupled features: (a) they record expected presence of strong seismic velocity contrast at shallow depth as due to the lower crustal and upper mantle transition; (b) they are decomposed due to anisotropic properties of rocks involved. The proto-continental Moho is recognized as an increase in S-wave velocity (∼0.4–1 km/s) at shallow depths of 5–10 km. The presence of anisotropy within the IB and overlying crustal rocks is evidenced by back-azimuthal dependence of the amplitude of P-to-S phases. The strength of anisotropy is ∼−14% on average pointing out the presence of metamorphosed/hydrated material (e.g., serpentinite) below the Moho. Anisotropic directions are consistent across Moho in both crust and upper mantle. The similarity of the anisotropy parameters between crust and upper mantle suggests they have been shaped by the same deformation event.

Published
2021

6. The Deep Structure of the Alps Based on the CIFALPS Seismic Experiment: A Synthesis

Author

Malusà, M. G., primary, Guillot, S., additional, Zhao, L., additional, Paul, A., additional, Solarino, S., additional, Dumont, T., additional, Schwartz, S., additional, Aubert, C., additional, Baccheschi, P., additional, Eva, E., additional, Lu, Y., additional, Lyu, C., additional, Pondrelli, S., additional, Salimbeni, S., additional, Sun, W., additional, and Yuan, H., additional

Published
2021
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7. Coda-Q in the 2.5-20 s period band from seismic noise : application to the greater Alpine area

Author

Soergel, D., Pedersen, H. A., Stehly, L., Margerin, L., Paul, A., Hetenyi, G., Abreu, R., Allegretti, I., Apoloner, M. T., Aubert, C., De Berc, M. B., Bokelmann, G., Brunel, D., Capello, M., Carman, M., Cavaliere, A., Cheze, J., Chiarabba, C., Clinton, J., Cougoulat, G., Crawford, W., Cristiano, L., Czifra, T., D'Alema, E., Danesi, S., Daniel, R., Dasovic, I., Deschamps, A., Dessa, J. X., Doubre, C., Egdorf, S., Fiket, T., Fischer, K., Friederich, W., Fuchs, F., Funke, S., Giardini, D., Govoni, A., Graczer, Z., Groschl, G., Heimers, S., Heit, B., Herak, D., Herak, M., Huber, J., Jaric, D., Jedlicka, P., Jia, Y., Jund, H., Kissling, E., Klingen, S., Klotz, B., Kolinsky, P., Korn, M., Kotek, J., Kuhne, L., Kuk, K., Loos, J., Malengros, D., Margheriti, L., Maron, C., Martin, X., Massa, M., Mazzarini, F., Meier, T., Metral, L., Molinari, I., Moretti, M., Munzarova, H., Nardi, A., Pahor, J., Pequegnat, C., Pesaresi, D., Piccinini, D., Piromallo, C., Plenefisch, T., Plomerova, J., Pondrelli, S., Prevolnik, S., Racine, R., Régnier, Marc, Reiss, M., Ritter, J., Rumpker, G., Salimbeni, S., Schulte-Kortnack, D., Scherer, W., Schippkus, S., Sipka, V., Spallarossa, D., Spieker, K., Stipcevic, J., Strollo, A., Sule, B., Szanyi, G., Szucs, E., Thomas, C., Tilmann, F., Ueding, S., Vallocchia, M., Vecsey, L., Voigt, R., Wassermann, J., Weber, Z., Weidle, C., Wesztergom, V., Weyland, G., Wiemer, S., Wolyniec, D., Zieke, T., Zivvic, M., and AlpArray Working Group

Subjects
Europe, surface waves and free oscillations, Coda waves, seismic attenuation, seismic noise, wave scattering and diffraction
Abstract

Coda-Q is used to estimate the attenuation and scattering properties of the Earth. So far focus has been on earthquake data at frequencies above 1 Hz, as the high noise level in the first and second microseismic peak, and possibly lower scattering coefficient, hinder stable measurements at lower frequencies. In this work, we measure and map coda-Q in the period bands 2.5-5 s, 5-10 s and 10-20 s in the greater Alpine region using noise cross-correlations between station pairs, based on data from permanent seismic stations and from the temporary AlpArray experiment. The observed coda-Q for short interstation distances is independent of azimuth so there is no indication of influence of the directivity of the incoming noise field on our measurements. In the 2.5-5 s and 5-10 s period bands, our measurements are self-consistent, and we observe stable geographic patterns of low and high coda-Q in the period bands 2.5-5 s and 5-10 s. In the period band 10-20 s, the dispersion of our measurements increases and geographic patterns become speculative. The coda-Q maps show that major features are observed with high resolution, with a very good geographical resolution of for example low coda-Q in the Po Plain. There is a sharp contrast between the Po Plain and the Alps and Apennines where coda-Q is high, with the exception a small area in the Swiss Alps which may be contaminated by the low coda-Q of the Po Plain. The coda of the correlations is too short to make independent measurements at different times within the coda, so we cannot distinguish between intrinsic and scattering Q. Measurements on more severely selected data sets and longer time-series result in identical geographical patterns but lower numerical values. Therefore, high coda-Q values may be overestimated, but the geographic distribution between high and low coda-Q areas is respected. Our results demonstrate that noise correlations are a promising tool for extending coda-Q measurements to frequencies lower than those analysed with earthquake data.

Published
2020

8. Shear wave velocities in the upper mantle of the Western Alps: new constraints using array analysis of seismic surface waves

Author

Lyu, C, Pedersen, HA, Paul, A, Zhao, L, Solarino, S, Aubert, C, Malusà, MG, Wang, Q, Guillot, S, Pondrelli, S, Salimbeni, S, Schwartz, S, Dumont, T, Zheng, T, Zhu, R, Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Tianjin University (TJU), State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China, Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Instituto Nationale di Geofisica e Vulcanologia (INGV), Lyu, C, Pedersen, H, Paul, A, Zhao, L, Solarino, S, Aubert, C, Malusà, M, Wang, Q, Guillot, S, Pondrelli, S, Salimbeni, S, Schwartz, S, Dumont, T, Zheng, T, and Zhu, R

Subjects
010504 meteorology & atmospheric sciences, 010502 geochemistry & geophysics, 01 natural sciences, Seismic wave, Mantle (geology), symbols.namesake, Receiver function, Lithosphere, Geochemistry and Petrology, Continental margins: convergent, Shear velocity, Rayleigh wave, Geophysic, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Massif, Europe, Geophysics, 13. Climate action, Surface wave, symbols, Surface waves and free oscillations, Surface waves and free oscillation, Seismology, Geology
Abstract

International audience; It remains challenging to obtain absolute shear wave velocities of heterogeneities of small lateral extension in the uppermost mantle. This study presents a cross-section of Vs across the strongly heterogeneous 3-D structure of the western European Alps, based on array analysis of data from 92 broad-band seismic stations from the CIFALPS experiment and from permanent networks in France and Italy. Half of the stations were located along a dense sublinear array. Using a combination of these stations and off-profile stations, fundamental-mode Rayleigh wave dispersion curves were calculated using a combined frequency-time beamforming approach. We calculated dispersion curves for seven arrays of approximately 100 km aperture and 14 arrays of approximately 50 km aperture, the latter with the aim of obtaining a 2-D vertical cross-section of Vs beneath the western Alps. The dispersion curves were inverted for Vs(z), with crustal interfaces imposed from a previous receiver function study. The array approach proved feasible, as Vs(z) from independent arrays vary smoothly across the profile length. Results from the seven large arrays show that the shear velocity of the upper mantle beneath the European plate is overall low compared to AK135 with the lowest velocities in the internal part of the western Alps, and higher velocities east of the Alps beneath the Po plain. The 2-D Vs model is coherent with (i) a ∼100 km thick eastward-dipping European lithosphere west of the Alps, (ii) very high velocities beneath the Po plain, coherent with the presence of the Alpine (European) slab and (iii) a narrow low-velocity anomaly beneath the core of the western Alps (from the Briançonnais to the Dora Maira massif), and approximately colocated with a similar anomaly observed in a recent teleseismic P-wave tomography. This intriguing anomaly is also supported by traveltime variations of subvertically propagating body waves from two teleseismic events that are approximately located on the profile great circle.

Published
2017
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9. Earthquakes in the western Alpine mantle wedge

Author

Malusa', M, Zhao, L, Eva, E, Solarino, S, Paul, A, Guillot, S, Schwartz, S, Dumont, T, Aubert, C, Salimbeni, S, Pondrelli, S, Wang, Q, Zhu, R, MALUSA', MARCO GIOVANNI, Salimbeni, S., Zhu, R., Malusa', M, Zhao, L, Eva, E, Solarino, S, Paul, A, Guillot, S, Schwartz, S, Dumont, T, Aubert, C, Salimbeni, S, Pondrelli, S, Wang, Q, Zhu, R, MALUSA', MARCO GIOVANNI, Salimbeni, S., and Zhu, R.

Abstract

The assessment of seismic activity in the shallow continental mantle has long been hindered by the low resolution of both seismic imaging and earthquake locations in young collision zones. Here, we combine the most recent and high-resolution image of the lithospheric structure of the Western Alps with a high quality dataset of anomalously deep earthquakes recorded in the same area in the past 25 yrs. We show that these earthquakes are aligned on an active lithospheric strike-slip fault, and we provide evidence that this fault is located in the mantle wedge beneath the Adriatic Moho. Our results: (i) provide direct evidence that deep material can be seismogenic or not depending on the lithology; (ii) confirm the role of serpentinization in favoring the aseismic creep of mantle rocks; and (iii) demonstrate that the upper mantle can be stiff and seismogenic not only in cold cratons, but also in young orogenic belts.

Published
2017

10. Il protocollo Diagnostico-Terapeutico e Assistenziale per il carcinoma mammario della Regione Emilia-Romagna. I edizione

Author

Ferretti, S, Bertozzi, N, Naldoni, Carlo, Sassoli de' Bianchi, P, De Palma, R, Frassoldati, A, Santini, D, Taffurelli, M, Macellari, G, Bella, M, Pancaldi, Mg, Musolino, A, Pessinaf, Petraglia, F, Castagnetti, F, Foroni, M, Gardini, G, Iotti, C, Vacondio, R, Versari, A, Galli, V, Pini, M, Lazzaretti, Mg, De Santis, G, Pignatti, M, Tazzioli, G, Frezza, Gp, Brandes, A, Salimbeni, S, Saguatti, G, Fiorentino, M, Rossi, Nc, Turchetti, D, Zamagni, C, Feggi, L, Querzoli, P, Succi, S, Bagli, E, Bucchi, Lauro, Danesi, R, Della Chiara, S, Falcini, F, Curcio, A, Maltoni, M, Gianni, L, Polico, R, Raulli, Gd, Sanna, P, and Serra, L

Subjects
Socio-culturale
Published
2018

11. Active and fossil mantle flows in the western Alpine region unravelled by seismic anisotropy analysis and high-resolution P wave tomography

Author

Salimbeni, S, Malusà, M, Zhao, L, Guillot, S, Pondrelli, S, Margheriti, L, Paul, A, Solarino, S, Aubert, C, Dumont, T, Schwartz, S, Wang, Q, Xu, X, Zheng, T, Zhu, R, Malusà, MG, Salimbeni, S, Malusà, M, Zhao, L, Guillot, S, Pondrelli, S, Margheriti, L, Paul, A, Solarino, S, Aubert, C, Dumont, T, Schwartz, S, Wang, Q, Xu, X, Zheng, T, Zhu, R, and Malusà, MG

Abstract

The anisotropy of seismic velocities in the mantle, when integrated with high-resolution tomographic models and geologic information, can be used to detect active mantle flows in complex plate boundary areas, providing new insights on the impact of mantle processes on the topography of mountain belts. Here we use a densely spaced array of temporary broadband seismic stations to analyze the seismic anisotropy pattern of the western Alpine region, at the boundary between the Alpine and Apenninic slabs. Our results are supportive of a polyphase development of anisotropic mantle fabrics, possibly starting from the Jurassic to present. Geophysical data presented in this work, and geologic evidence taken from the literature, indicate that: (i) fossil fabrics formed during Tethyan rifting may be still preserved within the Alpine and Apenninic slabs; (ii) mantle deformation during Apenninic slab rollback is not compensated by a complete toroidal flow around the northern tip of the retreating slab; (iii) the previously observed continuous trend of anisotropy fast axes near-parallel to the western Alpine arc is confirmed. We observe that this arc-parallel trend of fast axes is located in correspondence to a low velocity anomaly in the European upper mantle, beneath regions of the Western and Ligurian Alps showing the highest uplift rates. We propose that the progressive rollback of the Apenninic slab, in the absence of a counterclockwise toroidal flow at its northern tip, induced a suction effect at the scale of the supraslab mantle. The resulting mantle flow pattern was characterized by an asthenospheric counterflow at the rear of the unbroken Western Alps slab and around its southern tip, and by an asthenospheric upwelling, mirrored by low P wave velocities, that would have favored the topographic uplift of the Alpine belt from the Mont Blanc to the Mediterranean sea.

Published
2018

12. Mantle wedge exhumation beneath the Dora-Maira (U)HP dome unravelled by local earthquake tomography (Western Alps)

Author

Solarino, S, Malusà, M, Eva, E, Guillot, S, Paul, A, Schwartz, S, Zhao, L, Aubert, C, Dumont, T, Pondrelli, S, Salimbeni, S, Wang, Q, Xu, X, Zheng, T, Zhu, R, Malusà, MG, Solarino, S, Malusà, M, Eva, E, Guillot, S, Paul, A, Schwartz, S, Zhao, L, Aubert, C, Dumont, T, Pondrelli, S, Salimbeni, S, Wang, Q, Xu, X, Zheng, T, Zhu, R, and Malusà, MG

Abstract

In continental subduction zones, the behaviour of the mantle wedge during exhumation of (ultra)high-pressure [(U)HP] rocks provides a key to distinguish among competing exhumation mechanisms. However, in spite of the relevant implications for understanding orogenic evolution, a high-resolution image of the mantle wedge beneath the Western Alps is still lacking. In order to fill this gap, we perform a detailed analysis of the velocity structure of the Alpine belt beneath the Dora-Maira (U)HP dome, based on local earthquake tomography independently validated by receiver function analysis. Our results point to a composite structure of the mantle wedge above the subducted European lithosphere. We found that the Dora-Maira (U)HP dome lays directly above partly serpentinized peridotites (Vp ~ 7.5 km/s; Vp/Vs = 1.70-1.72), documented from ~ 10 km depth down to the top of the eclogitized lower crust of the European plate. These serpentinized peridotites, possibly formed by fluid release from the subducting European slab to the Alpine mantle wedge, are juxtaposed against dry mantle peridotites of the Adriatic upper plate along an active fault rooted in the lithospheric mantle. We propose that serpentinized mantle-wedge peridotites were exhumed at shallow crustal levels during late Eocene transtensional tectonics, also triggering the rapid exhumation of (U)HP rocks, and were subsequently indented under the Alpine metamorphic wedge in the early Oligocene. Our findings suggest that mantle-wedge exhumation may represent a major feature of the deep structure of exhumed continental subduction zones. The deep orogenic levels here imaged by seismic tomography may be exposed today in older (U)HP belts, where mantle-wedge serpentinites are commonly associated with coesite-bearing continental metamorphic rocks.

Published
2018

13. Seismic moment tensors of the April 2009, L'Aquila (Central Italy), earthquake sequence

Author

Pondrelli, S., Salimbeni, S., Morelli, A., Ekström, G., Olivieri, M., Boschi, E., Pondrelli, S., Salimbeni, S., Morelli, A., Ekström, G., Olivieri, M., and Boschi, E.

Abstract

On 2009 April 6, the Central Apennines were hit by an Mw = 6.3 earthquake. The region had been shaken since 2008 October by seismic activity that culminated in two foreshocks with Mw > 4, 1 week and a few hours before the main shock. We computed seismic moment tensors for 26 events with Mw between 3.9 and 6.3, using the Regional Centroid Moment Tensor (RCMT) scheme. Most of these source parameters have been computed within 1 hr after the earthquake and rapidly revised successively. The focal mechanisms are all extensional, with a variable and sometimes significant strike-slip component. This geometry agrees with the NE-SW extensional deformation of the Apennines, known from previous seismic and geodetic observations. Events group into three clusters. Those located in the southern area have larger centroid depths and a wider distribution of T-axis directions. These differences suggest that towards south a different fault system was activated with respect to the SW-dipping normal faults beneath L'Aquila and more to the north

Published
2017

14. Continuity of the Alpine slab unraveled by high-resolution P wave tomography

Author

Zhao, L, Paul, A, Malusa', M, Xu, X, Zheng, T, Solarino, S, Guillot, S, Schwartz, S, Dumont, T, Salimbeni, S, Aubert, C, Pondrelli, S, Wang, Q, Zhu, R, MALUSA', MARCO GIOVANNI, Zhu, R., Zhao, L, Paul, A, Malusa', M, Xu, X, Zheng, T, Solarino, S, Guillot, S, Schwartz, S, Dumont, T, Salimbeni, S, Aubert, C, Pondrelli, S, Wang, Q, Zhu, R, MALUSA', MARCO GIOVANNI, and Zhu, R.

Abstract

The question of lateral and/or vertical continuity of subducted slabs in active orogens is a hot topic partly due to poorly resolved tomographic data. The complex slab structure beneath the Alpine region is only partly resolved by available geophysical data, leaving many geological and geodynamical issues widely open. Based upon a finite-frequency kernel method, we present a new high-resolution tomography model using P wave data from 527 broadband seismic stations, both from permanent networks and temporary experiments. This model provides an improved image of the slab structure in the Alpine region and fundamental pinpoints for the analysis of Cenozoic magmatism, (U)HP metamorphism, and Alpine topography. Our results 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. A low-velocity anomaly is observed in the upper mantle beneath the core of the Western Alps, pointing to dynamic topography effects. A NE dipping Adriatic slab, consistent with Dinaric subduction, is possibly observed beneath the Eastern Alps, whereas the laterally continuous Adriatic slab of the Northern Apennines shows major gaps at the boundary with the Southern Apennines and becomes near vertical in the Alps-Apennines transition zone. Tear faults accommodating opposite-dipping subductions during Alpine convergence may represent reactivated lithospheric faults inherited from Tethyan extension. Our results suggest that the interpretations of previous tomography results that include successive slab break offs along the Alpine-Zagros-Himalaya orogenic belt might be proficiently reconsidered.

Published
2016

15. First seismic evidence for continental subduction beneath the Western Alps

Author

Zhao, L, Paul, A, Guillot, S, Solarino, S, Malusa', M, Zheng, T, Aubert, C, Salimbeni, S, Dumont, T, Schwartz, S, Zhu, R, Wang, Q, MALUSA', MARCO GIOVANNI, Wang, Q., Zhao, L, Paul, A, Guillot, S, Solarino, S, Malusa', M, Zheng, T, Aubert, C, Salimbeni, S, Dumont, T, Schwartz, S, Zhu, R, Wang, Q, MALUSA', MARCO GIOVANNI, and Wang, Q.

Abstract

The first discovery of ultrahigh-pressure coesite in the European Alps 30 years ago led to the inference that a positively buoyant continental crust can be subducted to mantle depth; this had been considered impossible since the advent of the plate tectonics concepts. Although continental subduction is now widely accepted, there remains debate because there is little direct (geophysical) evidence of a link between exhumed coesite at the surface and subducted continental crust at depth. Here we provide the first seismic evidence for continental crust at 75 km depth that is clearly connected with the European crust exactly along the transect where coesite was found at the surface. Our data also provide evidence for a thick suture zone with downward-decreasing seismic velocities, demonstrating that the European lower crust underthrusts the Adriatic mantle. These findings, from one of the best-preserved and long-studied ultrahigh-pressure orogens worldwide, shed decisive new light on geodynamic processes along convergent continental margins.

Published
2015

17. 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

Author

Anne Paul, Marco G. Malusà, Stefano Solarino, Simone Salimbeni, Elena Eva, Ahmed Nouibat, Silvia Pondrelli, Coralie Aubert, Thierry Dumont, Stéphane Guillot, Stéphane Schwartz, Liang Zhao, Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), INGV, ONT, Genova, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Bologna (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS), Programme Référentiel Géologique de la France, ANR-15-CE31-0015,AlpArray-FR,Voir et comprendre les Alpes en 3D, de la croûte au manteau(2015), ANR-10-LABX-0056,OSUG@2020,Innovative strategies for observing and modelling natural systems(2010), Paul, A, Malusa', M, Solarino, S, Salimbeni, S, Eva, E, Nouibat, A, Pondrelli, S, Aubert, C, Dumont, T, Guillot, S, Schwartz, S, and Zhao, L

Subjects
Geophysics, Western Alp, Space and Planetary Science, Geochemistry and Petrology, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Western Alps, Earth and Planetary Sciences (miscellaneous), seismic tomography, exhumation, continental subduction
Abstract

International audience; In complex plate-boundary settings, a reliable 3-D geophysical characterization of the deep tectonic structure is a fundamental starting point for a breakthrough in the analysis of processes controlling plate subduction and (U)HP rock exhumation. The Western Alps host one of the best-studied fossil subduction zones worldwide, with a well-defined deep structure in 2-D based on recent geophysical experiments. However, a full 3-D characterization of its deep tectonic structure is still lacking. Here we present a series of new receiver function cross-sections across the northern and southern Western Alps, validated and complemented by a S-wave velocity model from ambient-noise tomography that provides additional constraints between the profiles. We document a marked change in Moho attitude from the northern Western Alps, where the eastward-dipping European Moho reaches ~45 km depth beneath the Gran Paradiso dome, to the southern Western Alps, where the European Moho reaches ~70 km depth beneath the equivalent Dora-Maira dome. This change in Moho attitude takes place over a few tens of kilometers and was likely emphasized by deformation of the slab during subduction. The Western Alps subduction wedge is much thicker in the south than in the north, and the mantlewedge rocks are deeply involved in orogeny exclusively in the south, where coesite is found in continental (U)HP rocks at several locations. Our detailed information on the 3-D structure of the subduction wedge provides first-order constraints for the next-generation of thermomechanical numerical models and may help explain the lateral variations in exhumation style revealed by the geologic record.

Published
2022
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18. Receiver function mapping of the mantle transition zone beneath the Western Alps: New constraints on slab subduction and mantle upwelling

Author

Marco G. Malusà, Huaiyu Yuan, Stefano Solarino, Silvia Pondrelli, Liang Zhao, Anne Paul, Dongyang Liu, Elena Eva, Simone Salimbeni, Coralie Aubert, Stéphane Guillot, State Key Laboratory of Lithospheric Evolution (SKL), Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS)-Chinese Academy of Sciences [Beijing] (CAS), Institut des Sciences de la Terre (ISTerre), Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS), Macquarie University, Istituto Nazionale di Geofisica e Vulcanologia, ONT, Genova, Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Bologna (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), Liu, D, Zhao, L, Paul, A, Yuan, H, Solarino, S, Aubert, C, Pondrelli, S, Salimbeni, S, Eva, E, Malusà, M, and Guillot, S

Subjects
010504 meteorology & atmospheric sciences, mantle processes, Western Alp, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], 010502 geochemistry & geophysics, 01 natural sciences, Mantle plume, Mantle (geology), mantle processe, Geochemistry and Petrology, Receiver function, Lithosphere, Transition zone, Earth and Planetary Sciences (miscellaneous), Petrology, Foreland basin, 0105 earth and related environmental sciences, Subduction, Western Alps, receiver function, Geophysics, Space and Planetary Science, receiver functions, subduction zone processe, Slab, subduction zone processes, mantle transition zone, Geology
Abstract

To better constrain the deep structure and dynamics of the Western Alps, we studied the mantle transition zone (MTZ) structure using P-wave receiver functions (RFs). We obtained a total of 24904 RFs from 1182 events collected by 307 stations in the Western Alps. To illustrate the influence of the heterogeneity on the upper mantle velocity, we used both IASP91 and three-dimensional (3-D) velocity models to perform RF time-to-depth migration. We documented an MTZ thickening of about 40 km under the Western Alps and most of the Po Plain due to the uplift associated with the 410-km discontinuity and the depression associated with the 660-km discontinuity. Based upon the close spatial connection between the thickened MTZ and the location of the subducted slabs, we proposed that the thick MTZ was due to the subduction of the Alpine slab through the upper MTZ and the presence of remnants of subducted oceanic lithosphere in the MTZ. The uplift associated with the 410-km discontinuity provided independent evidence of the subduction depth of the Western Alps slab. In the Alpine foreland in eastern France, we observed localized arc-shaped thinning of the MTZ caused by a 12 km depression of the 410-km discontinuity, which has not been previously reported. This depression indicated a temperature increase of 120 K in the upper MTZ, and we proposed that it was caused by a small-scale mantle upwelling. Hardly any uplift of the 660 km discontinuity was observed, suggesting that the thermal anomaly was unlikely to be the result of a mantle plume. We observed that the thinning area of the MTZ corresponded to the area with the highest uplift rate in the Western Alps, which may have indicated that the temperature increase caused by the mantle upwelling contributed to the topographic uplift. (C) 2021 Elsevier B.V. All rights reserved.

Published
2022
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19. The Deep Structure of the Alps based on the CIFALPS Seismic Experiment: A Synthesis

Author

Marco G. Malusà, Stéphane Guillot, Stéphane Schwartz, Thierry Dumont, Anne Paul, Weidong Sun, Coralie Aubert, Chao Lyu, Elena Eva, Liang Zhao, Huaiyu Yuan, Stefano Solarino, Silvia Pondrelli, Yang Lu, Paola Baccheschi, Simone Salimbeni, Malusà, M, Guillot, S, Zhao, L, Paul, A, Solarino, S, Dumont, T, Schwartz, S, Aubert, C, Baccheschi, P, Eva, E, Lu, Y, Lyu, C, Pondrelli, S, Salimbeni, S, Sun, W, Yuan, H, Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Grenoble Alpes (UGA)-Université Gustave Eiffel-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Bologna (INGV), Istituto Nazionale di Geofisica e Vulcanologia, The University of Western Australia (UWA), ANR-15-CE31-0015,AlpArray-FR,Voir et comprendre les Alpes en 3D, de la croûte au manteau(2015), ANR-10-LABX-0056,OSUG@2020,Innovative strategies for observing and modelling natural systems(2010), Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), and Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA)

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Seismic anisotropy, 010504 meteorology & atmospheric sciences, Mantle wedge, serpentinized mantle wedge, Structure (category theory), seismic anisotropy, European Alp, 010502 geochemistry & geophysics, seismology, 01 natural sciences, Geophysics, 13. Climate action, Geochemistry and Petrology, slab breakoff, continental subduction, Geology, Seismology, 0105 earth and related environmental sciences
Abstract

International audience; The European Alps are the site where classic geologic concepts such as nappe theory, continental subduction and slab breakoff have been first proposed. However, the deep tectonic structure of the Alps has long been poorly constrained by independent geophysical evidence. This review paper summarizes the main results of the CIFALPS passive seismic experiment, that was launched by Chinese, French and Italian scientists in the 2010s to provide new insights on the deep tectonic structure of the Alpine region. The application of a wide range of tomographic methods to the analysis of a single fossil subduction zone makes the CIFALPS experiment a potential reference case for the analysis of other orogenic belts. Major results include: (i) the first seismic evidence of European continental crust subducted into the Adriatic upper mantle, beneath the place where coesite was first recognized in continental (U)HP rocks in the Alps; (ii) evidence of a major involvement of the mantle wedge during (U)HP rock exhumation; (iii) evidence of a serpentinized plate interface favoring continental subduction; (iv) evidence of a continuous slab beneath the Western and Central Alps, ruling out the classic model of slab breakoff magmatism; (v) evidence of a polyphase development of anisotropic fabrics in the Alpine mantle, either representing active mantle flows or fossil fabrics inherited from previous rifting stages. Detection of these major tectonic features allows to propose interpretive geologic cross‐sections at the scale of the lithosphere and upper mantle, providing a baseline for future analyses of active continental margins.

Published
2021
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20. Insights into the origin and deformation style of the continental Moho: a case-study from the Western Alps (Italy)

Author

Simone Salimbeni, Nicola Piana Agostinetti, Stéphane SCHWARTZ, Silvia PONDRELLI, Elena Eva, Salimbeni, S, Piana Agostinetti, N, and Pondrelli, S

Subjects
Ivrea body, Seismic anisotropy, Core Processes, harmonics decomposition, Earth's Interior: Composition and State, Mantle (geology), Structural Geology, Dynamics of Lithosphere and Mantle: General, Geomagnetism and Paleomagnetism, Geochemistry and Petrology, Passive seismic, Earth and Planetary Sciences (miscellaneous), Continental Margins: Divergent, Geodesy and Gravity, Instruments and Techniques, Petrology, Anisotropy, Seismology, Earth's Interior: Dynamics, Continental Moho, Peridotite, Deformation (mechanics), receiver function, seismic anisotropy, Crust, Tectonophysics, Geophysics, Amplitude, receiver functions, Space and Planetary Science, Kinematics of Crustal and Mantle Deformation, Core, Mantle, Geology, Research Article
Abstract

Several hypotheses on the origin of the continental Moho are still debated and multiple mechanisms may contribute to its formation. Here, we present quantitative estimation of the seismic properties and anisotropy of the crust‐mantle transition in the Western Alps where an example of newly formed (proto)‐continental Moho is unusually shallow. We make use of teleseismic P‐to‐S converted‐waves recorded by stations deployed on top of the Ivrea Body (IB), a volume of possibly serpentinized mantle peridotite below exhumed (ultra‐)high pressure crustal rocks. The IB has been mapped by gravity, magnetic, active and passive seismic surveys suggesting an extremely shallow Moho. We demonstrate that the P‐to‐S converted waves propagating through this region display coupled features: (a) they record expected presence of strong seismic velocity contrast at shallow depth as due to the lower crustal and upper mantle transition; (b) they are decomposed due to anisotropic properties of rocks involved. The proto‐continental Moho is recognized as an increase in S‐wave velocity (∼0.4–1 km/s) at shallow depths of 5–10 km. The presence of anisotropy within the IB and overlying crustal rocks is evidenced by back‐azimuthal dependence of the amplitude of P‐to‐S phases. The strength of anisotropy is ∼−14% on average pointing out the presence of metamorphosed/hydrated material (e.g., serpentinite) below the Moho. Anisotropic directions are consistent across Moho in both crust and upper mantle. The similarity of the anisotropy parameters between crust and upper mantle suggests they have been shaped by the same deformation event., Key Points Receiver Functions and harmonics decompositionContinental Moho and Ivrea BodySeismic anisotropy

Published
2020
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21. Dual Processing of R-Loops and Topoisomerase I Induces Transcription-Dependent DNA Double-Strand Breaks

Author

Agnese, Cristini, Giulia, Ricci, Sébastien, Britton, Simona, Salimbeni, Shar-Yin Naomi, Huang, Jessica, Marinello, Patrick, Calsou, Yves, Pommier, Gilles, Favre, Giovanni, Capranico, Natalia, Gromak, Olivier, Sordet, Centre de Recherches en Cancérologie de Toulouse (CRCT), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), University of Pisa - Università di Pisa, Institut de pharmacologie et de biologie structurale (IPBS), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Department of Pharmacy and Biotechnology [Bologna, Italy], University of Bologna [Italy], Laboratory of Molecular Pharmacology, National Institutes of Health [Bethesda] (NIH)-National Cancer Institute [Bethesda] (NCI-NIH), National Institutes of Health [Bethesda] (NIH), Cristini A., Ricci G., Britton S., Salimbeni S., Huang S.-Y.N., Marinello J., Calsou P., Pommier Y., Favre G., Capranico G., Gromak N., Sordet O., Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), and Britton, Sébastien

Subjects
XPF, Flap Endonucleases, [SDV]Life Sciences [q-bio], topoisomerase I, DNA repair, [SDV.BC]Life Sciences [q-bio]/Cellular Biology, [SDV.BC.BC]Life Sciences [q-bio]/Cellular Biology/Subcellular Processes [q-bio.SC], [SDV.BBM.BM] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology, Article, Cell Line, neurodegenerative disease, [SDV.BBM] Life Sciences [q-bio]/Biochemistry, Molecular Biology, [SDV.BC.BC] Life Sciences [q-bio]/Cellular Biology/Subcellular Processes [q-bio.SC], Humans, DNA Breaks, Double-Stranded, [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology, DNA Breaks, Single-Stranded, Senataxin, lcsh:QH301-705.5, [SDV.BC] Life Sciences [q-bio]/Cellular Biology, ComputingMilieux_MISCELLANEOUS, TDP1, RNA/DNA hybrid, Nuclear Proteins, [SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology, Endonucleases, DNA-Binding Proteins, [SDV] Life Sciences [q-bio], DNA Topoisomerases, Type I, lcsh:Biology (General), DNA double-strand break, R-loop, R-Loop Structures, transcription, Transcription Factors
Abstract

Summary: Although accumulation of DNA damage and genomic instability in resting cells can cause neurodegenerative disorders, our understanding of how transcription produces DNA double-strand breaks (DSBs) is limited. Transcription-blocking topoisomerase I cleavage complexes (TOP1ccs) are frequent events that prime DSB production in non-replicating cells. Here, we report a mechanism of their formation by showing that they arise from two nearby single-strand breaks (SSBs) on opposing DNA strands: one SSB from the removal of transcription-blocking TOP1ccs by the TDP1 pathway and the other from the cleavage of R-loops by endonucleases, including XPF, XPG, and FEN1. Genetic defects in TOP1cc removal (TDP1, PNKP, and XRCC1) or in the resolution of R-loops (SETX) enhance DSB formation and prevent their repair. Such deficiencies cause neurological disorders. Owing to the high frequency of TOP1cc trapping and the widespread distribution of R-loops, these persistent transcriptional DSBs could accumulate over time in neuronal cells, contributing to the neurodegenerative diseases. : Cristini et al. identify a mechanism of DSB formation in non-replicating cells, which strictly depends on transcription. They are formed by two single-strand breaks on opposing DNA strands resulting from the processing of both R-loops and topoisomerase I, and genetic defects increasing these transcriptional DSBs cause neurological disorders. Keywords: DNA double-strand breaks, transcription, R-loops, topoisomerase I, neurodegenerative diseases, DNA repair, TDP1, XPF, Senataxin, RNA/DNA hybrid

Published
2019
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22. Active and fossil mantle flows in the western Alpine region unravelled by seismic anisotropy analysis and high-resolution P wave tomography

Author

Stéphane Schwartz, Thierry Dumont, Qingchen Wang, Liang Zhao, Rixiang Zhu, Stefano Solarino, Stéphane Guillot, Anne Paul, Xiaobing Xu, Tianyu Zheng, Marco G. Malusà, Coralie Aubert, Simone Salimbeni, Silvia Pondrelli, Lucia Margheriti, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Bologna (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China, Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Roma (INGV), Instituto Nationale di Geofisica e Vulcanologia (INGV), Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS), University of Milano - Bicocca, Tianjin University (TJU), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Institut Camille Jordan [Villeurbanne] (ICJ), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Electronique et Electromagnétisme (L2E), Sorbonne Université (SU), Department of Earth and Planetary Sciences [Kobe], Kobe University, Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), Salimbeni, S, Malusà, M, Zhao, L, Guillot, S, Pondrelli, S, Margheriti, L, Paul, A, Solarino, S, Aubert, C, Dumont, T, Schwartz, S, Wang, Q, Xu, X, Zheng, T, and Zhu, R

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Seismic anisotropy, Alpine subduction, 010504 meteorology & atmospheric sciences, High resolution, Geophysics, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Topographic uplift, Fossil mantle flow, Asthenospheric counterflow, Apenninic subduction, Tomography, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

The anisotropy of seismic velocities in the mantle, when integrated with high-resolution tomographic models and geologic information, can be used to detect active mantle flows in complex plate boundary areas, providing new insights on the impact of mantle processes on the topography of mountain belts. Here we use a densely spaced array of temporary broadband seismic stations to analyze the seismic anisotropy pattern of the western Alpine region, at the boundary between the Alpine and Apenninic slabs. Our results are supportive of a polyphase development of anisotropic mantle fabrics, possibly starting from the Jurassic to present. Geophysical data presented in this work, and geologic evidence taken from the literature, indicate that: (i) fossil fabrics formed during Tethyan rifting may be still preserved within the Alpine and Apenninic slabs; (ii) mantle deformation during Apenninic slab rollback is not compensated by a complete toroidal flow around the northern tip of the retreating slab; (iii) the previously observed continuous trend of anisotropy fast axes near-parallel to the western Alpine arc is confirmed. We observe that this arc-parallel trend of fast axes is located in correspondence to a low velocity anomaly in the European upper mantle, beneath regions of the Western and Ligurian Alps showing the highest uplift rates. We propose that the progressive rollback of the Apenninic slab, in the absence of a counterclockwise toroidal flow at its northern tip, induced a suction effect at the scale of the supraslab mantle. The resulting mantle flow pattern was characterized by an asthenospheric counterflow at the rear of the unbroken Western Alps slab and around its southern tip, and by an asthenospheric upwelling, mirrored by low P wave velocities, that would have favored the topographic uplift of the Alpine belt from the Mont Blanc to the Mediterranean sea.

Published
2018
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23. First seismic evidence for continental subduction beneath the Western Alps

Author

Stefano Solarino, Simone Salimbeni, Rixiang Zhu, Stéphane Guillot, Qingchen Wang, Liang Zhao, Coralie Aubert, Marco G. Malusà, Tianyu Zheng, Stéphane Schwartz, Thierry Dumont, Anne Paul, Institut des Sciences de la Terre (ISTerre), Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Bologna (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS), ANR-10-LABX-0056,OSUG@2020,Innovative strategies for observing and modelling natural systems(2010), Zhao, L, Paul, A, Guillot, S, Solarino, S, Malusa', M, Zheng, T, Aubert, C, Salimbeni, S, Dumont, T, Schwartz, S, Zhu, R, and Wang, Q

Subjects
Continental collision, Subduction, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Earth science, Continental crust, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Geology, Collision zone, Continental subduction, exhumation, deep structure, Western Alps, Paleontology, Plate tectonics, Continental margin, [SDU]Sciences of the Universe [physics], Adakite, Eclogitization
Abstract

International audience; The first discovery of ultrahigh-pressure coesite in the European Alps 30 years ago led to the inference that a positively buoyant continental crust can be subducted to mantle depth; this had been considered impossible since the advent of the plate tectonics concepts. Although continental subduction is now widely accepted, there remains debate because there is little direct (geophysical) evidence of a link between exhumed coesite at the surface and subducted continental crust at depth. Here we provide the first seismic evidence for continental crust at 75 km depth that is clearly connected with the European crust exactly along the transect where coesite was found at the surface. Our data also provide evidence for a thick suture zone with downward-decreasing seismic velocities, demonstrating that the European lower crust underthrusts the Adriatic mantle. These findings, from one of the best-preserved and long-studied ultrahigh-pressure orogens worldwide, shed decisive new light on geodynamic processes along convergent continental margins.

Published
2015
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24. Mantle wedge exhumation beneath the Dora-Maira (U)HP dome unravelled by local earthquake tomography (Western Alps)

Author

Marco G. Malusà, Anne Paul, Silvia Pondrelli, Tianyu Zheng, Rixiang Zhu, Liang Zhao, Stéphane Guillot, Elena Eva, Stefano Solarino, Xiaobing Xu, Coralie Aubert, Stéphane Schwartz, Simone Salimbeni, Thierry Dumont, Qingchen Wang, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB), Instituto Nationale di Geofisica e Vulcanologia (INGV), Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), State Key Laboratory of Lithospheric Evolution (SKL), Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS)-Chinese Academy of Sciences [Beijing] (CAS), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Bologna (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Chinese Academy of Sciences [Beijing] (CAS), State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China, Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), University of Milano - Bicocca, Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Tianjin University (TJU), Modélisation mathématique, calcul scientifique (MMCS), Institut Camille Jordan [Villeurbanne] (ICJ), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS)-École Centrale de Lyon (ECL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Electronique et Electromagnétisme (L2E), Sorbonne Université (SU), Department of Earth and Planetary Sciences [Kobe], Kobe University, Solarino, S, Malusà, M, Eva, E, Guillot, S, Paul, A, Schwartz, S, Zhao, L, Aubert, C, Dumont, T, Pondrelli, S, Salimbeni, S, Wang, Q, Xu, X, Zheng, T, and Zhu, R

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Continental subduction, Local earthquake tomography, 010504 meteorology & atmospheric sciences, Mantle wedge, Western Alp, Geochemistry, Geology, 010502 geochemistry & geophysics, 01 natural sciences, Ultra-high-pressure metamorphism, Peridotite serpentinization, Mantle wedge exhumation, Geochemistry and Petrology, Tomography, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

In continental subduction zones, the behaviour of the mantle wedge during exhumation of (ultra)high-pressure [(U)HP] rocks provides a key to distinguish among competing exhumation mechanisms. However, in spite of the relevant implications for understanding orogenic evolution, a high-resolution image of the mantle wedge beneath the Western Alps is still lacking. In order to fill this gap, we perform a detailed analysis of the velocity structure of the Alpine belt beneath the Dora-Maira (U)HP dome, based on local earthquake tomography independently validated by receiver function analysis. Our results point to a composite structure of the mantle wedge above the subducted European lithosphere. We found that the Dora-Maira (U)HP dome lays directly above partly serpentinized peridotites (Vp ~ 7.5 km/s; Vp/Vs = 1.70-1.72), documented from ~ 10 km depth down to the top of the eclogitized lower crust of the European plate. These serpentinized peridotites, possibly formed by fluid release from the subducting European slab to the Alpine mantle wedge, are juxtaposed against dry mantle peridotites of the Adriatic upper plate along an active fault rooted in the lithospheric mantle. We propose that serpentinized mantle-wedge peridotites were exhumed at shallow crustal levels during late Eocene transtensional tectonics, also triggering the rapid exhumation of (U)HP rocks, and were subsequently indented under the Alpine metamorphic wedge in the early Oligocene. Our findings suggest that mantle-wedge exhumation may represent a major feature of the deep structure of exhumed continental subduction zones. The deep orogenic levels here imaged by seismic tomography may be exposed today in older (U)HP belts, where mantle-wedge serpentinites are commonly associated with coesite-bearing continental metamorphic rocks.

Published
2018
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25. Earthquakes in the western Alpine mantle wedge

Author

Marco G. Malusà, Anne Paul, Qingchen Wang, Liang Zhao, Elena Eva, Silvia Pondrelli, Stéphane Schwartz, Stefano Solarino, Thierry Dumont, Rixiang Zhu, Stéphane Guillot, Coralie Aubert, Simone Salimbeni, University of Milano - Bicocca, Tianjin University (TJU), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Laboratoire Central des Ponts et Chaussées (LCPC)-Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR), Institut des Sciences de la Terre (ISTerre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Institut Camille Jordan [Villeurbanne] (ICJ), École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Bologna (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS), Department of Earth and Planetary Sciences [Kobe], Kobe University, Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Malusa', M, Zhao, L, Eva, E, Solarino, S, Paul, A, Guillot, S, Schwartz, S, Dumont, T, Aubert, C, Salimbeni, S, Pondrelli, S, Wang, Q, and Zhu, R

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, geography, geography.geographical_feature_category, Focal mechanism heterogeneity, 010504 meteorology & atmospheric sciences, Mantle wedge, Lithology, Geology, Aseismic creep, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Craton, 13. Climate action, Lithosphere, Lithosphere rheology, Transition zone, Hotspot (geology), aseismic creep, deep Alpine structure, mantle earthquake, Seismology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

The assessment of seismic activity in the shallow continental mantle has long been hindered by the low resolution of both seismic imaging and earthquake locations in young collision zones. Here, we combine the most recent and high-resolution image of the lithospheric structure of the Western Alps with a high quality dataset of anomalously deep earthquakes recorded in the same area in the past 25 yrs. We show that these earthquakes are aligned on an active lithospheric strike-slip fault, and we provide evidence that this fault is located in the mantle wedge beneath the Adriatic Moho. Our results: (i) provide direct evidence that deep material can be seismogenic or not depending on the lithology; (ii) confirm the role of serpentinization in favoring the aseismic creep of mantle rocks; and (iii) demonstrate that the upper mantle can be stiff and seismogenic not only in cold cratons, but also in young orogenic belts.

Published
2017
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26. Continuity of the Alpine slab unraveled by high-resolution P wave tomography

Author

Zhao, Liang, Paul, Anne, Malusà, Marco, Xu, Xiaobing, Zheng, Tianyu, Solarino, Stefano, Guillot, Stéphane, Schwartz, Stéphane, Dumont, Thierry, Salimbeni, Simone, Aubert, Coralie, Pondrelli, Silvia, Wang, Qingchen, Zhu, Rixiang, Zhao, L, Paul, A, Malusa', M, Xu, X, Zheng, T, Solarino, S, Guillot, S, Schwartz, S, Dumont, T, Salimbeni, S, Aubert, C, Pondrelli, S, Wang, Q, Zhu, R, Institute of Geology and Geophysics [Beijing] (IGG), Chinese Academy of Sciences [Beijing] (CAS), Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Università degli Studi di Milano-Bicocca [Milano] (UNIMIB), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Bologna (INGV), Istituto Nazionale di Geofisica e Vulcanologia, ANR-10-LABX-0056,OSUG@2020,Innovative strategies for observing and modelling natural systems(2010), and Università degli Studi di Milano-Bicocca = University of Milano-Bicocca (UNIMIB)

Subjects
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Adriatic slab, slab breakoff, Alpine slab, P-wave tomography, finite frequency, Tethyan convergence
Abstract

International audience; The question of lateral and/or vertical continuity of subducted slabs in active orogens is a hot topic partly due to poorly resolved tomographic data. The complex slab structure beneath the Alpine region is only partly resolved by available geophysical data, leaving many geological and geodynamical issues widely open. Based upon a finite-frequency kernel method, we present a new high-resolution tomography model using P wave data from 527 broadband seismic stations, both from permanent networks and temporary experiments. This model provides an improved image of the slab structure in the Alpine region and fundamental pinpoints for the analysis of Cenozoic magmatism, (U)HP metamorphism, and Alpine topography. Our results 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. A low-velocity anomaly is observed in the upper mantle beneath the core of the Western Alps, pointing to dynamic topography effects. A NE dipping Adriatic slab, consistent with Dinaric subduction, is possibly observed beneath the Eastern Alps, whereas the laterally continuous Adriatic slab of the Northern Apennines shows major gaps at the boundary with the Southern Apennines and becomes near vertical in the Alps-Apennines transition zone. Tear faults accommodating opposite-dipping subductions during Alpine convergence may represent reactivated lithospheric faults inherited from Tethyan extension. Our results suggest that the interpretations of previous tomography results that include successive slab break offs along the Alpine-Zagros-Himalaya orogenic belt might be proficiently reconsidered.

Published
2016
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27. TDP1 mutation causing SCAN1 neurodegenerative syndrome hampers the repair of transcriptional DNA double-strand breaks.

Author

Geraud M, Cristini A, Salimbeni S, Bery N, Jouffret V, Russo M, Ajello AC, Fernandez Martinez L, Marinello J, Cordelier P, Trouche D, Favre G, Nicolas E, Capranico G, and Sordet O

Subjects
Humans, DNA-Binding Proteins metabolism, DNA-Binding Proteins genetics, DNA Topoisomerases, Type I metabolism, DNA Topoisomerases, Type I genetics, Transcription, Genetic, R-Loop Structures, CRISPR-Cas Systems genetics, DNA Breaks, Double-Stranded, DNA Repair, Phosphoric Diester Hydrolases metabolism, Phosphoric Diester Hydrolases genetics, Neurodegenerative Diseases genetics, Neurodegenerative Diseases metabolism, Neurodegenerative Diseases pathology, Mutation genetics
Abstract

TDP1 removes transcription-blocking topoisomerase I cleavage complexes (TOP1ccs), and its inactivating H493R mutation causes the neurodegenerative syndrome SCAN1. However, the molecular mechanism underlying the SCAN1 phenotype is unclear. Here, we generate human SCAN1 cell models using CRISPR-Cas9 and show that they accumulate TOP1ccs along with changes in gene expression and genomic distribution of R-loops. SCAN1 cells also accumulate transcriptional DNA double-strand breaks (DSBs) specifically in the G1 cell population due to increased DSB formation and lack of repair, both resulting from abortive removal of transcription-blocking TOP1ccs. Deficient TDP1 activity causes increased DSB production, and the presence of mutated TDP1 protein hampers DSB repair by a TDP2-dependent backup pathway. This study provides powerful models to study TDP1 functions under physiological and pathological conditions and unravels that a gain of function of the mutated TDP1 protein, which prevents DSB repair, rather than a loss of TDP1 activity itself, could contribute to SCAN1 pathogenesis., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Published
2024
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28. Insights Into the Origin and Deformation Style of the Continental Moho: A Case-Study From the Western Alps (Italy).

Author

Salimbeni S, Agostinetti NP, and Pondrelli S

Abstract

Several hypotheses on the origin of the continental Moho are still debated and multiple mechanisms may contribute to its formation. Here, we present quantitative estimation of the seismic properties and anisotropy of the crust-mantle transition in the Western Alps where an example of newly formed (proto)-continental Moho is unusually shallow. We make use of teleseismic P-to-S converted-waves recorded by stations deployed on top of the Ivrea Body (IB), a volume of possibly serpentinized mantle peridotite below exhumed (ultra-)high pressure crustal rocks. The IB has been mapped by gravity, magnetic, active and passive seismic surveys suggesting an extremely shallow Moho. We demonstrate that the P-to-S converted waves propagating through this region display coupled features: (a) they record expected presence of strong seismic velocity contrast at shallow depth as due to the lower crustal and upper mantle transition; (b) they are decomposed due to anisotropic properties of rocks involved. The proto-continental Moho is recognized as an increase in S-wave velocity (∼0.4-1 km/s) at shallow depths of 5-10 km. The presence of anisotropy within the IB and overlying crustal rocks is evidenced by back-azimuthal dependence of the amplitude of P-to-S phases. The strength of anisotropy is ∼-14% on average pointing out the presence of metamorphosed/hydrated material (e.g., serpentinite) below the Moho. Anisotropic directions are consistent across Moho in both crust and upper mantle. The similarity of the anisotropy parameters between crust and upper mantle suggests they have been shaped by the same deformation event., Competing Interests: The authors declare no conflicts of interest relevant to this study., (© 2021. The Authors.)

Published
2021
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29. Dual Processing of R-Loops and Topoisomerase I Induces Transcription-Dependent DNA Double-Strand Breaks.

Author

Cristini A, Ricci G, Britton S, Salimbeni S, Huang SN, Marinello J, Calsou P, Pommier Y, Favre G, Capranico G, Gromak N, and Sordet O

Subjects
Cell Line, DNA-Binding Proteins metabolism, Endonucleases metabolism, Flap Endonucleases metabolism, Humans, Nuclear Proteins metabolism, Transcription Factors metabolism, DNA Breaks, Double-Stranded, DNA Breaks, Single-Stranded, DNA Topoisomerases, Type I metabolism, R-Loop Structures
Abstract

Although accumulation of DNA damage and genomic instability in resting cells can cause neurodegenerative disorders, our understanding of how transcription produces DNA double-strand breaks (DSBs) is limited. Transcription-blocking topoisomerase I cleavage complexes (TOP1ccs) are frequent events that prime DSB production in non-replicating cells. Here, we report a mechanism of their formation by showing that they arise from two nearby single-strand breaks (SSBs) on opposing DNA strands: one SSB from the removal of transcription-blocking TOP1ccs by the TDP1 pathway and the other from the cleavage of R-loops by endonucleases, including XPF, XPG, and FEN1. Genetic defects in TOP1cc removal (TDP1, PNKP, and XRCC1) or in the resolution of R-loops (SETX) enhance DSB formation and prevent their repair. Such deficiencies cause neurological disorders. Owing to the high frequency of TOP1cc trapping and the widespread distribution of R-loops, these persistent transcriptional DSBs could accumulate over time in neuronal cells, contributing to the neurodegenerative diseases., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Published
2019
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