Orogen‐Parallel Migration of Exhumation in the Eastern Aar Massif Revealed by Low‐T Thermochronometry

Nibourel, Lukas; Rahn, Meinert; Dunkl, İstván; Berger, Alfons; Herman, Frédéric; Diehl, Tobias; Heuberger, Stefan; Herwegh, Marco

doi:10.1029/2020jb020799

Cited by 7 publications

(3 citation statements)

References 176 publications

(390 reference statements)

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“…In conclusion, our results regarding the Urnerboden earthquake suggest active strike‐slip deformation within the eastern Aar massif, which is possibly related to along‐strike differences in the present‐day uplift processes of this external massif as suggested by Nibourel et al. (2021).…”

Section: Discussionsupporting

confidence: 67%

“…In contrast, Subalpine Molasse and Flysch units as well as limestone dominated Helvetic nappes in the frontal part of the Alps are characterized by a high V P /V S ratio (Figures 11c), indicative for lithologies dominated by sedimentary rocks. In conclusion, our results regarding the Urnerboden earthquake suggest active strike-slip deformation within the eastern Aar massif, which is possibly related to along-strike differences in the present-day uplift processes of this external massif as suggested by Nibourel et al (2021).…”

Section: Seismicity and Joint Interpretation With Velocity The Centra...supporting

confidence: 51%

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Improving Absolute Hypocenter Accuracy With 3D Pg and Sg Body‐Wave Inversion Procedures and Application to Earthquakes in the Central Alps Region

et al. 2021

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Accuracy of hypocenter location, in particular focal depth, is a precondition for high‐resolution seismotectonic analysis of natural and induced seismicity. For instance, linking seismicity with mapped fault segments requires hypocenter accuracy at the sub‐kilometer scale. In this study, we demonstrate that inaccurate velocity models and improper phase selection can bias absolute hypocenter locations and location uncertainties, resulting in errors larger than the targeted accuracy. To avoid such bias in densely instrumented seismic networks, we propose a coupled hypocenter‐velocity inversion procedure restricted to direct, first‐arriving, mainly upper‐crustal Pg and Sg phases. On the basis of synthetic tests and selected ground‐truth events we demonstrate that a sub‐kilometer hypocenter accuracy can be achieved by regional‐scale, three‐dimensional Pg and Sg velocity models combined with dynamic phase selection and a non‐linear location algorithm. The tomographic inversion uses about 60,000 Pg and 30,000 Sg quality‐checked phases of local earthquakes in the Central Alps region. The derived models image the VP and VS structure of the Central Alps upper crust at unprecedented resolution, including small‐scale anomalies such as those caused by Subalpine Molasse units below the Alpine front. The relocation procedure is applied to more than 18,000 earthquakes and the relocated hypocenters reveal previously unrecognized seismogenic structures, for instance in the Swiss Molasse basin south of Bern. The ML 4.6 Urnerboden earthquake of 2017 is used as an example to demonstrate how the derived 3D velocity structure and relocated hypocenters can be jointly interpreted to constrain the lithology hosting upper‐crustal seismicity in the Central Alps.

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Section: Discussionsupporting

confidence: 67%

Section: Seismicity and Joint Interpretation With Velocity The Centra...supporting

confidence: 51%

Improving Absolute Hypocenter Accuracy With 3D Pg and Sg Body‐Wave Inversion Procedures and Application to Earthquakes in the Central Alps Region

et al. 2021

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“…In the Central Alps, the PT was uplifted during a late phase of crustal doming [156], which led to the tectonic exhumation of deeper parts of the PT footwall (i.e., the so-called North Penninic units derived from the northern margin of the Valais Basin (see [60,155]). In the southwest, the PT is difficult to map but seems to lie on the internal flank of the Mercantour-Argentera Massif that is in a more internal position compared to the rest of the Western Alps [157].…”

Section: The Basal Penninic Thrust (Pt)mentioning

confidence: 99%

The Importance of Rift Inheritance in Understanding the Early Collisional Evolution of the Western Alps

et al. 2022

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We reassess the architecture and tectonic history of the Western Alps based on recent knowledge developed at rifted margins. First, we replace the main Alpine units of our study area into a synthetic rifted margin template based on diagnostic petrologic, stratigraphic, and structural criteria. We find that some units previously attributed to the internal part of the thick-crusted Briançonnais domain may rather derive from the thin-crusted Prepiemonte hyperextended domain. We assert that the Briançonnais and Prepiemonte domains were separated by a mega-fault scarp. Second, we revisit the Paleogeography of the Alpine Tethys, suggesting that the Briançonnais was a ribbon of little thinned continental crust between two overstepping en-échelon rift basins, namely the Valais domain to the northwest and the Piemonte domain to the southeast. We affirm that this uneven-margin architecture can explain most of the Western Alps’ complexity. In our kinematic model, convergence between Adria and Europe was mainly accommodated by strike-slip movements in the Western Alps until the late Eocene. Orogeny began with the reactivation of the mega-fault scarp between the Briançonnais and Prepiemonte domains, which we name Prepiemonte Basal Thrust. Once hard collision started, the main shortening stepped inboard into the Valais/Subbriançonnais domain along the Penninic Basal Thrust.

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Evolution of the External Crystalline Massifs of the European Alps

HERWEGH,

BERGER,

BELLAHSEN

et al. 2024

Geodynamics of the Alps 3

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Orogen‐Parallel Migration of Exhumation in the Eastern Aar Massif Revealed by Low‐T Thermochronometry

Abstract: The exhumation of basement units from the thickened lower plate is a typical feature of advanced stages of collision in mountain belts such as the European Alps (e.g.,

Cited by 7 publications

References 176 publications

Improving Absolute Hypocenter Accuracy With 3D Pg and Sg Body‐Wave Inversion Procedures and Application to Earthquakes in the Central Alps Region

Improving Absolute Hypocenter Accuracy With 3D Pg and Sg Body‐Wave Inversion Procedures and Application to Earthquakes in the Central Alps Region

The Importance of Rift Inheritance in Understanding the Early Collisional Evolution of the Western Alps

Evolution of the External Crystalline Massifs of the European Alps

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