The structural history of the Mont Blanc massif with regard to models for its recent exhumation

Egli, Daniel; Mancktelow, Neil S.

doi:10.1007/s00015-013-0153-5

Cited by 45 publications

(45 citation statements)

References 46 publications

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“…The mechanism and amount of reactivation of the Jurassic normal faults are still debated (Bellahsen et al, , ; Gidon, ; Gillcrist et al, ). The Alpine deformation of these basement windows is generally weak and heterogeneous (Figure ), with a gradient of deformation increasing from NW to SE (Aar‐Gotthard: Berger et al, ; Choukroune & Gapais, ; Marquer, ; Mont Blanc: Egli & Mancktelow, ; Leloup et al, ; Rolland et al, ; Grand Châtelard: Marquer et al, ). The pre‐Triassic basement is affected by subgreenschist‐ to greenschist‐facies shear zones of Oligocene age (Cenki‐Tok et al, ; Egli et al, , ) predating the major (Miocene) phase of exhumation due to the initiation of frontal crustal ramps below the External Massifs (Boutoux et al, ).…”

Section: Geological Settingmentioning

confidence: 99%

Pre‐Alpine (Variscan) Inheritance: A Key for the Location of the Future Valaisan Basin (Western Alps)

2018

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The boundary between the Helvetic and the Penninic (=Briançonnais) Zones has long been recognized as a major fault (“Penninic Front”) in the Western Alps. A narrow oceanic domain has been postulated at least along part of this boundary (the Valaisan Basin). However, the information provided by the pre‐Triassic basement has not been fully exploited and will be discussed here in detail. The igneous and metamorphic history of the pre‐Triassic basement shows significant differences between the External Massifs from the Helvetic Zone, with abundant Late Carboniferous granites, and the basement of the Briançonnais Zone, including the Internal Massifs (Dora‐Maira, Gran Paradiso, and Monte Rosa), devoid of Carboniferous granites. A major coal‐bearing basin, the “Zone Houillère,” opened along this boundary. This limnic intramontane basin has never been properly investigated. The Zone Houillère is not comparable with the external, paralic, flexural, basins on both sides of the Variscan belt but shows similarities with the Saar‐Saale Basin. Like the latter, we interpret the Zone Houillère as a transtensional basin opened along a major, crustal‐scale, fault zone, namely, the East Variscan Shear Zone. The Permian magmatism and sedimentation displays contrasting distributions, being absent or very localized in the Helvetic Zone, and widespread in the Penninic Zone. The above data indicate that the structural inheritance from the Variscan belt plays a major role in defining the future location of the Valaisan Basin, that is, the boundary between the European paleomargin and the Briançonnais microcontinent.

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Section: Geological Settingmentioning

confidence: 99%

Pre‐Alpine (Variscan) Inheritance: A Key for the Location of the Future Valaisan Basin (Western Alps)

2018

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“…Several studies on the exhumation history of the External Crystalline Massifs of the Western Alps (Argentera: Bigot-Cormier and others, 2006;Pelvoux: van der Beek and others, 2010;Mont Blanc: Leloup andothers, 2005 andothers, 2008), indicate a three stage evolution: First, exhumation rates peaked at around 6 to 7 Ma, dropped by an order of magnitude later on, only to finally increase again during the Plio-Quaternary to values around 0.5 to 1 km/Myr. Egli and Mancktelow (2013) showed that none of the major faults or shear zones directly bounding the Mont Blanc massif were actively accommodating vertical motion in Late Neogene times and that young exhumation is therefore not controlled by these structures. This most recent and final increase in exhumation rate has been explained by recent valley carving in response to glacial erosion (Leloup and others, 2005;Glotzbach and others, 2008;Valla and others, 2011).…”

Section: Plio-pleistocenementioning

confidence: 99%

The Exhumation history of the European Alps inferred from linear inversion of thermochronometric data

Fox

Herman

Willett

et al. 2016

American Journal of Science

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ABSTRACT. Thermochronometric data collected across the Alps over the last three decades allows for investigation of the evolution of this orogen, which is subject to changes in climate and geodynamics. Exhumation rates are inferred from the thermochronometric ages using a statistical inversion method based on the fact that the distance a sample traveled since closure is equal to the integral of the exhumation rate from the present day to the age of the sample. Exhumation rates are assumed to be spatially correlated but are free to vary through time. This results in the quantification of exhumation rates across the Alps, since 32 Ma, along with assessments of the quality of these inferences. We find that exhumation rates are initially fast in the internal arc of the Western Alps at rates up to 0.8 km/Myr at 30 Ma, decreasing at 20 Ma to 0.3 km/Myr to remain slow to the present. At the same time, around 20 Ma, rates across the External Crystalline Massifs of Western Alps increase to 0.6 km/Myr. We also find that the onset of high exhumation rates in the Tauern Window and the Lepontine Dome occurs at around 20 Ma, a time characterized by major reorganizations in the Alpine chain. A general increase in exhumation rates at around 5 Ma over the entire Alps is not confirmed. Instead we find that the Western Alps exhibit a 2 to 3 fold increase in exhumation rate over the last 2 Ma, during a recent event not seen further east, in spite of very similar topographic characteristics. We attribute this strong signal to detachment of the European slab in the Western Alps, combined with efficient glacial erosion.

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“…The tectonic setting of the Rhône Basin is dominated by the Rhône-Simplon fault system, where dextral strike-slip movements since early Miocene times have accommodated most of the orogenic extension (Schlunegger and Willett, 1999;Egli and Mancktelow, 2013). Seward and Mancktelow (1994) suggested that faulting also had a normal slip component, which played an important role in the younger exhumation history of the area.…”

Section: Tectonicsmentioning

confidence: 99%

Lithological control on the landscape form of the upper Rhône Basin, Central Swiss Alps

2016

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Abstract. The development of topography depends mainly on the interplay between uplift and erosion. These processes are controlled by various factors including climate, glaciers, lithology, seismic activity and short-term variables, such as anthropogenic impact. Many studies in orogens all over the world have shown how these controlling variables may affect the landscape's topography. In particular, it has been hypothesized that lithology exerts a dominant control on erosion rates and landscape morphology. However, clear demonstrations of this influence are rare and difficult to disentangle from the overprint of other signals such as climate or tectonics.In this study we focus on the upper Rhône Basin situated in the Central Swiss Alps in order to explore the relation between topography, possible controlling variables and lithology in particular. The Rhône Basin has been affected by spatially variable uplift, high orographically driven rainfalls and multiple glaciations. Furthermore, lithology and erodibility vary substantially within the basin. Thanks to high-resolution geological, climatic and topographic data, the Rhône Basin is a suitable laboratory to explore these complexities.Elevation, relief, slope and hypsometric data as well as river profile information from digital elevation models are used to characterize the landscape's topography of around 50 tributary basins. Additionally, uplift over different timescales, glacial inheritance, precipitation patterns and erodibility of the underlying bedrock are quantified for each basin.Results show that the chosen topographic and controlling variables vary remarkably between different tributary basins. We investigate the link between observed topographic differences and the possible controlling variables through statistical analyses. Variations of elevation, slope and relief seem to be linked to differences in long-term uplift rate, whereas elevation distributions (hypsometry) and river profile shapes may be related to glacial imprint. This confirms that the landscape of the Rhône Basin has been highly preconditioned by (past) uplift and glaciation. Linear discriminant analyses (LDAs), however, suggest a stronger link between observed topographic variations and differences in erodibility. We therefore conclude that despite evident glacial and tectonic conditioning, a lithologic control is still preserved and measurable in the landscape of the Rhône tributary basins.

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The structural history of the Mont Blanc massif with regard to models for its recent exhumation

Cited by 45 publications

References 46 publications

Pre‐Alpine (Variscan) Inheritance: A Key for the Location of the Future Valaisan Basin (Western Alps)

Pre‐Alpine (Variscan) Inheritance: A Key for the Location of the Future Valaisan Basin (Western Alps)

The Exhumation history of the European Alps inferred from linear inversion of thermochronometric data

Lithological control on the landscape form of the upper Rhône Basin, Central Swiss Alps

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