Episodic exhumation and relief growth in the Mont Blanc massif, Western Alps from numerical modelling of thermochronology data

Glotzbach, Christoph; Beek, Peter van der; Spiegel, Cornelia

doi:10.1016/j.epsl.2011.02.020

Cited by 125 publications

(149 citation statements)

References 82 publications

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“…They base these arguments on the brittle character of the structure as well as on decreasing AFT ages along the Mont Blanc tunnel towards the SE. However, a more recent thermochronology study by Glotzbach et al (2008) contradicts these data, claiming that there is no jump in ages across the Mont Blanc back-thrust along the tunnel transect and therefore that no vertical offset took place across this structure after 4 Ma.…”

Section: Mont Blanc Back-thrustmentioning

confidence: 69%

“…The question remains as to what causes the strong exhumation signal in the last 2 Ma, as indicated from modelling of thermochronology data. The lack of evidence for tectonic control of recent localized uplift of the Mont Blanc massif directly favours an alternative scenario of enhanced erosion and denudation during a more regionally distributed uplift, possibly related to glaciation, as has also been proposed by Glotzbach et al (2008Glotzbach et al ( , 2011 and Fox (2012).…”

Section: Resultsmentioning

confidence: 92%

“…Lowtemperature thermochronology studies provide an extensive data set for estimating exhumation rates in Neogene and Quaternary times (e.g. Soom 1990; Seward and Mancktelow 1994;Fügenschuh et al 1999;Fügenschuh and Schmid 2003;Leloup et al 2005;Glotzbach et al 2008) but the processes leading to this exhumation are still a matter of debate and various models have been proposed. However, all these models include fundamental tectonic assumptions that are only partly confirmed by field observations.…”

Section: Introductionmentioning

confidence: 99%

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

Egli

Mancktelow

2013

Swiss J Geosci

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The tectonic evolution of the Mont Blanc range with regard to its cooling and exhumation history has been discussed and debated over many years and is still controversial. Recently, several low-temperature thermochronology studies have determined the cooling history of the massif in considerable detail and various tectonic models proposed to explain the young and fast exhumation signal established from these studies. Here we present detailed field data from the wider Mont Blanc area and assess possible exhumation processes in terms of these field constraints. Our observations indicate that none of the major faults or shear zones around the Mont Blanc massif (i.e. Mont Blanc shear zone, Mont Blanc back-thrust, Penninic thrust) was active in Late Neogene times and that young exhumation is therefore not controlled by movements along these structures. We demonstrate that the position of Mont Blanc in the bend of the western Alps plays an important role in its tectonic history and that simple 2D models are insufficient to explain its evolution. Interference between NW-SE compression and orogenparallel extension along the Rhône-Simplon fault system resulted in a complex regional structural pattern, with strike-slip movements on both sides of the Mont Blanc massif. Young brittle faults are predominantly strike slip without significant vertical offset. The young (\2 Ma) rapid exhumation of Mont Blanc is more broadly distributed and cannot be directly linked to discrete faults bounding the massif. The mechanisms driving this recent accelerated exhumation must similarly be of broader scale.

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Section: Mont Blanc Back-thrustmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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

Egli

Mancktelow

2013

Swiss J Geosci

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“…Assuming a constant AHe closure isotherm over the horizontal‐spatial and temporal extent of a given VT, we interpreted a simple age‐elevation relationship (AER) by fitting a straight line with elevation as the independent and age as the dependent variable, weighted according to the error (e.g., Glotzbach et al, 2011). While such an approach allows for some estimate of exhumation rates, this method is not ideal when applied to our samples because it does not quantify transient thermal conditions and we do not have a consistent suite of samples to robustly determine rates from them.…”

Section: Bedrock Thermochronometrymentioning

confidence: 99%

Slow Long‐Term Exhumation of the West Central Andean Plate Boundary, Chile

2018

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We present a regional analysis of new low‐temperature thermochronometer ages from the Central Andean fore arc to provide insights into the exhumation history of the western Andean margin. To derive exhumation rates over 10 million‐year timescales, 38 new apatite and zircon (U‐Th)/He ages were analyzed along six ~500‐km long near‐equal‐elevation, coast parallel, transects in the Coastal Cordillera (CC) and higher‐elevation Precordillera (PC) of the northern Chilean Andes between latitudes 18.5°S and 22.5°S. These transects were augmented with age‐elevation profiles where possible. Results are synthesized with previously published thermochronometric data, corroborating a previously observed trenchward increase in cooling ages in Peru and northern Chile. One‐dimensional thermal‐kinematic modeling of all available multichronometer equal‐elevation samples reveals mean exhumation rates of <0.2 km/Myr since ~50 Ma in the PC and ~100 Ma in the CC. Regression of pseudovertical age‐elevation transects in the CC yields comparable rates of ~0.05 to ~0.12 km/Myr between ~40 and 80 Ma. Differences between the long‐term mean 1‐D rates and shorter‐term age‐elevation‐derived rates indicate low variability in the exhumation history. Modeling results suggest similar background exhumation rates in the CC and PC; younger ages in the PC are largely a function of increased heat flow and consequently an elevated geothermal gradient near the arc. Slow exhumation rates are suggestive of semiarid conditions across the region since at least the Eocene and deformation and development of the Andean fore arc around this time.

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“…This magnitude of erosion accounts for a large part of the overall incision in the external Alpine Foreland (~1000 m according to Cederbom et al [2011], Müller et al [2002], and Mazurek et al [2006]). It also accounts for an important fraction of erosion in the internal Alpine Foreland and in the Alps over the last few million years [Vernon et al, 2008;Glotzbach et al, 2010Glotzbach et al, , 2011aGlotzbach et al, , 2011bPignalosa et al, 2011].…”

Section: Implications For the Erosion Of The Rhine River Basinmentioning

confidence: 99%

High magnitude and rapid incision from river capture: Rhine River, Switzerland

et al. 2013

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[1] Landscape evolution is controlled by the development and organization of drainage basins. As a landscape evolves, drainage reorganization events can occur via river capture or piracy, whereby one river basin grows at the expense of another. The river downstream of a capture location will generate a transient topographic response as the added water discharge increases sediment transport and erosion efficiency. This erosional response will propagate upstream through both the captured and original river basins. Here we focus on quantifying the impact of drainage reorganization along the Rhine/Aare River system (~45,000 km 2 ) during the late Pliocene/early Pleistocene, where gravel remnants indicate total incision of~650 m during the last~4.2 Myr in the region of the recent Aare-Rhine confluence. We develop a numerical model of drainage capture to quantify the range of possible magnitudes of erosion and the transient river response resulting from the reorganization of the Rhine River. The model accounts for both fluvial incision and sediment transport. Our model estimates 400-800 m of river elevation change (lowering profiles) during the last~4 Myr due to river capture events, providing an important component to the recent exhumation budget of the Swiss Alpine Foreland. The model indicates a rapid response to capture events (re-equilibration timescale of~1 Myr). The predicted incision magnitudes are consistent with incision measured from the elevation of Pliocene and early Pleistocene river gravels, suggesting that across northern Switzerland, a significant amount of incision can be explained by drainage reorganization.

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Episodic exhumation and relief growth in the Mont Blanc massif, Western Alps from numerical modelling of thermochronology data

Cited by 125 publications

References 82 publications

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

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

Slow Long‐Term Exhumation of the West Central Andean Plate Boundary, Chile

High magnitude and rapid incision from river capture: Rhine River, Switzerland

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