Massif-wide denudation of the Vosges Mountains (NE France) inferred from in situ 10Be concentrations in stream sediments

2021 ◽  
Author(s):  
Timothée Jautzy ◽  
Gilles Rixhon ◽  
Régis Braucher ◽  
Laurent Schmitt ◽  
Aster Team*
Keyword(s):  
Stream Sediments ◽  
Tectonic Activity ◽  
Mountain Range ◽  
Vosges Mountains ◽  
Eastern Side ◽  
Denudation Rates ◽  
The Alps ◽  
Western Side

<p><span>The Vosges Mountains in NE France belong to the belt of Variscan massifs located in the foreland of the Alps. Despite its rather limited extension barely reaching 6000 km², this range of low mountains peaking at ~1425 m presents three contrasting primary characteristics. Firstly, a bipartite N-S subdivision can be achieved based on the geological basement: whereas the southern part, traditionally referred to as the crystalline Vosges, is composed of a mosaic of Palaeozoic rocks, including igneous (mostly intrusive and secondarily extrusive), metamorphic, and sedimentary rocks, the northern part is much more homogeneous given its Triassic sandstone cover (“sandstone Vosges”). Secondly, a clear E-W topographic gradient characterises the mountain range. By contrast to the steep hillslopes and elevation drops regularly exceeding 600 m (sometimes reaching 900-1000 m) between the summits and the valley floors on the eastern side (Alsace; south-western border of the Upper Rhine Graben, URG), the western side exhibits more gently-sloping hillslopes along with a longer extension (Lorraine; eastern border of the Parisian Basin). This results from the sharp E-W contrast in Late Cenozoic tectonic activity between sustained subsidence in the URG to the east and weak rock uplift characterising the Parisian Basin to the west. Finally, the imprint left by Quaternary climatic fluctuations yielded a N-S gradient: whereas the southern part (roughly covering 80-90% of the crystalline Vosges) hosted abundant valley glaciers and still bears traces of significant glacial erosion (cirques and U-shaped valleys), the northern part (mostly the sandstone Vosges) was void of ice cover.</span></p><p><span>In spite of these advantageous characteristics, very little is known about the Quaternary evolution of the massif, in particular regarding the long-term interactions between denudation</span><span>, lithological control, climatic forcing and tectonic activity. </span><span>Against this background, this contribution aims to present the first data of long-term, massif-wide denudation. Modern stream sediments from 21 river catchments of different size draining the whole massif were thus sampled for </span><span><em>in situ</em></span> <sup><span>10</span></sup><span>Be concentration measurements at the outlet of their mountainous reach. Catchment-wide denudation rates inferred from cosmogenic </span><sup><span>10</span></sup><span>Be will be combined with the analysis of morphometric parameters and structural connectivity resulting from the processing of a high-resolution DEM (5 m). Catchment selection was operated according to the threefold subdivision above: i.e. heterogeneous vs homogenous petrography, tectonically-active eastern side vs “quiescent” western side and glaciated vs unglaciated catchments. We thus test the main hypothesis that the four NE, NW, SE, SW quarters of the Vosges massif shall be characterised by contrasting denudation rates, reflecting the respective role played by the controlling factors on long-term denudation. To our knowledge, this contribution is the first attempt to quantify denudation at the massif scale of a European low mountain range. This is especially relevant as long-term landscape evolution in the Variscan belt, by contrast to the numerous works focusing on denudation in high-mountains ranges (e.g. the Alps), has been regularly disregarded in recent geomorphological studies.</span></p><p><span>*Georges Aumaître, Didier L. Bourlès and Karim Keddadouche</span></p>

scholarly journals Autogenic versus allogenic controls on the evolution of a coupled fluvial megafan/mountainous catchment system: numerical modelling and comparison with the Lannemezan megafan system (Northern Pyrenees, France)

2016 ◽  
Author(s):  
Margaux Mouchené ◽  
Peter van der Beek ◽  
Sébastien Carretier ◽  
Frédéric Mouthereau
Keyword(s):  
Numerical Modelling ◽  
Temporal Variations ◽  
Tectonic Activity ◽  
Mountain Range ◽  
Stream Network ◽  
Mountainous Catchment ◽  
Isostatic Rebound ◽  
Base Level ◽  
Alluvial Terraces

Abstract. Alluvial megafans are sensitive recorders of landscape evolution, controlled by autogenic processes and allogenic forcing and influenced by the coupled dynamics of the fan with its mountainous catchment. The Lannemezan megafan in the northern Pyrenean foreland was abandoned by its mountainous feeder stream during the Quaternary and subsequently incised, leaving a flight of alluvial terraces along the stream network. We explore the relative roles of autogenic processes and external forcing in the building, abandonment and incision of a foreland megafan using numerical modelling and compare the results with the inferred evolution of the Lannemezan megafan. Autogenic processes are sufficient to explain the building of a megafan and the long-term entrenchment of its feeding river at time and space scales that match the Lannemezan setting. Climate, through temporal variations in precipitation rate, may have played a role in the episodic pattern of incision at a shorter time-scale. In contrast, base-level changes, tectonic activity in the mountain range or tilting of the foreland through flexural isostatic rebound appear unimportant.

scholarly journals <sup>10</sup>Be depth profiles in glacial sediments on the Swiss Plateau: deposition age, denudation and (pseudo-) inheritance

2017 ◽  
Vol 66 (2) ◽  
pp. 57-68 ◽  
Author(s):  
Lorenz Wüthrich ◽  
Claudio Brändli ◽  
Régis Braucher ◽  
Heinz Veit ◽  
Negar Haghipour ◽  
...  
Keyword(s):  
Radioactive Decay ◽  
Glacial Sediments ◽  
Depth Profiles ◽  
Denudation Rates ◽  
Last Glaciation ◽  
The Alps ◽  
Swiss Plateau ◽  
High Concentrations ◽  
Cosmogenic 10Be

Abstract. During the Pleistocene, glaciers advanced repeatedly from the Alps onto the Swiss Plateau. Numeric age control for the last glaciation is good and thus the area is well suited to test a method which has so far not been applied to till in Switzerland. In this study, we apply in situ produced cosmogenic 10Be depth profile dating to several till deposits. Three sites lie inside the assumed Last Glacial Maximum (LGM) extent of the Rhône and Aare glaciers (Bern, Deisswil, Steinhof) and two lie outside (Niederbuchsiten, St. Urban). All sites are strongly affected by denudation, and all sites have reached steady state, i.e., the 10Be production is in equilibrium with radioactive decay and denudational losses. Deposition ages can therefore not be well constrained. Assuming constant denudation rates of 5 cm kyr−1, total denudation on the order of 100 cm for sites within the extent of the LGM and up to tens of meters for older moraines are calculated. Denudation events, for example related to periglacial conditions during the LGM, mitigate the need to invoke such massive denudation and could help to explain high 10Be concentrations at great depths, which we here dub pseudo-inheritance. This term should be used to distinguish conceptionally from true inheritance, i.e., high concentrations derived from the catchment.

Long and short time evolution of deep seated gravitational slope deformation: contribution to knowledge of phenomena for the management of alea in the Alpine mountains

2020 ◽  
Author(s):  
Clément Boivin
Keyword(s):  
Time Evolution ◽  
Slope Deformation ◽  
Tectonic Activity ◽  
High Mountain ◽  
Mountain Range ◽  
Short Term ◽  
Future Evolution ◽  
Short Time ◽  
Short Time Evolution

&lt;p&gt;&quot;LONG AND SHORT TIME EVOLUTION OF DEEP SEATED GRAVITATIONAL SLOPE DEFORMATION: CONTRIBUTION TO KNOWLEDGE OF PHENOMENA FOR THE MANAGEMENT OF ALEA IN THE ALPINE MOUNTAINS&quot;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;C.Boivin &lt;sup&gt;a&lt;/sup&gt;, J.P. Malet &lt;sup&gt;a&lt;/sup&gt;, C. Bertrand &lt;sup&gt;b&lt;/sup&gt;, F. Chabaux &lt;sup&gt;c&lt;/sup&gt;, J. van der Woerd &lt;sup&gt;a&lt;/sup&gt;, Y. Thiery &lt;sup&gt;d&lt;/sup&gt;, F. Lacquement &lt;sup&gt;d&lt;/sup&gt;&lt;/p&gt;&lt;p&gt;&lt;sup&gt;a &amp;#160;&lt;/sup&gt;Institut de Physique du Globe de Strasbourg &amp;#8211; IPGS/DA - UMR 7516 CNRS-Unistra&lt;/p&gt;&lt;p&gt;&lt;sup&gt;b &lt;/sup&gt;&amp;#160;Laboratoire Chrono-Environnement &amp;#8211; LCE / UMR 6249 CNRS &amp;#8211; UFC&lt;/p&gt;&lt;p&gt;&lt;sup&gt;c&lt;/sup&gt;&amp;#160; Laboratoire d&amp;#8217;Hydrologie et de G&amp;#233;ochimie de Strasbourg &amp;#8211; BISE / UMR 7517 &amp;#8211; Unistra&lt;/p&gt;&lt;p&gt;&lt;sup&gt;d&lt;/sup&gt;&amp;#160; Bureau de Recherches G&amp;#233;ologiques et Mini&amp;#232;res&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; The &lt;strong&gt;Deep Seated Gravitational Slope Deformation (DSGSD)&lt;/strong&gt; are defined like a set of rock mass characterized by a generally slow movement and which can affect all the slopes of a valley or a mountain range (Agliardi and al., 2001, 2009; Panek and Klimes., 2016). The DSGSD is identified in many mountains (ex: Alps, Alaska, Rocky Mountains, Andes&amp;#8230;) and it can affect both isolated low relief and very high mountain ranges (Panek and Klimes., 2016). This deep instability are identified in many case like the origin zone for important landslide like the example of La Clapi&amp;#232;re landslide in the Alpes Maritimes (Bigot-Cormier et al., 2005). The DSGSD represent an important object we must understand to anticipate catastrophic landslides.&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Actually, many factors that could be at the origin or controlling the evolution of DSGSD have been identified such as for example the structural heritage, the climate or the tectonic activity (Agliardi 2000; 2009; 2013; Jomard 2006; Sanchez et al., 2009; Zorzi et al., 2013; Panek and Klimes., 2016; Ostermann and Sanders., 2017; Blondeau 2018). The long-term and short-term evolution of DSGSD is still poorly understood but represents an important point to characterize in order to predict future major landslides. A first inventory of DSGSD began to be carried out by certain studies such as Blondeau 2018 or Crosta et al 2013 in the Alps. These same studies have also started to prioritize the factors controlling the evolution of DSGSD.&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; It is in order to better understand the short-term (&lt;100 years) and long-term (&gt; 100 years) evolution of the DSGSD of the French Alpine massifs and the link with the occurrence of landslides, that this thesis project is developed. The main objective of this project, will be proposed models of the evolution of DSGSD since the last glaciations. But also to propose key interpretations of the future evolution to locate the areas likely to initiate landslides. Two study areas in the French Alpine massifs were chosen because they represent areas of referencing and localization gaps in DSGSD: Beaufortain and Queyras. They have the advantage of having a low lithological diversity making it possible to simplify the identification of the factors influencing the evolution of DSGSD. A geomorphological analysis on satellite data and on the ground is carried out to locate the DSGSD. Several dating (&lt;sup&gt;14&lt;/sup&gt;C, &lt;sup&gt;10&lt;/sup&gt;Be or &lt;sup&gt;36&lt;/sup&gt;Cl) will be carried out to reconstruct the history of these objects and understand the factors that controlled their evolution.&lt;/p&gt;

scholarly journals Denudation rates derived from spatially-averaged cosmogenic nuclide analysis in Nelson/Tasman catchments, South Island, New Zealand

2021 ◽  
Author(s):  
◽  
Abby Jade Burdis
Keyword(s):  
New Zealand ◽  
Dynamic Environment ◽  
Low Frequency ◽  
Short Term ◽  
Erosion Rates ◽  
Cosmogenic Nuclide ◽  
Denudation Rates ◽  
Conventional Methods

<p>New Zealand’s tectonically and climatically dynamic environment generates erosion rates that outstrip global averages by up to ten times in some locations. In order to assess recent changes in erosion rate, and also to predict future erosion dynamics, it is important to quantify long-term, background erosion. Current research on erosion in New Zealand predominantly covers short-term (100 yrs) erosion dynamics and Myr dynamics from thermochronological proxy data. Without competent medium-term denudation data for New Zealand, it is uncertain which variables (climate, anthropogenic disturbance of the landscape, tectonic uplift, lithological, or geomorphic characteristics) exert the dominant control on denudation in New Zealand. Spatially-averaged cosmogenic nuclide analysis can effectively offer this information by providing averaged rates of denudation on millennial timescales without the biases and limitations of short-term erosion methods.  Basin-averaged denudation rates were obtained in the Nelson/Tasman region, New Zealand, from analysis of concentrations of meteoric ¹⁰Be in silt and in-situ produced ¹⁰Be in quartz. The measured denudation rates integrate over ~2750 yrs (in-situ) and ~1200 yrs (meteoric). Not only do the ¹⁰Be records produce erosion rates that are remarkably consistent with each other, but they are also independent of topographic metrics. Denudation rates range from ~112 – 298 t km⁻² yr⁻¹, with the exception of one basin which is eroding at 600 - 800 t km⁻² yr⁻¹. The homogeneity of rates and absence of a significant correlation with geomorphic or lithological characteristics could indicate that the Nelson/Tasman landscape is in (or approaching) a topographic steady state.  Millennial term (¹⁰Be-derived) denudation rates are more rapid than those inferred from other conventional methods in the same region (~50 – 200 t km⁻² yr⁻¹). This is likely the result of the significant contribution of low frequency, high magnitude erosive events to overall erosion of the region. Both in-situ and meteoric ¹⁰Be analyses have the potential to provide competent millennial term estimates of natural background rates of erosion. This will allow for the assessment of geomorphic-scale impacts such as topography, tectonics, climate, and lithology on rates of denudation for the country where many conventional methods do not. Cosmogenic nuclides offer the ability to understand the response of the landscape to these factors in order to make confident erosion predictions for the future.</p>

Can 14C-10Be detect transient patterns of denudation ? Application to the French Massif Central.

2021 ◽  
Author(s):  
Sebastien J.P. Lenard ◽  
Maarten Lupker ◽  
Irene Schimmelpfennig ◽  
Vincent Godard ◽  
Clement Desormeaux ◽  
...  
Keyword(s):  
Agricultural Practices ◽  
Climatic Conditions ◽  
Integration Time ◽  
Mountain Range ◽  
River Sand ◽  
Massif Central ◽  
Erosion Processes ◽  
Denudation Rates ◽  
Extreme Precipitation Events

&lt;p&gt;Denudation rates are routinely derived from concentrations of terrestrial in situ produced cosmogenic nuclides (TCN), particularly from &lt;sup&gt;10&lt;/sup&gt;Be concentrations in river sand. Denudation rates are calculated assuming that they remain steady throughout the integration time scale of the TCN. However, such an assumption is possibly unverified in settings with negligible tectonics, where rates typically range from 10 to 100 mm/ky. In those settings, the TCN conveys a signal that integrates denudation over a time span longer than a few thousand years. The signal may include periods when anthropogenic and climatic forcing on denudation was distinct from modern times. For instance, agricultural practices were limited before 6,000 years B.P. and climatic conditions were colder and drier before 10,000 years B.P. A variable forcing may produce variable and transient denudation rates. In that case, the assumption of steady denudation rates is invalid, and their derivation may introduce a bias.&lt;/p&gt;&lt;p&gt;To detect transient landscapes and resolve such a bias, we can take advantage of the different sensitivity of the &lt;sup&gt;14&lt;/sup&gt;C and &lt;sup&gt;10&lt;/sup&gt;Be TCNs to recent and short-term changes in surface denudation. In situ &lt;sup&gt;14&lt;/sup&gt;C is more sensitive than &lt;sup&gt;10&lt;/sup&gt;Be to such changes, because of a shorter half-life (5,700 y compared to 1.4 My). This potential application of coupled &lt;sup&gt;14&lt;/sup&gt;C - &lt;sup&gt;10&lt;/sup&gt;Be measurements has recently been discussed in several theoretical studies (Hippe, 2017; Mudd, 2017; Skov et al., 2019). Despite the improvement of &lt;sup&gt;14&lt;/sup&gt;C extraction lines and measurement facilities (Hippe et al., 2009; Lupker et al., 2019), sensitivity tests remain limited on natural cases (Hippe et al., 2012).&lt;/p&gt;&lt;p&gt;Here, we propose assessing this new application by in situ &lt;sup&gt;14&lt;/sup&gt;C - &lt;sup&gt;10&lt;/sup&gt;Be measurements on river sand from the Cevennes and the Monts Margeride within the Variscan Massif Central in France. With an average elevation of ~700 m, this mountain range presents an asymmetrical topography, composed of a low-relief surface reaching 1,700 m, and bordered by a gently sloping flank to the west and a steep escarpment to the southeast, along the Cevennes fault. This escarpment receives frequent and seasonal extreme precipitation events (300-700 mm in 48h) on its southeast flank.&lt;/p&gt;&lt;p&gt;The range is subject to very limited seismic activity and appears relevant for an application of the &lt;sup&gt;14&lt;/sup&gt;C-&lt;sup&gt;10&lt;/sup&gt;Be couple. Basins are rich in quartz and have homogeneous lithology. The recent paleoclimatic context is well constrained, with substantial climatic variations but with limited Pleistocene glaciations (e.g. Fauquette et al., 1999; Magny et al., 2003; Mayewski et al., 2004). The Massif Central is subject to active erosion processes, without major contribution from stochastic events such as landslides. Denudation rates are in the range of the theoretical study of Skov et al. 2019 (Schaller et al. 2001; Molliex et al. 2016; Olivetti et al. 2016; Desormeaux et al., 2021) and several studies have suggested transient denudation patterns (Schaller et al. 2001; Olivetti et al. 2016). With our new measurements, we will verify whether the &lt;sup&gt;14&lt;/sup&gt;C-&lt;sup&gt;10&lt;/sup&gt;Be couple has sufficient resolution to detect such transience in natural cases.&lt;/p&gt;

Frost-cracking control on catchment denudation rates: Insights from in situ produced 10Be concentrations in stream sediments (Ecrins–Pelvoux massif, French Western Alps)

2010 ◽  
Vol 293 (1-2) ◽  
pp. 72-83 ◽  
Author(s):  
Romain Delunel ◽  
Peter A. van der Beek ◽  
Julien Carcaillet ◽  
Didier L. Bourlès ◽  
Pierre G. Valla
Keyword(s):  
Western Alps ◽  
Stream Sediments ◽  
Denudation Rates ◽  
Cracking Control

scholarly journals Autogenic versus allogenic controls on the evolution of a coupled fluvial megafan–mountainous catchment system: numerical modelling and comparison with the Lannemezan megafan system (northern Pyrenees, France)

2017 ◽  
Vol 5 (1) ◽  
pp. 125-143 ◽  
Author(s):  
Margaux Mouchené ◽  
Peter van der Beek ◽  
Sébastien Carretier ◽  
Frédéric Mouthereau
Keyword(s):  
Numerical Models ◽  
Temporal Variations ◽  
Tectonic Activity ◽  
Mountain Range ◽  
Stream Network ◽  
Mountainous Catchment ◽  
Isostatic Rebound ◽  
Base Level ◽  
Alluvial Terraces

Abstract. Alluvial megafans are sensitive recorders of landscape evolution, controlled by both autogenic processes and allogenic forcing, and they are influenced by the coupled dynamics of the fan with its mountainous catchment. The Lannemezan megafan in the northern Pyrenean foreland was abandoned by its mountainous feeder stream during the Quaternary and subsequently incised, leaving a flight of alluvial terraces along the stream network. We use numerical models to explore the relative roles of autogenic processes and external forcing in the building, abandonment and incision of a foreland megafan, and we compare the results with the inferred evolution of the Lannemezan megafan. Autogenic processes are sufficient to explain the building of a megafan and the long-term entrenchment of its feeding river on time and space scales that match the Lannemezan setting. Climate, through temporal variations in precipitation rate, may have played a role in the episodic pattern of incision on a shorter timescale. In contrast, base-level changes, tectonic activity in the mountain range or tilting of the foreland through flexural isostatic rebound do not appear to have played a role in the abandonment of the megafan.

Using 10Be dating to determine when the Cordilleran Ice Sheet stopped flowing over the Canadian Rocky Mountains

2021 ◽  
pp. 1-12
Author(s):  
Helen E. Dulfer ◽  
Martin Margold ◽  
Zbynĕk Engel ◽  
Régis Braucher ◽  
Aster Team
Keyword(s):  
Rocky Mountains ◽  
Ice Sheet ◽  
Mountain Range ◽  
Canadian Rocky Mountains ◽  
Weighted Mean ◽  
Exposure Age ◽  
Western Side ◽  
Cordilleran Ice Sheet ◽  
The Last Glacial

Abstract During the last glacial maximum the Cordilleran and Laurentide ice sheets coalesced east of the Rocky Mountains and geomorphological evidence indicates ice flowed over the main ridge of the Rocky Mountains between ~54–56°N. However, this ice flow has thus far remained unconstrained in time. Here we use in situ produced cosmogenic 10Be dating to determine when Cordilleran ice stopped flowing over the mountain range. We dated eight samples from two sites: one on the western side (Mount Morfee) and one on the eastern side (Mount Spieker) of the Rocky Mountains. At Mount Spieker, one sample is rejected as an outlier and the remaining three give an apparent weighted mean exposure age of 15.6 ± 0.6 ka. The four samples at Mount Morfee are well clustered in time and give an apparent weighted mean exposure age of 12.2 ± 0.4 ka. These ages indicate that Mount Spieker became ice free before the Bølling warming and that the western front of the Rocky Mountains (Mount Morfee) remained in contact with the Cordilleran Ice Sheet until the Younger Dryas.

In Situ Conservation of the Roman Mosaics at the Villa of Boscéaz (Orbe, Switzerland): Diagnosis of Risks Involved

1996 ◽  
Vol 462 ◽  
Author(s):  
R.J. Flatt ◽  
F.J. Girardet ◽  
D.C. Weidmann
Keyword(s):  
In Situ Conservation ◽  
Chemical Properties ◽  
Climatic Conditions ◽  
The Alps ◽  
Thermal Dilatation ◽  
High Degree ◽  
Physical And Chemical

ABSTRACTIn order to maintain the archaeological integrity of the site of Boscéaz, one of the most remarkable north of the Alps because of the number and quality of its roman mosaics, it is intended to maintain these in situ and on their original support. This mode of conservation implies many risks, mainly linked to the climatic variations and to the presence of water and salts in the ground and the mosaics. The high degree of damage observed on these mosaics discovered more than 150 years ago illustrates this fact.The aim of this study has been to establish a diagnosis of the risks linked to the uncovering and the in situ conservation of a mosaic recently discovered (currently covered with protective materials). This diagnosis has been established on the basis of the measurement of the physical and chemical properties of the mosaic and the ground.It turned out that the rising of salts from the ground to the mosaic would be the major problem and that consequently a dessalaision will have to be carried out. Concerning the choice of the climatic conditions for conservation, the critical zone in which the salts present crystallize was determined. The thermal dilatation of the materials appeared relatively small, but might become damageable in the long term because of a possible hysteresis. The hydrie dilatation turned out to be negligible.

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