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7. Didier L. BOURLÈS (1955-2021), the 5 MV cosmogenic rock star

Author

Braucher, R., Blard, P.-H., Brown, E. T., Carcaillet, J., Lebatard, A.-E., Siame, L., Simon, Q., Thouveny, N., Aumaître, G., Bard, E., Carretier, S., Cornu, S., Fink, D., Finkel, R., German, C., Godard, V., Hamelin, B., Hofmann, F. M., Jomelli, V., Keddadouche, K., Kurz, M. D., Palacios, D., Measures, C., Merchel, S., Regard, V., Schimmelpfennig, I., Blanckenburg, F., and Zerathe, S.

Abstract

paper without abstract

Published
2021

10. Toward the feldspar alternative for cosmogenic Be-10 applications

Author

Zerathe, Swann, Blard, P.H., Bourlès, D., Audin, Laurence, Carcaillet, J., Delgado, F., Benavente, C., and ASTER Team (collab.)

Abstract

The possibility of quantifying surface processes in mafic or volcanic environment using the potentialities offered by the in situ-produced cosmogenic nuclides, and more specifically by the in situ-produced Be-10, is often hampered by the rarity of quartz minerals in the available lithologies. As an alternative to overcome this difficulty, we explore in this work the possibility of relying on feldspar minerals rather that on quartz to perform in situ-produced Be-10 measurements in such environments. Our strategy was to cross-calibrate the total production rate of Be-10 in feldspar (P-10fsp) against the total production rate of He-3 in pyroxene (P-3px) by measuring He-3 and Be-10 in cogenetic pyroxene (He-3(px)) and feldspar (Be-10(fsp)). The samples were collected from eight ignimbritic boulders, exposed from ca 120 to 600 ka at elevations ranging from 800 to 2500 m, along the preserved rock-avalanche deposits of the giant Caquilluco landslide (18 degrees S, 70 degrees W), Southern Peru. Along with data recently published by Blard et al. (2013a) at a close latitude (22 degrees S) but higher elevation (ca. 4000 m), the samples yield a remarkably tight cluster of He-3(px) - Be-10(fsp) total production ratios whose weighted-mean is 35.6 +/- 0.5 (1 sigma). The obtained weighted mean He-3(px) - Be-10(fsp) total production ratio combined with the local He-3(py) total production rate in the high tropical Andes published by Martin et al. (2017) allows to establish a total SLHL Be-10 in situ-production rate in feldspar mineral (P-10fsp) of 3.57 +/- 0.21 at.g(-1).yr(-1) (scaled for the LSD scaling scheme, the ERA40 atm model and the VDM of Lifton, 2016). Despite the large elevation range covered by the whole dataset (800-4300 m), no significant variation of the He-3(px) - Be-10(fsp) total production ratios in pyroxene and feldspar was evidenced. As an attempt to investigate the effect of the chemical composition of feldspar on the total Be-10 production rate, major and trace element concentrations of the studied feldspar samples were analyzed. Unfortunately, giving the low compositional variability of our dataset, this issue is still pending.

Published
2017

11. Active transpressional tectonics in the Andean forearc of southern Peru quantified by 10Be surface exposure dating of an active fault scarp

Author

Benavente C., Zerathe S., Audin L., Hall S.R., Robert X., Delgado F., Carcaillet J., ASTER Team, Aumaître G., Bourlès D.L., and Keddadouche K.

Subjects
10Be exposure dating, active fault, fore arc, Peru, tectonic geomorphology, Andes, purl.org/pe-repo/ocde/ford#2.02.05 [http]
Abstract

Our understanding of the style and rate of Quaternary tectonic deformation in the forearc of the Central Andes is hampered by a lack of field observations and constraints on neotectonic structures. Here we present a detailed analysis of the Purgatorio fault, a recently recognized active fault located in the forearc of southern Peru. Based on field and remote sensing analysis (Pléiades DEM), we define the Purgatorio fault as a subvertical structure trending NW-SE to W-E along its 60 km length, connecting, on its eastern end, to the crustal Incapuquio Fault System. The Purgatorio fault accommodates right-lateral transpressional deformation, as shown by the numerous lateral and vertical plurimetric offsets recorded along strike. In particular, scarp with a 5 m cumulative throw is preserved and displays cobbles that are cut and covered by slickensides. Cosmogenic radionuclide exposure dating (10Be) of quartzite cobbles along the vertical fault scarp yields young exposure ages that can be bracketed between 0 to 6 ka, depending on the inheritance model that is applied. Our preferred scenario, which takes in account our geomorphic observations, implies at least two distinct rupture events, each associated with ~3 and ~2 m of vertical offset. These two events plausibly occurred during the last thousand years. Nevertheless, an interpretation invoking more tectonic events along the fault cannot be ruled out. This work affirms crustal deformation along active faults in the Andean forearc of southern Peru during the last thousand years. ©2017. American Geophysical Union. All Rights Reserved.

Published
2017

15. Regional moment tensors and stress field in South and Central America

Author

Angel, I., Audemard M., F.A., Carcaillet, J., Audin, Laurence, Audemard, F. (ed.), Zahradník, J. (ed.), and Assumpção, M. (ed.)

Abstract

In the Mérida Andes, a detailed deglaciation history reconstruction is difficult to achieve due to scattered deglaciation chronologies available. This paper contributes with 24 exposure ages of glacial landforms sampled in the Gavidia valley. Exposure ages were obtained based on terrestrial cosmogenic nuclide 10Be dating. Results indicate deglaciation mainly occurred between In the Mérida Andes, a detailed deglaciation history reconstruction is difficult to achieve due to scattered deglaciation chronologies available. This paper contributes with 24 exposure ages of glacial landforms sampled in the Gavidia valley. Exposure ages were obtained based on terrestrial cosmogenic nuclide 10Be dating. Results indicate deglaciation mainly occurred between ~21 ka and 16.5 ka and the complete deglaciation occurred at ∼16.0 ka. The glacier retreated in two different phases. The oldest one occurred since the LGM until middle OtD or the local climate event El Caballo Stadial. The youngest phase occurred at ages younger than ~16.5 ka until complete deglaciation. A combination of topographic features and changes in the paleoclimate conditions at the end of the El Caballo Stadial seems leaded the fastest former glacier extinction. The topographic feature which seems contributed to the fastest glacier extinction was the low valley bottom slopes. In addition, exposure ages of the Gavidia valley were integrated with deglaciation chronologies from the central Mérida Andes to compare deglaciation histories. Asynchronous deglaciation histories were observed. Local paleotemperatures and paleoprecipitations contrasts, different valleys aspects, insolation and catchments steepness could explain different deglaciation histories ~21 ka and 16.5 ka and the complete deglaciation occurred at ~16.0 ka. The glacier retreated in two different phases. The oldest one occurred since the LGM until middle OtD or the local climate event El Caballo Stadial. The youngest phase occurred at ages younger than ~16.5 ka until complete deglaciation. A combination of topographic features and changes in the paleoclimate conditions at the end of the El Caballo Stadial seems leaded the fastest former glacier extinction. The topographic feature which seems contributed to the fastest glacier extinction was the low valley bottom slopes. In addition, exposure ages of the Gavidia valley were integrated with deglaciation chronologies from the central Mérida Andes to compare deglaciation histories. Asynchronous deglaciation histories were observed. Local paleotemperatures and paleoprecipitations contrasts, different valleys aspects, insolation and catchments steepness could explain different deglaciation histories.

Published
2016

17. Sidewall erosion: Insights from in situ‐produced 10Be concentrations measured on supraglacial clasts (Mont Blanc massif, France).

Author

Sarr, A.‐C., Mugnier, J.‐L., Abrahami, R., Carcaillet, J., and Ravanel, L.

Subjects
EROSION, LONG-Term Evolution (Telecommunications), MOUNTAINS, GLACIAL erosion, SAND, TOPOGRAPHY, MASS-wasting (Geology)
Abstract

Sidewall erosion because of rockfalls is one of the most efficient erosional processes in the highest parts of mountain ranges; it is therefore important to quantify sidewall erosion to understand the long‐term evolution of mountainous topography. In this study, we analyse how the 10Be concentration of supraglacial debris can be used to quantify sidewall erosion in a glaciated catchment. We first analyse, in a glaciated catchment, the cascade of processes that move a rock from a rockwall to a supraglacial location and propose a quantitative estimate of the number of rockfalls statistically mixed in a supraglacial sand sample. This model incorporates the size of the rockwall, a power law distribution of the size of the rockfalls and the mean glacial transport velocity. In the case of the Bossons glacier catchment (Mont Blanc massif), the 10Be concentrations obtained for supraglacial samples vary from 1.97 ± 0.24 to 23.82 ± 1.68 × 104 atoms g−1. Our analysis suggests that part of the 10Be concentration dispersion is related to an insufficient number of amalgamated rockfalls that does not erase the stochastic nature of the sidewall erosion. In the latter case, the concentration of several collected samples is averaged to increase the number of statistically amalgamated rockfalls. Variable and robust 10Be‐derived rockwall retreat rates are obtained for three distinct rockfall zones in the Bossons catchment and are 0.19 ± 0.08 mm year−1, 0.54 ± 0.1 mm year−1 and 1.08 ± 0.17 mm year−1. The mean 10Be retreat rate for the whole catchment (ca. 0.65 mm year−1) is close to the present‐day erosion rate derived from other methods. © 2019 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2019
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18. Deciphering the driving forces of erosion rates on millennial to million-year timescales in glacially impacted landscapes: An example from the Western Alps

Author

Glotzbach, C., van der Beek, P., Carcaillet, J., Delunel, Romain, Institut des Sciences de la Terre (ISTerre), 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-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), 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), Institute of Geological Sciences [Bern], and University of Bern

Subjects
stomatognathic system, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, 550 Earth sciences & geology
Abstract

International audience; In many regions, tectonic uplift is the main driver of erosion over million-year (Myr) timescales, but climate changes can markedly affect the link between tectonics and erosion, causing transient variations in erosion rates. Here we study the driving forces of millennial to Myr-scale erosion rates in the French Western Alps, as estimated from in situ produced cosmogenic 10Be and a newly developed approach integrating detrital and bedrock apatite fission-track thermochronology. Millennial erosion rates from 10Be analyses vary between ~0.27 and ~1.33 m/kyr, similar to rates measured in adjacent areas of the Alps. Significant positive correlations of millennial erosion rates with geomorphic measures, in particular with the LGM ice thickness, reveal a strong transient morphological and erosional perturbation caused by repeated Quaternary glaciations. The perturbation appears independent of Myr-scale uplift and erosion gradients, with the effect that millennial erosion rates exceed Myr-scale erosion rates only in the internal Alps where the latter are low (

Published
2013

20. Application of the authigenic Be10/Be9 dating method to continental sediments: reconstruction of the Mio-Pleistocene sedimentary sequence in the early hominid fossiliferous areas of northern Chad Basin

Author

Anne Lebatard, Bourles, D. L., Regis Braucher, Arnauld, N., Ph. Duringer, Jolivet, M., Moussa, A., Deschamps, P., Roquin, C., Carcaillet, J., Mathieu Schuster, Lihoreau, F., Likius, A., Mackaye, H. T., Vignaud, P., Brunet, M., Dynamique de la lithosphère et des bassins sédimentaires (IPGS) (IPGS-Dylbas), Institut de physique du globe de Strasbourg (IPGS), and Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2010

21. Application of the authigenic Be-10/Be-9 dating method to continental sediments : reconstruction of the Mio-Pleistocene sedimentary sequence in the early hominid fossiliferous areas of the northern Chad Basin

Author

Lebatard, A. E., Bourles, D. L., Braucher, R., Arnold, M., Duringer, P., Jolivet, M., Moussa, A., Deschamps, Pierre, Roquin, C., Carcaillet, J., Schuster, M., Lihoreau, F., Likius, A., Mackaye, H. T., Vignaud, P., and Brunet, M.

Subjects
beryllium-10, cosmogenic nuclide, paleoenvironments, Chad Basin, Hominidae, paleontology
Abstract

The concentrations of atmospheric cosmogenic Be-10 normalized to the solubilized fraction of its stable isotope Be-9 have been measured in the authigenic phase leached from silicated continental sediments deposited since the upper Miocene in the northern Chad Basin. This method is validated by the systematic congruence with the biochronological estimations based on the fossil mammal evolutive degree of faunal assemblages. The fifty-five authigenic Be-10/Be-9 ages obtained along 12 logs distributed along two West-East cross sections that encompass best representative Mio-Pliocene outcrops including paleontological sites show a systematic stratigraphic decrease when considering all studied sedimentary fades extending from the Pleistocene up to 8 Ma and allow performing geologic correlations otherwise impossible in the studied area. The resulting global sequence evidences and temporally specifies the succession of the main paleoenvironments that have developed in this region since the Miocene. Under the special conditions encountered in the northern Chad Basin, this study demonstrates that the authigenic Be-19/Be-9 ratio may be used as a dating tool of continental sedimentary deposits from 1 to 8 Ma. The half-life of Be-10 theoretically allowing dating up to 14 Ma, it may have fundamental implications on important field research such as paleoclimatology and, through the dating of fossiliferous deposits in paleontology and paleoanthropology.

Published
2010

23. « Slope instability in relation to glacial debuttressing in alpine areas (Upper Durance catchment, southeastern France) : pieces of evidence from field data and 10Be cosmic ray exposure ages »

Author

Etienne Cossart, Regis Braucher, Monique Fort, Bourles, D. L., Carcaillet, J., Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Sorbonne (UP4)-École pratique des hautes études (EPHE)-Institut de Recherche pour le Développement (IRD)-Université Panthéon-Sorbonne (UP1), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), UMR PRODIG, PUBLICATIONS, Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École Pratique des Hautes Études (EPHE), and Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SHS.GEO] Humanities and Social Sciences/Geography, Slope instability, Upper Durance, [SHS.GEO]Humanities and Social Sciences/Geography, ComputingMilieux_MISCELLANEOUS, Southeastern France
Abstract

International audience

Published
2008

29. First cosmic ray exposure dating ( in situ produced 10Be) of the late pleistocene and holocene glaciation in the Nanhutashan Mountains (Taiwan).

Author

Carcaillet, J., Siame, L. L., Chu, H.-T., Bourlès, D. L., Lu, W.-C., Angelier, J., and Dussouillez, P.

Subjects
*COSMIC rays, *COSMOCHRONOLOGY, *PLEISTOCENE stratigraphic geology, *HOLOCENE stratigraphic geology, *ROCKS, *MOUNTAINS, *GLACIAL Epoch, *MONSOONS
Abstract

In Taiwan, efficient climate-driven strong erosion processes are the leading cause for low preservation of geomorphic landforms. Despite the absence of present-day glaciers, glacial relicts have been reported in high altitude areas. These scarce landforms provide opportunities for reconstructing the timing of the last deglaciation in a region where glacial history is poorly documented. We have collected boulders and striated bedrocks in the Nanhutashan area and calculated surface exposure ages based on in-situ produced 10Be concentrations. The oldest glacial remains, dated at 11.1 ± 3.3 ka, correspond to the last glacial advance. The Holocene is characterized by a continuous retreat of the ice-cap until at least 7.2 ± 1.0 ka. Our results are in agreement with a scenario where changes of monsoon regimes lead to a strong reduction of the winter monsoon during the early Holocene, causing a decrease of snow supply and disequilibrium of the hydrological budget. [ABSTRACT FROM AUTHOR]

Published
2007
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30. Geomagnetic moment instability between 0.6 and 1.3 Ma from cosmonuclide evidence

Author

Carcaillet, J. T., Nicolas THOUVENY, and Bourlès, D. L.

Subjects
paleointensity, authigenic (10)Be/(9)Be, geomagnetic excursions and reversals, geomagnetic moment, cosmogenic isotope production, marine sedimentary archives
Abstract

The reliability of paleomagnetic records as proxies of the geomagnetic field intensity is still a matter of controversy since volcanic materials hardly provide continuous records, and marine sediments are suspected to carry a remanence biased by post-depositional realignments and/or by overprints. Such long standing debate emphasizes the need for the development of methods independent from paleomagnetism to decipher geomagnetic intensity variations. High resolution measurements of authigenic (10)Be/(9)Be along with a detailed sedimentary record of directional and relative paleointensity variations evidence, over the 0.6-1.3 Ma time interval, frequent and recurrent excursions or short events in the late Matuyama and the early Brunhes epochs, among which two Brunhes-Matuyama reversal precursors and an intra-Jaramillo excursion. The results of this study confirm the idea of a highly unstable geomagnetic field as suggested by paleomagnetic evidences.

32. « Les potentialités d'un croisement des datations cosmogéniques avec une approche géomorphologique. Application à la mise en évidence de la décompression post-glaciaire (Haut-Gyr, Massif des Ecrins) »

Author

Etienne Cossart, Regis Braucher, Monique Fort, Bourles, D., Carcaillet, J., Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Departament de Geodinamica i Geofısica, Facultat de Geologia, Universitat de Barcelona (UB), Laboratoire de Géophysique Interne et Tectonophysique (LGIT), Laboratoire Central des Ponts et Chaussées (LCPC)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Sorbonne (UP4)-École pratique des hautes études (EPHE)-Institut de Recherche pour le Développement (IRD)-Université Panthéon-Sorbonne (UP1), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), 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), 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)-Institut des Sciences de la Terre (ISTerre), Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-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)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-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)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École Pratique des Hautes Études (EPHE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Laboratoire Central des Ponts et Chaussées (LCPC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Approche géomorphologique, Décompression post-glaciaire, Massif des Ecrins, Haut-Gyr, Datations cosmogéniques, France, [SHS.GEO]Humanities and Social Sciences/Geography

33. The consequences of glacial debuttressing in deglaciated areas: evidence from field data and cosmogenic datings

Author

Etienne Cossart, Regis Braucher, Monique Fort, Bourles, D., Carcaillet, J., Pôle de recherche pour l'organisation et la diffusion de l'information géographique (PRODIG), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris-Sorbonne (UP4)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Sorbonne (UP4)-École pratique des hautes études (EPHE)-Institut de Recherche pour le Développement (IRD)-Université Panthéon-Sorbonne (UP1), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Université Paris 1 Panthéon-Sorbonne (UP1)-Institut de Recherche pour le Développement (IRD)-École pratique des hautes études (EPHE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), and Cossart, Etienne

Subjects
Late Glacial, Paraglacial, [SHS.GEO] Humanities and Social Sciences/Geography, Stress release, Rock-slope failure, Cosmogenic nuclides, [SHS.GEO]Humanities and Social Sciences/Geography, Glacial debuttressing, French Alps
Abstract

International audience; The Upper Durance catchment is an area prone to rock-slope failures. Such failures reflect the combination of high relief, lithostructural controls and paraglacial stress release. The aim of this study is to determine the role of deglacial unloading and resulting paraglacial stress release in conditioning or triggering slope failure. Former dimensions of the Durance glacier are reconstructed, then combined with Digital Elevation Model data in a raster Geographic Information System to quantify the spatial pattern of stresses associated with glacial loading at the Last Glacial Maximum. Preliminary calculations suggest that major rock falls and rock avalanches are associated with areas subject to the highest decompression stresses. Focus on two case studies allows the consequences of paraglacial stress release on slope instability to be evaluated. Description of slope failure runout deposits allows reconstruction of the nature of slope failure. Surface exposure dates based on concentration of cosmogenic 10Be allows the timing of both deglaciation and that of post-glacial rock-slope failures to be established. It is shown that rock-slope failures are concentrated on lower valley-side slopes within the area occupied by ice at the Last Glacial Maximum, and that their locations coincide with zones of inferred high glacial loading stress, consistent with interpretation of both bedrock disruption and large-scale rock-slope failures as paraglacial phenomena induced by stress release following deglaciation. Timing of initial rock avalanche runout deposition at one site is consistent with this conclusion, though later instability episodes at the same site may have occurred independent of the influence of paraglacial stress release.

34. Linking morphology across the glaciofluvial interface: A 10Be supported chronology of glacier advances and terrace formation in the Garonne River, northern Pyrenees, France.

Author

Stange, K.M., van Balen, R.T., Kasse, C., Vandenberghe, J., and Carcaillet, J.

Subjects
*FLUVIAL geomorphology, *CHRONOLOGY, *GLACIERS, *TERRACES (Geology), *FLOODPLAIN ecology, *PALEOGEOGRAPHY
Abstract

Abstract: The Garonne River drains an important part of the northern Pyrenees and its northern foreland. We investigated the middle reaches of the Garonne River establishing a detailed morphogenetic profile of its foreland terrace staircase and the preserved palaeoglacier margins. We particularly focussed on the glaciofluvial interface, linking (also genetically) the fluvial sediment archives in the foreland with the terminal glacial basin upstream of the Pyrenees mountain front. Using cosmogenic nuclide 10Be analyses, two terrace exposures have been dated, including a prominent fluvioglacial outwash fan at the foreland transition. We identified three terminal margins of late Pleistocene glacier advances. The prominent Garonne staircase consists of three major terrace complexes, comprising eight individual terrace levels. Results indicate a young age of the lower terrace complex of the Garonne staircase (MIS 4–2). The morphogenetic relationships and the new 10Be exposure age constraints suggest that during the last glaciation (Würmian) the Garonne glacier reached its maximum extent at the north Pyrenean mountain front, apparently already during MIS 4. Two different ice margins were associated with MIS 2, indicating close to maximum ice-extent during early MIS 2 (LGM) and relatively stationary ice-recession in the late MIS 2. The extensive Garonne terrace complexes formed under cold-climate conditions and were abandoned by incision during major glacial–interglacial transitions. During warm–cold climate transitions lateral erosion caused the reworking of previously abandoned palaeofloodplains. The long-term (Quaternary) incision of the Garonne and other north Pyrenean rivers indicates that the proximal Aquitaine foreland basin experienced uplift. However, non-uniform lateral course migrations and valley asymmetries of the north Pyrenean piedmont rivers indicate that uplift magnitude is variable, with maximum amounts in the centre of the molasse-fan of Lannemezan: Rivers on the western part of the fan were tilted toward the west, whereas rivers in the eastern part, like the Garonne, were tilted to the east. [Copyright &y& Elsevier]

Published
2014
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35. Slope instability in relation to glacial debuttressing in alpine areas (Upper Durance catchment, southeastern France): Evidence from field data and 10Be cosmic ray exposure ages

Author

Cossart, E., Braucher, R., Fort, M., Bourlès, D.L., and Carcaillet, J.

Subjects
*GEOMORPHOLOGY, *COSMIC rays, *ASTROPHYSICAL radiation, *IONIZING radiation, *RADIOACTIVITY
Abstract

Abstract: The Upper Durance catchment is an area prone to rock-slope failures. Such failures reflect the combination of high relief, litho-structural controls and paraglacial stress release. The aim of this study is to determine the role of deglacial unloading and resulting paraglacial stress release in conditioning or triggering slope failure. Former dimensions of the Durance glacier are reconstructed, then combined with Digital Elevation Model data in a raster Geographic Information System to quantify the spatial pattern of stresses associated with glacial loading at the Last Glacial Maximum. Preliminary calculations suggest that major rock falls and rock avalanches are associated with areas subject to the highest decompression stresses. Focus on two case studies allows the consequences of paraglacial stress release on slope instability to be evaluated. Description of slope failure runout deposits allows reconstruction of the nature of slope failure. Surface exposure dates based on concentration of cosmogenic 10Be allows the timing of both deglaciation and that of post-glacial rock-slope failures to be established. It is shown that rock-slope failures are concentrated on lower valley-side slopes within the area occupied by ice at the Last Glacial Maximum, and that their locations coincide with zones of inferred high glacial loading stress, consistent with interpretation of both bedrock disruption and large-scale rock-slope failures as paraglacial phenomena induced by stress release following deglaciation. Timing of initial rock avalanche runout deposition at one site is consistent with this conclusion, though later instability episodes at the same site may have occurred independent of the influence of paraglacial stress release. [Copyright &y& Elsevier]

Published
2008
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36. Javanese Homo erectus on the move in SE Asia circa 1.8 Ma.

Author

Husson L, Salles T, Lebatard AE, Zerathe S, Braucher R, Noerwidi S, Aribowo S, Mallard C, Carcaillet J, Natawidjaja DH, and Bourlès D

Subjects
Humans, Animals, Indonesia, Asia, Fossils, Biological Evolution, Hominidae
Abstract

The migration of Homo erectus in Southeast Asia during Early Pleistocene is cardinal to our comprehension of the evolution of the genus Homo. However, the limited consideration of the rapidly changing physical environment, together with controversial datings of hominin bearing sites, make it challenging to secure the robust timeline needed to unveil the behavior of early humans. Here, we reappraise the first appearance datum of Javanese H. erectus by adding the most reliable age constraints based on cosmogenic nuclides [Formula: see text]Be and [Formula: see text]Al produced in situ to a compilation of earlier estimates. We find that H. erectus reached Java and dwelled at Sangiran, Java, ca. 1.8 Ma. Using this age as a baseline, we develop a probabilistic approach to reconstruct their dispersal routes, coupling ecological movement simulations to landscape evolution models forced by reconstructed geodynamic and climatic histories. We demonstrate that the hospitable terra firma conditions of Sundaland facilitated the prior dispersal of hominins to the edge of Java, where they conversely could not settle until the Javanese archipelago emerged from the sea and connected to Sundaland. The dispersal of H. erectus across Sundaland occurred over at least tens to hundreds kyr, a time scale over which changes in their physical environment, whether climatic or physiographic, may have become primary forcings on their behavior. Our comprehensive reconstruction method to unravel the peopling timeline of SE Asia provides a novel framework to evaluate the evolution of early humans., (© 2022. The Author(s).)

Published
2022
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37. Cosmogenic nuclide dating of Sahelanthropus tchadensis and Australopithecus bahrelghazali: Mio-Pliocene hominids from Chad.

Author

Lebatard AE, Bourlès DL, Duringer P, Jolivet M, Braucher R, Carcaillet J, Schuster M, Arnaud N, Monié P, Lihoreau F, Likius A, Mackaye HT, Vignaud P, and Brunet M

Subjects
Animals, Chad, Fossils, Humans, Isotopes analysis, Paleontology methods, Time Factors, Anthropology, Physical methods, Biological Evolution, Hominidae
Abstract

Ages were determined at two hominid localities from the Chad Basin in the Djurab Desert (Northern Chad). In the Koro Toro fossiliferous area, KT 12 locality (16 degrees 00'N, 18 degrees 53'E) was the site of discovery of Australopithecus bahrelghazali (Abel) and in the Toros-Menalla fossiliferous area, TM 266 locality (16 degrees 15'N, 17 degrees 29'E) was the site of discovery of Sahelanthropus tchadensis (Toumaï). At both localities, the evolutive degree of the associated fossil mammal assemblages allowed a biochronological estimation of the hominid remains: early Pliocene (3-3.5 Ma) at KT 12 and late Miocene ( approximately 7 Ma) at TM 266. Atmospheric (10)Be, a cosmogenic nuclide, was used to quasicontinuously date these sedimentary units. The authigenic (10)Be/(9)Be dating of a pelite relic within the sedimentary level containing Abel yields an age of 3.58 +/- 0.27 Ma that points to the contemporaneity of Australopithecus bahrelghazali (Abel) with Australopithecus afarensis (Lucy). The 28 (10)Be/(9)Be ages obtained within the anthracotheriid unit containing Toumaï bracket, by absolute dating, the age of Sahelanthropus tchadensis to lie between 6.8 and 7.2 Ma. This chronological constraint is an important cornerstone both for establishing the earliest stages of hominid evolution and for new calibrations of the molecular clock.

Published
2008
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