Deglaciation history at the Alpine-Mediterranean transition (Argentera-Mercantour, SW Alps) from 10Be dating of moraines and glacially polished bedrock

International audienceEstimating the extent and age of the last glacial maxima as well as the chronology of glacial recessions in various environmental contexts is key to source-to-sink studies and paleoclimate reconstructions. The Argentera-Mercantour massif being located at the transition between the Alps and the Mediterranean Sea, its deglaciation chronology can be compared to the sediment budget of the Var River marine delta. In this paper, the deglaciation is constrained by 13 new and 22 reassessed Cosmic-Ray Exposure (CRE) 10Be datings of moraines and polished crystalline bedrocks. These data allow for the first time to fully reconstruct the deglaciation history at the scale of the entire massif, in agreement with a major glacier recession at ca. 15 ka, at the onset of Bølling transition. This contribution reveals a glacier–climate relationship more sensitive to warming phases in the southern Alps highlighted by a major decrease of glaciers after ca. 15 ka. This major deglaciation is correlated with a 2.5 fold decrease of sediment discharge of rivers into the Mediterranean Sea. Main deglaciation of the massif upper slopes (2,700-2,800 m a.s.l.) occurred after the LGM at 20.8-18.6 ka, followed by the lower slopes (2,300 m a.s.l.) at 15.3-14.2 ka. Finally, the flat polished surfaces above 2,600 m a.s.l. and the zones confined within narrow lateral valleys were likely affected by progressive ice melting of remaining debris covered glaciers and moraine erosion following the Younger Dryas re-advance stage between 12 and 8-9 ka. At lower elevations, a sediment core in the Vens Lake located at 2,300 m a.s.l., shows onset of lake sedimentation at ca. 14 ka and a transition towards a vegetated environment after 8 ka. Final stabilization of moraines occurred at 5 ka, which might reflect denudation acceleration during the Holocene humid phase

Use of a new [10.Be] and [26] Al inventory method to date marine terraces, Santa Cruz, California, USA: Comment

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Quantification of Earth's surface processes and dating using the cosmogenic radionuclides10Be, 26Al and 36Cl [Quantification des processus superficiels et datation par les radionucléides cosmogéniques 10Be, 26Al et 36Cl]

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Applications of in situ-produced cosmogenic nuclides to quantitative geomorphology

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La spectrométrie de masse par accélérateur : Une technique de physique nucléaire appliquée à la reconstitution des variations passées du champ magnétique terrestre

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Quantitative evaluation of soil processes using in situ-produced cosmogenic nuclides

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Dating of the Kocabaş travertines with the 26Al/10Be cosmogenic nuclide method [Datation des travertins de Kocabaş par la méthode des nucléides cosmogéniques 26Al/10Be]

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Cosmic Ray Exposure (CRE) dating in a wet tropical domain: late Quaternary fan emplacements in central Sulawesi (Indonesia)

International audienceAccurate chronological records are critical for studying the alluvial fan sequences emplaced during local/global climatic changes but, in general, there are no satisfactory, quantitative dating methods available. In situ-produced Be-10 concentrations have been measured in quartz boulders exposed on Sulawesian late Quaternary fan surfaces. These concentrations suggest that the two fan units evidenced by geomorphic study were emplaced during two distinct major climatic events. The calculated minimum exposure ages imply abandonment ages of 11 kyr and 120 kyr, for the younger and older units, respectively. This study demonstrates that using both the neutron and muon components implicated in the in situ Be-10 production, surficial erosion rates can be estimated and alluvial fans dated. ln particular, it shows that in situ Be-10 may be used to date fan emplacement during the last 120 kyr under humid tropical conditions, significantly helping to constrain continental palaeoclimatology

Beryllium geochemistry constraints on the hydraulic behavior of mud volcanoes: The Trinidad Island case

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