Dénudations différentielles du massif cristallin externe alpin de l'Argentera (Sud-Est de la France) révélées par thermochronologie traces de fission (apatites, zircons)

Bigot-Cormier, Florence; Poupeau, Gérard; Sosson, Marc

doi:10.1016/s1251-8050(00)00127-0

Cited by 27 publications

(37 citation statements)

References 9 publications

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“…It occurred as the cover of the massif had already been largely eroded. The increase of exhumation rate recorded at 3.5 Ma by apatite fission tracks by Bigot-Cormier et al [1999 could well correspond to this late stage of out-of-sequence thrusts. These thrusts can also be considered responsible for the recent local uplift of the massif to present altitudes that exceed 3000m.…”

Section: Geodynamic Considerationssupporting

confidence: 58%

“…This massif is characterized by thrust-related exhumation that started as early as 34 Ma [Seward et al, 1999]. Further south, the Argentera Massif has yielded much younger exhumation ages [Bigot Cormier et al, 1999 with an uplift event starting at 28 -25 Ma and a marked increase in uplift rate since 3.5 m.y. This later uplift corresponds better to the exhumation history for the northern E.B.M.…”

Section: Introductionmentioning

confidence: 99%

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Control of Permian and Triassic faults on Alpine basement deformation in the Argentera massif (external southern French Alps)

Delteil¹,

Stéphan²,

Attal³

2003

Bulletin De La Société Géologique De France

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Abstract. -Structural investigations reveal intense and heterogeneous deformation of the sedimentary cover attached to the basement complex of the southern Argentera and Barrot massifs (southernmost External Basement Massifs of the French Alps). Permian and early Triassic syn-depositional extensional tectonics imparted a tilted block pattern to the massifs. An early Miocene first stage of Alpine compression caused pervasive cleavage. This cleavage was controlled by the former pre-existing faults but is nevertheless consistent with NNE contraction. Where regional shortening is orthogonal to the trend of pre-existing faults the pervasive deformation produced either irrotational compressional strain (where no fault inversion occurred), or rotational compressional strain involving syn-cleavage shearing (where faults with favorable paleo-dip were inverted). Where the shortening direction is oblique to the paleo-fault trends, a component of strike-slip movement may locally prevail. A 22 %, N020 o directed horizontal shortening, of 11 km, has been calculated based on deformed sedimentary markers in the Permian series and parallel folds in Lower Triassic quartzite. A shallower deformation as brittle reverse faults postdates the cleavage at the southwestern tip of the Argentera Massif and accounts for 4 km of extra shortening. Both types of deformation are connected at depth to a crustal blind thrust system and the Argentera Massif is over-thrust to the south-southwest. The observed strain indicates the Argentera Massif area underwent, from earliest Miocene to Present, a NNE to N rotating compression at distance from the left-lateral southwestern boundary of the Adria block. Contrôle de failles permiennes et triasiques sur la déformation alpine du socle dans le massif de l'Argentera (Alpes externes méridionales françaises)Mots clés. -Alpes françaises, Massifs externes, Argentera, Déformation de socle, Polyphasage, Failles, Schistosité, Contexte géody-namique.Résumé. -L'étude structurale du tégument des massifs de l'Argentera et du Barrot (massifs de socle les plus méridio-naux des Alpes françaises externes) met en évidence l'intensité et l'hétérogénéité de la déformation. Des failles synsédi-mentaires d'âge permien et triasique inférieur ont découpé ces massifs en une série de blocs basculés. Une première phase de compression alpine a engendré une schistosité pénétrative. Cette schistosité a été contrôlée par les failles héritées précédentes, mais reste néanmoins cohérente avec une direction de serrage NNE. Lorsque la direction du raccourcissement régional est orthogonale aux failles héritées, la déformation syn-schisteuse est soit associée à une défor-mation de type irrotationnel sans inversion tectonique, soit à une déformation rotationnelle avec cisaillement synschisteux là où les failles présentant des paléo-pendages favorables ont été inversées. Lorsque le raccourcissement régional s'est exercé obliquement sur les failles héritées, une composante de mouvement coulissant prédomine. Des marqueurs sédimentaires déformé...

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Section: Geodynamic Considerationssupporting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Control of Permian and Triassic faults on Alpine basement deformation in the Argentera massif (external southern French Alps)

Delteil¹,

Stéphan²,

Attal³

2003

Bulletin De La Société Géologique De France

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“…An important late modification was induced by the retreating Apenninic slab in Late Miocene to Pliocene times (Gueguen et al 1998;Rosenbaum and Lister 2004b). Apatite fission track data document exhumation and cooling ages of the Argentera massif and the Ligurian Alps at 11 Ma, with an acceleration at 5 Ma (Bigot-Cormier et al 2000;Bogdanoff et al 2000;Foeken et al 2003). The 11 Ma age corresponds to the transfer of extension from the Ligurian Sea to the Tyrrhenian (Kastens and Mascle 1990;Rollet et al 2002).…”

Section: Orogen-parallel Extensionmentioning

confidence: 99%

Extensional neotectonics around the bend of the Western/Central Alps: an overview

Sue

Delacou

Champagnac

et al. 2007

Int J Earth Sci (Geol Rundsch)

126

150

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The Western Alps' active tectonics is characterized by ongoing widespread extension in the highest parts of the belt and transpressive/compressive tectonics along its borders. We examine these contrasting tectonic regimes using a multidisciplinary approach including seismotectonics, numerical modeling, GPS, morphotectonics, fieldwork, and brittle deformation analysis. Extension appears to be the dominant process in the present-day tectonic activity in the Western Alps, affecting its internal areas all along the arc. Shortening, in contrast, is limited to small areas located along at the outer borders of the chain. Strike-slip is observed throughout the Alpine realm and in the foreland. The stress-orientation pattern is radial for r3 in the inner, extensional zones, and for r1 in the outer, transcurrent/tranpressional ones. Extensional areas can be correlated with the parts of the belt with the thickest crust. Quantification of seismic strain in tectonically homogeneous areas shows that only 10-20% of the geodesy-documented deformation can be explained by the Alpine seismicity. We propose that, Alpine active tectonics are ruled by isostasy/buoyancy forces rather than the ongoing shortening along the Alpine Europe/Adria collision zone. This interpretation is corroborated by numerical modeling. The Neogene extensional structures in the Alps formed under increasingly brittle conditions. A synthesis of paleostress tensors for the internal parts of the West-Alpine Arc documents major orogen-parallel extension with a continuous change in r3 directions from ENE-WSW in the Simplon area, to N-S in the Vanoise area and to NNW-SSE in the Briançon area. Minor orogen-perpendicular extension increases from N to S. This second signal correlates with the present-day geodynamics as revealed by focal-plane mechanisms analysis. The orogen-parallel extension could be related to the opening of the Ligurian Sea during the Early-Middle Miocene and to compression/ rotation of the Adriatic indenter inducing lateral extrusion.

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“…These massifs are characterised by some of the highest topography and relief of the Alpine orogen and concentrate most of it's >4000 m high peaks. Low-temperature thermochronology data indicate that the external crystalline massifs have undergone km-scale denudation since Late Pliocene times (3-5 Ma; e.g., Bigot-Cormier et al, 2000;Leloup et al, 2005;Michalski and Soom, 1990) and they are also the site of rapid present-day rock uplift (up to 1 mm/y; Jouanne et al, 1995;Kahle et al, 1997). …”

Section: Geological and Geomorphic Settingmentioning

confidence: 99%

A quantification of the glacial imprint on relief development in the French western Alps

Beek

Bourbon

2008

Geomorphology

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Mail: pvdbeek@ujf-grenoble.fr AbstractThe morphology of the western Alps has been strongly influenced by Quaternary glaciations.On the basis of observations of glacial morphology in the Belledonne, Grandes-Rousses, Taillefer and Pelvoux-Ecrins Massifs (south-eastern France), we reconstitute the glacial trimline and equilibrium line altitude (ELA) during the most extensive glaciation (MEG). Our best estimate of the MEG ELA is 1800±100 m. Using digital elevation models, we compare our glacial reconstruction with the relief structure of 9 major catchments draining the massifs. This number is insufficient to substantially offset topographic lowering due to regional denudation, and we conclude that the isostatic response to glacial valley carving has not increased peak elevations significantly.

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Dénudations différentielles du massif cristallin externe alpin de l'Argentera (Sud-Est de la France) révélées par thermochronologie traces de fission (apatites, zircons)

Cited by 27 publications

References 9 publications

Control of Permian and Triassic faults on Alpine basement deformation in the Argentera massif (external southern French Alps)

Control of Permian and Triassic faults on Alpine basement deformation in the Argentera massif (external southern French Alps)

Extensional neotectonics around the bend of the Western/Central Alps: an overview

A quantification of the glacial imprint on relief development in the French western Alps

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