Thrust Propagation and Syntectonic Sedimentation in the Savoy Tertiary Molasse Basin (Alpine Foreland)

Deville, É.; Blanc, E.; Tardy, Marc; Beck, Christian; Cousin, Michel; Ménard, Gilles

doi:10.1007/978-3-642-78849-9_19

“…Exhumation occurred with little deformation in the central Dauphiné until the lower Miocene, coeval with westward propagation of subsidence and deformation in the foreland molasse basins (Ménard 1988;Guellec et al 1990;Deville et al 1994). During late Miocene times, the exhumation of the Belledonne massif resulted in the study area in backward buttressing, renewed shortening at shallow structural levels (D4) and final exhumation and bending of the Grandes Rousses massif.…”

Section: Integration Of Our Observations With the Alpine Collisionalmentioning

confidence: 99%

Multistage shortening in the Dauphiné zone (French Alps): the record of Alpine collision and implications for pre-Alpine restoration

Dumont

¹

,

Champagnac

²

,

Crouzet³

et al. 2008

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Three-dimensional modelling tools are used with structural and palaeomagnetic analysis to constrain the tectonic history of part of the Dauphiné zone (external Western Alps). Four compressive events are identified, three of them being older than the latest Oligocene. Deformation D1 consists of W-SW directed folds in the Mesozoic cover of the study area. This event, better recorded in the central and southern Pelvoux massif, could be of Eocene age or older. Deformation D2 induced N-NW-oriented basement thrusting and affected the whole southern Dauphiné basement massifs south of the study area. The main compressional event in the study area (D3) was WNW oriented and occurred before 24 Ma under a thick tectonic load probably of Penninic nappes. The D2-D3 shift corresponds to a rapid transition from northward propagation of the Alpine collision directly driven by Africa-Europe convergence, to the onset of westward escape into the Western Alpine arc. This Oligocene change in the collisional regime is recorded in the whole Alpine realm, and led to the activation of the Insubric line. The last event (D4) is late Miocene in age and coeval with the final uplift of the Grandes Rousses and Belledonne external massifs. It produced strike-slip faulting and local rotations that significantly deformed earlier Alpine folds and thrusts, Tethyan fault blocks and Hercynian structures. 3D modelling of an initially horizontal surface, the interface between basement and Mesozoic cover, highlights large-scale basement involved asymmetric folding that is also detected using structural analysis. Both, Jurassic block faulting and basement fold-and-thrust shortening were strongly dependent on the orientation of Tethyan extension and Alpine shortening relative to the late Hercynian fabric. The latter's reactivation in response to oblique Jurassic extension produced an en-échelon syn-rift fault pattern, best developed in the western, strongly foliated basement units. Its Alpine reactivation occurred with maximum efficiency during the early stages of lateral escape, with tectonic transport in the overlying units being sub-perpendicular to it.

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“…4): between Annecy and Geneva (section A), between Aix-les-Bains and Annecy (section B), and south of Les Echelles (section C). They were prepared and balanced using surface surveys, well logs, and various unpublished seismicreflection profiles (Philippe 1994); for this procedure (see also Deville et al 1994), the UMM was treated as a unique volume. …”

Section: Structural Settingmentioning

confidence: 99%

“…1 also Guellec et aL 1990a;Blanc 1991;Allen & Bass 1993;Deville et al 1994). A structural, stratigraphical and sedimentological analysis has been carried out to determine how a shallow-water siliciclastic sedimentation accommodated the compressive deformation of underlying upper crust, and what structural information can be inferred from the internal architecture of the sediments.…”

mentioning

confidence: 99%

“…From the External Crystalline Massifs to the front of the Jura, the westernmost and latest (Oligocene-Miocene) horizontal shortening (several tens of kilometres) was accommodated by a basal d6collement of the Mesozoic-Cenozoic sedimentary pile (Laubscher 1992), associated thrusts and ramp anticlines, transcurrent faults and lateral ramps (Burkhard 1990;Deville et al 1994;Laubscher 1974Laubscher , 1981Laubscher , 1992Mugnier & M6nard 1986;Philippe 1994;Wildi et al 1991;Signer & Gorin 1995;and many others). The aforementioned foreland is widely developed in the Swiss part of the western Alps (approximately north of Geneva, Fig.…”

mentioning

confidence: 99%

“…A structural, stratigraphical and sedimentological analysis has been carried out to determine how a shallow-water siliciclastic sedimentation accommodated the compressive deformation of underlying upper crust, and what structural information can be inferred from the internal architecture of the sediments. Both approaches were aimed to ascertain the timing of deformation, and test previous estimation of the horizontal shortening velocity (Deville et al 1994). Two sets of data are presented: (1) present-day geometrical setting of the different molassic units and (2) internal configuration of these different units, based on a combination of surface geological surveying and oil-industry seismic-reflection data.…”

mentioning

confidence: 99%

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Horizontal shortening control of Middle Miocene marine siliciclastic accumulation (Upper Marine Molasse) in the southern termination of the Savoy Molasse Basin (northwestern Alps/southern Jura)

Beck

¹

,

Deville

²

,

Blanc

³

et al. 1998

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Between the southern Jura and the Subalpine Chains (Bornes, Bauges, and Chartreuse Massifs), the Burdigalian-Langhian-Serravalian tidal siliciclastic 'Upper Marine Molasse' (UMM) outcrops in N-S synclines between N-S-trending ramp anticlines separating southward-narrowing synclines. A surface survey and an interpretation of transverse seismic-reflection profiles across the latter confirm that they represent progressively individualized and separated sedimentation areas. Combined seismic configuration and surface geometry show westward migration of depo-axes, and coeval progressive steepening close to each ramp, upon blind thrusts. Several thick earthquake-disturbed layers offer further evidence of a syntectonic sedimentation. A regime of flexure-subsidence prevailing during the Chattian-Aquitanian (the so-called Lower Freshwater Molasse, LFM) was overprinted by thin-skin shortening. The latter, combined with Burdigalian-Langhian higher eustatic sea-level, favoured the accumulation and the preservation of abundant tidal bedforms and sequences, which are generally poorly preserved in stable settings.

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Multistage shortening in the Dauphiné zone (French Alps): the record of Alpine collision and implications for pre-Alpine restoration

Dumont

¹

,

Champagnac

²

,

Crouzet³

et al. 2008

Orogenic Processes in the Alpine Collision Zone

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Three-dimensional modelling tools are used with structural and palaeomagnetic analysis to constrain the tectonic history of part of the Dauphiné zone (external Western Alps). Four compressive events are identified, three of them being older than the latest Oligocene. Deformation D1 consists of W-SW directed folds in the Mesozoic cover of the study area. This event, better recorded in the central and southern Pelvoux massif, could be of Eocene age or older. Deformation D2 induced N-NW-oriented basement thrusting and affected the whole southern Dauphiné basement massifs south of the study area. The main compressional event in the study area (D3) was WNW oriented and occurred before 24 Ma under a thick tectonic load probably of Penninic nappes. The D2-D3 shift corresponds to a rapid transition from northward propagation of the Alpine collision directly driven by Africa-Europe convergence, to the onset of westward escape into the Western Alpine arc. This Oligocene change in the collisional regime is recorded in the whole Alpine realm, and led to the activation of the Insubric line. The last event (D4) is late Miocene in age and coeval with the final uplift of the Grandes Rousses and Belledonne external massifs. It produced strike-slip faulting and local rotations that significantly deformed earlier Alpine folds and thrusts, Tethyan fault blocks and Hercynian structures. 3D modelling of an initially horizontal surface, the interface between basement and Mesozoic cover, highlights large-scale basement involved asymmetric folding that is also detected using structural analysis. Both, Jurassic block faulting and basement fold-and-thrust shortening were strongly dependent on the orientation of Tethyan extension and Alpine shortening relative to the late Hercynian fabric. The latter's reactivation in response to oblique Jurassic extension produced an en-échelon syn-rift fault pattern, best developed in the western, strongly foliated basement units. Its Alpine reactivation occurred with maximum efficiency during the early stages of lateral escape, with tectonic transport in the overlying units being sub-perpendicular to it. IntroductionThe origin of the arcuate shape of the Western Alpine fold belt is still debated. Some models regard it as inherited either from the shape of the Jurassic margins (Lemoine et al. 1989) or from the shape of the Adriatic indenter (Coward & Dietrich 1989). Other authors propose that the arc was created during Alpine collision due to indentation and lateral escape (e.g. Tapponnier

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Thrust Propagation and Syntectonic Sedimentation in the Savoy Tertiary Molasse Basin (Alpine Foreland)

Cited by 32 publications

References 11 publications

Multistage shortening in the Dauphiné zone (French Alps): the record of Alpine collision and implications for pre-Alpine restoration

Multistage shortening in the Dauphiné zone (French Alps): the record of Alpine collision and implications for pre-Alpine restoration

Horizontal shortening control of Middle Miocene marine siliciclastic accumulation (Upper Marine Molasse) in the southern termination of the Savoy Molasse Basin (northwestern Alps/southern Jura)

Multistage shortening in the Dauphiné zone (French Alps): the record of Alpine collision and implications for pre-Alpine restoration

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