Flysch et molasse, approche sedimentologique

Beaudoin, Bernard; Gigot, Patrick; Haccard, D.

doi:10.2113/gssgfbull.s7-xii.4.664

Cited by 6 publications

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“…The sedimentological characteristics of molasse are distinctive (Beaudoin et al 1970), but such facies are not found exclusively in molasse sequences. Thus, clastic wedges in cratonic settings may be stratigraphicaliy and sedimentologically identical to molasse, and a few workers would broaden this term to include them (Mazarovich 1972).…”

Section: Classification Of Nonmarine-paralic Sedimentarymentioning

confidence: 99%

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Tectonic setting and syndepositional deformation of molasse and other nonmarine-paralic sedimentary basins

Miall¹

1978

Can. J. Earth Sci.

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Molasse is a distinctive sedimentary facies consisting of alluvial and shallow marine deposits derived from source areas undergoing rapid uplift and erosion. The characteristic setting of molasse is within or adjacent to fold belts, and most molasse basins can be classified as foreland basin (external) or intermontane (internal) in type. Thick alluvial and shallow marine sequences in cratonic settings (e.g., taphrogenic troughs) have been classified as molasse by some workers, but this is not generally accepted.Most molasse is synorogenic, and the interdependence of sedimentation and tectonism results in structural and stratigraphic complexity. Intermontane basins generally are tensional in origin and are bounded by high angle (commonly normal) faults. Facies distributions adjacent to each fault depend on relative rates of differential movement, erosion, and sedimentation; accelerated source area uplift causes segmentation and progradation of alluvial fans and generates coarsening-upward sedimentary cycles. Complications are introduced if tectonism occurs in discrete pulses and if basins enlarge themselves along systems of stepped faults.Basins of compressional origin, such as those in a foreland setting, show a greater variety of internal complexity. Facies belts and trends of maximum thickness move progressively out from the core of the fold belt in response to a migration of the zone of active deformation. Conversely, broad structural warps may develop in response to alocally increased sedimentary load, such as a major delta. Folds or thrust faults growing within the basin cause local thinning or unconformable relationships, and may breach the surface so as to isolate parts of the alluvial plain as a synorogenic intermontane basin. Uplift of the fold belt may be discontinuous, causing the generation of stacked sedimentary megacycles. Basin margins commonly are characterized by intraformational angular unconformities and syndepositional folds.Rates of alluvial sedimentation and tectonic movement measured in modern environments are one to two orders of magnitude higher than rates deduced from ancient nonmarine sequences. This lends support to the idea that much sedimentation may be very episodic in nature, but it could also imply that alluvial sequences are deposited much more rapidly than current interpretations of the ancient record would imply, based as they are on relatively crude dating techniques. Only in some wrench-fault basins do calculated sedimentation rates compare with those measured in modern environments. -A .Les taux de sedimentation alluviale et de mouvement tectonique dans des milieux recents sont d'un a deux ordres de grandeur plus eleves que les taux deduits pour les sequences non marines anciennes. Ceci supporte I'idee qu'une grande partie de la sedimentation pourrait Ctre de nature tres episodique mais pourrait aussi impliquer que les sequences alluviales se sont deposees beaucoup plus rapidement que les interpretations courantes des dep6ts anciens le laissent supposer, puisqu'elles sont ba...

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Section: Classification Of Nonmarine-paralic Sedimentarymentioning

confidence: 99%

“…8). Incipient structures of this type are present in the molasse of southeast France (Beaudoin et al 1970), and a transverse structure, the Lochinvar Anticline, is present in the Permian coal measures of the Sydney Basin (Branagan 1976). Weimer (1970, Fig.…”

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confidence: 99%

Tectonic setting and syndepositional deformation of molasse and other nonmarine-paralic sedimentary basins

Miall¹

1978

Can. J. Earth Sci.

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“…The terms 'underfilled' and 'overfilled' (Allen, Crampton & Sinclair 1991) can be used qualitatively to describe the depositional state of a foreland basin. These terms are directly comparable with 'flysch' and 'molasse' which have been used to describe the stratigraphy of the Alpine Foreland Basin (Beaudoin, Gigot & Haccard 1970 ;Matter, Homewood et d. 1980;Homewood ct d..1986), and the Apennines (reviewed in Ricci-Lucchi 1986). Similar deep to shallow-water trends in depositional environments have been described from the Himalayan foredeep (Graham, Dickinson & Ingersoll 1975;Parkash, Sharma 8i Roy 1980), the South Pyrenean foredeep (Labaume, %wet & Seyve 1980), the Plio-Pleistocene foreland basin of western Taiwan (Covey 1986), the Cretaceous-Temary Colville Trough of northern Alaska (CoPkIey & Watts 199 I), and the Carboniferous Arkoma Basin ofSE USA (Houseknecht 1986).…”

Section: Introductionmentioning

confidence: 99%

Vertical versus horizontal motions in the Alpine orogenic wedge: stratigraphic response in the foreland basin

Sinclair

Allen²

1992

Basin Research

191

183

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The long‐term (50 Myr) development of orogenic thrust wedges and their neighbouring foreland basins are inextricably linked. Foreland basins, such as occur nonh of the Alps, flanking the Pyrenees, east of the Apennines and south of the Himalayas, are characterized by an early underfilled (deep‐water) phase, followed by a filled (shallow‐marine) or overfilled (continental) phase. The extent to which a foreland basin is filled to sea‐level can be understood by comparing, over time, the rate at which sediment is delivered to the basin with the rate at which accommodation space is generated within the basin. This approach is applied to the Alpine thrust wedge/North Alpine Foreland Basin (NAFB) system. Using simple geometrical calculations assuming a critically tapered thrust wedge sliding over a foreland plate, preceded by a flexurally induced trough (foreland basin), it is possible to develop some general parameter relationships for the system. The thrust wedge is described firstly in terms of the history of exhumation which is directly linked to denudation and hence sediment generation, and secondly to thrust front advance rates. The accommodation space can be approximated by the product of the thrust front advance rate and the deflection of the basin at the thrust front. The extent to which a basin is, at one instant, being undersupplied or oversupplied (F) can then be described by the ratio of sediment supply to accommodation space generated: F=exhumation rate. width of thrust wedgeladvance rate. deflection at thrust front When F> I, the basin is on a trend towards overfilling, and when F< 1 the basin is on a trend towards underfilling. The value for the width of the thrust wedge undergoing exhumation is held as a constant for most of the evolution of the NAFB. The development of the Alpine thrust wedge/NAFB system is characterized by an initial submarine phase (Cenomanian to mid‐Oligocene) of rapid thrust front advance and slow exhumation rates; this resulted in deep‐water and shelfal sedimentation in the foreland basin (F< 1), and is described as the occretionary wedge phase. By the mid‐Oligocene, exhumation rates were accelerating associated with major backthrusting, and frontal advance rates were slowing down; this resulted in the foreland basin being filled to sea‐level (F← 1), accumulating shallow‐marine and continental sediments. This period is described as the continental wedge phase. Although F‐values probably fell back to close to 1 following the period of major Oligocene exhumation, the basin remained in its filled state for the remainder of its geological history. Modern studies indicate that rapid exhumation rates lead to increased local relief and denudation. The increased relief causes increased maximum elevations, so enhancing orographic precipitation and glaciation leading to further increases in denudation. This positive feedback loop between denudation, exhumation and climate may have enhanced the rapid inversion of the core of the orogenic wedge during the latter part of its growth.

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“…The transgressive Aquitanian-Burdigalian Lower Marine Molasse Formation consists in tidal facies deposited in major subsiding environment that pass northward into siliciclastic deposits sourced from the inner Alps domain (Couëffe et al, 2004). The Langhian to Tortonian-lower Messinian succession is composed of marls, coarse-grained sandstones and limestones alternations of the Upper Marine Molasse Formation that pass laterally to prograding fluviodeltaic conglomerate sequences of the Valensole 1 Formation (Beaudouin et al, 1966(Beaudouin et al, , 1970Dubois and Curnelle 1978;Mercier, 1979;Aguilar and Clauzon, 1981;Haccard et al, 1989b;Clauzon et al, 1989;Besson, 2005;Cojan et al, 2013;Fig. 5b).…”

Section: Cenozoic Foreland Successions In Subalpine Zone: Barles Zone...mentioning

confidence: 99%

Structural evolution of the superimposed Provençal and Subalpine fold-thrust belts (SE France)

Balansa

Espurt

Hippolyte

et al. 2022

Earth-Science Reviews

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Flysch et molasse, approche sedimentologique

Abstract: Examples from France and Italy of both rock types, differences in characteristics, evolution of basins

Cited by 6 publications

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Tectonic setting and syndepositional deformation of molasse and other nonmarine-paralic sedimentary basins

Tectonic setting and syndepositional deformation of molasse and other nonmarine-paralic sedimentary basins

Vertical versus horizontal motions in the Alpine orogenic wedge: stratigraphic response in the foreland basin

Structural evolution of the superimposed Provençal and Subalpine fold-thrust belts (SE France)

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