Salt tectonics, Tethyan rifting and Alpine folding in the French Alps

Mascle, Georges; Arnaud, Hubert; Dardeau, G.; Debelmas, Jacques; Delpech, P.-Y.; Dubois, Pierre; Gidon, M.; Graciansky, P. C. de; Kerckhove, Christian Van; Lemoine, Maël

doi:10.2113/gssgfbull.iv.5.747

Cited by 26 publications

(16 citation statements)

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“…The "Terres Noires" Formation has also been identified in boreholes in the south in Camargue and Provence (Dardeau, 1988). Subsidence was mostly due to basement faults with kinematics controlled by salt withdrawal in the extensional domain of the margin (Mascle et al, 1988). The fluid seep sites are bounded to the west by major salt-rooted faults which facilitated growth of the main salt diapirs into the marls, as at Propiac and Condorcet (Fig.…”

Section: Geological Settingmentioning

confidence: 94%

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3D morphology and timing of the giant fossil pockmark of Beauvoisin, SE Basin of France

Gay

López

Potdevin

et al. 2018

JGS

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The resolution of data acquired over modern seafloors does not allow imaging of the inner features of a fluid seep structure, particularly in the shallow subsurface. In the SE Basin of France (Drôme), fossil cold seep structures comprising fossil-rich carbonate lenses were identified about 30 years ago within the Oxfordian (Late Jurassic) Terres Noires Formation. These structures were first interpreted as pseudo-bioherms related to hydrothermal activity, but comparison with active seep sites on modern margins, together with isotopic analyses, led to a reinterpretation involving cold fluids instead. To date, all seep sites have generally been studied individually without considering any link to neighbouring or more distant sites. Based on 23 high-resolution stratigraphic logs within the structure coupled to mosaicked aerial photographs from a drone survey, 19 fluid seep events were correlated in the area, including two new sites exposed as a result of weathering. We have shown that each identified sub-site is composed of subvertically stacked fossil-rich carbonate lenses interbedded with marls, which developed in smooth, 4–6 m deep depressions beneath the local seabed. The nodules present within the depressions are of primary importance as they mark the area of active seeping. This general organization is very similar to the modern Regab giant pockmark in the Lower Congo Basin where only a few sub-sites are active at the same time. A spatio-temporal 3D reconstruction of the position of these sub-sites shows that the carbonate lenses are organized into clusters comprising up to seven sub-sites grouped together in the same stratigraphic interval and the same geographical zone. A sandbox experiment where gas is injected at constant flow rate at the base of a box filled with a matrix of water-saturated grains displays a pattern consisting of disturbed sediments inside a parabolic-shaped area. This parabolic shape was also identified on a seismic profile across the Regab giant pockmark, suggesting that the processes are similar for the Beauvoisin and Regab seep areas. The laboratory experiments also show that the seeping conduit is stable during a given period of time and suddenly shifts laterally. This is mainly as a result of the collapse of the conduit, the lateral migration and the reopening at a new position. The general log obtained in the Beauvoisin seep area suggests a similar pattern with periods of seeping alternating with periods of quiescence, each of which is c . 200 kyr. Even if a pockmark seems to have been inactive for a long period of time, this could be due to the lateral shift of the feeder conduit, meaning that the sub-seafloor is still charged with gas. This is of primary importance for risk assessment, hydrocarbon exploration and general understanding of geobiology at seafloor seeps.

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Section: Geological Settingmentioning

confidence: 94%

“…To date the origin of focused fluids has never been clearly elucidated. They were hypothetically related to crustal faults (Lemoine, 1988), to halokinesis (Mascle et al, 1988) or to biogenic origin derived from the decomposition of organic matter contained in the "Terres Noires" Formation (Gaillard et al, 1996).…”

Section: Geological Settingmentioning

confidence: 99%

3D morphology and timing of the giant fossil pockmark of Beauvoisin, SE Basin of France

Gay

López

Potdevin

et al. 2018

JGS

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“…They may have a deep origin, related to crustal faults (Lemoine 1985; Lemoine et al. 1986), an intermediate provenance related to halokinesis (Mascle et al. 1988) or a superficial source related to simple undercompaction of the thick Terres Noires Formation that is rich in organic matter.…”

Section: Geological Settingmentioning

confidence: 99%

Tithonia oxfordiana, a new irregular echinoid associated with Jurassic seep deposits in south‐east France

2011

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Abstract:The infaunal irregular echinoid, Tithonia oxfordiana, is described and compared to congeneric species previously described from Upper Jurassic and lowermost Cretaceous strata. This new species characterizes a monospecific echinoid assemblage, which occurs only in some places where deep-marine middle Oxfordian deposits are exposed in south-east France. Specimens are closely packed and clearly concentrated at the top of small carbonate chemoherms; a close connection of the echinoids with the emission of reduced chemicals, which were oxidized by chemoautotrophic bacteria, is highly probable. Based on general test shape and plate architecture, T. oxfordiana probably was a deposit feeder on chemosynthetic organic matter produced by such bacteria. In view of the fact that T. oxfordiana is the sole species of the Jurassic genus Tithonia known from Oxfordian strata, it is postulated that chemoherms possibly acted as refugia for these peculiar echinoids, which have an episodic record between the Callovian and Valanginian.

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“…These evaporitic levels, which acted as a prominent thrust décollement levels during the compressional stages, were also associated with pre-contractional salt-related structures (Mennessier, 1959a;Guieu, 1968;Angelier and Aubouin, 1976;Tempier, 1987;Philip et al, 1987;Mascle et al, 1988;Dardeau et al, 1990;Roure and Colletta, 1996;Huyghe et al, 1999;Bestani et al, 2015Bestani et al, , 2016. Isolated diapiric salt structures were described in detail decades ago along the inverted southern Alpine Tethys-North Provence passive margin transition as, for example, the Condorcet, Propiac, Suzette, Lazer and Barles diapirs (Emré and Truc, 1978;Casagrande et al, 1989;Dardeau et al, 1990;Dardeau and de Graciansky, 1990; Huyghe et al, 1999;Graham et al, 2012).…”

Section: Introductionmentioning

confidence: 96%

Mesozoic halokinesis and basement inheritance in the eastern Provence fold-thrust belt, SE France

et al. 2019

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The Provence Chain incorporated preexisting halokinetic and basement features which have played a key role in the structural evolution of the thrust systems. Field structural data, previously published geological maps and exploration well data have been used to interpret a new ~80 km-long balanced and restored cross section across the eastern Provence fold-thrust Diapiric structures were mainly eroded during and after the Pyrenean-Provence compression then reactivated during Oligocene extension and Miocene to present-day Alpine compression. Cross section balancing shows a total horizontal shortening of 28.5 km related to the Pyrenean-Provence and Alpine compressions. The eastern Provence fold-thrust belt integrates preexisting halokinetic folding which can be misinterpreted as resulting to compression. This suggests that a significant amount of folding in fold-thrust belts can results from an early halokinetic fold system developed during the pre-contractional passive margin evolution.

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Salt tectonics, Tethyan rifting and Alpine folding in the French Alps

Cited by 26 publications

References 0 publications

3D morphology and timing of the giant fossil pockmark of Beauvoisin, SE Basin of France

3D morphology and timing of the giant fossil pockmark of Beauvoisin, SE Basin of France

Tithonia oxfordiana, a new irregular echinoid associated with Jurassic seep deposits in south‐east France

Mesozoic halokinesis and basement inheritance in the eastern Provence fold-thrust belt, SE France

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