How the presence of a salt <i>décollement</i> in the sedimentary cover influences the behavior of subsalt thrusts in fold-and-thrust belts

Vendeville, Bruno C.; Tang, Ping; Graveleau, Fabien; Huang, Shilin; Wang, Xin

doi:10.1051/bsgf/2017202

Cited by 6 publications

(2 citation statements)

References 28 publications

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“…Evaporites are found all over the world in fold and thrust belts including among others: Alps (e.g., Malavieille and Ritz, 1989;Graham et al, 2012), Himalaya (e.g., Baker et al, 1988), Pyrénées (e.g., Canérot et al, 2005), Turkey (e.g., Kergaravat et al, 2016), Zagros (e.g., Callot et al, 2012). Evaporites are well documented in many orogenic structures as remarkable décollement layers (Davis and Engelder, 1985;Vendeville et al, 2017). Geomechanical experiments and models both under compressive (e.g., Costa and Vendeville, 2002;Gemmer et al, 2005;Dooley et al, 2012) and extensive regimes (e.g., Vendeville et al, 1995) have brought a series of key information on its mechanism.…”

Section: Introductionmentioning

confidence: 99%

Tectono-metamorphic evolution of an evaporitic décollement as recorded by mineral and fluid geochemistry: The “Nappe des Gypses” (Western Alps) case study

Barré

Strzerzynski

Michels

et al. 2020

Lithos

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Evaporites play a major role on the structuration of collisional orogens especially when they act as décollement units. However, their exact pressure-temperature-deformation (P-T-d) paths are poorly documented. In this study, the first direct P-T-d constraints of the "Nappe des Gypses" formation (western French Alps) have been established. An innovative association of structural geology, petrography, crystallochemistry, and detailed study of both fluid inclusions and stable isotopes (C, O) analysis has been applied to this evaporitic facies. Geochemical analysis shows that the "Nappe des Gypses" formation has recorded the three typical metamorphic and deformational events of the Alps (namely D1, D2 and D3). These different constraints allow the determination of the first determination of the P-T path for this unit. Metamorphic peak conditions of the "Nappe des Gypses" are at 16.6 ± 2.3 kbars and 431°C ± 28°C. This formation was buried at similar conditions than the oceanic units. During the exhumation path, the D1-D2 transition is reached at 350°C ± 20°C and 6.5 ± 1.8 kbars and the D2-D3 transition is assumed to be at 259°C ± 24°C and 2.0 ± 1.0 kbars (Strzerzynski et al., 2012). Peak P-T conditions overlap those of the median Liguro-Piemontese units but are different from those of the Briançonnais units. It implies 1) an active and crucial role of the "Nappe des Gypses" during the exhumation of the Alpine oceanic complex. And 2) confirms the allochthonous and more distal origin of the European Thetysian passive margin of the "Nappe des Gypses" formation. Consideration of sulfates dehydration probably between 15.0 and 16.6 kbars and 200 and 300°C, allows to discuss pore pressure excess and its mechanical consequences on the exhumation process. This process is very likely to amplify the "décollement" effect of the evaporites and allow the nappe stack formation. This illustrates the role of this formation as a décollement surface. This difference of evolution highlights the major role of the evaporitic formations on the exhumation and structuration of a collisional chain. Such methodology could contribute to decipher the role of evaporites in the structural context of other collisional chains such as Himalaya, Pyrenees or Zagros.

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Section: Introductionmentioning

confidence: 99%

Tectono-metamorphic evolution of an evaporitic décollement as recorded by mineral and fluid geochemistry: The “Nappe des Gypses” (Western Alps) case study

Barré

Strzerzynski

Michels

et al. 2020

Lithos

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“…This is the case with clay-rich or evaporite-rich strata (so-called décollement layers). Such a weak and continuous décollement layer will allow the displacement of allochton units over significant distances whatever the orientation of the fault zone with respect to the stress axes is favorable or not [Davis and Engelder, 1985, Weijermars et al, 1993, Costa and Vendeville, 2002, Vendeville et al, 2017.…”

Section: The Reactivation Of Moderately To Severely Misoriented Fault...mentioning

confidence: 99%

Fluids, faulting and earthquakes in the brittle crust: recent advances and new challenges

Fabbri,

Raimbourg,

Leclère

2024

Comptes Rendus. Géoscience

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Interactions between fluids and deformation are widespread in the brittle crust. As experimentally shown, a high pore fluid pressure p f can fracture intact rocks or reactivate pre-existing fractures. The preference of reactivation over the formation of a new fracture depends on the orientation of the pre-existing fracture with respect to the stress axes and on p f . In nature, the predominant reactivation of misoriented pre-existing faults rather than the formation of new faults with more favorable orientations suggests that pressurized fluids are present in the brittle crust. There is a large body of evidence indicating that supra-hydrostatic p f contributes to the reactivation of lowangle thrust faults or normal faults. Conversely, supra-hydrostatic p f values are less common along vertical or steeply dipping plate boundary transform faults or intra-continental strike-slip faults. If these faults are severely misoriented with respect to the ambient stress field, their reactivation may not be due to supra-hydrostatic p f but to other mechanisms such as shear-enhanced compaction or thermal pressurization. Supra-hydrostatic p f also plays a role in the nucleation or propagation of seismic ruptures in the continental or oceanic crust, and in subducting slabs in convergent margins, as reported for aftershocks, swarms, slow earthquakes, and to a lesser extent for major earthquakes. Lastly, increase or decrease of p f in depth due to human activities such as hydrocarbon extraction, dam impoundment, gas storage or geothermal energy production result in many cases in the inception or enhancement of seismic activiy, adding clues in favor of a relationship between fluids and earthquakes.

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Analogue modeling as a tool to assist seismic structural interpretation in the Andean fold-and-thrust belt

Ferrer¹,

Santolaria²,

Muñoz³

et al. 2022

Andean Structural Styles

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How the presence of a salt décollement in the sedimentary cover influences the behavior of subsalt thrusts in fold-and-thrust belts

Cited by 6 publications

References 28 publications

Tectono-metamorphic evolution of an evaporitic décollement as recorded by mineral and fluid geochemistry: The “Nappe des Gypses” (Western Alps) case study

Tectono-metamorphic evolution of an evaporitic décollement as recorded by mineral and fluid geochemistry: The “Nappe des Gypses” (Western Alps) case study

Fluids, faulting and earthquakes in the brittle crust: recent advances and new challenges

Analogue modeling as a tool to assist seismic structural interpretation in the Andean fold-and-thrust belt

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