Presence d'une marge meridionale a l'emplacement de la zone des chainons bearnais (Pyrenees basco-bearnaises)

Canérot, J.; Peybernès, Bernard

doi:10.2113/gssgfbull.s7-xx.5.673

Cited by 25 publications

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“…Only few half‐graben basins (i.e., low‐ β extensional settings; Figure ) are described from the hyperthinned domain of the Armorican margin [ Thinon , ; Thinon et al , ]. Remnants of extensional rift structures and top basement extensional detachment faults are described locally onshore in the Mauléon basin [e.g., Canérot et al , ; Canérot , ; Johnson and Hall , , ; Jammes et al , ; Masini et al , ], in the Aulus basin [e.g., Lagabrielle et al , ], or in the Basque‐Cantabrian basin [e.g., Tavani and Muñoz , ; Bodego and Agirrezabala , , and references therein].…”

Section: Map Of the Bay Of Biscay‐pyrenean Rift Systemmentioning

confidence: 99%

“…Only few half-graben basins (i.e., low-β extensional settings; Figure 2) are described from the hyperthinned domain of the Armorican margin [Thinon, 1999;Thinon et al, 2003]. Remnants of extensional rift structures and top basement extensional detachment faults are described locally onshore in the Mauléon basin [e.g., Canérot et al, 1978;Canérot, 1989;Hall, 1989a, 1989b;Jammes et al, 2009;Masini et al, 2014] characterized by NE-SW transfer faults [Derégnaucourt and Boillot, 1982;Thinon et al, 2003] that may be partly related to the Variscan structuration observed onshore [Thinon, 1999]. The offshore prolongation over the continental shelf is underlined by magnetic and gravity trends and is suggested to be partly controlled by the Armorican shear zone [e.g., Sibuet, 1973;Thinon, 1999].…”

Section: Extensional Faultsmentioning

confidence: 99%

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Formation and deformation of hyperextended rift systems: Insights from rift domain mapping in the Bay of Biscay-Pyrenees

et al. 2014

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The Bay of Biscay and the Pyrenees correspond to a Lower Cretaceous rift system including both oceanic and hyperextended rift domains. The transition from preserved oceanic and rift domains in the West to their complete inversion in the East enables us to study the progressive reactivation of a hyperextended rift system. We use seismic interpretation, gravity inversion, and field mapping to identify and map former rift domains and their subsequent reactivation. We propose a new map and sections across the system illustrating the progressive integration of the rift domains into the orogen. This study aims to provide insights on the formation of hyperextended rift systems and discuss their role during reactivation. Two spatially and temporally distinct rift systems can be distinguished: the Bay of Biscay-Parentis and the Pyrenean-Basque-Cantabrian rifts. While the offshore Bay of Biscay represent a former mature oceanic domain, the fossil remnants of hyperextended domains preserved onshore in the Pyrenean-Cantabrian orogen record distributed extensional deformation partitioned between strongly segmented rift basins. Reactivation initiated in the exhumed mantle domain before it affected the hyperthinned domain. Both domains accommodated most of the shortening. The final architecture of the orogen is acquired once the conjugate necking domains became involved in collisional processes. The complex 3-D architecture of the initial rift system may partly explain the heterogeneous reactivation of the overall system. These results have important implications for the formation and reactivation of hyperextended rift systems and for the restoration of the Bay of Biscay and Pyrenean domains.

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Section: Map Of the Bay Of Biscay‐pyrenean Rift Systemmentioning

confidence: 99%

Section: Extensional Faultsmentioning

confidence: 99%

Formation and deformation of hyperextended rift systems: Insights from rift domain mapping in the Bay of Biscay-Pyrenees

et al. 2014

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“…They form a succession of three E‐W trending, parallel fold structures, the Mail Arrouy, Sarrance, and Layens anticlines, bounded by north and south verging, post‐Cenomanian thrusts (Casteras et al, ; Figure ). The prerift stratigraphic sequence of the Chaînons Béarnais includes basal Keuper evaporites, breccia, and ophites and is followed by Mesozoic platform carbonates, both forming the original cover of the northern Iberian margin (Canérot et al, ; Canérot & Delavaux, ). The platform carbonates include Lower Jurassic dolomites and Upper Jurassic to Aptian platform limestones and form the present‐day main relief.…”

Section: Geological Settingmentioning

confidence: 99%

How Do Continents Deform During Mantle Exhumation? Insights From the Northern Iberia Inverted Paleopassive Margin, Western Pyrenees (France)

et al. 2019

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Extreme crustal thinning associated with subcontinental mantle exhumation characterizes the distal domain of some current, magma‐poor continental passive margins. Since these domains lie at abyssal depths and are hardly accessible, their internal structure and the finite strain of the stretched crust are not directly observed and are only inferred. A detailed field study was conducted on exceptionally preserved Cretaceous distal margin analogs in two key areas of the western Pyrenees (North Pyrenean Zone): the Urdach and Saraillé ultramafic massifs in the Chaînons Béarnais range. A tight sampling allowed us to characterize the conditions of the ductile deformation of the continental crust exhumed together with the mantle. New 40Ar/39Ar dating on muscovite constrains the timing of the last deformation of the continental crust in relation with mantle exhumation to the late Albian. We propose a new reconstruction for the distal part of the North Iberian paleopassive margin based on the following constraints: (i) post‐Silurian Paleozoic rocks are never found in the distal domain; (ii) lower crustal levels are not found in the exhumed crustal units; (iii) extension in the pre‐Silurian series is accomplished by lenticular deformation and pervasive ductile flattening through anastomosing extensional mylonitic shear zones at temperatures of 350–450 °C; and (iv) at the final step of exhumation, only pre‐Silurian crustal lenses remained welded on the exhumed mantle. Finally, we discuss the importance of the crustal structure inherited from previous Paleozoic and Mesozoic tectonic events and we state that mantle exhumation was partially achieved before the Cretaceous North Pyrenean rifting.

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“…The Mesozoic sediments form a succession of three E-W trending, parallel fold structures, the Mail Arrouy, Sarrance and Layens anticlines, bounded by north (Layens) and south (Mail Arrouy and Sarrance) verging, post-Cenomanian thrusts [Castéras et al, 1970] ( Figures 5 and 8). The base of the stratigraphic sequence is represented by Upper Triassic evaporites, breccias and ophites and is followed by Mesozoic platform carbonates, both forming the original cover of the northern Iberian margin [Canérot et al, 1978;Canérot and Delavaux, 1986] [Ternet et al, 1997] and on our own field observations. quent transition between the platform carbonates and the flysch deposits [Castéras, 1970] document an onset of tectonic instabilities at the Aptian-Albian transition.…”

Section: Tectonic Type (T Type): Lherzolites Lenses Associated With Tmentioning

confidence: 99%

Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): Insights from the geological setting of the lherzolite bodies

2010

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[1] The Pyrenean peridotites (lherzolites) form numerous small bodies of subcontinental mantle, a few meters to 3 km across, exposed within the narrow north Pyrenean zone (NPZ) of Mesozoic sediments paralleling the north Pyrenean Fault. Recent studies have shown that mantle exhumation occurred along the future NPZ during the formation of the AlbianCenomanian Pyrenean basins in relation with detachment tectonics. This paper reviews the geological setting of the Pyrenean lherzolite bodies and reports new detailed field data from key outcrops in the Béarn region. Only two types of geological settings have to be distinguished among the Pyrenean ultramafic bodies. In the first type (sedimented type or S type), the lherzolites occur as clasts of various sizes, ranging from millimetric grains to hectometric olistoliths, within monogenic or polymictic debris flow deposits of Cretaceous age, reworking Mesozoic sediments in dominant proportions as observed around the Lherz body. In the second type (tectonic type or T type), the mantle rocks form hectometric to kilometric slices associated with crustal tectonic lenses. Both crustal and mantle tectonic lenses are in turn systematically associated with large volumes of strongly deformed Triassic rocks and have fault contacts with units of deformed Jurassic and Lower Cretaceous sediments belonging to the cover of the NPZ. These deformed Mesozoic formations are not older that the Aptian-early Albian. They are unconformably overlain by the Albian-Cenomanian flysch formations and have experienced high temperature-low pressure mid-Cretaceous metamorphism at variable grades. Such a tectonic setting characterizes most of the lherzolite bodies exposed in the western Pyrenees. These geological data first provide evidence of detachment tectonics leading to manle exhumation and second emphasize the role of gravity sliding of the Mesozoic cover in the preorogenic evolution of the Pyrenean realm. In the light of such evidence, a simple model of basin development can be inferred, involving extreme thinning of the crust, and mantle uprising along a major detachment fault. We demonstrate coeval development of a crust-mantle detachment fault and generalized gravitational sliding of the Mesozoic cover along lowangle faults involving Triassic salt deposits as a tectonic sole. This model accounts for the basic characteristics of the precollisional rift evolution in the Pyrenean realm. Citation: Lagabrielle, Y., P. Labaume, and M. de Saint Blanquat (2010), Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): Insights from the geological setting of the lherzolite bodies, Tectonics, 29, TC4012,

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Presence d'une marge meridionale a l'emplacement de la zone des chainons bearnais (Pyrenees basco-bearnaises)

Cited by 25 publications

References 0 publications

Formation and deformation of hyperextended rift systems: Insights from rift domain mapping in the Bay of Biscay-Pyrenees

Formation and deformation of hyperextended rift systems: Insights from rift domain mapping in the Bay of Biscay-Pyrenees

How Do Continents Deform During Mantle Exhumation? Insights From the Northern Iberia Inverted Paleopassive Margin, Western Pyrenees (France)

Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): Insights from the geological setting of the lherzolite bodies

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