Sur la structure, l'âge et l'origine des « brèches de Bosmendiette » (Pyrénées-Atlantiques)

Canérot, J.; Bauer, Jacques; Bilotte, Michel; Bourdillon, Chantal; Colin, Jean-Paul; Debroas, Elie-Jean; Magniez, F.; Mediavilla, F.; Ternet, Yves

doi:10.1016/j.crte.2004.02.012

Cited by 6 publications

(5 citation statements)

References 3 publications

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“…As clarified by our compilation in section 3 above, sedimentological analysis of the chaotic Larrau‐Sainte‐Engrâce unit, the Lauriolle breccias, the Betchat complex, and well data in the Aquitaine region, collectively demonstrate that the evaporitic chaotic formations were exposed by place on the seafloor during Albian and Cenomanian times. Such situations have been explained by pure diapiric tectonics, without horizontal mobility and by local sliding in response to diapiric extrusion [e.g., Mediavilla and Mauriaud , 1987; James and Canérot , 1999; Canérot et al , 2004]. But evidence of generalized sliding of large portions of the margin favors the hypothesis of diapiric tectonics during generalized horizontal transport as confirmed by the tectonic fabric of the eastern NPZ metaevaporites (Figure 14).…”

Section: Discussion—detachment Tectonic and Gravity Sliding: The Missmentioning

confidence: 94%

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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Section: Discussion—detachment Tectonic and Gravity Sliding: The Missmentioning

confidence: 94%

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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“…Plusieurs travaux [1][2][3]5] ont, ces dernières années, révélé ponctuellement l'inexactitude des arguments cités à l'appui de l'âge Paléocène des formations magmatiques ou sédimentaires concernées. Cette remise en question de la « révolution danienne » est ici développée à l'échelle de l'ensemble du domaine pyrénéen.…”

Section: Selon L'interprétation Classique La Période Danienne Est Con...unclassified

“…These new data have been summarized in a recent paper entitled The Pyrenean 'Danian revolution' [28]. Previous works [1][2][3]5] have shown that these new interpretations were locally unfounded. The so-called Danian revolution is questioned hereafter all over the Pyrenean area.…”

Section: Introductionmentioning

confidence: 99%

Réflexions sur la « révolution danienne » dans les Pyrénées

Canérot¹

2006

Comptes Rendus. Géoscience

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Les arguments magmatiques (mise en place des ophites) ou sédimentologiques (remplissage d'un sillon transpyrénéen sousmarin à brèches et hémipélagites), récemment avancés en faveur d'une étape danienne distensive faisant suite à une phase pyrénéenne compressive majeure, néo ou fini-crétacée, sont ici contestés. Pour nous, le magmatisme tholéiitique des Pyrénées béarnaises est bien triasico-liasique et non paléocène. Le contact entre ophites et encaissant sédimentaire, toujours mécanique, ne se marque en effet jamais par une auréole métamorphique au sein des terrains jurassiques ou crétacés, qui aurait justifié l'âge Danien proposé pour la mise en place de ces roches vertes. Quant aux sédiments bréchiques prétendus sous-marins et riches en foraminifères pélagiques dano-sélandiens, ils correspondent pour nous, soit à des brèches diapiriques éocrétacées, soit à des brèches tectono-karstiques crétacées ou tertiaires, soit à des colluvions quaternaires : le sillon marin danosélandien à brèches n'existe pas. Selon l'interprétation ici retenue, le Paléocène s'inscrit dans la longue période de compression qui s'amorce au Crétacé supérieur et s'accélère au début du Cénozoïque pour conduire à l'étape de structuration majeure des Pyrénées, à l'Éocène moyen-supérieur.

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“…This situation leads us to the following critical observations: 1) every scientific fact must be reproduced. So, if the micro-biophase is abundant, it really might be present in our repeated washings taken in the same places [20,21,22,24]. Unless the pyrenean outcrops result as fossiliferous as those of the preceding BasLanguedoc ones!…”

Section: Biostratigraphical Argumentsmentioning

confidence: 99%

Comment to “Latest-Cretaceous/Paleocene karsts with marine infillings from Languedoc (South of France); paleogeographic, hydrogeologic and geodynamic implications by P. J. Combes et al.”

Bilotte¹,

Bruxelles

Canérot³

et al. 2007

Geodinamica Acta

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Sur la structure, l'âge et l'origine des « brèches de Bosmendiette » (Pyrénées-Atlantiques)

Cited by 6 publications

References 3 publications

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

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

Réflexions sur la « révolution danienne » dans les Pyrénées

Comment to “Latest-Cretaceous/Paleocene karsts with marine infillings from Languedoc (South of France); paleogeographic, hydrogeologic and geodynamic implications by P. J. Combes et al.”

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