Evolution of salt structures of the Pyrenean rift (Chaînons Béarnais, France) : From hyper-extension to tectonic inversion
Labaume, Pierre (Centre National de la Recherche Scientifique. Université de Montpellier)
Teixell Cácharo, Antonio (Universitat Autònoma de Barcelona. Departament de Geologia)

Fecha:	2020
Resumen:	The Chaînons Béarnais is a salt-detached fold belt in the northern Pyrenees that formerly occupied the axis of the Cretaceous Pyrenean rift. Geological map revision and cross-section construction from surface geology and industrial well and seismic reflection data emphasize the role of salt diapirism in the folding of the belt during the Cretaceous extension and the subsequent Pyrenean orogeny. Pre-rift Triassic evaporites played a fundamental role during rifting, allowing the sedimentary basin lying above to detach and slide down the hyper-extended margins onto a central exhumed mantle tract. Since the Early Cretaceous (and locally probably since the Jurassic) a system of low-amplitude salt walls evolved in shallow marine environments punctuated by episodic emersion. During the main stage of crustal extension, in late Aptian to early Cenomanian times, carbonate shelves rapidly drowned giving rise to deeper marine sedimentation. This was a period of major rise of salt walls, progressively detached from their substratum. These salt walls enclosed minibasins that accumulated thick flysch deposits arranged in growth stratal patterns. Depocenter migration and foundering of previous diapiric highs controlled further flysch deposition during the Late Cretaceous, while moderate extension probably persisted until the onset of the Pyrenean compression. During the late Santonian to Paleogene Pyrenean orogeny, the sedimentary lid of the Chaînons Béarnais basin climbed back along the Triassic detachment onto the colliding continental margins, leading to salt wall squeezing and further rising. Based on the Cretaceous timing and style of growth folding, we suggest that salt wall squeezing was not solely related to the Pyrenean compression, but shortening affected the diapiric ridges during the syn-rift sliding by gravity and crowding in the basin center, as the rifted margins were pulled apart from beneath. This makes the Chaînons Béarnais belt a unique field analog for contractional salt-tectonic systems in distal continental margins.
Ayudas:	Ministerio de Economía y Competitividad CGL2014-54180 Agencia Estatal de Investigación PGC2018-093903-B-C21
Derechos:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió acceptada per publicar
Materia:	Salt tectonics ; Minibasin ; Continental margin ; Hyper-extension ; Tectonic inversion ; Pyrenees
Publicado en:	Tectonophysics, Vol. 785 (June 2020) , art. 228451, ISSN 1879-3266

DOI: 10.1016/j.tecto.2020.228451

Postprint 89 p, 36.5 MB

El registro aparece en las colecciones:
Artículos > Artículos de investigación
Artículos > Artículos publicados