Skip to Main content Skip to Navigation
Journal articles

Exhumation of the Ronda peridotite during hyper‐extension: New structural and thermal constraints from the Nieves Unit (western Betic Cordillera, Spain)

Eloïse Bessiere 1, 2, 3 Romain Augier 1, 2 Laurent Jolivet 3 Jacques Précigout 1, 2 Adrien Romagny 3
2 Géodynamique - UMR7327
INSU - CNRS - Institut national des sciences de l'Univers, UO - Université d'Orléans : UMR7327, BRGM - Bureau de Recherches Géologiques et Minières (BRGM), ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327 : UMR7327
Abstract : The Ronda peridotite (Betic Cordillera, Southern Spain) is the largest alpine-type peridotite massif worldwide. Yet, the emplacement mechanism of these mantle rocks is still a highly debated topic. In this study, we aim at better constraining their context of exhumation by focusing on the Nieves Unit, which is mostly composed of Mesozoic metasediments displaying HT metamorphism and deformation along the contact with peridotite. The topmost parts of the peridotites and the bottom parts of the Nieves Unit share the same planar/linear fabric parallel to the contact accompanied by component of sinistral kinematic indicators. Raman Spectroscopy on Carbonaceous Material geothermometry then shows a contraction of peak-temperature conditions within metasediments of the Nieves Unit, as well as a northeastward decrease along strike, highlighting a strong thinning of the unit and a significant obliquity of the isograds to the contact with the peridotites. Local magnetite ores and ophicalcite bodies are finally observed nearby the contact, suggesting a hyper-extension context for the mantle exhumation. Indeed, the Nieves Unit, the Ronda peridotite and the Jubrique Unit, where a strong thinning has also been documented, are all in contact at a triple junction between the western contact of the peridotite and the Nieves/Jubrique contact. Altogether, these features support the idea that the western shear zone limiting the peridotites from the Nieves and Jubrique units is a tilted large-scale extensional detachment that has exhumed mantle rocks from beneath the continental basement (Jubrique Unit) and its Mesozoic cover (Nieves Unit) during an episode of hyper-extension.
Complete list of metadata

https://hal-insu.archives-ouvertes.fr/insu-03336275
Contributor : Nathalie Pothier Connect in order to contact the contributor
Submitted on : Tuesday, September 7, 2021 - 10:14:41 AM
Last modification on : Friday, December 3, 2021 - 11:42:55 AM

File

 Restricted access
To satisfy the distribution rights of the publisher, the document is embargoed until : 2022-03-07

Please log in to resquest access to the document

Identifiers

Citation

Eloïse Bessiere, Romain Augier, Laurent Jolivet, Jacques Précigout, Adrien Romagny. Exhumation of the Ronda peridotite during hyper‐extension: New structural and thermal constraints from the Nieves Unit (western Betic Cordillera, Spain). Tectonics, American Geophysical Union (AGU), 2021, ⟨10.1029/2020tc006271⟩. ⟨insu-03336275⟩

Share

Metrics

Record views

93