The evolution of Alpine-type orogens with respect to its pre-orogenic rift history: the Western Pyrenees case-study
Abstract
It is commonly accepted that many orogens form by contractional reactivation of earlier continental rifts or rifted margins. Despite of this assumption, the role that rift domains play in orogenic processes remains poorly understood.
We investigate the importance of the inversion of rift domains developed during the pre-orogenic rift history on orogen development. To achieve our aim, we use a kinematic forward lithosphere deformation model (RIFTER) to produce flexural isostatically compensated as well as balanced cross-sections showing the structural and stratigraphic development of both the rift and orogenic stages of the Western Pyrenees. Prior to the Alpine orogeny the Western Pyrenees underwent Late Jurassic to Cretaceous rifting characterized by three tectonic stages consisting of; (i) early rifting producing slight crustal thinning now seen in the proximal rift domain, (ii) stronger rifting and crustal thinning creating the necking rift domain and (iii) hyper-extension rifting leading to continental crustal breakup and mantle exhumation, forming the hyper-extended rift domain. Our modelling results show how rift-domains are sequentially reactivated and incorporated into the present-day Western Pyrenees architecture during Alpine contractional tectonics. This is achieved through two tectonic stages; (i) the inversion of the hyper-extended and necking rift domains and (ii) the shortening of the proximal rift domain. The first tectonic contractional stage leads to the recovery of normal thickness continental crust and is accomplished by the inversion of inherited structures while the second contractional stage of the proximal domain gives thickening of continental crust through the formation of new structures. Based on the Western Pyrenees case-study, two orogenic stages characterized by the inversion and shortening of continental lithosphere are identified. The style and amount of contraction involved in orogen formation are determined by the pre-orogenic rift domain configuration. Other convergent orogens with different amounts of shortening and inversion with respect to the Pyrenees case-study should be investigated to better understand the control of rift domains on orogenesis.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T41D0295G
- Keywords:
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- 8104 Continental margins: convergent;
- TECTONOPHYSICS;
- 8108 Continental tectonics: compressional;
- TECTONOPHYSICS;
- 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICS;
- 8178 Tectonics and magmatism;
- TECTONOPHYSICS