Julia GOMEZ-ROMEU

How a divergent template controls the onset and evolution of convergence?

Supervisors:
Emmanuel Masini – M&U; ISTerre, Grenoble, France
Nick Kusznir – University of Liverpool, UK
Sylvain CALASSOU – Total R&D, Pau, France

Major Results

Convergence initiates within the hyper-extended basin in the Western Pyrenees.
The reactivation of necking domain leads to the normal thickness continental crust.
The reactivation of proximal domain provides crustal thickening.

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 how rift domains may control the onset and dynamics of convergent processes. 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 magma-poor rifting characterized by a hyper-extended rift basin. Results from our modelling show that convergence initiates within the hyper-extended rift basin followed by the recovery of normal thickness continental crust when the necking domain reactivates. Finally crustal thickening is produced when the proximal domain reactivates.

Despite of these results, little is known about the tectonic control of magma-rich rifted and transform margins in convergent settings. We use the Caribbean region to investigate the nature and architecture of segmented magma-rich rifted margins and how they may have controlled the initiation and dynamics of subduction.

Evolutionary chart summarizing the rifling and orogenic evolution of the Western Pyrenees showing the different tectonic stages and their geological times.
a) Early rifling, b) Necking rifling, c) Hyper-extension rifling, d) Post-rifling subsidence giving the pre-orogenic template, e) Hyper-extended domain reactivation, f) Necking domain reactivation and g) Proximal domain shortening.

Role of rift structural inheritance in orogeny highlighted by the Western Pyrenees case-study

Gómez-Romeu, J., Masini, E., Tugend, J., Ducoux, M., Kusznir, N. (2019). Role of rift structural inheritance in orogeny highlighted by the Western Pyrenees case-study. Tectonophysics, Elsevier, 2019, 766, pp.131-150.

keywords: Western Pyrenees, Rift structural inheritance, Flexural isostatically and structurally balanced cross-section

DOI: https://doi.org/10.1016/j.tecto.2019.05.022