Abstract
Mantle lithosphere heterogeneities are well documented, are ubiquitous, and have often been thought to control lithosphere-scale deformation. Here, we explore the influence of deep scarring in crustal deformation in three dimensions by considering the Ouachita orogeny in the southeastern United States, an example of a continental collision where mantle structure is present but not previously linked to the regional crustal tectonics. We present state-of-the-art continental compressional models in the presence of inherited three-dimensional lithospheric structure. Our models find that the surface expression of the Ouachita orogeny is localized by, and projected from, the controlling mantle scarring, in keeping with geological and geophysical observations. We are able to produce a large-scale arcuate orogeny with associated basin development appropriate to the Ouachita orogeny, alongside smaller-scale crustal faulting related to the region. This study offers a new and alternative hypothesis to the tectonic history of the Ouachita orogeny, with previous research having focused exclusively on crustal structures. The findings have broad implications, demonstrating the important potential role of the mantle lithosphere in controlling crustal dynamics and highlighting the requirement to consider deeper structure and processes when interpreting tectonic evolution of lithospheric-scale deformation.
Highlights
A catalogue of structures within the mantle lithosphere has been available and the structures’ genesis widely interpreted (e.g., Vauchez et al, 1997; Holdsworth et al, 2001)
The mantle lithosphere heterogeneity, modeling the suture of the Sabine block, produces basin deformation and an arcuate orogeny with a main front generated at an offset of ~100 km from the edge of the mantle lithosphere (Fig. 2C)
In keeping with an extensive suite of simulations analyzing the importance of lithosphere rheology in the role of mantle lithosphere scars (Heron et al, 2016b), Jourdon et al (2017) found that the reactivation of a mantle suture strongly influences the localization and deformation of tectonics
Summary
A catalogue of structures within the mantle lithosphere has been available and the structures’ genesis widely interpreted (e.g., Vauchez et al, 1997; Holdsworth et al, 2001). We outline a two-phase tectonic history where a mantle suture is generated and contributes to crustal deformation. This deep seismic-velocity heterogeneity and density contrast between mantle blocks (Mickus and Keller, 1992) is interpreted to be a lithosphere shear zone that we propose has facilitated the intracontinental collisional tectonics of the Ouachita orogeny (Fig. 1C).
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