Rifted continental margins: The case for depth-dependent extension

The crustal evolution of the west-central Pyrenees revisited: Inferences from a new kinematic scenario

“…Most of these crustal fragments show mylonitic deformation (Corre et al, this volume). Hence, this distal upper crust was probably ductily stretched and left behind a dismembered lower crust, in analogy with observations in modern distal margins (Angola, Brasil; Contrucci et al, 2004;Unternehr et al, 2010) and numerical models (Huismans and Beaumont, 2014).…”

“…Diverse mechanisms of lower crust removal in distal margins are discussed by Reston (2007); a detailed assessment of these mechanisms is beyond the scope of this paper, although for the Pyrenean paleomargins we favor models involving heterogeneous stretching at the crustal scale. The restored geometry for the Iberian margin here proposed could be a representative of Huismans and Beaumont's (2014) model III for continental margins, where a strong lower crust is removed and advected away from the thinned margin.…”

Rifted margins: Ductile deformation, boudinage, continentward-dipping normal faults and the role of the weak lower crust

“…The presence of a weak lower crust may favor an early necking and lead to an extensive spreading of the thinned continental crust (Huismans & Beaumont, 2011;Huismans & Beaumont, 2014). For Brune et al, (2014) spreading of the continental crust is attributed to a rift migration maintained by sequential faulting in the brittle crust and lower crustal flow.…”

From orogen to rifted passive margin formation in Brazil: Geodynamic numerical modeling considering the effects of structural inheritance and rheology

“…Pérez-Gussinyé, 2013;Sibuet and Tucholke, 2013). Numerical models corroborate this lateral flow based on depth-dependent extension, showing that weak lower crust can be extruded towards the rifting axis like a channel flow (Huismans & Beaumont, 2011), a mechanism that can explain the formation of metamorphic cores complexes like in the Basin and Range (Huismans & Beaumont, 2014). The same authors also show strong lower crust being laterally advected and removed coupled to the mantle lithosphere.…”

“…where f is a scaling factor that allows modifying viscous strength without recourse to additional flow laws (Huismans & Beaumont, 2014), A is the pre-exponential scaling factor, n is the power law exponent, ! is the second invariant of the deviatoric strain rate tensor…”