The surface tectonics of mantle lithosphere delamination following ocean lithosphere subduction: Insights from physical‐scaled analogue experiments

Abstract

[1] Many postulated lithospheric removal events occur in regions with an earlier history of subduction, but the relationship between the two processes has not been explored. In this work, we use physical-scaled analogue experiments to investigate the evolution from ocean lithosphere subduction to collision and possible delamination of the mantle lithosphere from the crust. We test how varying the magnitude of plate convergence alters the behavior of the subduction-delamination model. Our experiments show that a retreating ocean proplate can evolve to continental mantle lithosphere delamination. Negative surface topography is supported at the delamination hinge, and this migrates back with the peeling lithosphere. With high plate convergence, delamination is suppressed. Rather, the crust and mantle lithosphere split at the collision zone in a form of flake tectonics as oncoming procrust is accreted on top of the retroplate and the promantle lithosphere subducts below. Localized high topography develops at this zone of crustal accretion and thickening. The results suggest that delamination may be a continental continuation of plate retreat and that lithospheric removal is triggered by the transition from one process to another.

Delamination in collisional orogens: Thermomechanical modeling

“…Delamination modes differ in timing, location and conditions of initiation, but have in common a lateral propagation of delamination along the subducting plate. Mechanisms similar to incipient syn‐collisional delamination have been observed in numerical studies [ Gerya et al , 2008; Warren et al , 2008; Faccenda et al , 2009; Duretz et al , 2011] and scaled analogue experiments [ Boutelier et al , 2004; Göğüs et al , 2011]. Faccenda et al [2009] emphasized the importance of mobile volatile phases for decoupling along the subduction zone, producing precursors of transitional arrest and syn‐collisional delamination.…”

“…These assumptions have pre‐empted to relate the characteristic development of a delaminating collision zone to the preceding orogenic history. Delamination observed in numerical and analogue models of collision zones and methodological advances allow further steps to refine the numerical treatment [ Gerya and Yuen , 2003, 2007; Boutelier et al , 2004; Gerya et al , 2008; Faccenda et al , 2009; Duretz et al , 2011; Göğüs et al , 2011]. Improvements concern (1) the dynamically unconstrained development of models from as early as possible, ideally not imposing any initial weakness for delamination to start and develop from subduction models; (2) the thermodynamical implementation of a layered mantle (resulting in reduced permeability of transition zones for sinking slabs) in order to capture as accurately as possible the characteristics of upper mantle flow; and (3) consideration of phase changes, hydration and melting in order to account for reduced coupling at the plate interface and to generate crustal characteristics comparable to geological observations (e.g., partially molten rocks).…”

Delamination vs. break-off: the fate of continental collision

“…[16] Previous numerical and analogue studies on continental collision showed that both delamination [Schott and Schmeling, 1998;Morency and Doin, 2004;Göğüş and Pysklywec, 2008;Valera et al, 2008;Göğüş et al, 2011;Bajolet et al, 2012;Ueda et al, 2012] and slab detachment [Davies and Von Blanckenburg, 1995;Wong A Ton and Wortel, 1997;Gerya et al, 2004;Toussaint et al, 2004;Andrews and Billen, 2009;Burkett and Billen, 2009;Duretz et al, 2011;van Hunen and Allen, 2011] are likely to occur. The major control of the lower crustal strength on the evolution of delamination that we observe is consistent with previous models [Schott and Schmeling, 1998;Morency and Doin, 2004].…”

Numerical models of slab migration in continental collision zones

“…In the retreating subduction system, the lithospheric mantle detaches from the buoyant continental crust and it keeps subducting into the mantle (Cloos, 1993;Kerr and Tarney, 2005;Brun and Faccenna, 2008;Bialas et al, 2010). This crustal delamination process is possible if there is a layer of weak material within the continental crust, for example, the lower crust (Ranalli et al, 2000;Toussaint et al, 2004;Gogus et al, 2011). In contrast, in advancing subduction systems, hundreds of kilometres of continental lithosphere can subduct without significant crustal delamination (Royden, 1993).…”