Analogue modelling of the initiation of subduction

Abstract

S U M M A R YWe report the results of experiments on the initiation of subduction, using stratified analogue models in a large centrifuge, where the experiments are driven only by the enhanced gravity of the centrifuge without the effect of external lateral stresses. The scaled density of the stratified components resembles that of the asthenosphere and the continental and oceanic lithospheres. The experiments demonstrate that under the effect of enhanced gravity, the layers simulating the oceanic lithosphere detach from the front of the 'continental lithosphere' and plunge under it, pushing the more pliable asthenosphere downwards. Simultaneously, the 'continental lithosphere' is thrust over the downgoing slab; where friction is low, the 'continental lithosphere' extends considerably so that the 'ductile continental lithosphere' is exposed in some places. The rate of thrusting of the experimental continental slab over the oceanic one, as well as the amount of extension of the overriding slab and the extent of the rollback of the subduction zone that follows the initial lithospheric detachment, are controlled by friction and density differences between the subducting and the overthrust slabs. The analogue experiments emphasize the role of lateral density variations in incipient subduction and the effect of differential seismic friction along the subduction plane on the evolution of subduction zones, their shape and the evolution of their backarc basins. The morphological resemblance of the experimental results to various subduction systems seems to support their applicability to real subduction systems.

The subduction initiation stage of the Wilson cycle

“…Some analogue models (e.g. Mart et al 2005) do resemble aspects of the examples described here; experiments by Lévy & Jaupart (2012) are closest to what is observed in eastern Indonesia, where subduction began during crustal extension at a continental margin.…”

Recent and active deformation pattern off the easternmost Algerian margin, Western Mediterranean Sea: New evidence for contractional tectonic reactivation

“…at the foot of the margin (e.g. Mart et al, 2005). The use of deep seismic tools for fault geometry at depth and the mapping and dating of turbidites in the deepest part of the basin may help in the future to further mitigate the seismic hazards of this fault system and to clarify the mechanisms of subduction inception.…”

Future directions in subduction modeling

“…(8) Addition of water into the lithosphere ; Van der Lee et al, 2008). (9) Spontaneous thrusting of the buoyant continental/arc crust over the oceanic plate (Mart et al, 2005;Goren et al, 2008;Nikolaeva et al, 2010Nikolaeva et al, , 2011. (10) Small-scale convection in the sub-lithospheric mantle (Solomatov, 2004).…”

“…3b, 1.9-3.2 Myr). This type of subduction nucleation has been systematically modeled with both analogue (Mart et al, 2005;Goren et al, 2008) and 2D numerical (Nikolaeva et al, 2010(Nikolaeva et al, , 2011 techniques. With 2D models Nikolaeva et al (2010) investigated the factors controlling passive margins' stability and showed that three subsequent tectonic regimes can develop at a passive margin: (1) stable margin, (2) overthrusting, and (3) subduction.…”