Benchmarking numerical models of brittle thrust wedges

TY - JOUR

T1 - Benchmarking numerical models of brittle thrust wedges

AU - Buiter, Susanne J H

AU - Schreurs, Guido

AU - Albertz, Markus

AU - Gerya, Taras V.

AU - Kaus, Boris

AU - Landry, Walter

AU - le Pourhiet, Laetitia

AU - Mishin, Yury

AU - Egholm, David L.

AU - Cooke, Michele

AU - Maillot, Bertrand

AU - Thieulot, Cedric

AU - Crook, Tony

AU - May, Dave

AU - Souloumiac, Pauline

AU - Beaumont, Christopher

PY - 2016/11/1

Y1 - 2016/11/1

N2 - We report quantitative results from three brittle thrust wedge experiments, comparing numerical results directly with each other and with corresponding analogue results. We first test whether the participating codes reproduce predictions from analytical critical taper theory. Eleven codes pass the stable wedge test, showing negligible internal deformation and maintaining the initial surface slope upon horizontal translation over a frictional interface. Eight codes participated in the unstable wedge test that examines the evolution of a wedge by thrust formation from a subcritical state to the critical taper geometry. The critical taper is recovered, but the models show two deformation modes characterised by either mainly forward dipping thrusts or a series of thrust pop-ups. We speculate that the two modes are caused by differences in effective basal boundary friction related to different algorithms for modelling boundary friction. The third experiment examines stacking of forward thrusts that are translated upward along a backward thrust. The results of the seven codes that run this experiment show variability in deformation style, number of thrusts, thrust dip angles and surface slope. Overall, our experiments show that numerical models run with different numerical techniques can successfully simulate laboratory brittle thrust wedge models at the cm-scale. In more detail, however, we find that it is challenging to reproduce sandbox-type setups numerically, because of frictional boundary conditions and velocity discontinuities. We recommend that future numerical-analogue comparisons use simple boundary conditions and that the numerical Earth Science community defines a plasticity test to resolve the variability in model shear zones.

AB - We report quantitative results from three brittle thrust wedge experiments, comparing numerical results directly with each other and with corresponding analogue results. We first test whether the participating codes reproduce predictions from analytical critical taper theory. Eleven codes pass the stable wedge test, showing negligible internal deformation and maintaining the initial surface slope upon horizontal translation over a frictional interface. Eight codes participated in the unstable wedge test that examines the evolution of a wedge by thrust formation from a subcritical state to the critical taper geometry. The critical taper is recovered, but the models show two deformation modes characterised by either mainly forward dipping thrusts or a series of thrust pop-ups. We speculate that the two modes are caused by differences in effective basal boundary friction related to different algorithms for modelling boundary friction. The third experiment examines stacking of forward thrusts that are translated upward along a backward thrust. The results of the seven codes that run this experiment show variability in deformation style, number of thrusts, thrust dip angles and surface slope. Overall, our experiments show that numerical models run with different numerical techniques can successfully simulate laboratory brittle thrust wedge models at the cm-scale. In more detail, however, we find that it is challenging to reproduce sandbox-type setups numerically, because of frictional boundary conditions and velocity discontinuities. We recommend that future numerical-analogue comparisons use simple boundary conditions and that the numerical Earth Science community defines a plasticity test to resolve the variability in model shear zones.

KW - Benchmarking

KW - Critical taper

KW - Numerical modelling

KW - Plasticity

KW - Shear zones

KW - Thrust wedges

U2 - 10.1016/j.jsg.2016.03.003

DO - 10.1016/j.jsg.2016.03.003

M3 - Journal article

AN - SCOPUS:84977100188

SN - 0191-8141

VL - 92

SP - 140

EP - 177

JO - Journal of Structural Geology

JF - Journal of Structural Geology

ER -