Publication

H. Koyi and B. Vendeville, 2003, The effect of decollement dip on geometry and kinematics of model accretionary wedges: Journal of Structural Geology, v. 25, p. 1445-1450 [PDF]

We conducted a series of sand-box models shortened asymmetrically above a frictional-plastic de´collement to study the influence of amount and sense of the de´collement dip on the geometry and kinematics of accretionary wedges. Model results illustrate that the amount and direction of de´collement dip strongly influence the geometry and mode of deformation of the resulting wedge. In general, for models having similar de´collement frictional parameters, the resulting wedge is steeper, grows higher and is shorter when shortened above a de´collement that dips toward the hinterland. At 42% bulk shortening, the length/height ratio of wedges formed above a 58-dipping de´collement was equal to 2.4 whereas this ratio was equal to 3 for wedges shortened above a horizontal de´collement. Moreover, models with a hinterland dipping de´collement undergo larger amounts of layer parallel compaction (LPC) and area loss than models shortened above a non-dipping de´collement. The effect of de´collement dip on wedge deformation is most pronounced when basal friction is relatively high (?b = 0.55), whereas its effect is less significant in models where the basal de´collement has a lower friction (?b = 0.37). Model results also show that increasing basal slope has a similar effect to that of increasing basal friction; the wedge grows taller and its critical taper steepens.