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. 14451450 [PDF]

The
Effect of Decollement Dip on Geometry and Kinematics of Model Accretionary
Wedges

We conducted
a series of sandbox models shortened asymmetrically above a frictionalplastic
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 58dipping
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 nondipping 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.
