 |
| Titel |
Stability of accretionary wedges with heterogeneous basal pressure and frictional properties |
| VerfasserIn |
A. Pons, Y. M. Leroy |
| Konferenz |
EGU General Assembly 2012
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250060249
|
|
|
|
|
|
| Zusammenfassung |
| Frictional (coefficient μ) and pressure (ratio λ) properties in the bulk and the décollement are
usually combined in an equivalent friction coefficient, μ′ = μ(1 - λ)-(1 - λbulk)
to question the stability of accretionary wedges according to the classical critical
taper theory. Although this theory deals with homogeneous wedges, the equivalent
friction coefficient is widely used even for complex pressure and frictional properties
distributions. The interest of this work is to understand the role of heterogeneous
properties on the wedge stability and thus to question the merits of this equivalent
coefficient.
To this end, a general procedure is proposed to extend the critical taper theory to
heterogeneous wedges of arbitrary topography. We present a stability study on a wedge
whose décollement is partitioned into an internal and an external section, with
different λ’s and μ’s. The method relies on the kinematic approach of limit analysis
[1] extended for fluid-saturated rocks [2]. The stability conditions relies on the
search for the position of the collapse mechanism composed of two faults, the ramp
and the back-thrust, rooting at the same point on the décollement. The root is at
the front or towards the back of the wedge for sub- and super-critical conditions,
respectively. It is shown that stability depends in a complex manner on the λ’s and μ’s
but also on the relative extent of the two sections [2]. For example, the equivalent
friction coefficient approach, based on the external section, is misleading if that
region extends less than over 80 % of the décollement. The equivalent friction
coefficient should be divided by more then a factor of two for two sections of the same
length.
[1] Cubas N., Leroy Y. M. and Maillot B., 2008. Prediction of thrusting sequences in
accretionary wedges, Journal of Geophysical Research, doi10.1029/2008JB005717.
[2] Pons A. and Y. M. Leroy, 2012. Stability of accretionary wedges based on the
maximum strength theorem for fluid-saturated porous media, Journal of the Mechanics and
Physics of Solids, doi10.1016/j.jmps.2011.12.011. |
|
|
|
|
|
|