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Out‐of‐sequence thrusting in experimental Coulomb wedges: Implications for the structural development of mega‐splay faults and forearc basins
Author(s) -
Haq Saad S. B.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl053176
Subject(s) - geology , accretionary wedge , forearc , slip (aerodynamics) , wedge (geometry) , seismology , imbrication , thrust fault , thrust , subduction , geometry , fault (geology) , tectonics , physics , mathematics , thermodynamics
We have investigated how an arc‐ward increase in bulk mechanical strength in an experimental accretionary prism influences the development, timing, and duration of slip on out‐of‐sequence thrusts. We have monitored the structural development and kinematics, in side‐view, during the development of a frontally accreting Coulomb wedge growing out in front of a critically tapered and mechanically stronger inner wedge. The inner‐wedge initially behaved as classic backstop to deformation with the most actively slipping thrust occurring near the deformation front on the forward most thrust structures. With continued growth, however, significant out‐of‐sequence slip on reactivated fore‐thrusts occurred in conjunction with slip on newly formed back‐thrusts in the inner‐wedge. This out‐of‐sequence deformation resulted in punctuated, rapid uplift of the model forearc basin and a noticeable break in topographic slope in the outer pro‐wedge. Cyclical out‐of‐sequence fore‐ and back‐thrusting, driven by ongoing frontal thrust imbrication, continued with periodic recovery of taper and was followed by additional out‐of‐sequence faulting and associated basin uplift.