HR: 0830h
AN: T21C-0464    [PDF]
TI: Lateral propagation of folding and thrust faulting at Mahan, S.E. Iran
AU: * Walker, R T
EM: rwalker@esc.cam.ac.uk
AF: University of Cambridge, Bullard Laboratories, Department of Earth Sciences, Madingley Road,, Cambridge, CB3 0EZ United Kingdom
AB: Folding identified near the town of Mahan in S.E. Iran has no record of historical activity, and yet there are clear geomorphological indications of recent fold growth, presumably driven by movements on underlying thrust faults. The structures at Mahan may still be capable of producing destructive earthquakes, posing a considerable hazard to local population centres. We describe a drainage evolution that shows the effect of lateral propagation of surface folding and the effect of tilting above an underlying thrust fault. River systems cross and incise through the fold segments. Each of these rivers show a distinct deflection parallel to the fold axis. This deflection starts several kilometres into the hanging-wall of the underlying thrust fault. Remnants of several abandoned drainage channels and abandoned alluvial fans are preserved within the folds. The westward lateral propagation of folding is also suggested by an increase in relief and exposure of deeper stratigraphic layers across fold segments in the east of the system, implying a greater cumulative displacement in the east than in the west. The preservation of numerous dry valleys across the fold suggests a continual forcing of drainage around the nose of the growing fold, rather than an along strike variation in slip-rate.
DE: 7223 Seismic hazard assessment and prediction
DE: 8005 Folds and folding
DE: 8040 Remote sensing
DE: 8107 Continental neotectonics
SC: Tectonophysics [T]
MN: 2003 Fall Meeting