Open AccessStrike‐slip faulting, rotation, and along‐strike elongation in the Kopeh Dagh mountains, NE Iran
Author(s) -
Hollingsworth James,
Jackson James,
Walker Richard,
Reza Gheitanchi Mohammad,
Javad Bolourchi Mohammad
Publication year - 2006
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2006.02983.x
Subject(s) - geology , seismology , basin and range province , echelon formation , structural basin , slip (aerodynamics) , seismic hazard , shear (geology) , quaternary , fault (geology) , basin and range topography , strike slip tectonics , tectonics , paleontology , physics , thermodynamics
SUMMARY The Kopeh Dagh is a linear mountain range separating the shortening in Iran from the stable, flat Turkmenistan platform. In its central part is an array of active right‐lateral strike‐slip faults that obliquely cut the range and produce offsets of several kilometres in the geomorphology and geological structure. They are responsible for major destructive earthquakes in the 19th and 20th centuries and represent an important seismic hazard for this now‐populous region of NE Iran. These strike‐slip faults all end in thrusts, revealed by the uplift and incision of Late Quaternary river terraces, and do not continue beyond the Atrak river valley, which forms the southern margin of the Kopeh Dagh. The cumulative offset on these strike‐slip faults, and their associated rotation about vertical axes, can account for ∼60 km of N–S shortening. This value is similar to estimates of the Late Quaternary N–S right‐lateral shear between central Iran and Afghanistan, which must be accommodated in NE Iran. The strike‐slip faults also require ∼30 km of along‐strike extension of the Kopeh Dagh, which is taken up by the westward component of motion between the South Caspian Basin and both Eurasia and Central Iran. It is probable that these motions occurred over the last ∼10 Ma.