Mark B. Allen¹, Simon Inger¹, Eric J-P. Blanc¹, Mohammad Ghassemi², James Jackson³, Morteza Talebian³, Richard Walker³

(1) CASP, Department of Earth Sciences, University of Cambridge, Cambridge, England
(2) Geological Survey of Iran, Tehran
(3) Bullard Laboratories, University of Cambridge, Cambridge

ABSTRACT: Neotectonic Orogeny and Basin Development in Iran

This paper summarises active research projects on Iranian neotectonics, involving several major hydrocarbon provinces. Neotectonic deformation across Iran is a consequence of the Arabia-Eurasia collision, but strain is accommodated by very different mechanisms across the country, resulting in a wide range of deformation styles. At 35N 55E (roughly Tehran) the Arabia/Eurasia motion is 33 mm/yr (direction 005). Strain partitioning in the northwestern Zagros (Lurestan) occurs by NW-SE folds and thrusts and dextral slip on the Main Zagros Recent Fault. Fold geometries indicate that more than one detachment level operates. It is unclear how exposed folds are coupled with seismogenic faults in the basement. N-S dextral faults within the Simple Fold Zone link Lurestan to the E-W trending structures of Fars, in the eastern Zagros. Central Iran is less active than the Zagros seismically, and has subdued relief and elevations. Major active strike-slip faults deform this region. In eastern Iran, the Gowk Fault is one of several major N-S dextral faults accommodating right-lateral shear between deforming Iran and Afghanistan. The Alborz range of northern Iran borders the South Caspian Basin. Whereas thrusts in the Alborz accommodate part of the regional Arabian convergence, range-parallel sinistral faults indicate westward motion of the South Caspian Basin relative to Iran. Several detachment levels operate in the Alborz, but seismicity indicates basement faulting too. As with the Zagros, it is a key question how and to what extent basement and cover are coupled.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado