Congervence history across Zagros (Iran) : contraints from collisional and earlier deformation
Abstract
The Zagros orogen provides a unique opportunity within the Alpine system to evaluate the interplay between a young Tertiary collision and earlier subduction/obduction processes. Within the Crush zone and the Sanandaj-Sirjan (internal) zone separating the Zagros Fold belt from Central Iran, we document several major tectonic events taking place at the end of the Cretaceous, of the Eocene and from the Mio-Pliocene onwards (ca. <20-15 ma). contrary="" to="" recent="" interpretations,="" our="" data="" (cross-sections="" and="" description="" of="" the="" overall="" deformation="" style)="" strongly="" suggest="" that="" the="" main="" zagros="" thrust="" (mzt)="" is="" deeply="" rooted,="" possibly="" to="" moho="" depths,="" and="" that="" the="" suture="" zone="" effectively="" runs="" along="" the="" mzt.="" field="" observations="" show="" that="" the="" final="" resorption="" of="" the="" oceanic="" domain="" took="" place="" slightly="" after="" 35 ma="" and="" that="" collision="" must="" have="" started="" before="" ca.="" 23-25 ma="" in="" northern="" zagros.="" the="" shortening="" rate="" across="" the="" crush="" zone="" since="" the="" mid-miocene="" (20-15 ma)="" is="" estimated="" at="" a="" minimum="" 3-4 mm/year.="" shear="" movements="" in="" the="" crush="" zone="" during="" the="" eocene-oligocene="" period="" and="" extensional/strike-slip="" movements="" in="" the="" internal="" zones="" during="" the="" late="" cretaceous="" point="" to="" an="" oblique="" setting="" early="" in="" the="" convergence="" history.="" a="" geotectonic="" scenario="" for="" convergence="" from="" the="" time="" of="" obduction="" to="" the="" present="" is="" finally="">