Kinematic Linkages Among Extrusion, Fold-thrust Shortening, and Foreland Basin Evolution During Early Continental Collision, Zagros Mountains, Iran

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

The principal investigators of this study are conducting a three-year study of the geologic history of the Zagros fold-thrust belt and adjacent High Zagros. The goal is to determine the relative roles and interactions of (1) a seismogenic, crustal-scale, dextral fault (the Main Recent Fault) and (2) the thin-skinned fold-thrust belt during deformation related to the Arabian tectonic plate converging with the Eurasian plate. Ongoing research suggests, contrary to previous studies, that these two structural elements may form a kinematically linked system and were active contemporaneously for a significant period of time during the plate collision over the last approximately 10-20 million years. The Eurasian-Arabian continental collision is the world's youngest and provides opportunities to study early structural processes that are strongly overprinted in older collisional mountain belts such as the Alps, Himalaya, and Appalachians. A temporal record of fold-thrust deformation resides within the extensive, superbly exposed foreland-basin deposits of the Zagros, including crosscutting structures, overlapping strain markers, and sediments deposited synchronously with faulting and folding. The project employs stratigraphic and structural analysis, and includes significant new field data collection, isotopic age dating to determine the low-temperature thermal history of key rock units, and magnetic methods applied to dating sedimentary strata. This research on the Zagros system of Iran is improving understanding of tectonic processes in early continent-continent collision by characterizing the sequence of deformational, depositional, erosional, and magmatic episodes during early collision and providing strong timing constraints on their rates of development. The study is also addressing the general question of how the age of onset of continental collision is determined from the geologic record of more evolved and more complex collisional mountain belts.