LISTRIC NORMAL FAULTING OF WEST CENTRALIRAN
|Category||Tectonic & Seismotectonic|
|Location||21th symposium on geosciences|
|Holding Date||24 May 2008|
The studied area is situated in the northwest of Esfahan province in central Iran. The oldest outcropped rocks are Upper Triassic (Ratian) units called Nayband Shale, which their upper contact is unconformable. Lower Cretaceous units are composed of conglomerate, sandstone, orbitolinaferous limestone (Aptian-Albian). Upper Cretaceous units are composed of Limestone and marl with interbeds of orbitolinaferous limestone. According to the study of TM Land sat 7 satellite images, systematic conjugate mega-joints generally are observed in the whole of the studied area. Also these joints are observed in Triassic and Cretaceous units. Triassic units are ductile and Cretaceous units are brittle. Transtensional faults were existed in Pre-Triassic units. These faults activities formed new normal fault in Cretaceous units. Syntectonic Oligo-Miocene limestone is deposited on the Cretaceous units (Aptian-Albian) disconformably. So that, Lower Cretaceous units show normal faults (listric) and also Oligo-Miocene units show syncline structures. The fault system of the studied area is part of the Alpine orogeny. Based on the TM Land sat 7 satellite data, a clockwise rotation could be observed in the whole of the area. These tectonic activities are caused the shearing of the systematic conjugate mega-joints. Restricted blocks between these mega-joints have suffered extension and elongation. So far, the listric normal faults are created.