CONTINUATION OF MAIN RECENT FAULT TREND IN THE 32 TO 33N IN THE ZAGROS BELT (IRAN)

Main Recent Fault (MRF) includes segments of a series of faults with approximately vertical dips and 100km average lengths. Right lateral strike slip mechanism of this fault was suggested by presence of various features (Tchalenko and Braud 1974).

Segments of MRF that have been introduced earlier include Piranshahr, Marivan, Sarthakht, Morvarid, Dinvar, Sahneh, Nahavand, and Doroud faults; this assemblage forms a seismic and active trend.

In this research Bakhtyari-Kohrang (BK) and Ardal (Ar) faults, which are continuation of MRF in the SE, have been introduced.

BK Fault is divided from Doroud fault in 33N as an Enechelon structure and extends with N135-143 trend, vertical dip and 80-km length to the 30,32N. It seems this fault has been divided by a fault with N-S trend, which should be further studied.

The second segment, which is called Ardal, with 120km length and vertical dip shows right lateral strike slip mechanism. This segment is divided from BK in the 32 30N by a set of two NS faults. The former extends towards the Naghan area by clear traces; although it could not be traced afterward, but it seems it has been extended toward the Dena fault. Seismic activities along these two faults are not in harmony with each other. Seismic information indicates that at least seven major earthquakes have been occurred along AR fault.

In comparison, seismic activities along BK are weaker than the other MRF segments. These weak seismic activities could be attributed to the absence of the historical records (due to remoteness of the area) or lubricating effects of the evaporite deposits; this could have been caused creep and aseismic activities along this fault.