REVISITING OF THE LATE QUATERNARY SLIP-RATE OFTHE KHIJ FAULT IN SOUTH-EAST OF ALBORZMOUNTAINS (NE IRAN) OBTAINED FROM IRSL DATING OFALLUVIAL SEDIMENTS

The ۵۵ km long left lateral Khij fault is in the middle part of Astaneh-Shahrud fault system (NEIran). Alluvial terraces in the Khij valley, have been displaced by the Khij fault, which can show theevidence of faulting in late Quaternary sediments. In this study, samples were re-examined in terms ofslip-rate using OSL (Optically stimulated luminescence) dating method. Cumulative left-lateraloffsets created in the sediments for the fault is about ۴۰۰ meters. Sediment samples collected fromKhij faults were dated by IRSL (infrared stimulated luminescence of feldspar) method. The twoIRSL samples of Khij fault show ages (۲۷۷.۲۱ ± ۳۴.۶۲ ka and ۲۹۸.۲۹ ± ۲۱.۲۸ ka) much older than thepreviously reported CRE ages (۱۵۲ ± ۱۰ ka to ۳۶۴ ±۲۴ ka). According to the cumulative left-lateraloffsets of ۴۰۰±۵۰ m of Khij fault and the IRSL ages, slip-rate values of ۱.۴±۰.۲۵ mm yr-۱ and۱.۳±۰.۱۹ mm yr-۱ are calculated for the fault, which is within the range of slip-rates (۱-۳ mm yr-۱)previously reported for this fault using CRE (Cosmic Ray Exposure) dating method. Our studyconfirms that the simultaneous use of luminescence and Terrestrial Cosmogenic Nuclides (TCN)dating methods to study the slip-rate not only increases the reliability of the results but also cansimplifies the related interpretations. Also, the luminescence method can narrow the age intervals andmay simplify the interpretations of TCN (e.g. CRE) ages, which can result in higher accuracy of sliprateresearches.

کلیدواژه ها:

Khij Faults ، IRSL ، CRE ، Slip-Rate