Determination of extension directions in naturally deformed limestones within strike-slip fault zones using microfractures; Niksar basin (Turkey) as a case study

Abstract

Microfracture analysis in rocks of the Niksar area, located within the North Anatolian Fault Zone shows a close correspondence with the data obtained from the macroscopic structures and points to the importance of 1) NW-SE extension near NW-SE dextral faults and 2) NE-SW to E-W extension near transfer normal faults. The extension directions commonly have a moderate to steep plunge, in contrast to the horizontal extension direction predicted by the ideal strike-slip model. This suggests that, as with the mesoscopic faults, the true displacement mode is typically oblique-slip with a normal component.