Permeability study of structures associated with Kuh Banan fault zone (north of Kerman, Central Iran)

In this study, the permeability of structures associated with Kuhbanan fault zone has been investigated. The Kuhbanan fault zone is one of the most seismically active structural trends in Kerman province. The behaviour of fault zones against groundwater flow (conduit, barrier, or a combination of both) is relatively controlled by fault core, damage zone, and permeability of fractures and rock units in the fault zone. In this research, qualitative and quantitative data, together with field observations and numerical models have been used. In order to measure the structures in the Kuhbanan fault zone, 23 outcrops were selected for model parameters. Results show that the fault zone acted as barrier in 12 outcrops, conduit in 4 outcrops and a combined barrier-conduit in 6 outcrops. In total, the 61-m-wide southern part of the Kuhbanan fault zone is composed of a fault core of 38 m and a damage zone of 23 m wide, respectively. Therefore, this segment of the Kuhbanan faul zone acts as a combination of conduit and strong barrier for fluid flow. The fault core is well developed but the damage zone is weakly developed , and therefore deformation has been largely localized within the fault core and distributed in the damage zone. To analyze the architecture of the fault zone three Fa, Fs, Fm indices were used. For the southern segment of the Kuhbanan fault zone, the Fa, Fs and Fm were measured as 0.47, 0.73 and 0.51, respectively. The relatively low Fa and high Fs indicate that the Kuhbanan fault zone in this area is not associated with uniform architecture. Also the numerous fault springs in the area are affected by this fault zone.