Fracture networks and strike-slip deformation along reactivated normal faults in Quaternary travertine deposits, Denizli Basin, western Turkey

The Denizli Basin in the West Anatolian Extensional Province in western Turkey is known for its numerous Quaternary travertine occurrences. Travertine morphology is often dependant on the relative position of the deposition with respect to basin-bounding faults. The travertine occurrences examined in this study are situated at the intersection of the locally E-W oriented Denizli Basin and the adjacent NE-SW oriented Baklan Graben in the NE. Based on an extensive field campaign, including LIDAR scanning, several high-resolution fault/fracture maps of five large quarries (>300m in length and >60m in height) are constructed in which this world-class travertine deposit is currently excavated. A structural analysis is performed in order to determine the tectonic overprinting of the travertine body and to derive the stress states of the basin after travertine deposition. The mostly open, non-stratabound joints are several tens of metres long and often bifurcate creating a dense fracture network. Minor infill of the joints resulted in the presence of a few colour-banded calcite veins. Based on the E-W, NE-SW and NW-SE orientation of three dominant joint sets it is concluded that the joint network is caused by local N-S extension, alternated by NW-SE and NE-SW extension exemplifying the presence of stress permutations in the Quaternary. High angle E-W to WNW-ESE faults cross-cut the quarries. Faults are filled with travertine debris and clastic infill of above lying sedimentary units indicative of the open nature of the faults. The specific E-W fault orientation in the locally E-W trending Denizli Basin indicates that they initiated as normal faults. A paleostress inversion analysis performed on kinematic indicators such as striations on the clayey fault infill and the sinistral displacement of paleosols shows that some of the normal faults were reactivated causing left-lateral deformation in a transient strike-slip stress field with a NE-SW oriented σ1. © 2013 Elsevier B.V