GEOLOGY OF THE SAVCILI FAULT ZONE, CENTRAL TURKEY

Understanding the nature of fault zones is sometimes essential to interpret their regional geology. There are two contrasting tectonic models proposed for origin of the Savcili fault zone. One view has been that this zone is characterized by the development of structures typically associated with crustal contraction. The others have interpreted that this zone refers to crustal extension.

The Savcili fault zone is one of the significant structural features exposed in the western portion of the central Anatolian core complex. It contains numerous parallel to sub-parallel thrust/reverse faults mainly a WNW-striking and SW-dipping and is cross-cut by later normal and strike-slip faults. Along the zone, the faults mostly places metamorphic and granitoidic rocks over Paleogene sedimentary rocks, which are overlaid by Miocene-Pleistocene deposits. It is therefore inferred that movement along the SFZ was ceased by Miocene.

The Savcili fault zone possesses a well-developed zone of brittle deformation, called here cataclastic zone, in both the hanging wall and footwall. The cataclastic zone is characterized by two main architectural components; core and damage zone. The core is characterized by cohesive and non-cohesive fault rocks (mainly cataclasite and gauge). The damage zone surrounding the core consists of a well-developed fracturing and cohesive and non-cohesive fault rocks (mainly breccia). Kinematic indicators include steps, fractures, trains of inclined planar structures and asymmetric cavities, suggesting that hanging wall block has moved up approximately northwards with respect to footwall block.

The models for evolution of the Savcili fault zone advocated in the literature do not fit our integrated field and microstructural data providing evidence of episodic cataclasis and diffuse mass transfer deformation mechanisms.