Extensional structures and hydrothermal fluid flow in Western Anatolia: a review from the Neogene-Quaternary Dinar and Denizli Basins

This paper focuses on the state of the art of two main research themes, developed through the collaboration between Italian and Turkish geoscientists, concerning the geological setting of western Anatolia: (i) the Neogene-Quaternary fault evolution; and (ii) the relationships between extensional structures and hydrothermal fluids flow. The Dinar and Denizli Basins were chosen as key areas. Concerning the fault evolution, structural and kinematic studies indicate that the NW- and NE-trending faults were characterized by different kinematics through time, therefore implying an articulated tectonic activity. NW-trending faults played a role of transfer zones during late Miocene-Pliocene, accompanying the main activity of the NE-trending normal faults and the related basin development. During Quaternary, the NW-trending faults were reactivated as normal faults, providing accommodation space for Quaternary sediments. At that time the NE-trending faults synchronously played as transfer zones accommodating the different amounts of extension. As a consequence, both NW- and NE-trending faults played a primary role in controlling hydrothermal fluid circulation. It is demonstrated by the fact that, at basinal scale, the location of significant hydrothermal manifestations (i.e. Pamukkale, Kamara) and volcanism (i.e. Gölcük) is controlled by the intersection between NE- and NW-trending faults systems, thus defining important structurally-driven conduits able to channel large volumes of fluids from depth to the surface. Travertine deposits and their feeding conduits (i.e. banded calcite veins) developed within the damaged rock volumes associated to both NW- and NE-trending fault zones, implying a genetic and temporary link between faults and hydrothermal circulation.