(Pamukkale, Turkey)

In recent decades various interpretations have been proposed to explain the evolution of fissure-ridge-type travertine deposits. In this paper, we discuss the relationships between fissure-ridges and brittle structures affecting their substratum, through a detailed analysis of an inactive fissure-ridge (near Cukurbag) located in the Pamukkale geothermal area (western Turkey). The Cukurbag fissure-ridge can be taken as a model as it offers an opportunity to examine its internal structure on the walls of a Roman quarry; in addition, this ridge has been studied by several researchers who have discussed the processes promoting the fissure-ridge evolution. The Cukurbag fissure-ridge is composed of irregularly alternating travertine laminated facies (bedded travertine) crosscut into rather large lithons by subvertical crystalline veins (banded travertine). The relationships between bedded and banded travertine indicate that the banded veins are diachronous and migrated through time, suggesting a progressive fault zone enlargement in the footwall. Such a fault zone was characterized by polycyclic activity, with normal to transtensional kinematics, and was active during the latest Quaternary. We demonstrate that formation of banded veins is coeval with bedded travertine deposition and strictly depends on fault activity, therefore highlighting the fundamental role of travertine fissure-ridges in reconstructing palaeotectonic activity in a region