Abstract In regions of neotectonic activity geothermal waters flow into extensional fissures and deposit successive layers of carbonate as fissure travertine incorporating small amounts of ferromagnetic grains. The same waters spill out onto the surface to deposit bedded travertine, which may also incorporate wind-blown dust with a ferromagnetic component. Travertine deposits are linked to earthquake activity because geothermal reservoirs are reset and activated by earthquake fracturing but tend to become sealed by deposition of carbonate between events. A weak ferromagnetism records the ambient field at the time of deposition and sequential deposition can identify cycles of secular variation of the geomagnetic field to provide a means of estimating the rate of travertine growth. The palaeomagnetic record in three travertine fissures from the Sıcak Çermik geothermal field in central Anatolia dated to between 100 and 360 ka by U–Th determinations has been examined to relate the geomagnetic signature to earthquake-induced layering. Sequential sampling from the margins (earliest deposition) to the centres (last deposition) identifies directional migrations reminiscent of geomagnetic secular variation. On the assumption that these cycles record time periods of 1–2 ka, the number of travertine layers identifies resetting of the geothermal system by earthquakes every 50–100 years. Travertine precipitation occurs at rates of 0.1–0.3 mm a −1 on each side of the extensional fissures and at a rate an order higher than for bedded travertine on the surface. Earthquakes of magnitude M≤4 occur too frequently in the Sivas Basin to have any apparent influence on travertine deposition but earthquakes with M in the range 4.5–5.5 occur with a frequency compatible with the travertine layering, and it appears to be events of this order that are recorded by sequential travertine deposition. Two signatures of much larger earthquakes on a 1–10 ka time scale are also present in the travertine deposition: (1) the incidental emplacement of massive travertine or fracturing of earlier travertine without destruction of the fissure as a site of travertine emplacement; (2) termination of the fissure as a site of deposition with transfer of the geothermal activity to a new fracture. The presence of some 25 fractures in the c . 300 ka Sıcak Çermik field growing at rates of 0.1–0.6 mm a −1 suggests that the type (2) signature may be achieved by an M c . 7.5 event approximately every 10 ka.

Closure of the Neo-Tethyan Ocean in the Turkish sector of the Alpine-Himalayan orogen by ca. 12 Ma was succeeded by deformation of a domain between the Eurasia plate, presently bounded by the North Anatolian fault, and the Arabian indenter. Facets of this deformation comprise the crustal thickening and uplift that produced the Anatolian plateau, the establishment of transform faults, and tectonic escape as Arabia has continued to impinge into the collage of Anatolian terranes accreted by closure of the Neo-Tethys. We have compiled a database of neotectonic paleomagnetic results from Anatolia to analyze this deformation. Large rotations (up to 5°/10,000 yr) of small fault blocks along the intracontinental transform faults but do not extend away from these zones and show that seismogenic upper crust is decoupled from lower continental lithosphere undergoing continuum deformation. Between the transforms, large fault blocks exhibit slower rotation rates (mostly <1°/100,000 yr), varying systematically across Anatolia. Large counterclockwise rotations near the Arabian indenter diminish westward, becoming zero, and then move clockwise near the limit of tectonic escape. The view that the collage has rotated counterclockwise as a single plate, either uniformly or episodically, during the Neotectonic era is refuted. Instead, deformation has been distributed and differential as the collage adapted to changing tectonic regimes. Crustal extrusion to the west and south has expanded the curvature of the Tauride arc and combined with back-roll on the Hellenic arc to produce the extensional horst and graben province in western Turkey. The latitudinal motions are close to confidence limits but consistent with ∼800 km of northward motion of Anatolian terranes over 40 m.y., a figure including up to a few hundred kilometers of closure linked to crustal thickening since the demise of the Neo-Tethys.