U-series dating and geochemical tracing of late Quaternary travertine in co-seismic fissures I. Tonguç Uysal a, ⁎ , Yuexing Feng a , Jian-xin Zhao a , Erhan Altunel b , Dion Weatherley c , Volkan Karabacak b , Oya Cengiz d , Suzanne D. Golding a , Michael G. Lawrence a , Kenneth D. Collerson a a Earth Sciences and Centre for Microscopy and Microanalysis, University of Queensland, Brisbane QLD 4072, Australia b Department of Geological Engineering, Eskisehir Osmangazi University, Eskisehir, Turkey c Earth Systems Science Computational Centre and Australian Computational Earth Systems Simulator, University of Queensland, Brisbane QLD, 4072, Australia d Department of Geological Engineering, Süleyman Demirel University, Isparta, Turkey Received 29 June 2006; received in revised form 28 February 2007; accepted 4 March 2007 Editor: R.D. van der Hilst Available online 12 March 2007 Abstract We present a method to constrain the timing of fissure generation related to late Quaternary seismic events using the uranium-series technique. Dated samples were from travertine deposits precipitated in co-seismic extensional fissures along major active faults in Western Turkey. Stable isotope and REE data indicate that the precipitation of the fissure travertines was not controlled by the hydrologic regime that is responsible for the speolethem deposition in the same region. Moreover, the REE composition and concentration of the water from which the fissure travertine precipitated were significantly different from those of the current geothermal waters in the study area. The carbonate generation in the co-seismic fissures is interpreted to be the product of rapid precipitation from deeply infiltrated and CO 2 -enriched surface water during seismic strain cycles. Results show that U-series dating of fracture-filling travertine deposits from seismically active areas provide important temporal information relevant to establishing recurrence intervals of late Quaternary and prehistoric major earthquake events. Precise dating of prehistoric earthquakes may be of great value for seismic hazard studies and earthquake forecasting research, for which accurate estimates of recurrence intervals are critical. © 2007 Elsevier B.V. All rights reserved. Keywords: earthquake; hydrothermal; travertine; Turkey; U-series dating 1. Introduction The application of the 238 U– 234 U– 230 Th disequilib- rium provides great opportunities for dating carbonate crystallisation ages of less than 500,000 yr before present, especially since development of the thermal ionization mass spectrometric (TIMS) technique [1]. While U-series disequilibria have been applied routinely to corals, speleothems and calcite veins for paleocli- matic studies [2–4], TIMS U/Th dating technique has not been used previously as a routine method for dating vein formations related to paleo-seismic events. Only a few attempts have been reported in the literature dealing Earth and Planetary Science Letters 257 (2007) 450 – 462 www.elsevier.com/locate/epsl ⁎ Corresponding author. Tel.: +61 7 33652166; fax: +61 7 33651277. E-mail address: t.uysal@earth.uq.edu.au (I.T. Uysal). 0012-821X/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.epsl.2007.03.004