Temporal changes in geochemical-isotopic systematics of the late Pleistocene Akkaya travertines (Turkey) – Implications for fluid flow circulation and seismicity

We investigate the temporal variations in stable carbon and oxygen and radiogenic Sr isotope as well as rare earth element contents of Akkaya travertine deposits in the Eskipazar region, northwest Turkey. U-Th age data indicate that studied travertines in the periphery of the 1944-earthquake rupture of the North Anatolian Fault Zone formed in a time span of 93 to 1.8 ka BP. The younger group is represented by fissure-filling carbonates whereas the older sequence is composed of veins with varying crystallization ages that are injected to bedded travertines. The age data on vein injections and fissure-ridge travertines in the Akkaya site indicate the seismic reactivation along the west-central part of the North Anatolian Fault Zone to be intensified at least 4 periods (1.8, 20, 47 and 88 ka BP) during the last 90 ka.