Ali Gökgöz

Depositional Properties and Geochemistry of Holocene Perched Springline Tufa Deposits and Associated Spring Waters: A Case Study from the Denizli Province, Western Turkey

Abstract The Güney waterfall area is a perched springline tufa site developed on the southeast slope of the Büyük Menderes River near Güney town, in the Denizli province, Western Turkey. The site is 12 km away from Güney and 72 km from the city centre of Denizli. The spring waters emerge from the boundary between Palaeozoic marble and micaschist and precipitated tufa deposits downslope at the altitudes ranging from 220 to 400 metres. The tufa deposits cover an area of about 20 hectares. Flat upper surfaces of the deposits are indicative of mature stage. The waters are of the Ca–HCO3 type and supersaturated with respect to CaCO3. The stable isotope values of the spring waters are −49.94 for δ2H and −7.15 for δ18O. The δ13C and δ18O values of active and passive tufa samples are in the range from −9.13 to −6.0‰, and from −8.44 to −7.40‰, respectively. These isotopic values are typical for fresh water tufa. The passive tufas give the 14C age in the range from 2000 to 5800 yr BP. According to the 14C age data, passive tufas are not older than Holocene. The stable isotope composition is similar south European examples.

Deadly CO2 gases in the Plutonium of Hierapolis (Denizli, Turkey)

Using a portable gas analyzer system, the geogenic gas regime below and around an ancient gate to hell at Hierapolis/Phrygia was characterized. The site was first described by Strabo and Plinius as a gate to the underworld. During centuries, it attracted even ancient tourists. In a grotto below the temple of Pluto, CO2 was found to be at deadly concentrations of up to 91%. Astonishingly, these vapors are still emitted in concentrations that nowadays kill insects, birds, and mammals. The concentrations of CO2 escaping from the mouth of the grotto to the outside atmosphere are still in the range of 4–53% CO2 depending on the height above ground level. They reach concentrations during the night that would easily kill even a human being within a minute. These emissions are thought to reflect the Hadean breath and/or the breath of the hellhound Kerberos guarding the entrance to hell. The origin of the geogenic CO2 is the still active seismic structure that crosses the old town of ancient Hierapolis as part of the Babadag fracture zone. Our measurements confirm the presence of geogenic CO2 in concentrations that explain ancient stories of killed bulls, rams, and songbirds during religious ceremonies. They also strongly corroborate that at least in the case of Hierapolis, ancient writers like Strabo or Plinius described a mystic phenomenon very exactly without much exaggeration. Two thousand years ago, only supernatural forces could explain these phenomena from Hadean depths whereas nowadays, modern techniques hint to the well-known phenomenon of geogenic CO2 degassing having mantle components with relatively higher helium and radon concentrations.