11 Amik Basin
Determination of fault activity by soil and groundwater degassing: The extension of Dead Sea Fault Zone (DSFZ) in the Amik Basin (Hatay) and its relation with Karasu Fault Zone and origin of thermal waters in Amik Basin, TUBITAK-COST Research Project in the frame of COST Action, Project No: 111Y090
The study area is close to the boundary of three tectonic plates (Anatolian, Arabian and African plates) and is characterised by important tectonic lineaments such as the Dead Sea Transform fault and the Karasu Fault which connects the former to the East Anatolian fault system. Based on the analytical results, water samples can be identified in three groups as hypersaline NaCl type deep circulated groundwater, low sulphate and magnesium water from ophiolites, CaHCO3 and CaSO4 type shallow groundwater. According to gas geochemistry results, the deep saline groundwaters are biogenic, Tahtakopru spring waters and the Kurtbag gas seeps come from the abiogenic source. Major gas compounds of the Kurtbag gas seeps are CH4, H2 and N2. The serpentinisation process of the ultramafic rocks to olivine is dominant in the Kızıldag ophiolite complex which caused to form hyperalkaline water springs. Volcanic rocks cropped out along the Karasu fault and at the west, northwest of the study area are alkaline basalts and basanites. Geochemical, mineralogical and petrographic analyses besides helium isotopes ratio show OIB-like origin while alkaline basalts MORB-type compositions. The relationship between local seismicity and soil degassing could not be obtained due to limited seismic network in the area. There is no evidence of extra thermal heat source rather the local geothermal gradient for the geothermal waters in the study area (Yuce et al., 2014).
The dry seep covers an area of about 200 m2 and has two main emission points. One of this comes from an outcrop of ophiolithic rocks and the gas when ignited gives flames up to 50 cm high. Methane flux measurements gave values up to 105 g/m2 /day (highest emission). Estimated methane output from the area is about 0.3 ton per year. The hyperalkaline springs have all pH comprised between 10.4 and 12.2 and have the typical Ca-(OH)2 type water and precipitation as CaCO3(whitish-color). Environmental isotopic compositions of water (O, D and T) indicate long hydrologic circuits.