Geochemical Monitoring of the Seismic Activities and Noble Gas Characterization of the Geothermal Fields along the Eastern Segment of the Büyük Menderes Graben

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Tezin Türü: Doktora

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Jeoloji Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2010

Tezin Dili: İngilizce

Öğrenci: SELİN SÜER

Asıl Danışman (Eş Danışmanlı Tezler İçin): Nilgün Türkan Güleç

Eş Danışman: Jörg Erzinger

Özet:

This study aims the real-time monitoring of gases (CO2, N2, O2, H2, H2S, CH4, He, Ar) discharging from natural pools in the Tekke Hamam geothermal field (Denizli) in addition to the geochemical characterization of the field along with the Kızıldere geothermal field, both located at the eastern segment of the Büyük Menderes Graben. The continuous gas monitoring experiment (November 2007-October 2008) conducted in the Tekke Hamam geothermal field has revealed temporal variations in the gas compositions, gas flow rate and pool temperature. Different variation components, such as daily variation profiles and peak/Multi-day signals, are detected in the monitored data, which are mainly correlated with shallow and deep processes involving mainly meteorological factors and seismicity induced variations, respectively. Particularly, the coupled variations in the gas compositions and flow rate seem to correlate with seismicity induced permeability modifications within the subsurface during the absence of significant meteorological factors, such as high rainfall and varying atmospheric pressure. The noble gas characterization of the fields have revealed both high 3He/4He and 4He/20Ne isotopic ratios, suggesting a mantle contribution of about 18% for Kızıldere and 34% for Tekke Hamam, whereas the other noble gases (Ar, Ne, Kr, Xe) are of atmospheric nature. The different mantle contributions observed in both fields can suggest a different mantle-He flux variably contaminated by crustal helium. The chemical (cation-trace element-anion) and stable isotopic (δ18O-δD) contents of the thermal waters reveal high temperature water-rock interaction accompanied by the effects of deep origined gases (mainly CO2 and H2S) discharging from the fields.