Noble gas isotopes and the chemical composition of geothermal gases from the eastern part of the Büyük Menderes Graben (Turkey)

Helium and carbon isotope composition of gas discharges in the Simav Geothermal Field, Turkey: Implications for the heat source

“…Areas of Cenozoic extensional tectonics typically have 3 He/ 4 He ratios that contain a 3 He component from a mantle source (Torgersen, 1993). Similarly, geothermal fluids in western Anatolia have 3 He/ 4 He ratios varying from 0.2 R A to 3.68 R A (Güleç , 1988;Ercan et al, 1994;Mutlu et al, 2008;Wiersberg et al, 2011;Karakuş and Ş imş ek, 2013) that indicate variable mantle-derived helium inputs. Güleç , (1988), Mutlu et al (2008), and Wiersberg et al (2011) reported helium isotope ratios up to 2.91 R A , which show strong evidence of mantle volatiles in high-temperature Kızıldere and Tekkehamam geothermal fields, situated at the eastern segment of the BMG.…”

“…Similarly, geothermal fluids in western Anatolia have 3 He/ 4 He ratios varying from 0.2 R A to 3.68 R A (Güleç , 1988;Ercan et al, 1994;Mutlu et al, 2008;Wiersberg et al, 2011;Karakuş and Ş imş ek, 2013) that indicate variable mantle-derived helium inputs. Güleç , (1988), Mutlu et al (2008), and Wiersberg et al (2011) reported helium isotope ratios up to 2.91 R A , which show strong evidence of mantle volatiles in high-temperature Kızıldere and Tekkehamam geothermal fields, situated at the eastern segment of the BMG. The localization of the highest heat and highest R A values at the eastern segment of the BMG, where there is no evidence of surface volcanism, led Güleç and Hilton (2006) and Mutlu et al, (2008) to suggest transfer of mantle volatiles to the crust, likely associated with (extension related) mantle melting, while the fault systems of the graben acting as conduits for the geothermal fluids to carry the mantle-He to the surface.…”

Turkish geothermal fields as natural analogues of CO 2 storage sites: Gas geochemistry and implications for CO 2 trapping mechanisms

“…While variations in CO 2 / 3 He values and He contents were attributed to preferential degassing of He from geothermal waters, the principal controls on CO 2 contents and ı 13 C values seemed to be the interplay between CO 2 dissolution and calcite precipitation (de Leeuw et al, 2010). Geochemical anomalies likely related to seismic activity were recorded for two localities: on Table 3 Reservoir lithologies, physicochemical parameters and hydrogeochemical facies of geothermal fluids from western Anatolia where He-CO2 data are available (Data sources: Eriş en, 1976;Ş imş ek, 1984;Mutlu, 1998Mutlu, , 2007Mutlu and Güleç , 1998;Vengosh et al, 2002;Karamanderesi and Helvacı, 2003;Tarcan and Gemici, 2003;Serpen, 2004;Ş imş ek et al, 2005;Aksoy et al, 2008Aksoy et al, , 2009Baba et al, 2009;Süer, 2010;Wiersberg et al, 2011;Karakuş and ş 11imş ek, 2013 …”

“…Regarding the He-CO 2 systematics of the western Anatolian fields, although 3 He/ 4 He and CO 2 / 3 He ratios, and the relative gas abundances (including noble gases), are reported for a number of samples from Kızıldere and Tekkehamam (Wiersberg et al, 2011), the datasets covering ı 13 C values (i.e., "R/R A − ı 13 C − CO 2 / 3 He and/or CO 2 concentration") are restricted generally to a single sample or a couple of samples for each specific field (Table 6). Overall, R/R A , CO 2 / 3 He and ı 13 C(CO 2 ) values cover ranges from 0.2 to 3.69, 1.66 × 10 9 to 2.35 × 10 13 , and −8.04 to +0.45‰, respectively (Table 6).…”

“…The database utilized in this study is produced essentially from the results of our studies in different regions of Turkey since 2000 (Güleç et al, 2002;Mutlu et al, 2008Mutlu et al, , 2012de Leeuw et al, 2010;Aydın et al, 2015), as well as from studies by other researchers (Wiersberg et al, 2011;Italiano et al, 2013;Karakuş and Ş imş ek, 2013). In the EAFZ and western Anatolia, there is widespread coverage of the He and CO 2 systematics of geothermal systems (Mutlu et al, , 2012Wiersberg et al, 2011;Italiano et al, 2013;Karakuş and Ş imş ek, 2013), whilst in the NAFZ there is the added advantage of temporal monitoring at individual localities (de Leeuw et al, 2010). Taken together, the database provides a unique opportunity to refine our knowledge about prospective storage systems in Turkey and compare results with those from gas fields where wells are more widely distributed and there is little or no temporal He-CO 2 data.…”