Duraylı İzotop (δ18O, δD, δ13C, δ34S) ve Ana-İz Element Bileşimleri ile Balıkesir (Türkiye) Sıcak Sularının Kökeninin İrdelenmesi

Kuzeybat› Anadolu’da yer alan Bal›kesir bölgesi termal sular› 31.8–98.5 ºC aras›nda de¤iflen s›cakl›k, 6.40 ile 8.40 aras›nda seyreden nötre yak›n pH ve 327–2578 mg/l aral›¤›ndaki Toplam Çözünmüfl Madde (TDS) de¤erleri sergilemektedir. Bölgede, s›cakl›klar› yüksek olan sular Na2SO4-NaHCO3, ›l›k sular ise CaHCO3 tipte bir bileflime sahiptir. Bal›kesir bölgesi s›cak sular›ndaki iz element bileflimleri önemli de¤iflimler göstermektedir. Sulardaki ve karbonat çökellerindeki alkali toprak metal bileflimlerinin karfl›laflt›r›lmas› sonucunda, magnezyum ve baryumun hareketli davran›fl sergiledikleri tespit edilmifltir. Kat› ve ak›flkan fazlardaki stronsiyum bileflimi genellikle sabit bir de¤er göstermektedir. Sulardaki ve karbonat çökellerindeki Li/Cs ve B/Cl oranlar›n›n benzer de¤erler göstermeleri, bu iyonlar›n basit kayaç çözünme ifllevi neticesinde suya kat›ld›klar›na iflaret etmektedir. Mineraldenge hesaplamalar›, CO2‘in termal sular›n kimyasal bileflimi üzerinde önemli bir etkisi oldu¤unu göstermifl ve ak›flkan bileflimlerinin denge durumu ile de¤il kayaç çözünme ifllevi taraf›ndan denetlendi¤ini ortaya koymufltur. Bal›kesir bölgesi termal sular›na uygulanan jeotermometre hesaplamalar› 200 °C’lik maksimum rezervuar s›cakl›¤› öngörmüfltür. δ18O-δD bileflimleri sular›n kökeninin meteorik oldu¤unu göstermifltir. Termal sulardaki sülfat için analiz edilen δ34S bileflimleri -5.5 ile +25.2‰ aras›nda de¤iflmektedir. Baz› sular›n kükürt izotop bileflimleri karasal evaporitlere karfl›l›k gelirken, bir k›s›m sulardaki kükürt ise sülfat indirgenme ifllevi neticesinde oluflmufltur. Termal sulardaki çözünmüfl inorganik karbon üzerinde analiz edilen δ13C bileflimleri -17.7 ile +0.7‰ aras›nda de¤iflmektedir. Kükürt gibi, karbonun da farkl› kökenler sergiledi¤i tespit edilmifltir. S›cakl›klar› yüksek olan sulardaki karbonun denizel karbonatlar›n çözünmesinden kaynakland›¤› düflünülmektedir. Bölgedeki denizel karbonat kayalar›n›n karbon izotop bileflimleri bunu destekler niteliktedir. Buna karfl›n, düflük s›cakl›ktaki sulardaki karbon ise organik bir köken sunmaktad›r.

Anahtar Kelimeler:

su-kayaç etkileflimi, durayl› izotop bileflimleri, ana-iz element jeokimyas›, Bal›kesir s›cak sular›, Türkiye

Constraints on the Origin of the Bal›kesir Thermal Waters (Turkey) from Stable Isotope (δ18O, δD, δ13C, δ34S) and Major-Trace Element Compositions

The Balıkesir thermal waters in northwestern Turkey have discharge temperatures in the range of 31.8-98.5 ºC, near neutral pH values of 6.40 to 8.40 and TDS contents between 327 and 2578 mg/l. Samples display variable chemical compositions changing from high-temperature Na2SO4-NaHCO3 waters to warmer CaHCO3 waters. Trace element concentrations of the waters show significant variation. Comparison between the concentrations of alkaline earth metals in waters and carbonate deposits reveals mobile behavior for Mg and Ba. The ratio of strontium to calcium concentrations in solid and liquid phases was found to be almost the same. Li/Cs and B/Cl ratios of waters and carbonates are similar suggesting the operation of a simple rock leaching process. Mineral equilibrium calculations imply that the CO2 concentration has a great effect on the chemistry of the thermal waters and that most fluid compositions are controlled by rock dissolution rather than equilibration. The chemical geothermometers applied to the Balıkesir thermal waters yield a maximum reservoir temperature of 200 °C. The d18O-dD compositions clearly indicate a meteoric origin for the waters. d34S contents of sulfate in thermal waters range from -5.5 to +25.2%o. Sulfur isotope compositions of some waters correspond to those of non-marine evaporates while sulfur in others is derived from sulfate reduction. The d13C ratio for dissolved inorganic carbonate in the waters lies between -17.7 and +0.7%o. There are also multiple sources of carbon. In high-temperature waters carbon is thought to originate from the dissolution of marine carbonates, an interpretation supported by carbon isotope compositions of marine carbonate rocks in the region. Carbon in low-temperature waters is derived from an organic source.

Keywords:

water-rock interaction, stable isotope compositions, major-trace element geochemistry, Balıkesir thermal waters, Turkey,

PDF

___

ALDANMAZ, E. 2006. Mineral-chemical constraints on the Miocene calc- alkaline and shoshonitic volcanic rocks of western Turkey: disequilibrium phenocryst assemblages as indicators of magma storage and mixing conditions. Turkish Journal of Earth Sciences 15, 47–73.
AKYÜZ, H.S. 1997. Geological units and structures in suture zone around Balıkesir NW Anatolia. Turkish Journal of Earth Sciences 6, 143–153.
ARNÓRSSON, S. 1985. The use of mixing models and chemical geothermometers for estimating underground temperatures in geothermal systems. Journal of Volcanology and Geothermal Research 23, 209–335.
ARNÓRSSON, S., GUNNLAUGSSON, E. & SVAVARSSON, H. 1983. The chemistry of geothermal waters in Iceland III. Chemical geothermometry in geothermal investigations. Geochimica et Cosmochimica Acta 47, 567–577.
BOZKURT, E. 2001. Neotectonics of Turkey - a synthesis. Geodinamica Acta 14, 3–30.
CLARK, I.D. & FRITZ, P. 1997. Environmental Isotopes in Hydrogeology. Lewis Publishers, CRC Press, New York.
DELALOYE, M. & BİNGÖL, E. 2000. Granitoids from Western and Northwestern Anatolia: Geochemistry and modeling of geodynamic evolution. International Geology Review 42, 241–268.
ERKÜL, F., HELVACı, C. & SÖZBİLİR, H. 2005. Stratigraphy and geochronology of the Early Miocene volcanic units in the Bigadiç borate basin, Western Turkey. Turkish Journal of Earth Sciences 14, 227–253.
FOURNIER, R.O. 1977. Chemical Geothermometers and Mixing Models for Geothermal Systems. Geothermics 5, 41–50.
FOURNIER, R.O. & POTTER, R.W. 1979. Magnesium correction to the Na- K-Ca chemical geothermometers. Geochimica et Cosmochimica Acta 43, 1543–1550.
FOURNIER, R.O. & POTTER, R.W. 1982. A revised and expanded silica (quartz) geothermometers. Geothermal Resources Council Bulletin 11, 3–12.
FOURNIER, R.O. & TRUESDELL, A.H. 1973. An empirical Na-K-Ca geothermometer for natural waters. Geochimica et Cosmochimica Acta 37, 1255–1275.
GENÇ, fi.C. 1998. Evolution of the Bayramiç magmatic complex, northwestern Anatolia. Journal of Volcanology and Geothermal Research 85, 233–249.
GENÇ, fi.C. & YıLMAZ, Y. 1997. An Example of post-collisional magmatism in northwestern Anatolia: the Kızderbent volcanics (Armutlu peninsula, Turkey). Turkish Journal of Earth Sciences 6, 33–42.
GIGGENBACH, W.F. 1988. Geothermal solute equilibria. Derivation of Na- K-Ca-Mg geoindicators. Geochimica et Cosmochimica Acta 52, 2749–2765.
GIGGENBACH, W.F. 1991. Chemical techniques in geothermal exploration. In: D'AMORE, F. (co-ordinator), Application of Geochemistry in Geothermal Reservoir Development, UNITAR, United States of America, 119–144.
GRASBY, S.H., HUTCHEON, I. & KROUSE, H.R. 2000. The influence of water-rock interaction on the chemistry of thermal springs in western Canada. Applied Geochemistry 15, 439–454.
HELVACı, C., STAMATAKIS, M., ZAGOUROGLOU, C. & KANARIS, J. 1993. Borate minerals and related authigenic silicates in northeastern Meditarranean Late Miocene continental basins. Exploration and Mining Geology 2, 171–178.
IZBICKI, J.A., CHRISTENSEN, A.H., NEWHOUSE, M.W. & AIKEN, G.R. 2005. Inorganic, isotopic, and organic composition of high-chloride water from wells in a coastal southern California aquifer. Applied Geochemistry 20, 1496–1517.
KARA, İ., YÜCEL, B., ÖZÇELİK, N., ÖLMEZ, E. & KAHRAMAN, E. 2002. Balıkesir-Pamukcu-3 (P-3) Sıcaksu Kuyusu Bitirme Raporu [Well Completion Report for the Balıkesir-Pamukcu-3 (P-3) Thermal Well]. Mineral Research and Exploration Institute (MTA) of Turkey Report no. 10525 [in Turkish, unpublished].
KHARAKA, Y.K. & MARINER, R.H. 1988. Chemical geothermometers and their application to formation waters from sedimentary basins. In: NAESER, N.D. & MCCULLOH, T. (eds), Thermal History of Sedimentary Basins. Springer Verlag, New York, 99–117.
KROUSE, H.R. 1976. Sulphur isotope variations in thermal and mineral waters. In: CADEK, J. & PACES, T. (eds), Proceedings International Symposium on Water-Rock Interaction, 343–347.
KROUSE, H.R. 1980. Sulfur isotopes in our environment. In: FRITZ, P. & FONTES, J.CH. (eds), Handbook of Environmental Isotope Geochemistry I, The Terrestrial Environment, A. Elsevier, Amsterdam, 435–472.
KROUSE, H.R. & MAYER, B. 2000. Sulphur and oxygen isotopes in sulphate. In: COOK, P. & HERCZEG, A.L. (eds), Environmental Tracers in Subsurface Hydrology. Kluwer Academic Publishers, Boston, 95–231.
LANGELIER, W. & LUDWIG, H. 1942. Graphical methods for indicating the mineral character of natural waters. Journal of American Water Association 34, 335–352.
MTA 2002. 1/500.000 Scale Geological Map of Turkey. İzmir and İstanbul Quadrangles. Ankara.
MUTLU, H. & GÜLEÇ, N. 1998. Hydrogeochemical outline of thermal waters and geothermometry applications in Anatolia, Turkey. Journal of Volcanology and Geothermal Research 85, 495–515.
ÖKTÜ, G. & DİLEMRE, A. 1997. Türkiye Termal ve Mineralli Sular Envanteri Balıkesir [Thermal and Mineralized Waters Inventory of Turkey]. Mineral Research and Exploration Institute (MTA) of Turkey Report no. 10474 [in Turkish, unpublished].
ÖLMEZ, E., ERTÜRK, İ., EKİCİ, S., DEMİREL, V., YıLDıZ, S., GÖKALP, Y. & SÖZEN, İ. 2001a. Balıkesir-Edremit-Derman Jeotermal Alanı Ed1, Ed2, Ed3 Sondajları Kuyu Bitirme Raporu [Well Completion Report for Ed1, Ed2 and Ed3 Geothermal Wells in the Balıkesir- Edremit-Derman Geothermal Area]. Mineral Research and Exploration Institute of (MTA) Turkey Report no. 10512 [in Turkish, unpublished].
ÖLMEZ, E., GEVREK, A.İ., YıLDıZ, S. & GÜDÜCÜ, A. 2001b. Balıkesir-Bigadiç- Hisarköy Jeotermal Alanı Hk-2, Hk-3, Hk-4 Jeotermal Sondajları Kuyu Bitirme Raporu [Well Completion Report for Hk-2, Hk-3 and Hk-4 Geothermal Wells in the Balıkesir-Bigadiç-Hisarköy Geothermal Area]. Mineral Research and Exploration Institute (MTA) of Turkey Report No. 10517 [in Turkish, unpublished].
PALMER, M.R. & HELVACı, C. 1997. The boron isotope geochemistry of the Neogene borate deposits of Western Turkey. Geochimica et Cosmochimica Acta 61, 3161–3169.
PALMER, M.R., HELVACı, C. & FALLICK, A.E. 2004. Sulphur, sulphate oxygen and strontium isotope composition of Cenozoic Turkish evaporates. Chemical Geology 209, 341–356.
REES, C.E., JENKINS, W.J. & MONSTER, J. 1978. The sulfur isotopic composition of ocean water sulphate. Geochimica et Cosmochimica Acta 42, 377–381.
fiENGÖR, A.M.C. & YıLMAZ, Y. 1981. Tethyan evolution of Turkey – A plate tectonic approach. Tectonophysics 75, 181–241.
TONANI, F. 1980. Some remarks on the application of geochemical techniques in geothermal exploration. In: Proceedings Advanced European Geothermal Resource 2ndSymposium. Strasbourg, 428–443.
WIGLEY, T.M.L. 1977. WATSPEC: a computer program for determining the equilibrium speciation of aqueous solutions. British Geomorphological Research Group Technical Bulletin 20, p. 48.
YALÇıN, T. 1997. Hydrogeological investigation of the Gönen and Ekflidere thermal waters (northwest Turkey). In: SCHINDLER, C. & PFISTER, M. (eds), Active Tectonics of Northwestern Anatolia – the Marmara Poly-Project. Vdf Hochschulverlag an der ETH, Zurich, 275–300.
YıLMAZ, Y., GENÇ, fi.C., KARACıK, Z. & ALTUNKAYNAK, fi. 2001. Two contrasting magmatic associations of NW Anatolia and their tectonic significance. Journal of Geodynamics 31, 243–271.
YÜCEL-ÖZTÜRK, Y., HELVACı, C. & SATıR, M. 2005. Genetic relations between skarn mineralization and petrogenesis of the Evciler granitoid, Kazdağ, Çanakkale, Turkey and comparison with world skarn granitoids. Turkish Journal of Earth Sciences 14, 255–280.