Ünsal Gemici

Water geochemistry of the Seferihisar geothermal area, İzmir, Turkey

Abstract The Na–Cl thermal waters of Seferihisar have measured temperatures of 30–153°C, and conductivities of 7400–55200 μS/cm. They issue from Upper Cretaceous to Paleocene Bornova melange rocks, which are made up of sandstone–shale intercalations, conglomerate, mafic submarine volcanics, limestone lenses, serpentinite and limestone bodies, and their complexes, through the intersection of faults. The clay-rich zones of the overlying Neogene terrestrial sediments cap the system. The heat source is the high geothermal gradient caused by graben tectonics of the area. Na and Cl ions mainly dominate the chemistry of thermal waters, thus thermal waters of the Seferihisar area appear to be mixtures of groundwaters and seawater. The seawater contribution in thermal waters varies from 10% to 80%. Assessments from empirical chemical geothermometers, mineral equilibria and silica-mixing model applied on the thermal waters of the Seferihisar geothermal area suggest that the temperatures of the reservoir systems vary between 60 and 180°C. The Seferihisar geothermal area has been physically divided into five main groups and estimated reservoir temperatures provided by the entire methods give the increase as: Doganbey Burnu, Karakoc spa, Doganbey, Tuzla and Cumali spa areas in ascending order of reservoir temperature. Hydrogeochemical assessments indicate that thermal waters were mixed with cold waters before and/or after heating at depth in different proportions. The results of mineral equilibrium modeling indicate that the thermal waters of Seferihisar are undersaturated with respect to gypsum and amorphous silica, oversaturated with respect to calcite, dolomite and aragonite, and undersaturated or oversaturated with respect to quartz, chalcedony and anhydrite.

Hydrogeochemistry of the Simav geothermal field, western Anatolia, Turkey

Thermal waters hosted by Menderes metamorphic rocks emerge along fault lineaments in the Simav geothermal area. Thermal springs and drilled wells are located in the Eynal, Citgol and Nasa locations, which are part of the Simav geothermal field. Studies were carried out to obtain the main chemical and physical characteristics of thermal waters. These waters are used for heating of residences and greenhouses and for balneological purposes. Bottom temperatures of the drilled wells reach 163°C with total dissolved solids around 2225 mg/kg. Surface temperatures of thermal springs vary between 51°C and 90°C. All the thermal waters belong to Na–HCO3–SO4 facies. The cold groundwaters are Ca–Mg–HCO3 type. Dissolution of host rock and ion-exchange reactions in the reservoir of the geothermal system shift the Ca–Mg–HCO3 type cold groundwaters to the Na–HCO3–SO4 type thermal waters. Thermal waters are oversaturated at discharge temperatures for aragonite, calcite, quartz, chalcedony, magnesite and dolomite minerals giving rise to a carbonate-rich scale. Gypsum and anhydrite minerals are undersaturated with all of the thermal waters. Boiling during ascent of the thermal fluids produces steam and liquid waters resulting in an increase of the concentrations of the constituents in discharge waters. Steam fraction, y, of the thermal waters of which temperatures are above 100°C is between 0.075 and 0.119. Reservoir pH is much lower than pH measured in the liquid phase separated at atmospheric conditions, since the latter experienced heavy loss of acid gases, mainly CO2. Assessment of the various empirical chemical geothermometers and geochemical modelling suggest that reservoir temperatures vary between 175°C and 200°C.

The Effects of Colemanite Deposits on the Arsenic Concentrations of Soil and Ground Water in Igdeköy-Emet, Kütahya, Turkey

The hydrochemical study of the area surrounding the Hisarcık (Emet-Kütahya) colemanite mine shows extremely high arsenic contamination in ground water between 0.07 to 7.754 mg L-1. This contamination in and around the Igdeköy village of Emet was caused by naturally occurring arsenic dissolution from a borate bearing clay zone due to the leaching of arsenic bearing minerals. The arsenic concentration in the ground water varies locally from spring to spring and is related to the mineralogical and geochemical compositions and lithofacies of the contaminant aquifer. The Neogene borate-bearing clay unit, which contains some arsenic minerals such as realgar (AsS) and orpiment (As2S3) observed in colemanite (Ca2B6O11⋅5H2O) nodules, is responsible for the arsenic contamination in ground waters in the study area. Soil geochemical analyses show unremarkable concentrations, varying from <0.01 to 7.11 mg kg-1.

Hydrogeochemical and hydrogeological investigations of thermal waters in the Emet area (Kütahya, Turkey)

Metamorphic rocks host the majority of the thermal waters of the Emet area. Only Dereli springs are hosted by nonmetamorphic carbonates and ophiolitic rocks. The carbonated rocks of the lower parts of the Neogene sequence are also secondary reservoir rocks. The measured surface temperatures of thermal waters are between 33 and 54 C. Most of the thermal waters are characterized as Ca–Mg–SO4–HCO3 type although there are a few Ca–Na–HCO3, Na–Ca– SO4 and Ca–Mg–HCO3 waters. Calcium concentrations in the thermal waters are 89–354 mg/kg. High SO4 contents of the thermal waters (up to 1309 mg/kg) are related to rocks and minerals in the Red Unit below the Emet borate deposits. Although the SO4 concentrations are high and SO4 is the major anion, gypsum and anhydrite are undersaturated for all of the thermal waters indicating that dissolution of SO4 is still taking place in the reservoir. Thermal waters are oversaturated at outlet conditions with respect to calcite, chalcedony, dolomite and quartz. According to the activity diagrams thermal waters are likely to form illite as an alteration product in the reservoir and Ca and Mg contents are controlled by exchange with smectite. Reservoir temperatures obtained by silica geothermometers and assessments of the saturation states of minerals are more appropriate for Emet geothermal waters. Assessments of the various geothermometers suggest that reservoir temperature is around 75–87 C.

The influence of the abandoned Kalecik Hg mine on water and stream sediments (Karaburun, İzmir, Turkey)

This study covers the geochemical investigations on water and stream sediments to evaluate the influence from the abandoned Kalecik Hg mine. The groundwater samples (S5, S8, S9, WW10) are neutral, slightly alkaline waters which have pH values varying between 7.3 and 7.5. Electrical conductivity (EC) values of groundwaters for spring samples are low (250-300 microS/cm). However, groundwater obtained from a deep well has a higher EC value of 950 microS/cm. Hg concentrations of groundwater samples vary between 0.01 and 0.13 microg/l. Hg concentrations of other water samples taken from mining area from surface waters and adits are between 0.10 and 0.99 microg/l. Adit water (A4) collected at the mine has the highest Hg content of 0.99 microg/l and a pH of 4.4. Trace element concentrations of mine water samples show variable values. As is observed only in MW1 (310 microg/l). A4 was enriched in Cd, Co and Cr and exceed the Turkish drinking water standards (Türk Standartlari Enstitüsü, 1997). Cu concentrations vary between 6.0 and 150 microg/l and are below the Turkish water standards. Mn concentrations in mine waters are between 0.02 and 4.9 mg/l. Only for sample A4 Mn value (4.9 mg/l) exceeds the standard level. Ni was enriched for all of the mine water samples and exceeds the safe standard level (20 microg/l) for drinking water. Of the major ions SO(4) shows a notable increase in this group reaching 650 mg/l that exceeds the drinking water standards. Stream sediment samples have abnormally high values for especially Hg and As, Sb, Ni, Cr metals. With the exception of sample Ss6 of which Hg concentration is 92 mg/kg, all the other samples have Hg contents of higher than 100 mg/kg. Pollution index values are significantly high and vary between 69 and 82 for stream sediment samples.

Numerical investigations of fault-induced seawater circulation in the Seferihisar-Balçova Geothermal system, western Turkey

The Seferihisar-Balçova Geothermal system (SBG), Turkey, is characterized by temperature and hydrochemical anomalies along the faults: thermal waters in northern Balçova are heated meteoric freshwater, whereas the hot springs of the southern Seferihisar region have a strong seawater contribution. Previous numerical simulations of fluid flow and heat transport indicated that focused upsurge of hot water in faults induces a convective-like flow motion in surrounding units. Salt transport is fully coupled to thermally driven flow to study whether fault-induced convection cells could be responsible for seawater encroachment in the SBG. Isotope data are presented to support the numerical findings. The results show that fault-induced convection cells generate seawater plumes that extend from the seafloor toward the faults. At fault intersections, seawater mixes with rising hot thermal waters. The resulting saline fluids ascend to the surface along the fault, driven by buoyant forces. In Balçova, thick alluvium, minor faults and regional flow prevent ascending salty water from spreading at the surface, whereas the weak recharge flow in the thin alluvium of the southern SBG is not sufficient to flush the ascending hot salty waters. These mechanisms could develop in any faulted geothermal system, with implications for minerals and energy migration in sedimentary basins.ResumeLe système géothermal de Seferihisar-Balçova (SGSB), en Turquie, est caracterisé par des anomalies thermiques et hydrochimiques le long de failles : les eaux thermales dans la Balçova du Nord sont des eaux douces météoriques réchauffées, tandis que les sources chaudes de la région de Seferihisar ont une contribution forte de l’eau de mer. Des simulations numériques antérieures des écoulements de fluide et du transport de chaleur indiquent que des venues d’eau chaude dans les failles provoquent un mouvement de l’eau de type convectif dans les terrains alentours. Le transport du sel est complètement couplé avec le calcul des écoulements induits par la chaleur pour étudier si les cellules de convection crées par les failles pouvaient être responsables de l’invasion marine dans le SGBS. Les données isotopiques sont présentées pour appuyer les conclusions des calculs numériques. Les résultats montrent que la convection induite par les failles crée un panache d’eau salée qui s’étend du fond de la mer vers les failles. A l’intersection avec les failles, l’eau de mer se mélange avec l’eau des sources chaudes. Les fluides salins qui en résultent montent et atteignent la surface le long des failles, sous l’effet de la poussée d’Archimèdes. A Balçova, des alluvions épaisses, des failles mineures et l’écoulement régional empêchent l’eau salée qui remonte de s’étaler en surface, alors que la faible recharge des alluvions peu épaisses du sud du SGBS est insuffisante pour repousser l’eau chaude salée en mouvement ascendant. Ces mécanismes pourraient se développer dans n’importe quel système faillé géothermal, avec des implications sur la migration des minéraux et de l’énergie dans les bassins sédimentaires.ResumenEl sistema geotermal de Seferihisar-Balçova (SBG), Turquía, está caracterizado por anomalías de la temperaturas e hidroquímicas a lo largo de las fallas: las aguas termales en el norte de Balçova son agua dulces meteóricas calientes, mientras que los manantiales calientes de la región del sur de Seferihisar tienen una fuerte contribución de agua de mar. Las simulaciones numéricas previas del flujo del fluido y el transporte de calor indicaban que la surgencia focalizada de agua caliente en las fallas inducen un movimiento de flujo convectivo en las unidades circundantes. El transporte de sales se acopla totalmente al flujo térmicamente forzado para estudiar si las celdas de convección inducidas por las fallas podrían ser responsables de la invasión de agua de mar en el SBG. Se presentan los datos de isótopos para respaldar los hallazgos numéricos. Los resultados muestran que las celdas de convección inducidas por las fallas generan plumas de agua de mar que se extienden desde el fondo del mar hacia las fallas. En las intersecciones de las fallas, el agua de mar se mezcla con las aguas termales calientes surgentes. Los flujos salinos resultantes ascienden a la superficie a lo largo de la fallas, forzados por las fuerzas de flotación. En Balçova el grueso aluvio, las fallas menores y el flujo regional impiden que el agua salada ascendente se propague en la superficie, mientras que el flujo débil de la recarga en el aluvio delgado del sur del SBG no es suficiente para barrer el flujo ascendente de las aguas saladas. Estos mecanismos podrían desarrollarse en cualquier sistema geotermal fallado, con implicancias para la migración de minerales y de energía en las cuencas sedimentarias.摘要土耳其Seferihisar-Balçova(SBG)地热系统表现为沿着断裂的温度和水化学异常:北部Balçova地区的热水来源于大气降水,南部Seferihisar地区热水海水来源较多。前期水流场和热传导的数值模拟表明断裂里热水的集中涌出导致邻近单元里出现对流。盐分运移模拟耦合了热导致的水流,用于研究SBG地热系统中断层导致的对流是否产生了海水入侵。同位素数据用于为模拟结果提供依据。结果表明断裂导致的对流产生了海水晕,且其从海底直接延伸至断裂处。在断裂交汇处,海水与上升的热水发生混合。在浮力作用下,形成的咸水沿着断裂上升至地表。在Balçova地区较厚的冲积层处,基本上没有断裂和区域水流阻碍上升的咸水扩展到地表,而南部SBG地热系统中薄层冲积层里的补给较差的水流不足以冲散上升的咸水。这些过程在任何有断裂的地热系统中都能产生,也能应用于沉积盆地中矿物和能源的运移研究。RiassuntoLe falde acquifere del sistema geotermico del Seferihisar-Balçova (SBG), Turchia, sono caratterizzate da anomalie termiche e chimiche lungo le faglie: le acque termali a Nord di Balcova sono acque meteoriche riscaldate mentre le sorgenti di acqua calda nella regione meridionale di Seferihisar hanno salinità molto elevate. Simulazioni numeriche di flussi idrici e di calore hanno indicato che la fuoriuscita di acque termali focalizzata nelle faglie induce una circolazione convettiva negli acquiferi circostanti. Il trasporto di sale viene ora accoppiato ai flussi idrici indotti termicamente per studiare se questi flussi convettivi possano essere responsabili delle intrusioni marine nel SBG. Dati isotopici vengono presentati a sostegno dei risultati numerici. Questi ultimi mostrano che le cellule convettive indotte dalle faglie generano piume di acqua marina che si estendono dal fondo marino verso le faglie stesse. All’intersezione delle faglie, l’acqua marina si mescola con le acque termali ascendenti. I fluidi salini risultanti da questa miscela raggiungono la superficie lungo le faglie grazie alle forze di galleggiamento. In Balcova, lo spesso strato di sedimenti alluvionali, le faglie minori e il flusso idrico regionale impediscono alle acque termali ascendenti di diffondersi mentre le deboli ricariche idriche nel sottile deposito alluvionale nel SBG meridionale non sono sufficienti a diluire le acque termali ascendenti. Questi meccanismi possono svilupparsi in qualsiasi sistema geotermico con faglie, il che ha implicazioni per il trasporto di minerali ed energia in bacini sedimentari.ResumoO sistema Geotérmico de Seferihisar-Balçova (SBG), na Turquia, é caracterizado por anomalias hidroquímicas e de temperatura ao longo das falhas: as águas termais no norte de Balçova são águas quentes de origem meteórica, ao passo que as fontes termais da região sul de Seferihisar têm uma forte contribuição de água do mar. Anteriores simulações numéricas de fluxo de fluidos e transporte de calor indicaram que a ascenção localizada de água quente nas falhas induz um movimento de fluxo de tipo convectivo nas unidades vizinhas. O transporte do sal foi totalmente associado ao fluxo termo-induzido para estudar de que modo as células de convecção induzidas pelas falhas poderiam ser responsáveis pela invasão da água do mar no SBG. São apresentados dados isotópicos para apoiar as constatações numéricas. Os resultados mostram que as células de convecção induzidas pelas falhas geraram plumas de água salgada que se estendem desde o fundo do mar em direção às falhas. Nos cruzamentos de falhas, a água do mar mistura-se com as águas termais quentes ascendentes. Os fluidos salinos resultantes ascendem até à superfície ao longo das falhas, actuados por forças de impulsão. Em Balçova, as aluviões espessas, as falhas menores e o fluxo regional evitam que a água salgada ascendente se espalhe até à superfície, enquanto que o fraco fluxo de recarga na fina camada de aluvião no sul do SBG não é suficiente para repelir as águas salgadas quentes ascendentes. Estes mecanismos podem desenvolver-se em qualquer sistema de falhas geotérmicas, com implicações na migração de minerais e energia em bacias sedimentares.ÖZTürkiye’nin batısındaki Seferihisar-Balçova Jeotermal Sistemi (SBJS), faylar boyunca oluşan sıcaklık ve hidrokimyasal anomalilerle tanımlanır. Seferihisar bölgesinde sıcak su kaynaklarında güçlü bir deniz suyu katkısı varken Balçova’da sıcak sular, ısınmış meteorik tatlı sulardan meydana gelmektedir. Önceki akışkan akımı ve ısı taşınım sayısal modellemeleri, faylardaki sıcak sulardaki yükselmenin çevre birimlerde konvektif akım benzeri harekete neden olduğunu belirtmektedir. SBJS’de faylarla kontrol edilen konveksiyon hücrelerinin, deniz suyu girişiminden sorumlu olup olmadığını araştırmak için tuz taşınımı tamamen sıcak su kontrollü akımla birleştirilmiştir. İzotop verileri de, sayısal sonuçları desteklemek için sunulmuştur. Sonuçlar, fay kontrollü konveksiyon hücrelerinin, deniztabanından faylara doğru uzanan denizsuyu girişimini yarattığını göstermiştir. Fay arayüzeylerinde deniz suları, yükselen sıcak sular ile karışmaktadır. Sonuçta oluşan tuzlu akışkanlar, sıcaklık farkı ile oluşan kuvvetlerle faylar boyunca yükselmektedir. Seferihisar’da ince alüvyondaki zayıf akımlar yükselen sıcak tuzlu sular üzerinde etkisiz kalırken, Balçova’da kalın alüvyon, faylar ve bölgesel akım tuzlu suyun yükselerek yüzeyden çıkmasına engel olmaktadır. Bu mekanizmalar sedimanter havzalardaki mineral ve enerji göçünün oluştuğu herhangi bir faylı jeotermal sistemde gelişebilir.

Hydrogeochemical study of the gümüşköy spa (Aydin) and its vicinity

Gümüşköy Kaplıcası Batı Anadolu Bölgesi’nde Büyük Menderes Grabeni’nin güneybatı kısmında yer almaktadır. İnceleme alanındaki termal suların kaynak çıkış sıcaklıkları 20-36 °C, pH değerleri 6.4-7.5 ve elektriksel iletkenlikleri (EC) 2000-11230 μS/cm arasındadır. Termal sular genel olarak Na-Cl su tipindedirler. Jeotermal sistemin rezervuar kayaçları Menderes Masifi’nin karstik mermerleri ve çatlaklı şist birimleridir. Neojen’in geçirimsiz birimleri jeotermal sistemin örtü kayalarını oluşturmaktadır. Sistemin ısı kaynağı ise tektonizmaya bağlı yüksek jeotermal gradyandır. Termal sular Giggenbach Diyagramı’na (1988) göre çoğunlukla ham sular sınıfındadır ve kimyasal jeotermometrelerle hesaplanan rezervuar sıcaklıkları 55-114 °C arasında değişmektedir. Ölçülmüş sıcaklıklardaki mineral doygunlukları, termal sularda genellikle kalsit, aragonit ve dolomit minerallerinin çökel oluşturduğunu gösterir. Suların jips, anhidrit, sölestin ve barit minerallerini ise çözündürücü özellikte oldukları görülmektedir. Termal suların üretim ve iletim hatlarında ve atık suların reenjeksiyonu sırasında kalsit, aragonit ve dolomit minerallerinin kabuklaşma riski oluşturacağı belirlenmiştir. Silis mineralleri ise kinetik özelliklerinden dolayı amorf silis özelliğinde çökelebilir. Gümüşköy Spa is located in southwest of the Büyük Menderes Graben in Western Anatolia. The thermal waters of the area have spring temperatures of 20-36 °C, pH of 6.4-7.5 and EC of 4960 to 5079 μS/cm. Water type of thermal waters is generally Na-Cl type. Reservoir rocks of geothermal systems are marble and fissured schist units of Menderes Massif. Impermeable units of Neogene are the cap rocks of geothermal systems. Heat source of system is also geothermal gradient connected with tectonism. According to Giggenbach Diagram (1988), thermal waters mostly fall into the immature fields and reservoir temperatures vary between 55-114 °C. Mineral saturation in outlet temperatures indicates that calcite, aragonite, and dolomite minerals are generally oversaturated in the thermal waters. However, it is seen that the thermal waters is undersaturated with gypsum, anhydrite, celestite, and barite. It is determined that calcite, aragonite and dolomite minerals will be created scaling risk in production and conduction line of the thermal waters and during the reinjection of waste water. Silica minerals may also precipitate amorphous silica due to kinetic properties.