Geochemistry of the thermal springs of Mount Taftan, southeastern Iran
Ata Shakeri a, Farid Moore a,⁎, Mazda Kompani-Zare b
a Department of Earth Sciences, College of Sciences, Shiraz University, Shiraz 71454, Iranb Department of Desert Management, School of Agriculture, Shiraz University, Shiraz 71441, Iran
emistry from the southern flank of Mount Taftan was investigated in order todiscriminate among hydrochemical facies, isotopic characteristics, geothermal reservoir and identify themajor geochemical processes that affect water composition.The waters from both the hot and cold springs show high total dissolved solids content, and are strongly tolightly acidic. Calcium is the dominant cation; in terms of anions, the Taftan hot springs are Cl–SO4 type.There is also a HCO3 type cold spring. The SO4/Cl ratios on an SO4–Cl–HCO3 diagram confirm the volcanicorigin of the hot waters. Conservative elements indicate that the three types of analysed water have similarorigin and the difference in concentration is due to dilution of thermal water with almost shallow freshgroundwater, not affecting the elements' proportions. Also, the retrogressive δ18O-enrichment with respectto the meteoric water line (MWL), confirms that thermal waters (andesitic water) have been diluted byshallow waters of meteoric origin.Comparison of the chemistry of thermal and cold springs and other evidences are indicative of an immaturehydrothermal water system in Taftan volcano.Because of waters immaturity, temperatures in the geothermal reservoir in Taftan region cannot be estimatedaccurately by applying Na–K, K–Mg and quartz geothermometers.
Numerous thermal and cold springs are located in active volcanicregions all over the world, as a result of eruptive events, as well asobvious manifestations of long-lived hydrothermal systems. Thetemperature and rate of discharge of thermal springs depend onfactors such as the rate at which water circulates through the systemof underground channel ways, the amount of heat supplied at depth,and the extent of dilution of the heated water by cold ground waternear the surface.
These springs are frequently developed as spas and bathingfacilities, improving social and economic well-being. Other usefulapplications of thermal springs in volcanic regions are related to directapplication of heat production for domestic use, greenhouse heatsupply, and power production. The applications depend on thedischarge volume and temperature of geothermal resources (Wohletzand Heiken, 1992). Numerous studies have been conducted in activevolcanic regions worldwide (Gigeenbach, 1997a,b; Valentino et al.,1999; Varekamp et al., 2001). The geochemistry of thermal waters hasbeen used by many authors as a useful tool for volcanic activitymonitoring (e.g. Oskarsson, 1995; Valentino and Stanzione, 2004).
.
l rights reserved.
Extensive areas of Iran are made up of Tertiary volcanic rock in along belt from Turkey to Pakistan. According to the geologicalinformation, geothermal resources are available throughout Iran in avariety of geothermal form and settings with thermal springs. Taftanstratovolcano is one of the largest geothermal fields located in flyschzone of eastern Iran about 100 km South–southeast of Zahedan city(Figs. 1 and 2).
Several surveys are already carried out in this area (Gansser, 1971;Boomeri, 2004; Moore et al., 2005). The studies mainly deal withgeological, petrological, environmental, geochemical, and hydrother-mal and hydrogeological aspects of the area. However, there is nopublished data on water chemistry.
The present study is aimed at defining the hydrochemistry of thehot and cold springs of the Taftan volcano, mixing of geothermal fluidswith cold fresh water, estimating reservoir temperatures, anddetermining the isotopic characteristics in order to infer the sourceof the thermal waters. The final results can be used to plan futuredevelopment of the geothermal resources on the southern flank ofMount Taftan.
2. Regional setting
The study area lies within the Makran structural zone in south-eastern Iran. This zone is an accretionary wedge (Demets et al., 1990)resulting from the convergence of the Eurasian and Arabian Plates(Fig. 1). Up to 7 km of sediments have been deposited in the Oman Sea,
Fig. 1. Tectonic map of Makran subduction zone, showing Taftan area (after Alavi, 1994).
830 A. Shakeri et al. / Journal of Volcanology and Geothermal Research 178 (2008) 829-836
comprising a lower unit of the Himalayan turbidites, which isunconformably overlain by an upper unit of the Makran sands. Theincreasing depth of the seismic events in Iran indicates that the Benioffzone continues to extend under the Bazman–Taftan–Sultan volcanic arc.The volcanic centers of Taftan and Bazman in Iran and Sultan in Pakistanwere formed by the subduction of the Oman oceanic crust under thesouthern margin of the Makran zone (Farhoudi and Karige, 1977).
The oldest rocks in the Taftan region are the Upper Cretaceouspelagic limestones. This rock unit is composed of pelagic limestonesand calcareous shales, intruded by basic volcanic rocks that showepidote hydrothermal alteration and pillow structures.
Eocene flysch-type sediments are widespread in northern Taftan;the area forms part of the flysch zone of eastern Iran. These sedimentsconsist of sandstones and shales with thin intercalated basalt flowsand greywackeswith interlayered argillaceous sandstones, mudstonesand shales. Pleistocene and Quaternary volcanics consist of tuff andandesitic flows. The andesitic flows are less than a million year old(Moinvaziri and Aminsobhaniet, 1978).A simplified geological map ofthe Taftan area is presented in Fig. 2.
The existence of active volcanism, shallowmagmatically-heated rocks,anddeep fracture and fault systemshave created favourable conditions forthe development of hydrothermal systems in the Taftan region.
3. Taftan volcano
Mount Taftan is characterized by a steep topography with deep V-and U-shaped river valleys. Winters are cold and summers warm anddry; in the hottest months, from June to August, the mean maximumtemperature is about 30 °C. Snowgenerally falls between December andFebruary, when the temperatures drop to a minimum of several degreesbelow freezing; rainfall in the region is scanty. Taftan is a strongly erodedandesitic stratovolcano with two prominent summits. The higher,3940 m SE summit cone is well preserved and has been the source ofvery fresh-looking lava flows. Highly active, sulfur-encrusted fumarolesoccur at the summit of the SE cone. The deeply dissected NW cone is ofPleistocene age. A lavaflowwas reported at Taftan in 1993 by Siebert andSimkin (2002), but may have been a mistaken observation of a moltensulfurflow.MountTaftan is now in an active, post-volcanic and fumarolicstage.
The calk-alkaline volcanic rocks at Taftan are the product of amagma formed during a compressive tectonic phase (Berberian andKing,1981). The rocks are similar to island-arc, calk-alkaline series andare related to the subduction of the Arabian Plate underneath theMakran region (Farhoudi and Karige, 1977). The Taftan volcanic rocksare pyroclastic and epiclastic, with lava flows consisting mainly of
porphyry andesites, dacites and rhyolites; their main minerals areplagioclase, hornblende, biotite, quartz, orthopyroxene and clinopyr-oxene. The opaque minerals comprise magnetite, hematite, pyrite,chalcopyrite, titanomagnetite and ilmenite (Boomeri, 2004). The SiO2
content of the rocks varies from 54.43 to 68.74 wt.%.The Taftan volcanic rocks are strongly enriched in incompatible
elements such as Sr, K, Rb, and Th and REE relative to both primitivemantle and chondrites. According to Boomeri (2004), the volcano hasprobably evolved in an active continental margin tectonic setting froman enriched mantle and with the involvement of crustal materials.
4. Material and methods
Water samples were collected from thermal and cold springs onthe SSE flank of Mount Taftan in two periods i.e., Feb 2006 and June2006. The discharge rates of these springs vary from less than 0.5 to10 L/s and their fluid temperatures range between 6° and 48 °C.Physicochemical parameters of the waters, such as temperature, pHand electrical conductivity (EC), were measured in the field, whilecalcium, potassium, magnesium, sodium, bicarbonate, sulfate andchloride ions weremeasured in the laboratory using standard titrationand Inductively Coupled Plasma (ICP) methods. Silica was determinedusing a HACH DR/2000 spectrophotometer. Trace elements Li, Cs, Rband B, and Br were measured using ICP-MS. The water samples wereanalysed in Akita University, Japan, for δ18O and δD isotope analysesusing an isotopic ratio mass spectrometer. The results of the chemicaland isotope analyses are presented in Table 1. The detection limit foreach element is also given in the table.
5. Results and discussion
5.1. Water chemistry
The analyses show that Cl (10–5600 mg/l) and Ca (53–453mg/l) arethe dominant anion and cation, respectively. Sodium (29–407mg/l) andpotassium (9–294 mg/l) are also significant. On the basis of theirchemistry, pH and EC, the Taftan springwaters can be divided into threegroups.
The first group consists of waters from high elevation (about3200 m) near the western crater and includes the Taftan1 (Taf1) andTaftan2 (Taf2) thermal springs. Their waters have EC in the 28,780–29,400 μs/cm range, and pH from 1.5 to 1.8. Chloride and SO4 are thedominant anions in this group; major cations are Ca, Na, and K withlesser amounts of Mg. The waters in this group have the highestmeasured spring temperatures (37°–48 °C).
The secondgroupof springs (TVS andFWT inTable 1) is cooler (about14 °C), occurs at lower elevations (about 2350m) and is associated withhydrothermal alteration zones. Their waters EC and pH range from 1220to 2780 μs/cm and from 3.9 to 5.6, respectively. As in the first group, themain anions are Cl and SO4; the main cations are Ca and Mg.
The third group (FWP in Table 1) consists of a single mineral wateron the lower flank of Mount Taftan (at about 2200 m elevation). Thewater has EC in the 303–308 μs/cm range and a pH between 7.5 and7.6. The main anion in this spring is HCO3; like the other two groups,the main cation is Ca.
5.2. Cl–HCO3–SO4 content
The relative proportion of Cl, HCO3 and SO4 are reported in thediagram Cl–HCO3–SO4 (Fig. 3) proposed by Giggenbach (1991).MostTaftan spring samples plot in the field corresponding to volcanic waters(Fig. 3). Typically these waters are highly acidic, oxidizing solutionscontaining Cl and S due to the absorption of magmatic vapours by thedeep circulating groundwaters. The proportion of Cl and S in thesewaters depends upon the composition of the original magmatic vapour(Gigeenbach, 1997a,b). A low SO4/Cl ratio is found in the Taftan springs
Fig. 2. Simplified geological map of the Taftan area, showing spring fluid sampling sites.
831A. Shakeri et al. / Journal of Volcanology and Geothermal Research 178 (2008) 829-836
(Fig. 3) suggesting a loss of S through precipitation of sulfides (pyrite),sulfates (anhydrite, alunite) or elemental sulfur. All these mineral formsoccur in the vicinity of the Taftan springs (Moore et al., 2005). Theposition of the data along the SO4–Cl axis indicates immaturity and aprobable volcanic origin of water. Only the FWP samples plot in the fieldof “peripheral and waters”.
5.3. Na–K–Mg content
The Na–K–Mg diagram of Giggenbach (1988) can be used todetermine thematurity of water samples as well as to obtain Na/K andMg/K geothermometer temperatures.
Fig. 4 shows Taftan analyses plotted onNa–K–Mgdiagram showingfields of full and partial equilibrium. The samples form two distinct
clusters, one made up of TAF1 and TAF2 samples away from the Mgcorner and a second consisting of TVS, FWPand FWTsamples plot nearthe Mg corner below the partial-equilibrium line in the field ofimmaturewaters. Thehigh relative concentration ofMg in these springsamples suggests that they are immature waters that are not inequilibriumwith the host rock.Waterswith higher pH such as FWParealso immature.
There are three probable reasons for the observed difference in thepositions of the two clusters, and for the proximity of thewaters to theMgcorner: (1) mixing of deep immature thermal waters with shallow coldmeteoric waters; (2) circulation of hot water through evaporiticformations and alteration zones, and (3) mixing with connate marinebrines (Giggenbach,1988). The high Cl content, relatively low SO4 contentand moderate temperature indicate that the most probable mechanism
832 A. Shakeri et al. / Journal of Volcanology and Geothermal Research 178 (2008) 829-836
for high Mg content is mixing of deep immature thermal waters withshallow cold ground water.
5.4. Na–K–Mg–Ca content
TheNa–K–Mg–Ca diagram (Giggenbach andGlover,1992) can also beused todetermine theoriginof thewaters and the reservoir temperature.Fig. 5 shows the Na–K–Mg–Ca diagram as applied to the Taftan data. Itshows that all samples plot near the “rock dissolution region” close to theupper right corner of the diagram. The plots of the samples coincide inthis diagram because of the similarity between the Na/K and Mg/Caratios in the spring waters, indicating that all the waters are immature,i.e. they are not in chemical equilibriumwith the host rocks.
5.5. Conservative elements
5.5.1. Variation of element concentrations relative to that of chlorideIn geothermal systems chloride can be regarded as a chemically
conservative ion (Motyka et al., 1993). Showing the concentration of
Fig. 3. Plot of data given in Table 1 for Mount Taftan spring waters, u
ions or elements relative to chloride will reveal the changes in theconcentration of ions. For comparison purposes, we plotted thevariation in the concentrations of some major ions such as Na, Mg, Ca,and K and some conservative elements such as Br, F, B, Cs, Rb and Liversus Cl concentration (Fig. 6a and b). Fig. 6a shows the trends for themajor ions in the spring waters, indicating the dilution of the thermalwaters by shallow (colder) groundwaters. The higher relative contentof Ca and Na ions in Fig. 6a reflects the dissolution of the country rocks(see Fig. 5).
On a log–log plot a linear function (dilute trend) will have a 0.7slope. As can be seen in Fig. 6b all lines are parallel to dotted line with0.7 slopes, which in this type of graph indicate that the ratio betweenthe elements is constant. This diagram shows that the three types ofanalysedwater have similar origin. The diagram also indicates that thedifference in concentration is due to dilution of thermal water withalmost shallow fresh groundwater, not affecting the elements,
proportions.The relative proportion of conservative elements in the waters is a
useful datum for tracing the source of the thermal fluids since the
sing the triangular Cl–SO4–HCO3 diagram of Giggenbach (1991).
Fig. 4. Plot of data given in Table 1 for Mount Taftan spring waters, using the triangular Na–K–Mg diagram of Giggenbach (1991).
833A. Shakeri et al. / Journal of Volcanology and Geothermal Research 178 (2008) 829-836
relative proportion tend to be unaffected by shallow processes such asdilution or boiling. Fig. 7 shows a Li–Rb–Cs triangular diagram for thewater samples. The spring waters are plotted near the Rb corner andshow the compositional range from basalt to rhyolite. The miner-alization trends and water composition paths depicted in Fig. 7 arediscussed in Giggenbach and Goguel (1989). Generally, Li is incorpo-rated into secondary quartz and chlorite (Reyes et al., 1993) may beacquired directly by rock dissolution. Rubidium behaves much as Kand at high-temperatures (N300 °C) is taken up by secondary claysand alteration products such as illite, while Cs is incorporated intozeolites, especially at temperatures below 250 °C.
The average Li/Cs ratio of the acidic thermal spring waters on thesouthern flank of Mount Taftan is 7. This ratio is close to that ofintermediate volcanic rocks, suggesting that Li and Cs in the spring
Fig. 5. Plot of RK=10CK/(10CK+cNa) versus RMg=10CMg/(10CMg+CCa), Ci in mg/kg forMount Taftan spring waters (Table 1), using the Na–K–Mg–Ca diagram of Giggenbachand Glover (1992).
waters are the result of water–rock interactions (Giggenbach andGlover, 1992). In Fig. 7, the Taftan thermal spring waters plot close tothe rock dissolution region showing that highly acid-sulfate watersprobably result from the dissolution of magmatic gases into circulat-ing ground water, followed by the isochemical dissolution of rock. Itmust be noted that the term isochemical dissolution is utilized for theprocesses involving the entire rock dissolution (Giggenbach, 1988).
The absolute concentrations of boron in the Taftan thermal springs(4.53–5.14 mg/L) are much higher than the background levels detectedin nearby normal springs (0.08–1.41 mg/L). A high Cl/B ratio is typical offluids discharged from arc-type systems, essentially andesitic magmas(Gigeenbach, 1997a,b). The low ratio of B and Li relative to Cl alsoconfirms the low-grade leaching of B from the host (sedimentary) rocksand small proportion of water originating from rock minerals, inaddition to the very short high-temperature residence time for thewaters. The low B/Cl ratio of near surface water is possibly also due todilution of deep Cl waters (Reyes et al., 1993).
The relatively high concentrations of boron in the Taftan thermalwaters also indicate a relatively young geothermal system because Bwould likely be expelled during the early heating-up stages of thegeothermal system (Giggenbach and Goguel, 1989). Concentrations ofB and Cl are not controlled by temperature-dependent chemicalequilibrium; both could have been extracted from the country rocksby the circulating thermal waters (Ellis, 1970), in which case theirrelative content would be similar. Because of very high ratio of Cl/B, inthe range of about 600 to 5000, it is more probable that they do nothave the same origin. It is more likely that the Cl is contributed bymagmatic (volcanic) waters and that the B is extracted from the wallrock.
5.6. Geothermometry
Chemical composition of the spring's water is used to estimate thereservoir temperature. For this reason the solubility and exchangereactions of various solid phases must be taken into account.
Fig. 7. Relative Li, Rb and Cs contents in fluids from Taftan therm
Table 2Measured discharge temperatures during different seasons and inferred reservoirtemperatures, Taftan area spring waters (°C)
Fig. 6. a. Plot of Ca2+, Mg2+, K+, and Na+ versus Cl− concentrations relative to the MountTaftan spring waters; data given in Table 1. b. Log–log plot of Br, F, B, Cs, Rb, and Li versusCl concentrations relative to the Mount Taftan spring waters; data given in Table 1.
834 A. Shakeri et al. / Journal of Volcanology and Geothermal Research 178 (2008) 829-836
Application of the Na–K and K–Mg geothermometers yieldedinconsistent and unrealistic estimates, as might be expected con-sidering the lack of equilibrium between the water and rocks. Usingthe Quartz and Chalcedony geothermometers (Fournier, 1973;Arnosson et al., 1983; Fournier, 1985), a rang of reservoir temperaturesfrom 104 °C to 210 °C and 75 °C to 185 °C were obtained for acidicsprings in the southern flank of Taftan, respectively (Table 2).
The Quartz and Chalcedony geothermometers provided relativelyconsistent temperatures in the case of slightly acidic hot springs. Thevalues obtained for high-temperature springs range between 164 and210 °C, comparable with the minimum temperature estimated for theTaftan spring reservoir on the basis of the low-temperature argillicalteration of the host rocks (Boomeri, 2004; Moore et al., 2005).
5.7. Isotopic composition of water
The stable isotope analyses of two Taftan thermal springs and twonormal springs are given in Table 1. The waters are plotted on theisotopically heavier part of SMOW line. This is because of the shortdistance from the coast, the low latitude and fractionation due toevaporation resulted from high-temperature and the aridity of theregion. For thermal springs(Taf1 and Taf2), the average δ18O is −2‰and δD ranges between −25 and −26‰.The values for δ18O and δD inthe two cold springs, TVS and FWP range from −5 to −6‰ and −30 to−35‰, respectively. It should be noted that a δD of about −20 to −30
al and cold acidic springs (Giggenbach and Goguel, 1989).
Fig. 8. Plot of the concentrations of δD vs. δ18O in spring waters from the Taftan area (Gigeenbach, 1997a,b).
835A. Shakeri et al. / Journal of Volcanology and Geothermal Research 178 (2008) 829-836
permil is generally ascribed to water related to arc-type or andesiticvolcanoes (Barnes, 1997). The results are plotted in Fig. 8.The meteoricwater line (MWL) of Craig (1961), based on analyses of worldwideprecipitations and arc-type magmatic water region, are also plottedfor comparison. The parallel lines to meteoric water line show thepercentage of magmatic water in mixture with meteoric water. In theδD vs δ18O diagram (Fig. 8), the cold FWP and TVS samples plot on themeteoric water line. The TAF1 and TAF2 hot water samples lie well tothe right of the meteoric water line(on 20% line), and may indicate ashift caused by dilution of andesitic water with shallow groundwaters(Sepulveda et al., 2004). The plot suggests that thermal water samplesTaf1 and Taf2 contain 20% magmatic water, whereas in TVS and FWP,there is very little (if any) magmatic contribution.
Craig (1963) presented evidence from a number of geothermal areasshowing thermal waters undergo a progressive 18O-enrichment withrespect to the MWL, due to water–rock oxygen exchange, and that δDvalues remain relatively constant throughout this process. Later,Giggenbach (1992) described a positive shift in both δ18O and δD withrespect to the localmeteoric composition in several thermal areas,whichhe ascribed tomixing of localmeteoric andmagmatic (andesitic)waters.
6. Conclusion
Geothermal springs at Mount Taftan occur in an area of Quaternaryvolcanics consisting of altered andesites, dacites and rhyodacites(Boomeri, 2004). The hydrothermal systems overlie a magmachamber, a source of heat and ascending magmatic fluids. Infiltratingmeteoric waters also recharge these systems and are mineralized bywater–rock–gas interactions as they flow through the volcanics.
Chemical analyses of waters show that concentrations of the majorions belong to Cl, SO4 and Ca. Also, they can bedivided into three groups.The first group with high EC, high-temperature and low pH is located athigh elevation and consisted of Taf1 and Taf2 thermal springs. Thesecond group comprising TVS and FWT springs occur at moderateelevation and display moderate EC, low-temperature and slightly acidiccondition. The third group (FWP spring) occur at low elevation and ischaracterized by low EC, low-temperature, and neutral pH.
Different plots of water chemistry suggest thermal and cold springsare immature water, not in equilibrium with the host rock. The high Clcontent, relatively low SO4 content and moderate temperature indicatethat the most probable mechanism for high Mg content is mixing withshallow cold groundwater.
Conservative elements indicate that the three types of analysedwater have similar origin and the difference in concentration is due todilution of thermal water with almost shallow fresh groundwater, notaffecting the elements, proportions. Also, the constant ratio of theconservative elements with respect to Cl concentration, and theretrogressive δ18-enrichment with respect to the meteoric water line(MWL), indicate that thermalwaters (andesiticwater) have beendilutedby shallow waters of meteoric origin.
Isotopic results suggest that thermal water samples Taf1 and Taf2contain 20% andesitic water, whereas in samples TVS and FWP, there isvery little (if any) andesitic contribution.
The results demonstrate that thermal waters have not reachedchemical equilibrium with the host rocks. Therefore, because of theimmaturity and high acidity of the thermal waters, the temperaturesinferred from geothermometer data are not reliable. However,considering the low-temperature argillitic alteration of the volcanicrocks, a minimum temperature of 150 °C is estimated for the MountTaftan reservoir.
High Cl–SO4 concentration and highly acid springs at the higherelevations (Gigeenbach, 1997a,b) and other evidences, are indicativeof an immature hydrothermal water system in Taftan volcanic.
Acknowledgements
The authors would like to thank the research committee of ShirazUniversity for financial support and also Dr. Boomeri of ZahedanUniversity for providing the isotopic data.
References
Alavi, M., 1994. Tectonics of the Zagros orogenic belt of Iran: new data andinterpretation. Tectonophysics 229, 211–238.
836 A. Shakeri et al. / Journal of Volcanology and Geothermal Research 178 (2008) 829-836
Arnosson, S., Gunnlaugsson, E., Svavarsoon, H., 1983. The chemistry of geothermalwaters in Iceland. III. Chemical geothermometry in geothermal investigations.Geochim. Cosmochim. Acta 42, 567–577.
Barnes, H.L., 1997. Geochemistry of Hydrothermal Ore Deposits, third ed. Wiley, NewYork, NY, pp. 737–796.
Berberian, M., King, G., 1981. Towards a paleogeography and tectonic evolution of Iran.Can. J. Earth Sci. 18, 210–265.
Boomeri, M., 2004. Geochemistry, petrography and formation style of Taftan Volcano.Research Project Report. Iran. University of Sistan & Baluchistan, Iran, p. 118 (in Farsi).
Craig, H., 1961. Isotopic variations in meteoric waters. Science 133, 1702–1703.Craig, H., 1963. The isotopic geochemistry of water and carbon in geothermal areas. In:
Tongiorgi, E. (Ed.), Nuclear Geology on Geothermal Areas, Spoleto, pp. 17–53.Demets, C., Gordon, R.G., Argus, D.F., Stein, S., 1990. Current plate motions. Geophys.
J. int. 101, 425–478.Ellis, A., 1970. Quantitative interpretation of chemical characteristics of hydrothermal
systems. Geothermics 2, 516–528.Farhoudi, G., Karige, D.E., 1977. Makran of Iran and Pakistan as an active arc system.
Geology 5 (11), 664–668.Fournier, R.O., 1973. Silica in thermal waters: laboratory and field investigations.
Proceedings International Symposium on Hydrogeology and Biogeochemistry,Tokyo, Japan. Hydrogeochemistry, vol. 1, pp. 122–139.
Fournier, R.O., 1985. The behavior of silica in hydrothermal solutions. Rev. Econ. Geol. 2,45–62.
Gansser, A., 1971. The Taftan volcano (SE Iran). Eclogae Geol. Helv. 64, 319–334.Giggenbach, W., 1988. Geothermal solute equilibria. Derivation of Na–K–Mg–Ca
geoindicators. Geochim. Cosmochim. Acta 52, 2749–2756.Giggenbach, W.F., 1991. Chemical techniques in geothermal exploration. Application of
Geochemistry in Geothermal Reservoir Development (Co-ordinator D'Amore, F.).UNITAR/UNDP Centre on Small Energy Resources, Rome, pp. 119–144.
Giggenbach, W., 1992. Isotopic shifts in waters from geothermal and volcanic systemsalong convergent plate boundaries and their origin. Earth Planet. Sci. Lett. 113,495–510.
Giggenbach, W., 1997a. The origin and evolution of fluids in magmatic–hudrothermalsystems, In: Barnes, H.L. (Ed.), Geochemistry of Hydrothermal Ore Deposits, 3rdEdition. Jone Wiley and Sonc, Inc, New York, NY, pp. 737–796.
Giggenbach, W., 1997b. The origin and evolution of fluids in magmatic-hydrothermalsystems, In: Barnes, H.L. (Ed.), Geochemistry of Hydrothermal Ore Deposits, 3rd ed.Wiley, New York, NY, pp. 737–796.
Giggenbach, W.F., Goguel, R.L., 1989. Collection and Analysis of Geothermal andVolcanic Water and Gas Discharges. Report No. CD 2401. Chemistry Division, DSIR,Petone, New Zealand.
Giggenbach, W., Glover, R.B., 1992. Tectonic regime and major processes governing thechemistry of water and gas discharges from the Rotorua geothermal field, NewZealand. Geothermics 21, 121–140.
Moinvaziri, H., Aminsobhani, E., 1978. Etudes Volcanologique du Taftan. Ecole normalesuperieure de Tehran.
Moore, F., Shakeri, A., Kompani-Zare, M., Raeisi, A., 2005. Geothermometry andhydrogeochemistry of Taftan thermal springs. Proceeding 9th Symposium ofGeological Society of Iran, 30–31AUG, Tehran, Iran, vol. 2, pp. 22–36 (in Farsi).
Motyka, R., Nye, C., Turner, D., Liss, S., 1993. The geyser Bight geothermal area, UmnakIsland, Alaska. Geothermics 22, 301–327.
Oskarsson, N., 1995. Volcanic components in groundwater: monitoringand interpretation. In: Barberi, F., Casale, R., Fantechi, R. (Eds.), The Mitiga-tion of Volcanic Hazards Course Proceedings. European Commission, Brussels,pp. 393–401.
Sepulveda, F., Dorsch, K., Lahsen, A., Bender, S., Palacios, C., 2004. Chemical and isotopiccomposition of geothermal discharges from the Puyehue-Cordón Caulle area(40.5°S), Southern Chile. Geothermics 33, 655–673.
Siebert, L., Simkin, T., 2002. Volcanoes of the World: an illustrated catalogof Holocene Volcanoes and their eruptions. Smithsonian Institution, GlobalVolcanism Program Digital Information Series, GVP-3. http://www.volcano.si.edu/world/.
Valentino, G.M., Stanzione, D., 2004. Geochemical monitoring of the thermal waters ofthe Phlegraean Fields. J. Volcanol. Geotherm. Res. 133, 261–289.
Valentino, G.M., Cortecci, G., Franco, E., Stanzione, D., 1999. Chemical and isotopiccompositions of minerals and waters from the Campi Flegrei volcanic system,Naples, Italy. J. Volcanol. Geotherm. Res. 91, 329–344.
Varekamp, J.C., Ouinette, A., Herman, S., Bermudez, A., Delpino, D., 2001. Hydrothermalelemental fluxes during the 2000 eruptions of Copahue, Argentina. A “beehivevolcano in turmoil”. Geology 29, 1059–1062.
Wohletz, K., Heiken, G., 1992. Volcanology and Geothermal Energy. Univ. CaliforniaPress, Berkeley.
![[The Greek illustrations of the human diseases: Mount Athos]](https://static.documents.page/doc/80x56/634c3d6a8b264d9afb05a7b7/the-greek-illustrations-of-the-human-diseases-mount-athos.jpg)
