Occurrence Of Thermal Waters Research Articles

Geofluids as a possible unconventional tool for seismic hazard assessment

In recent decades, phenomenological methods known as Recognition of Earthquake-Prone Areas (REPA) were set up for identifying potential sites of powerful earthquakes. The information on potential earthquake sources provided by the REPA method is an essential part of seismic hazard assessment methodology. For the first time, we have combined global-scale information on the geographic occurrence of geofluids with global-scale information on earthquake occurrence, heat flow distribution, and S-wave dispersion, to gain insights into the evolution of local stress-strain fields. We focused on areas characterized by the occurrence of thermal waters and/or by the release of deep-seated gases, as traced by the isotope composition of associated helium. We noticed that the geographic distribution of these geofluids could serve as an indirect indicator of crustal permeability anomalies generated by crustal deformation procedures. This study proposes adding geofluids to the list of fundamental geological parameters to be considered in hazard assessment research.

Conceptual model of the formation of nitrogen thermal waters in crystalline rock massifs (example of the Kuldur Spa)

The study of the influence of hydrodynamic factors on the occurrence of nitrogen thermal waters in crystalline massifs, by the example of the Kuldur field, is presented in the article. The results of two-dimensional modeling (based on FEFLOW code) of several variants of formation and circulation of therms in the study area are considered. Model parameters included temperature (130–140 °C), calculated on the basis of geothermometers, and the residence time of waters in the rock massif (68 800–254 000 years), estimated by means of 14C and 4He dating. The modeling results show that exactly the filtration parameters of the granite massif are the main factor controlling the dynamics of fluid movement and, consequently, the relative age of thermal waters. It is also found that the filtration characteristics of the fault zone have a significant influence on the temperature of thermal water discharge.

Hydrogeochemistry and geothermometry of the carbonate-evaporite aquifers controlled by deep-seated faults using major ions and environmental isotopes

Carbonate aquifers probably constitute the most important thermal water resources in non-volcanic areas, and are characteristic of great energy potential and easier production as the most ideal targets for development in the future. The thermal waters in the aquifers within Southeast Chongqing (SEC) of China occur in an extensive region with an area of 198,000 km2, which are mainly hosted in the Cambrian and Ordovician carbonate-evaporite rocks. The thermal waters are mainly in pristine conditions and their genesis has not yet been fully understood. The occurrence of thermal waters in SEC is closely related to the presence of deep-seated faults which constitute pathways for the hydrothermal circulation. In this study, an investigation of water major ions and environmental isotopes from 14 hot springs and three drilled wells was carried out to examine their hydrogeochemical evolution and to estimate reservoir temperature. The thermal waters have outflow temperatures from 19 to 54.2 °C. They are divided into two hydrochemical groups with the Yushan Fault as a boundary: Group A, located to the west of the fault, are characterized by facies of chloride sodium waters with higher TDS; Group B, to the east of the fault, are more complicated sulfate-bicarbonate-chloride alkaline-earth waters with lower TDS. The hydrochemical processes such as dissolution of carbonate, gypsum and/or anhydrite, and halite, the common ion effect, and dedolomitization are evident based on the major ions and δ34SSO4 and δ18OSO4. The δ18O and δD compositions of the thermal waters suggest a meteoric recharge in a relatively wetter and colder climatic condition. The silica geothermometers show that the average reservoir temperatures are 63 ± 18 °C for Group A, and 82 ± 15 °C for Group B. The corresponding average reservoir depths are estimated to be 2.5 ± 0.7 km for Group A, and 3.2 ± 0.7 km for Group B. The corrected 14C ages of the thermal waters average at 14.8 ka BP, corresponding to the late Pleistocene. A conceptual circulation model is proposed for the thermal waters. Driven by gravity of topographic gradients, the percolating groundwater circulates at a specific depth, reaching a higher temperature and interacting with the host carbonate with imbedded evaporitic minerals (gypsum and/or anhydrite, and additional halite for Group A) to be saline deep-seated thermal fluids. The fluids rise along faults and emerge at the surface as thermal springs. The slow renewability rate of the thermal aquifers highlights the importance of assessing the resource before groundwater exploitation and extraction.

Geochemistry and Conditions of the Formation of the Ulsk Thermal Spring (Coasts of the Sea of Okhotsk, Khabarovsk Krai)

The report presents original data on the isotope and chemical composition of the nitric thermal, cold underground, and surface natural waters, along with the water-enclosing rocks, of the Ulsk occurrence of thermal mineral waters (coasts of the Sea of Okhotsk, Khabarovsk krai). The data on the concentrations of oxygen and nitrogen isotopes and rare-earth elements, as well as on the volume activity of radon, in the treated underground and surface waters are obtained for the first time. Based on the data of automated monitoring of the physical parameters, the hydrogeological characteristics of the thermal waters are determined and the balneal properties are evaluated. The results obtained show the atmospheric origin of the nitric thermal waters of the Ulsk spring; however, the indicative chemical elements occurring in the considered waters represent the effects of deep-seated high-temperature processes as well. It is found that the waters warmed to 31°C within fractured Paleocene granites do not show significant variations of temperature, and the chemical composition varies exclusively under the interaction with the water-enclosing rocks. The profiles of the distribution of rare-earth elements (REEs) in the thermal waters represent the REE distribution in the water-enclosing granitoids and point to the limitation of the thermal water circulation with the area of the occurrence of the Paleocene granites of the Bekchi–Ul Massif. The temperature of the deep-seated reservoir measured by geothermometers was 80°C or below, which may indicate a depth of water circulation of 1–2 km or less.

Occurrence, management and protection of mineral and thermal waters in some volcanic areas of Italy: current knowledge and future directions

This study provides a review of the issues of occurrence, management and protection of mineral and thermal waters in volcanic areas of central and southern Italy. These waters have a great economic importance being widely used for therapeutic and water bottling purposes, although they have a limited influence on the total yield of hydrogeological systems (generally below 17%). The present study examines the hydrogeological environment where mineral and thermal waters originate, focusing on the hydrostratigraphic and structural conditions generating different hydrochemical facies. The complexity of the examined volcanic systems makes the interpretation of the hydrochemical facies and the building of reliable hydrogeological models often difficult. Mineral and thermal waters (up to 100 °C) originate from different flow paths and interactions among waters with different qualities. In this framework, current European, national and regional regulations do not specify the criteria of abstraction and management. The examined cases show how the management and protection of mineral and thermal waters are inseparable from the management of the other groundwater resources used for drinking, irrigation and industrial purposes, being the various hydrochemical facies related to different circuits within the same system. To maintain different water qualities and permit a sustainable multipurpose use of groundwater resources, a participatory and unitary management of the aquifer system seems to be the most appropriate approach.

Occurrence and use of mineral and thermal waters in Poland

Mineral and thermal waters are defined according to Polish geological and mining law. Their occurrence in particular hydrogeological provinces of the country is characterized. Besides their use in balneotherapeutics, their role as a heat carrier and source of chemical raw materials is stressed. Topics mentioned requiring further research are: the origin of saline formation waters and the origin of CO2 in carbonated waters.

Thermal and mineral waters in north-eastern Slovenia

The Mura basin in north-eastern Slovenia is made up of two depressions, developed during the Late Neogene and Early Pliocene all within a widespread system of Pannonian basins. Both depressions are characterized by the occurrence of thermal waters of somewhat different hydrogeochemical character. Radgona depression is in the northern part of the basin and reaches depths of about 2 km. Thermal waters are generally dominated by sodium-bicarbonate, not related to the age of an aquifer, its wallrock composition, the type of porosity or total concentration of dissolved solids. Locally, sulphate-rich waters are encountered, and they are related to the presence of gypsum in the rocks of pre-Tertiary basement. The adjacent Ljutomer depression is over 4 km deep and comprises compartments with stagnant or semi-stagnant aquifers. Herein saline waters predominate, even in the aquifers of carbonate composition and abundant CO2 gas. In shallower, unconsolidated, intergranular aquifers sodium-bicarbonate waters predominate. Thermal aquifers of this type are very important to the economy of the region, but they are also subjected to overexploitation which is reflected in time-dependent changes of dynamic pressures, temperature, conductance, salinity, pH and concentration of major ions, trace elements, dissolved gasses, and total organic carbon. Mineral waters occur in shallow aquifers or springs in marginal areas of the Radgona depression. Bicarbonate waters are dominated by calcium, or both calcium and sodium. Some mineral waters are formed mainly by penetration of CO2 gas into shallow aquifers and consequent water–rock interaction. Composition of some mineral waters indicate their possible evolution from thermal waters which have risen from central parts of the Radgona depression along deep-seated faults, and have been modified by cooling and mixing processes.

Hydrology, geochemistry and geothermal aspects of the thermal waters from Switzerland and adjacent alpine regions

Waters of 19 thermal areas in Switzerland and adjacent alpine regions were studied to acquire a better knowledge of their deep thermal circulation, geochemistry and low-temperature geothermal potential. A systematic multisampling and multitracing program was executed over a complete hydrologic cycle for each of the 19 thermal areas. Pertinent physical, chemical and isotopic parameters were measured and analyzed on thermal and nonthermal waters during nine sampling periods. Thermal water occurrences are generally related either to Triassic evaporites or to the weathered and fractured zone between crystalline basements (or ranges) and their sedimentary cover. Emergence areas are located in faulted or overthrust zones. Sulfate and calcium are the two principal ions responsible for the mineralization of most thermal waters. Actually, gypsum and anhydrite are more often encountered in Triassic evaporites than halite. Many variations of the water geochemistry, caused by seasonal changes, have been recorded during the hydrologic cycle. From mineralization, temperature and discharge variations, it has been possible to distinguish fast or delayed responses to rain or snow-melt events and mixing between deep-thermal and shallow-cold waters. Chemical geothermometers were tested on these warm waters. The chalcedony and Na-K-Ca geothermometers seem to be the only ones which display calculated temperatures in reasonable agreement with known local geothermal gradients or bottom-hole temperatures. The majority of inferred reservoir temperatures ranges from 40° to 60°C. Oxygen-18 and deuterium results show that most thermal waters fit along the meteoric water line, with some exceptions due to Mediterranean precipitation, possible water-rock isotopic exchange or mixing with connate waters. A regional oxygen-18 gradient has been established with altitude in order to locate and determine the elevation of intake areas. Tritium is very useful in the detection of mixing between deep-old and shallow-recent waters. Numerous mixing models using isotopic and chemical parameters have been established to extrapolate the characteristics of the warm end-members. These models are based on parameters such as tritium, oxygen-18 or discharge, whose behaviors are generally in inverse ratio with temperature and/or a main chemical component such as sulfate or chloride. Examples of the use and interpretation of these mixing models are described for the thermal areas of Schinznach, Combioula, Vals, and Bormio.

Geothermal Anomalies in Western Trans-Pecos Texas: ABSTRACT

Several major geothermal anomalies are present in Trans-Pecos Texas because of warm to hot water springs and wells, silica geochemical indicators, and shallow thermal gradient measurements. Forty-four thermal water (30°C or above) occurrences have been located in the area. The largest concentration of thermal waters is in southern Hudspeth and western Presidio Counties adjacent to the Rio Grande. The thermal waters range from slightly fresh to salty; total dissolved solids range from 275 to 11,500 ppm. Major ions in the high dissolved solid waters include sodium and chloride. As indicated by the silica geothermometer temperatures, subsurface waters above 125°C exist at seven locations in northeast El Paso, western and southeastern Jeff Davis, western and northern Presidio, and southern Brewster Counties. The areas having highest silica temperatures are (1) west of the Hueco Mountains in northeastern El Paso County and extending northward into southwestern Otero County, New Mexico; here maximum silica temperatures are 151°C and maximum measured water temperatures reach 71°C; and (2) north of Candelaria in western Presidio County where maximum silica temperatures reach 177°C and maximum measured water temperatures are 72°C. Geothermal gradients have been measured in over 70 wells and boreholes, most of these in Presidio County. Average gradient is 77°C/km in the Rio Grande Valley, with 30°C/km in the highlands east of the valley; this would seem to reflect the possible boundary of the Basin and Range and Great Plains tectonic provinces. In addition, a drilling program has been underway in northeastern El Paso County to investigate the geochemical anomaly west of the Hueco Mountains. Twelve to 14 holes drilled yielded gradients of over 100°C/km, and two of these penetrated the limestone bedrock, where the elevated gradients continued to increase with depth. Heat-flow values of 9 and 11 HFU were calculated for these latter two holes. On the basis of these gradients a geothermal resource may xist close to El Paso. End_of_Article - Last_Page 762------------

Geological aspects of thermal water occurrences in Hungary

In Hungary geothermal resources are in the form of low enthalpy waters within Pliocene - Upper Pannonian reservoirs consisting of sand and sandstone series, and within fractured carbonate rocks mainly of Triassic age. These low temperature reservoirs, maximum water temperature is about 100°C, are presumably heated by conduction and little is known about the nature of the heat source. Geothermal phenomena are controlled primarily by sub-crustal magmatic processes and secondarily by other geologic factors such as tectonics, sedimentation, compaction. Due to a particular crustal structure, the resulting geothermal anomaly accompanied by favorable hydrogeologic conditions, allows an abundance of thermal waters in many parts of the country, particularly in the SE part of the Great Hungarian Plain. For the time being there are more than 450 thermal water wells producing waters warmer than 35°C in Hungary.

Types of commercial deposits of thermal underground waters and some views on the assessment of their reserves

All known ground thermal occurrences of the world may be grouped into the following main industrial types, based on geological and hydrodynamic conditions: 1. 1. Thermal water occurences of large artesian basins of platform areas. 2. 2. Thermal water occurrences of small artesian basins of intermontane areas and submontane troughs of the Alpine zone of folding. 3. 3. Thermal water occurrences of crystalline massifs connected with fissure-vein systems of recent tectonic disturbances. The first type of the above thermal water occurrences occur usually at a great depth and are notable for a high salinity. Thermal water occurrences of the second type are characterized by smaller areal distribution but their exploitation resources, as a rule, are greatly higher than those of the first type. Among the thermal water occurrences of this type a group of thermal water occurrences confined to the areas of late and recent volcanism is clearly singled out. According to the generating capacity of thermal energetic resources and economic effectivity of practical use, they are of the greatest industrial interest. Thermal waters and superheated waters of volcanic areas are different regarding their high temperature, small depth of occurrence and low salinity. The resources and areal distribution of thermal water occurrences of the third type are, as a rule, small. In accordance with initial and boundary conditions, which predetermine the character of the ground thermal water flow, each of the above types of thermal water occurrences is divided into two subtypes. Thermal water occurrences of the first subtype are confined to bed-porous, bed-fissure or fissure-vein systems. The second subtype, called «focuså, is characterized by a highly specific mechanism of interaction of ground-waters in bed or fissure systems with ascending deeper confined thermal water along separate rupture dislocations. The purpose and scope of prospecting-exploration works and the technique of estimating exploitation resources, as well as technico-economical conditions of thermal water exploitation, depend upon the type of thermal water occurrences. According to the character of carrying out exploration works thermal water occurrences of the «focuså subtype is of special complexity.

The importance of information on the hydrological and geothermal situation with respect to the prospection of the new sources of low enthalpy water in Slovakia

Slovakia is situated on the territory of West Carpathian Mts., representing a part of the young Alpine-Carpathian foldnappe system. Considering the small extension of Slovakia, about 49,000 km 2, one could say that the country is considerably rich in thermal water. Up till now about 60 localities with thermal water occurrences have been discovered, with a total yield of about 700 l/s. The yield of the separate localities fluctuates within 0.5–50 l/s and the temperature of natural springs within 20–70 °C. The thermal power obtainable from these waters may range up to about 60 million kcal/h ( Franko 1969 b). From the point of view of chemistry there are predominantly calcium-magnesium-sulphate-bicarbonate waters with mineralization usually within 0.5 ÷ 0.8 to 3.0, and in some places up to 4.0–6.0 g/l. The thermal waters are bound to the tectonic zone of the Inner West Carpathians, i. e. to its Mesozoic limestone-dolomite complexes. Mesozoic formations are on a row of parallel anticlinorii and synclinorii formed by Cretaceous folding. These anticlinorii and synclinorii follow approximately the direction of the Carpathian arch (SW-NE, W-E, NW-SE), being composed of a whole row of partial synclines and anticlines. The Cretaceous structural forms (morphotectonic units), i. e. mega-anticlines representing mountain-ranges, and megasynclines, representing Tertiary depression and lowlands are divergent according to their direction ( Mahel' 1966). The Cretaceous and post-Paleogene structural forms are deformed by the Neogene german-typical directional and transversal fault tectonics. The hydrogeological systems represent the result of the above three evolutionary tectonic stages. These systems include Cretaceous, post-Paleogene and Neogene forms, and determine the infiltration, accumulation and the spring areas, as well as the circuit, descent and ascent, of the thermal waters ( Franko 1969 a). The above mentioned lithological and tectonical situation caused the rise of thermal waters and presented the possibility of finding new sources of low enthalpy waters. Natural thermal springs occur in the fault on the border of depressions and lowlands. The temperature of the waters is mostly influenced by cold shallow subsurface waters in the spring area and in its close vicinity. For this reason the prospection of low enthalpy waters will be oriented into the deepest parts of depressions and lowlands with respect to the favourable structural situation. Another factor offering the possibilities of finding new sources of low enthalpy waters is represented by the favourable geothermal conditions ( Franko 1969 c). The average value of the heat flow is 2.13 μcal/cm 2 sec: the values move within 1.32–2.70. It is a higher value than the central-European 1.67 (Čermák 1968) and the world average 1.58 ( Lee, Uyeda 1965). Also the average value of the geothermal degree on territories including thermal water is higher than the world average 33 m/°C. The increased values of the flow indicate, that for the heating of a certain amount of cold water less extensive areas are necessary than those found by geothermal balance with the use of the values of the world or the central-European average. The decreased values of the geothermal degree indicate the possibilities for the drilling and finding of warmer waters than those with the temperature calculated for the same depth according to the world average values. Favourable hydrogeological structures and geothermal situation offer opportunities for finding new sources of low enthalpy waters in Slovakia.

Occurrence and utilization of thermal waters in Poland

This paper describes the conditions in which thermal waters occur in Poland and their utilization. The possibilities for obtaining thermal waters in Poland are interesting though the exploitation temperatures are rather low. It is possible that, along with the extension of deep prospection borings, zones of hot waters occurrence may be discovered in the next future.

The geothermal system of the Hakone volcano

The isothermal map of the Hakone volcano at sea level shows that the geothermal area now 12 by 13 km in diameter is clearly related with the present volcanic activity in central cones. Four zones are recognized in the distribution of thermal waters. Zone I is characterized by acid-sulfate water associated with solfataric gases, and is found at the highest elevation of the volcano. Zone II is characterized by bicarbonate-sulfate water issuing at the middle elevation. Zone III is high-temperature streams rich in sodium chloride, poor in bicarbonate and sulfate, flowing from the depth of active fumaroles across the zone of bicarbonate-sulfate water (zone II). Zone IV is characterized by sodium chloride-bicarbonate-sulfate water discharged at the lowest elevation. Chemistry and occurrence of thermal waters suggest the following mechanism for the genesis of thermal waters. Groundwater which infiltrates through the western side of the caldera seems to be flowing eastward passing through the basal part of central cones, where high-temperature dense steam is coming up through volcanic vents. Subsurface streams of high-temperature waters thus start from the vent area, run through the permeable zone mixing with groundwater and appear as hot springs on the steep slopes of the Hayakawa gorge at the east. The average contribution of volcanic dense steam rich in sodium chloride is estimated to be 25 ∼ 35% to the sodium chloride water of zone III. Thermal discharge evaluated by the geochemistry of sodium chloride water is 2.1 ∼ 3.0 × 10 7 cal/sec, which in turn suggests that the energy economy of the Hakone geothermal system is essentially controlled by the activity of dense steam carrying a considerable amount of sodium chloride. The bicarbonate waters are widely distributed over the area remote from the fumarole. Hot waters and volcanic gases directly coming from the vent area are relatively poor in carbonate matter. All these facts suggest that most of the carbonate materials are supplied by decomposition of fossil plants intercalated in volcanic formations. It is also suggested that acid volcanic gases rich in hydrogen sulfide are secondary products by repeated processes of vaporization and condensation of volcanic steam in the hot shallow depth of central cones. The relation between the earthquake activity and the thermal water of the volcano is briefly discussed.

Thermal waters as a source for extraction of chemicals

In recent years much attention is being given in the USSR, as well as in a number of other countries, to the study of the mineral content of thermal waters which do constitute an important portion of subsurface hydrosphere. This interest finds its explanation in the fact of the possible utilization of such waters — either their heat, or valuable chemical components — for the purposes of national economy. Starting from the evidence available on naturally existing conditions for the origin and spatial distribution of thermal waters, it seems reasonable to examine the geothermal search-indices with the following implications taken into account. Only those areas or regions may be of potential geothermal importance, either in the field of balneology (with sulphurated, acid, radon-waters etc.), or in the commercial sphere (with iodine, bromine, boron lithium-bearing, potassium-bearing waters etc.), which are characterized by particular geological, thermal and geochemical features. Generally these areas are represented by folded belts or zones (characteristic) of recent or lately extinguished volcanic activity. These may be, again, mobile structural units associated with belts (foredeeps, intermontane and marginal troughs), and filled with volcanic-sedimentary or or normal sedimentary rocks. Chloride waters, rich in salts, and revealing high concentrations of bromine potassium, lithium and strontium are being formed because of halogen formations found throughout the sedimentary sequence. Concentration of bromine, strontium, lithium and rubidium is increasing with depth of occurrence of thermal waters and rising mineralization, while boron and iodine show a reverse regional dependence — their concentration goes down with depth and rising mineralization.