Origin and Quality of Thermal Groundwaters in the Region of Farsala (E. Thessaly/Greece) (original) (raw)
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Bulletin of the Geological Society of Greece, 2017
Ampelia area is a newly discovered area with geothermal interest and no surface manifestations (hidden resource). It is located in Farsala basin and belongs to the Enipeas graben. The geothermal anomaly is related with the E-W trending faults, which mainly control the basin development and the NNW-SSE trending faults of the area. The temperature values from the deep water boreholes (>200m depth) range from 20 to 41oC. The chemical composition of the studied groundwater samples varies in all chemical parameters. Most of the samples have affected by shallow cold aquifers (high E.C. and NO3- values). The most representative samples (T > 30oC) are from the deepest boreholes (hydrochemical type Na-HCO3), which cut the fractured crystalline basement, i.e. limestones, flysch and ophiolitic rocks. They present the highest pH values (pH > 8) and the lowest E.C. compared with the rest of the samples. Their Ni and Cr concentrations are very low, indicating that the groundwater is noti...
4.1 INTRODUCTION Greece is particularly rich in geothermal resources due to favorable geologic conditions. The intense tectonic and, in some cases, magmatic activity as well as increased heat flow have created extended thermal anomalies with geothermal gradients reaching up to 100 • C/km. In the southern Aegean, geothermal activity is often associated with volcanism and the presence of shallow magma chambers, especially along the South Aegean Active Volcanic Arc (SAAVA) (Megalovassilis, 2005), which is characterized by high heat flow and several high, medium, and low enthalpy geothermal fields (Fytikas, 1977). The active fault systems favor the circulation of deep hot fluids and the development of thermal springs. High-enthalpy fluids have been discovered at the volcanic islands of Milos and Nisyros, whereas low-enthalpy geothermal systems have been found in Milos (shallow reservoirs), Kimolos, Santorini, Chios, Kos, and Ikaria islands (Fig. 4.1b). Numerous investigations were carri...
Kougoulis C., Arvanitis A., Kolios N., Koutsinos S. & Kougoulis J. (2007) “Geothermal exploration in the Sani - Afytos area of the Kassandra Peninsula (Chalkidiki Peninsula, Northern Greece)”, Bulletin of the Geological Society of Greece, 40(3), 1162-1176, 2007
The Sani-Afytos area in the Kassandra Peninsula (Chalkidiki) was the area of systematic geothermal exploration. Based on deep oil borehole data, the Paleogene, Neogene and Quaternary sediments show significant thickness reaching 3600m and cover the metamorphosed Mesozoic, mainly carbonate, basement. The detailed water temperature investigation proved the presence of sub-thermal waters (20-28°C) at depths up to 300m and the spatial distribution of the isothermal curves at depths of 150 and 200m according to the main NW-SE and SE-NW tectonic structures of the area. Through the construction of geothermal exploration and production wells at depths of 422-583m, thermal waters of 31.7-36°C were detected within the Upper Miocene sediments. The average value of the geothermal gradient was calculated to be 3-4°C/100 m. One production well of 520m depth provides waters of 34°C while its potential flow rate is approximately 50 m3/h. The geothermal waters were classified in Na-HCO3 and Na-CI types of waters with T.D.S. 0.89-2.03 g/l. With the aid of chemical geothermometers the deep temperature was estimated to be 80-100°C. In one exploration well, the presence of gas phase (77% v/v CH4, 21.8% v/v N2) was detected. The geothermal exploration resulted in the characterization of the area as the "geothermal field of Sani-Afytos" and in the prospective development using the geothermal fluids in the tourism and other activities.
Hydrogeology Journal, 2004
A large number of chemical analyses of Greek thermal waters were evaluated in order to investigate spring water origin, water-rock interaction mechanisms, and estimate the thermal potential of the geothermal areas. Four water types were distinguished from geochemical diagrams. The relatively fresher waters include samples of Ca-HCO 3 and Mg-HCO 3 type waters originating from the schistose Rhodope Massif and the Quaternary basin of Aridea, respectively. Samples of the Na-HCO3 water type are typical of springs located in the post-orogenic basins of northern Greece. These hot, deep-rising Na-HCO 3 waters circulate in a CO 2-rich environment that favours the solubility of alkaline ions such as Na from siliceous rocks. Most of the samples belong to the Na-Cl water type and originate from Greek islands and coastal springs. These are characterized by the mixing of deep thermal solutions with seawater and fresh water. The presence of CO 2 in thermal and mineral springs is due to the metamorphism of buried marine carbonate horizons while H 2 S is due to both local pyrite oxidation and the reduction of sulphates. The use of geothermometers suggested that the investigated geothermal areas have low enthalpy fluids at depth, while higher temperatures are likely present in Milos, Lesvos, Nisyros islands and Xanthi Basin.
A comprehensive hydrogeochemical study of the cold and thermal groundwaters of the presently quiescent volcanic system of Methana was undertaken collecting 59 natural water samples during the period 2004-2007. Methana is a peninsula whose climatology and hydrology can be compared to the nearby small islands of the Aegean Sea. Similarly the chemical and isotopic composition of its water is dominated by the mixing of seawater with meteoric water. But the simple mixing trend is modified by water-rock interaction processes, enhanced by the dissolution of endogenous CO2, leading to strong enrichments in Alkalinity, Calcium, Barium, Iron and Manganese. Published Athens, Greece 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
Geochemical Study of the Geothermal Field of Νigrita, Greece
Diamantopoulos G., Poutoukis D., Raco B., Arvanitis A., Karalis P. and Dotsika E. (2018), “Geochemical Study of the Geothermal Field of Nigrita, Greece”, In: Proceedings of the International Workshop on Environmental Management, Science and Engineering (IWEMSE), Volume 1, ISBN 978-989-758-344-5, ...
In order to investigate the mineralisation process, we conducted geochemical and isotopic analyses (major ions, 18 O, 2 H) of the thermal waters of springs and boreholes of Nigrita. This study shows that the thermal waters are o f meteoric origin. Appropriate geothermometers were applied on selected samp les of thermal waters for the determination of the deep aquifer temperature.
Preliminary geothermal investigation in the basin of Katerini (Northern Greece)
Papachristou M., Arvanitis A. & Kolios N. (2016), “Preliminary geothermal investigation in the basin of Katerini (Northern Greece)”, Bulletin of the Geological Society of Greece, 50(2), 907-916, doi: http://dx.doi.org/10.12681/bgsg.11796 , 2016
This paper describes the results of the preliminary surface geothermal exploration conducted by IGME in the basin of Katerini (Northern Greece). It mainly regards temperature measurements at the wellhead of 73 wells and in the interior of five boreholes, as well as sampling and chemical analyses from 18 selected sites. Based on the collected data, three sub-regions of geothermal interest can be distinguished, the most important of which is the area of Kato Agios Ioannis (to the south of the basin), with temperatures around 27 o C at the depth of 340m. Nonetheless, the detailed geothermal investigation of this basin requires further systematic research as well as the drilling of at least one deep geothermal exploration borehole.
Fluid geochemistry of the Methana Peninsula and Loutraki geothermal area, Greece
Journal of Geochemical Exploration, 2010
A geochemical survey on the thermal fluids released by the volcanic/geothermal system of Methana Peninsula and Loutraki area was undertaken. The Loutraki area is found in the southern part of Athens and the Methana volcano in the north-eastern part of Peloponnesus, which is characterized by high salinity waters. Chemical and isotopic contents were used for the investigation of the origin of thermal water, for the estimation of the mixing process between meteoric, magmatic and sea water involved in the deep geothermal systems and for the evaluation of the deep aquifer temperature. The chemical and isotopic data of the thermal Cl-rich water springs of Methana suggest that they are fed by thermal water mixed with local groundwater and seawater respectively. The parent hydrothermal liquid is a mixture of local groundwater (∼ 43%), seawater (∼ 34%) and arc-type magmatic water (∼ 23%). The chemical and isotopic data of the thermal HCO 3 -rich water springs of Loutraki samples indicate a purely meteoric origin. Assessments from chemical and isotopic geothermometer applied on the thermal waters springs suggest the probable existence of a deep geothermal reservoir of middle enthalpy (150°C) a Methana and low enthalpy (80°C) in Loutraki area. However, the contribution of marine solutions to the geothermal fluids of Methana and Loutraki area is one of the main cases for the disturbance of the chemical and isotopic geothermometers rendering these calculated temperatures questionable.
Bulletin of the Geological Society of Greece, 2017
In Edipsos area many hot springs occur, as a result of both active tectonic of the area and recent volcanism (Lichades volcanic center). A geochemical study of Edipsos hot groundwaters was undertaken, in order to assess the hydrochemistry of hot springs from Edipsos and re-evaluate the geothermal situation of the area. For that purpose, 12 water samples were collected and analyzed by Spectrophotometry for the main ions and by AAS, ICP-OES and ICP-MS for major and trace elements. The interpretation of the analytical data showed that the geochemistry of Edipsos hot groundwaters is controlled by three factors i) a deep magmatic source, ii) the chemical composition of the local rocks (ultramafic and carbonates) and iii) sea water. The application of chemical geothermometers is problematic because of the chemical composition of the hot groundwaters and especially the high participation of the sea water. The temperature which derives from the use of Na-K-Ca geothermometer is greater than ...
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