scholarly journals Geothermal system boundary at the northern edge of Patuha Geothermal Field based on integrated study of volcanostratigraphy, geological field mapping, and cool springs contamination by thermal fluids

Author(s):  
Suryantini ◽  
C Rachmawati ◽  
M Abdurrahman
Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1631
Author(s):  
Fan ◽  
Pang ◽  
Liao ◽  
Tian ◽  
Hao ◽  
...  

The Ganzi geothermal field, located in the eastern sector of the Himalayan geothermal belt, is full of high-temperature surface manifestations. However, the geothermal potential has not been assessed so far. The hydrochemical and gas isotopic characteristics have been investigated in this study to determine the geochemical processes involved in the formation of the geothermal water. On the basis of δ18O and δD values, the geothermal waters originate from snow and glacier melt water. The water chemistry type is dominated by HCO3-Na, which is mainly derived from water-CO2-silicate interactions, as also indicated by the 87Sr/86Sr ratios (0.714098–0.716888). Based on Cl-enthalpy mixing model, the chloride concentration of the deep geothermal fluid is 37 mg/L, which is lower than that of the existing magmatic heat source area. The estimated reservoir temperature ranges from 180–210 °C. Carbon isotope data demonstrate that the CO2 mainly originates from marine limestone metamorphism, with a fraction of 74–86%. The helium isotope ratio is 0.17–0.39 Ra, indicating that the He mainly comes from atmospheric and crustal sources, and no more than 5% comes from a mantle source. According to this evidence, we propose that there is no magmatic heat source below the Ganzi geothermal field, making it a distinctive type of high-temperature geothermal system on the Tibetan Plateau.


2018 ◽  
Vol 37 (2) ◽  
pp. 626-645
Author(s):  
Wei Zhang ◽  
Guiling Wang ◽  
Linxiao Xing ◽  
Tingxin Li ◽  
Jiayi Zhao

The geochemical characteristics of geothermically heated water can reveal deep geothermal processes, leading to a better understanding of geothermal system genesis and providing guidance for improved development and utilization of such resources. Hydrochemical and hydrogen oxygen isotope analysis of two geothermal field (district) hot springs based on regional geothermal conditions revealed that the thermal water in the Litang region is primarily of the HCO3Na type. The positive correlations found between F−, Li2+, As+, and Cl− indicated a common origin, and the relatively high Na+ and metaboric acid concentrations suggested a relatively long groundwater recharge time and a slow flow rate. The values of δD and δ18O were well distributed along the local meteoric line, indicating a groundwater recharge essentially driven by precipitation. The thermal reservoir temperature (152°C–195°C) and thermal cycle depth (3156–4070 m) were calculated, and the cold water mixing ratio (60%–68%) was obtained using the silica-enthalpy model. Finally, hydrogeochemical pathway simulation was used to analyze the evolution of geothermal water in the region. The results were further supported by the high metasilicate content in the region. Of the geothermal fields in the region, it was found that the Kahui is primarily affected by albite, calcite precipitation, and silicate, while the Gezha field is primarily affected by calcite dissolution, dolomite precipitation, and silicate.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. Dotsika ◽  
P. Dalampakis ◽  
E. Spyridonos ◽  
G. Diamantopoulos ◽  
P. Karalis ◽  
...  

AbstractHydrochemical and isotopic characteristics of fluids from major geothermal fields of middle/low temperature in N/NE Greece are examined [basins: Strymon River (SR), Nestos River Delta (ND), Xanthi–Komotini (XK), Loutros–Feres–Soufli (LFS) and Rhodope Massif]. The geodynamic context is reflected to isotopic/chemical composition of fluids, heat flow values and elevated CO2 concentrations in emitted fluids. B and Li are derived from leaching of the geothermal systems hosting rocks. δ18OH2O, δ18OSO4, δ13CCO2 values and chemical compositions of Cl, B and Li of geothermal discharges suggest two distinct source fluids. Fluids in SR exhibit high B/Cl and Li/Cl ratios, suggesting these constituents are derived from associated magmas of intermediate composition (andesitic rocks). Geothermal discharges in LFS exhibit low B/Cl and Li/Cl ratios, implying acid (rhyolitic) magmatism. δ13CCO2 and CO2/(CO2 + 105He) ratios in the west part, suggest fluids affected by addition of volatiles released from subducted marine sediments. For the eastern systems, these ratios suggest gas encountered in systems issued from mixing of crustal and mantle-derived volatiles. Isotopic geothermometers reflect, for the same direction, equilibrium processes more (LFS, XK) or less (SR) pronounced and discriminate the geothermal field from low to middle [SR, ND (Erasmio)] and middle to high enthalpy [ND (Eratino), LFS, XK].


Geophysics ◽  
1973 ◽  
Vol 38 (6) ◽  
pp. 1130-1144 ◽  
Author(s):  
A. A. R. Zohdy ◽  
L. A. Anderson ◽  
L. J. P. Muffler

The Mud Volcano area in Yellowstone National Park provides an example of a vapor‐dominated geothermal system. A test well drilled to a depth of about 347 ft penetrated the vapor‐dominated reservoir at a depth of less than 300 ft. Subsequently, 16 vertical electrical soundings (VES) of the Schlumberger type were made along a 3.7‐mile traverse to evaluate the electrical resistivity distribution within this geothermal field. Interpretation of the VES curves by computer modeling indicates that the vapor‐dominated layer has a resistivity of about 75–130 ohm‐m and that its lateral extent is about 1 mile. It is characteristically overlain by a low‐resistivity layer of about 2–6.5 ohm‐m, and it is laterally confined by a layer of about 30 ohm‐m. This 30‐ohm‐m layer, which probably represents hot water circulating in low‐porosity rocks, also underlies most of the survey at an average depth of about 1000 ft. Horizontal resistivity profiles, measured with two electrode spacings of an AMN array, qualitatively corroborate the sounding interpretation. The profiling data delineate the southeast boundary of the geothermal field as a distinct transition from low to high apparent resistivities. The northwest boundary is less distinctly defined because of the presence of thick lake deposits of low resistivities. A broad positive self‐potential anomaly is observed over the geothermal field, and it is interpretable in terms of the circulation of the thermal waters. Induced‐polarization anomalies were obtained at the northwest boundary and near the southeast boundary of the vapor‐dominated field. These anomalies probably are caused by relatively high concentrations of pyrite.


Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1279
Author(s):  
Santiago Nicolás Maza ◽  
Gilda Collo ◽  
Diego Morata ◽  
Carolina Cuña-Rodriguez ◽  
Marco Taussi ◽  
...  

Detailed mineralogical analyses in areas with surface hydrothermal alteration zones associated with recent volcanism (<1 Ma) in the Central Andean Volcanic Zone could provide key information to unravel the presence of hidden geothermal systems. In the Cordón de Inacaliri Volcanic Complex, a geothermal field with an estimated potential of ~1.08 MWe·km−2 has been recently discovered. In this work, we focus on the hydrothermal alteration zones and discharge products of this area, with the aim to reconstruct the geological processes responsible for the space-time evolution leading to the geothermal records. We identified (1) discharge products associated with acid fluids that could be related to: (i) acid-sulfate alteration with alunite + kaolinite + opal CT + anatase, indicating the presence of a steam-heated blanket with massive fine-grained silica (opal-CT), likely accumulated in mud pots where the intersection of the paleowater table with the surface occurred; (ii) argillic alteration with kaolinite + hematite + halloysite + smectite + I/S + illite in the surrounding of the acid-sulfate alteration; and (2) discharge products associated with neutral-alkaline fluids such as: (i) discontinuous pinnacle-like silica and silica deposits with laterally developed coarse stratification which, together with remaining microorganisms, emphasize a sinter deposit associated with alkaline/freshwater/brackish alkaline-chlorine water bodies and laterally associated with (ii) calcite + aragonite deriving from bicarbonate waters. The scarce presence of relics of sinter deposits, with high degree crystallinity phases and diatom remnants, in addition to alunite + kaolinite + opal CT + anatase assemblages, is consistent with a superimposition of a steam-heated environment to a previous sinter deposit. These characters are also a distinguishing feature of paleosurface deposits associated with the geothermal system of the Cordón de Inacaliri Volcanic Complex. The presence of diatoms in heated freshwater bodies at 5100 m a.s.l. in the Atacama Desert environment could be related with the last documented deglaciation in the area (~20–10 ka), an important factor in the recharge of the hidden geothermal systems of the Pabelloncito graben.


2019 ◽  
Vol 1 (2) ◽  
pp. 41
Author(s):  
Triana Triana ◽  
Tony Yulianto ◽  
Udi Harmoko ◽  
Iqbal Takodama

Magnetotelluric data has been carried out at the "WS" geothermal field to analyze the resistivity model resulting from 2D inversion of magnetotelluric data in TE, TM and TE-TM modes. Base on the three models produced, the mode is determined to produce the most representative model to assist in the interpretation of the "WS" geothermal system. There is a step of modes separation, namely TE (Tranverse Electric) and TM (Transverse Magnetic) modes in processing MT data. Each mode produces a 2D model with different conductivity properties. The analysis results of the three modes explain that TE mode is dominated by low resistivity with a range of values of 10-35 Ωm and medium resistivity with a value range of 35-250 Ωm and a vertical resistivity contrast. The TM mode describes the high resistivity in the Southwest and the center of the track with a value of more than 470 sehinggam resulting in lateral resistivity contrast. While the TE-TM mode produces a model that is not much different from TM mode, only the distribution of the resistivity value is a combination with TE mode. This mode describes the distribution of resistivity both vertically and laterally. Based on the analysis of the three modes, it can be concluded that the TE-TM mode is the mode that produces the most representative model. Interpretation model shows that from the TE-TM mode we have a low resistivity distribution (10-35 Ωm) represent a cap rock zone, reservoir rock with a medium resistivity distribution (35-380 Ωm), resistive zone with a high resistivity distribution (more than 380 Ωm), and the existence of the three of faults structures ro be a controller system of the "WS" geothermal.


1986 ◽  
Vol 50 (355) ◽  
pp. 75-84 ◽  
Author(s):  
S. Douglas McDowell

AbstractActive metamorphism of fine grained sandstone in the c.16000 year old Salton Sea geothermal system has produced a suite of chemically equilibrated coexisting authigenic alkali feldspars and re-equilibrated detrital feldspars in the 250–360°C temperature range. At c.335°C the average compositions, 2 Vs, and (t1o+t1m) and Z ordering parameters of coexisting authigenic feldspars are [Or0.52Ab97.40An2.08, 2Vx = 91.3±4.8, (t1o + t1m) = 0.89±0.05, Z = 0.79±0.09], and [Or94.42 Ab5.10An0.48, 2Vx = 70, (t1o + t1m) = 0.90, Z = 0.81]. At c.360°C authigenic albite becomes more An-rich and less ordered [Or1.21Ab92.83An5.97, 2Vx = 87.5±3.4, (t1o + t1m) = 0.85±0.03, Z = 0.70±0.07] and K-feldspar is no longer stable. Detrital plagioclase (An up to 40%) is preserved metastably to temperatures up to c.190°C in strongly carbonate-cemented sandstone which forms part of a geothermally produced permeability cap. It undergoes rapid alkali exchange at temperatures near 200°C, and by 250°C no plagioclase with An-content over 12% is observed. At > 250°C authigenic and most detrital alkali feldspar compositions are in excellent agreement with the Bachinski and Muller (1971) microcline-low-albite solvus.


2021 ◽  
Author(s):  
Alberto Ardid ◽  
Rosalind Archer ◽  
David Dempsey

&lt;p&gt;In high-temperature geothermal systems, understanding heat transfer helps conceptualize the whole system as well as estimating the resource size. To obtain the fullest picture, it is necessary to integrate different types of data, e.g., surface electromagnetic surveys, wellbore lithology, geochemistry, and temperature logs. This can be achieved through joint modelling. Here, we quantify the spatial distribution of heat transfer through the hydrothermally-altered, impermeable smectite layer that has developed atop the Wair&amp;#257;kei-Tauhara geothermal system, New Zealand. Our approach involves first constraining 1D magnetotelluric (MT) inversion models with methylene blue analysis (MeB, an indicator of conductive smectite clay) and mapping these onto temperature and lithology data from geothermal wells. Then, one-dimensional models of heat transfer are fitted to well temperature logs to estimate heat flux variations across the field.&amp;#160;We use our integrated method to estimate the average heat flux through the clay cap (2.2 W/m2) and total heat flow (380 &amp;#177; 21 MW) of the Wair&amp;#257;kei-Tauhara geothermal field. This approach models multiple datasets for estimating heat fluxes and could be applied in geothermal provinces around the world with implications for sustainable resource management and our understanding of magmatic systems.&lt;/p&gt;


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