Geothermics最新文献

{"title":"A conceptual model and changing trends for the Yangbajing geothermal field in the Tibetan Plateau: New insights from hydrochemistry and multi-isotopes","authors":"Huan Luo ,&nbsp;Xingcheng Yuan ,&nbsp;Xiaoyan Zhao ,&nbsp;Ying Wang ,&nbsp;Hua Wu ,&nbsp;Peng Zhou ,&nbsp;Haichao Zhang ,&nbsp;Gongxi Liu ,&nbsp;Yunhui Zhang","doi":"10.1016/j.geothermics.2025.103391","DOIUrl":"10.1016/j.geothermics.2025.103391","url":null,"abstract":"<div><div>High-temperature geothermal resources have enormous potential for geothermal power generation, such as the first and largest geothermal power station of the Yangbajing geothermal field (YGF) in China. However, the understanding of geothermal genesis has yet to be improved, and changes in the geothermal system under long-term exploitation remain unclear, hampering the sustainable development of the YGF. Hence, this study conducted hydrochemical and multi-isotopic (D-O-Sr-Li-C) isotopic analyses to improve the genesis model of the YGF and to investigate the changes in the geothermal system compared with the samples from 1995 and 2006. The results show that the hydrochemical processes are mainly determined by the leaching of silicate minerals (albite and K-feldspar) and cation exchange. δD and δ¹⁸O indicate that the recharge source is primarily snowmelt water (5,221–5,788 m) from the Nyenchen Tonglha Mountains, mixed with the magmatic fluids (10–20 %). δ¹³C results suggest that the dissolved inorganic carbon (DIC) is derived from the thermal decomposition of deep marine carbonate rocks and magma degassing, and the corrected ¹⁴C ages show the residence time of geothermal waters is from 16,035 to 28,283 years. ⁸⁷Sr/⁸⁶Sr and δ⁷Li results identify that geothermal waters are formed by mixing between deep melt and shallow cold water, which are stored in a Pliocene granite reservoir. The comparisons with previous data show that the hydrochemical types of geothermal waters changed from Cl-Na in 1995 and 2006 to Cl·HCO₃-Na and HCO₃-Na in 2022. The hydrochemical differences are caused by the decreasing contribution (20–26 % to 10–20 %) of deep fluids and the increasing mixing (55 % to 68 %) of snowmelt water due to continuous exploitation and rising global temperatures over decades. Therefore, the reservoir temperatures declined from 274 °C to 189 °C from 1995 to 2022. The research achievements deepen the understanding of the geothermal genesis and clarify the changes of geothermal systems under long-term exploitation in the YGF, providing a scientific basis for the sustainable utilization of the high-temperature geothermal fields worldwide.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"131 ","pages":"Article 103391"},"PeriodicalIF":3.5,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144185387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrochemistry and isotope geochemistry of Bailing geothermal water in northwest Jiangxi: Implications for water-rock interaction","authors":"Xinghua Shi ,&nbsp;Ximin Bai ,&nbsp;Zhanxue Sun ,&nbsp;Jinhui Liu ,&nbsp;Hailong Ye ,&nbsp;Longlong Pang ,&nbsp;Gongxin Chen ,&nbsp;Haohao Yan","doi":"10.1016/j.geothermics.2025.103402","DOIUrl":"10.1016/j.geothermics.2025.103402","url":null,"abstract":"<div><div>Geothermal energy development and utilization can contribute to the achievement of China's dual carbon goals and energy security. Bailing area in northwest Jiangxi province is abundant of geothermal manifestations like hot springs and geothermal wells. However, due to the limited understanding of the genetic mechanism of these geothermal resources, the utilization efficiency of these geothermal waters is not sufficient at present. In this study, the hydrochemcial characteristics and water-rock interaction process of geothermal waters of 3 typical hot springs and 3 geothermal wells in Bailing area were researched by using hydrogeochemistry, isotope geochemistry, multi-mineral equilibrium simulation and silicon enthalpy graphic method. The results show that the geothermal waters in Bailing area are HCO₃-Na type weakly alkaline silicon-fluorine water with temperature 32.7–85 °C, pH 8.27–8.82, H₂SiO₃ 77.74–115.36 mg/L and F^- 3.74–5.47 mg/L. These geothermal waters have experienced a very strong water-rock interaction process, isotope and ion exchanges, resulting in the enrichment of ion component and trace elements (such as Al, B, Li, Sc, Ti, V, W, Rb, Ga, Mo, Cs and U). Geothermal waters originate from atmospheric precipitation with the recharge elevation varying from 243 m to 1455 m, and then infiltrated to depth about 4–5 Km to be heated along weathering fissures and secondary faults. The radioactive heat generation of granites provided the heat source and the reservoir temperature determined by quartz geothermometer ranges from 109.9 to 130.6 °C. After undergoing a deep circulation of 2483 to 3034 years, these geothermal waters emerged on the surface along the northeast-trending fault to form hot springs, and mixed with cold water (mixing ratio: 21 %-67 %) during the rising process. ‌This research is helpful to provide a more comprehensive understanding of the origin, circulation and evolution of geothermal waters in Bailing area.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"131 ","pages":"Article 103402"},"PeriodicalIF":3.5,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144177800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Review of simulation methods for co-axial ground heat exchangers: Simplified models, predictions, and comparisons","authors":"Z.D. Ma ,&nbsp;J.C. Chai ,&nbsp;J.K. Hao ,&nbsp;M. Zhang ,&nbsp;G.S. Jia ,&nbsp;L.W. Jin","doi":"10.1016/j.geothermics.2025.103389","DOIUrl":"10.1016/j.geothermics.2025.103389","url":null,"abstract":"<div><div>The calculation of heat extraction for buried ground heat exchangers (GHEs) is a significant research topic in the geothermal energy utilization field. Due to the considerable size of computational domain of buried pipes, various simplified models and solutions have been developed to achieve efficient simulation. However, the characteristics of existing simplified methods have yet to be comprehensively evaluated and compared. This article presents critical reviews of simplified solution models for co-axial GHEs, comparisons between available experimental measurements and predictions, and comparative analysis of various prediction methods. Unlike detailed numerical methods that solve full set of governing equations including continuity, momentum, energy, and coupled turbulence transport, simplified models use a one-dimensional (axial) approach to simulate fluid flow and heat transfer of the working fluid, assuming azimuthal symmetry. Radial heat transfer is modelled applying Newton's law of cooling, Nusselt number correlations and thermal resistance from Fourier's law of conduction. Either two-dimensional or three-dimensional rock-soil models are applied mostly. This review focuses on elucidating various Nusselt number correlations and the thermal properties of working fluid and rock-soil. Additionally, the relatively small discrepancies in various simulation methods can be primarily attributed to that the validations for the accuracy of these methods predominantly rely on the short-term results of working fluid temperatures. This review aims to clearly outline the advantages and disadvantages of existing simplified model algorithms, providing a reference for the accurate prediction of heat exchange rates in buried pipes.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"131 ","pages":"Article 103389"},"PeriodicalIF":3.5,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144177799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Survey and observation of earthquake swarm and buried geothermal resources by seismological analyses, seismic tomography, magnetotelluric, and gravity modeling of the upper crustal structure of the Yalova-Termal Region","authors":"Ertan Pekşen ,&nbsp;Deniz Çaka ,&nbsp;Berna Tunç ,&nbsp;Bülent Oruç ,&nbsp;Emrah Budakoğlu ,&nbsp;Taylan Türkmen ,&nbsp;Fatih Sevim ,&nbsp;Doğukan Durdağ ,&nbsp;Kader Zengin ,&nbsp;Mahmure Ezgi Erkan ,&nbsp;Gamze Ayhan Durdağ ,&nbsp;Şerif Barış","doi":"10.1016/j.geothermics.2025.103401","DOIUrl":"10.1016/j.geothermics.2025.103401","url":null,"abstract":"<div><div>This study presents the results of various geophysical methods applied in and around a thermal source in Yalova, Türkiye. Termal town, located on the seismically active Armutlu Peninsula, is the focus of the investigation. The research explores earthquake swarms and their relationship with hydrothermal activity in the area. The findings are compared using seismological analyses and different geophysical techniques, including seismic tomography, magnetotelluric (MT), and gravity surveys. A previously unrecognized boundary of the geothermal source was identified using 3D resistivity models derived from MT data, corroborated by the location of an existing well. Key observations include a high density of earthquake events, sharp variations in seismic tomography parameters (Vp, Vs, and Vp/Vs ratio) particularly along fault zones, as well as high-resistivity and negative Bouguer gravity anomalies in and around Termal town. Despite differences in resolution among the three geophysical methods, their results were consistent and complementary. The MT and gravity data show comparable features down to approximately 1 km depth. While exact comparisons at shallow depths are limited, the anomalies identified in the seismic tomography appear to extend from those observed in the MT and gravity datasets.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"131 ","pages":"Article 103401"},"PeriodicalIF":3.5,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144177795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A sparrow search algorithm optimized GAN-stacking model for the evaluation of geothermal resource potential assessment","authors":"Haibin Li ,&nbsp;Yang Yang ,&nbsp;Qiang Xu","doi":"10.1016/j.geothermics.2025.103398","DOIUrl":"10.1016/j.geothermics.2025.103398","url":null,"abstract":"<div><div>Currently, in the field of geothermal resource potential prediction, smaller datasets and complexity of geothermal energy formation are the problems that should be effectively addressed. In this work, a GAN-stacking model optimized using sparrow search algorithm (SSA) is constructed, based on artificial neural network (ANN), random forest (RF), support vector machine (SVM), XGBoost, Catboost model, and GIS platform, to predict and evaluate the potential of geothermal resources in Sichuan Province, China. The features include distance from water systems, distance from fracture zones, distance from mountain ranges, seismic kernel density, geothermal heat flow, magnetic anomaly data, distance from igneous rocks, and gravitational gradient anomalies. The receiver operating characteristic curve (ROC) is used for validation. The AUROC values for ANN, RF, SVM, XGBoost, and Catboost are 0.785, 0.834, 0.787, 0.811, and 0.818, respectively, and the AUROC values after enhancing the training set using GAN are 0.793, 0.853, 0.791, 0.840, and 0.839, respectively. The accuracies of all models improve when using extra samples. In addition, the SHAP algorithm is added to analyze the models. The SHAP values of the vast majority of the samples are higher than the SHAP values of the five machine learning models compared in this work, except for the individual extra samples. Subsequently, the sparrow search algorithm-optimized GAN-stacking model is constructed for prediction, and its obtained AUROC value is 0.95. This study shows that the use of GAN to generate extra samples improves the accuracy of geothermal potential prediction models to a certain extent, and the extra samples generated by GANS have a certain degree of confidence. The GAN-stacking model constructed in this study has high accuracy in this study area, and can provide a decision-making basis for the exploration and development of geothermal resources.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"131 ","pages":"Article 103398"},"PeriodicalIF":3.5,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144177798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Meso-damage mechanism and physico-mechanical properties of Zhangzhou granite subjected to water-cooling treatment after elevated temperatures","authors":"Jiamin Wang ,&nbsp;Yun Wu ,&nbsp;Pengyu Mu ,&nbsp;Chongyuan Zhang ,&nbsp;Xiangshang Li","doi":"10.1016/j.geothermics.2025.103397","DOIUrl":"10.1016/j.geothermics.2025.103397","url":null,"abstract":"<div><div>In order to exploit deep geothermal resources, it is critical to comprehensively understand the meso‑damage mechanism and physico-mechanical properties of high-temperature rocks after water-cooling treatment. In this paper, water-cooling experiments were carried out on granite at varying temperatures (20 °C, 150 °C, 300 °C, 450 °C, 600 °C and 750 °C), and the corresponding damage degree of microstructure was quantitatively assessed by computed tomography, optical electron microscopy, and nuclear magnetic resonance The effects of thermal shock on physical and mechanical parameters such as elastic wave velocity, permeability, uniaxial compressive strength (UCS) and elastic modulus of granite were analyzed. The results showed that the number and size of cracks in granite increase gradually with the increase in heating temperature; in particular, when the temperature rises to 600 °C and 750 °C, the proportion of macropores significantly increase, indicating the development and penetration of pores and cracks, which leads to the aggravation of the meso‑damage degree of granite. The fractal dimension of pores decreases with the increase in temperature, which shows that high temperature refines the pore structure. However, the fractal dimension of mesopores and macropores is insensitive to temperature variations. The meso‑damage of granite directly affects its physical and mechanical properties. The P-wave velocity, uniaxial compressive strength and elastic modulus of granite gradually decrease with temperature increase, whereas the peak strain gradually increases. The permeability of granite also exhibits a trend of slow increase first and then rapid rise, similar to the porosity variation trend. The results provide valuable theoretical support for evaluating the thermal energy utilization efficiency of hot dry rock and the stability analysis of reservoir reconstruction projects.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"131 ","pages":"Article 103397"},"PeriodicalIF":3.5,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144131314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An integrated study to detect geothermal anomalies based on Landsat 8, Geological, and Geophysical data sets in Southeast Pakistan","authors":"Muhsan Ehsan ,&nbsp;Rujun Chen ,&nbsp;Ahsan Shafi ,&nbsp;Danish Raza ,&nbsp;Kamal Abdelrahman ,&nbsp;Rui Li ,&nbsp;Jar Ullah ,&nbsp;Zohaib Naseer ,&nbsp;Momin Ahmed Butt","doi":"10.1016/j.geothermics.2025.103399","DOIUrl":"10.1016/j.geothermics.2025.103399","url":null,"abstract":"<div><div>Geothermal resource exploration has grown in importance globally as a research hotspot due to the depletion of conventional fossil fuel reserves and green energy initiatives. This research's prime objective is to explore the geothermal potential, primarily focused on the Paleocene rock geothermal systems in Southeast Pakistan. Globally, the use of remote sensing for geothermal anomaly detection has gained much attention recently due to the increased focus on green energy. This study aimed to identify regions with geothermal anomalies using land surface temperature (LST) data, a geospatial dataset to develop geological mapping, and geophysical well logs analysis to compute heat production and petrophysical analysis. An overview of geo-pressurized systems and geothermal resources’ location in Southeast Pakistan has been provided to get an idea of the geothermal target in this region. The LST values were quantitatively classified into five categories: very high, high, medium, low, and very low, and LST results indicate that the data cluster lies in 20 %, 54 %, 4 %, 3 %, and 19 %, respectively. Normalized difference vegetation index results showed that 96 % of the study area lies in bare soil to mixed surface, and only 4 % of the region lies in full vegetation. Petrophysics results indicate that the Ranikot Formation has very good effective porosity ranges of 20–24 % in the studied wells, suggesting a potential candidate for enhanced geothermal systems (EGS). Basin modeling was performed to delineate subsurface heat flow (109–113 mW/m²), temperature (60–150 °C), and effective porosity (22–24 %) distribution mapping. The concentration number (C<img>N) model and log-log plots techniques were employed to map gamma-ray and heat production values to separate the geothermal anomaly and spatial correlation from its background. Emerging advancements in technologies such as EGS for exploiting geothermal energy and reducing exploration risk are crucial economically in geothermal reservoirs. These innovations have attracted researchers to explore the potential to utilize geothermal energy significantly. Still, their successful implementation principally relies on an in-depth understanding of the local geological conditions of the basin.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"131 ","pages":"Article 103399"},"PeriodicalIF":3.5,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144115289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morphostructural controls on heat flow and fluid circulation in the Valle de Nereidas geothermal field, Nevado del Ruiz, Northern Andes, Colombia","authors":"Luis Alvaro Botero-Gómez ,&nbsp;Hugo Murcia ,&nbsp;Martha Gabriela Gómez-Vasconcelos ,&nbsp;John J. Sánchez ,&nbsp;Julián López-Palacio ,&nbsp;Julián Andrés Ortiz-González","doi":"10.1016/j.geothermics.2025.103393","DOIUrl":"10.1016/j.geothermics.2025.103393","url":null,"abstract":"<div><div>Morphostructural features are essential for geothermal resource evaluation. They provide insights into geological structures and surface features that are linked to geothermal activity, thus enhancing exploration and resource characterization efficiency. This study assesses a place with recognized geothermal energy via structural lineaments, and morphological environments and geological units using diverse satellite images information and fieldwork resources to define the morphostructural framework of the <em>Valle de Nereidas</em> geothermal field. The results indicate that: 1) heat contribution in the study area is primarily associated with volcanic emission centers and units younger than 2 Ma, extending beyond the Nevado del Ruiz volcanic complex; and 2) fluid circulation and recharge zones correspond to fractured lava flows, where thermal contraction facilitates the infiltration and movement of regional groundwater. These findings suggest that the geothermal system in the <em>Valle de Nereidas</em> is controlled by both volcanic and structural features, where young volcanic edifices act as heat sources, and faulted and fractured zones enhance fluid circulation. Data from the drilled well Nereidas-1, including lithological descriptions, helped to establish relationships between subsurface geology and surface expressions of geothermal activity. These results help to define the spatial distribution of thermal anomalies and recharge areas, which directly impact resource sustainability and reservoir management. Furthermore, they provide valuable information for improving geothermal exploration strategies in the area by refining the model of subsurface heat transport and fluid dynamics.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"131 ","pages":"Article 103393"},"PeriodicalIF":3.5,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144115287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comments to Olvera-Garc?a, E., Avila-Olivera, J.A., Figueroa-Soto, A., Coolbaugh, M., Liotta D., 2025. Data-driven play fairway analysis applied to Los Humeros geothermal field, Mexico. Geothermics, 130, 103,337","authors":"Rosa Maria Prol-Ledesma","doi":"10.1016/j.geothermics.2025.103385","DOIUrl":"10.1016/j.geothermics.2025.103385","url":null,"abstract":"<div><div>The integration methodologies were developed first for GIS models in the exploration program of specific prospects and were further extended using geothermal play characterization to be applied in a regional scale. The exploration of geothermal resources takes as guide conceptual models that allow identification of promising areas based on a reduced set of parameters that characterize a specific type of geothermal systems. In regional exploration, the conceptual models are commonly based on geothermal play definition and the geothermal Play Fairway Analysis (PFA) is a systematic method that describes areas corresponding to the conditions that characterize a specific type of play. As stated, PFA is a regional exploration method; nevertheless, some studies for the expansion of active fields have been incorrectly denominated as Play Fairway Analysis; therefore, the application of the term Play Fairway Analysis must be clarified to avoid its misuse that may derive in erroneous conclusions in the exploration results.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"131 ","pages":"Article 103385"},"PeriodicalIF":3.5,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144115288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrochemical characteristics of carbonated waters and non-carbonated thermal waters of the Heyuan Deep Fault Zone in Guangdong, Southern China","authors":"Xianxing Huang ,&nbsp;Linjun Xie ,&nbsp;Yan Li ,&nbsp;Guoping Lu","doi":"10.1016/j.geothermics.2025.103390","DOIUrl":"10.1016/j.geothermics.2025.103390","url":null,"abstract":"<div><div>This paper studied both carbonated geothermal waters and generic geothermal waters, to better understand deep groundwater circulations in deep fault-basin system in the Heyuan Deep Fault Zone. Uniquely occurring carbonated geothermal waters are not well known in their origin-evolution process, geologic settings of deep ground water systems, and their flow behaviors in response to the unique physicochemical properties. Through deep-borehole data, and field samplings of various isotope and aqueous geochemistry data, we characterized these carbonated and generic geothermal waters, and analyzed water-rock reactions in relevant silicate rocks. Carbonated waters have high contents of HCO₃⁻ and dissolved CO₂, and enhance their leaching effect in such a way consequently leading to much higher major ion concentrations than non-carbonated thermal waters. According to δD and δ¹⁸O data, both carbonated waters and non-carbonated waters are of local meteoric origin and recharge from the hilly areas scattering throughout the study area at elevations ranging from 492 to 602 m (masl). The δ¹³C results confirm that the high DIC contents in carbonated waters have their deep sources of both mantle and carbonate rock thermal metamorphism genesis. Thermal reservoir temperatures are estimated for water samples, yielding a temperature range of 48.2 to 134.8 °C, based on chalcedony and quartz geothermometers. A 3500-m-deep borehole for carbonated water has revealed the relatively low geothermal gradient (2.35 °C/100 m) in the carbonated water convergence zone, which is related to the localized depression of the granitic-igneous basement within the study area. Relatively low-temperature environments have formed in localized basement depressions with thick cover of sedimentary rocks, and thus have provided excellent storage condition for deep-derived CO₂ rising along deep faults, forming carbonated waters when combined with groundwater systems. The deep crustal groundwater flow was further examined for the crustal thermo-structure, showing the heat flow and temperature distribution in each layer of the crust. The findings and insights could provide further understanding of deep ground water flow systems and deep groundwater circulations. The implications involve effective exploitations and utilizations for carbonated water and non-carbonated thermal water. This study is the first of the kind to study the deep ground water systems including carbonated waters and non-carbonated thermal waters in deep fault-basin systems, in terms of the deep sourcing, ground-water circulation, and thermal structure of the deep crust, and deep groundwater circulation in deep fault settings.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"131 ","pages":"Article 103390"},"PeriodicalIF":3.5,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144105166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}