Geothermal Resources Research Articles

Research on Geothermal Geology and Heat-Forming Conditions in the Tangyuan Fault Depression

In order to gain an in-depth understanding of the geothermal geological characteristics and heat-forming conditions in the Tangyuan fault-depression area, this paper has carried out a series of detailed geological works, including geological surveys and geophysical explorations. Through these works, combined with the results of systematic drilling, sampling tests, and dynamic monitoring, we have studied, analyzed, and compared the relevant data to achieve a comprehensive understanding of the geological characteristics in the Tangyuan fault-depression area. During the research process, we preliminarily determined the stratigraphic structure and geological structure in this area and clarified the characteristics of the main geothermal reservoir and its burial conditions. These findings provide basic data support for our understanding of the formation and distribution of geothermal resources. At the same time, we have carried out a systematic analysis of the basic geothermal geological parameters, laying the foundation for the future calculation and evaluation of geothermal resource reserves. Through the collation and analysis of these research results, this paper not only provides a scientific basis for the development of geothermal resources in the Tangyuan fault-depression area but also provides specific references for future development prospect plans. This series of work will lay a solid foundation for further development and utilization of geothermal resources and promote the sustainable development of the regional economy.

Characteristics and Formation Mechanism of Geothermal Resources in Tectonically Active Regions: A Case Study of the Red River Fault in Western Yunnan Province, China

Characteristics and Formation Mechanism of Geothermal Resources in Tectonically Active Regions: A Case Study of the Red River Fault in Western Yunnan Province, China

3D Surface Velocity Field Inferred from SAR Interferometry: Cerro Prieto Step-Over, Mexico, Case Study

The Cerro Prieto basin, a tectonically active pull-apart basin, hosts significant geothermal resources currently being exploited in the Cerro Prieto Geothermal Field (CPGF). Consequently, natural tectonic processes and anthropogenic activities contribute to three-dimensional surface displacements in this pull-apart basin. Here, we obtained the Cerro Prieto Step-Over 3D surface velocity field (3DSVF) by accomplishing a weighted least square algorithm inversion from geometrically quasi-orthogonal airborne UAVSAR and RADARSAT-2, Sentinel 1A satellite Synthetic Aperture-Radar (SAR) imagery collected from 2012 to 2016. The 3DSVF results show a vertical rate of 150 mm/yr and 40 mm/yr for the horizontal rate, where for the first time, the north component displacement is achieved by using only the Interferometric SAR time series in the CPGF. Data integration and validation between the 3DSVF and ground-based measurements such as continuous GPS time series and precise leveling data were achieved. Correlating the findings with recent geothermal energy production revealed a subsidence rate slowdown that aligns with the CPGF’s annual vapor production.

Investigation of geochemically induced permeability alteration in geothermal reservoirs and its implications for sustainable geothermal energy production

Geothermal resources constitute a significant portion of the world's low-carbon, renewable energy potential, with about 75% classified as low-temperature. One such potential resource exists in Precambrian basement rocks underlying the Williston Basin in southern Saskatchewan, Canada, with a reservoir temperature of 120 °C. However, geochemically induced permeability alteration in these highly reactive low-temperature granitoid resources poses a significant risk to long-term heat production. To assess and potentially mitigate this risk, we conducted a geochemical and mineralogical study of both altered and unaltered samples. Our findings facilitated the parameterization of geochemical simulations of water-rock interactions to predict mineral volume changes and, by extension, draw inferences on porosity and permeability changes resulting from these interactions. The simulations indicate an increased mineral volume in both samples, yet geothermal alteration of the unaltered, and thus more reactive, rocks induced relative mineral volume changes about 30% greater than those in the altered rocks. The resulting absolute change in porosity is 0.5 vol% for the unaltered rocks and 0.35 vol% for the altered rocks. Utilizing an empirical porosity-permeability relationship, the computed change in permeability indicates that the unaltered basement rock experienced a greater change in total permeability than the altered basement rocks. Additional calculations demonstrate the sensitivity of the porosity-permeability equation to critical porosity and power exponent, forecasting various scenarios with permeability changes ranging from 1.0 × 10−13 to 1 × 10−20 m2. Consequently, we infer that altered, permeable zones of the examined Precambrian basement rocks are likely to offer favourable conditions for sustained, multi-decade heat production, and thus should be targeted over less altered zones to justify initial capital expenditures. Globally, geothermal heat extraction from these rocks remains an underexplored yet promising resource for generating reliable, low-carbon renewable energy, crucial in our efforts to decarbonize the global economy.

Modeling of calculations on the performance optimization of a double-flash geothermal renewable energy-based combined heat/power plant coupled by transcritical carbon dioxide rankine cycle

This study investigates the integration of a double-flash geothermal system with a transcritical CO2 Rankine cycle, presenting a groundbreaking approach for enhancing efficient and sustainable energy generation. By harnessing renewable geothermal resources, this combined heat and power system aims to minimize greenhouse gas emissions, contributing to a more sustainable future. The research emphasizes multi-objective optimization to maximize net power output, net heating capacity, and overall system efficiency. The expanded stream pressures from the expansion valves, denoted as P2 and P6, are systematically varied to evaluate their impact on system performance. Significant findings reveal that as P6 increases from 260 kPa to 640 kPa, net power output rises dramatically from 2688 kW to 3163 kW. The optimal conditions for peak performance are identified at P2 of 820 kPa and P6 of 640 kPa, resulting in impressive outcomes: a net power output of 3392 kW, a net heating capacity of 14,586 kW, and an overall efficiency of 52.65 %. By delineating these relationships and establishing benchmarks for performance, this research offers valuable insights for the scientific community, policymakers, and industry stakeholders aiming to advance geothermal energy technologies.

Energy, exergy and exergoeconomic analyses and ANN-based three-objective optimization of a supercritical CO2 recompression Brayton cycle driven by a high-temperature geothermal reservoir

The use of CO2-based power cycles to harness high-temperature geothermal resources is an interesting application that has been little explored. Therefore, to obtain a more holistic understanding of these systems, in this work, a supercritical CO2 recompression Brayton cycle is assessed. For comparison, the performances of a recuperative cycle and a recompression cycle with intercooling were also computed. Detailed mathematical models were developed and then, artificial neural network-based surrogate models were adopted to conduct multi-objective optimization. Results of the baseline simulations show that, the high temperature recuperator and the turbine are the most important components from both exergy and exergoeconomic approaches. The optimizations reveal that the intercooled cycle is superior to the other layouts in all the cases while the recuperative cycle is not feasible with reinjection temperatures greater or equal to 150 °C. When the reinjection temperature is constrained to 150 °C, the intercooled cycle attains 4472.70 kW, 62.10 % and 14.42 $/GJ for net power, exergy efficiency and product unit cost, respectively, whereas without this constraint, it achieves 5394.09 kW, 61.83 %, 11.79 $/GJ. In conclusion, the adoption of advanced layouts of the CO2 cycle is beneficial for this application from both technical and economic points of view.

Hydrochemical Characteristics and Formation Mechanism of Geothermal Fluids in Zuogong County, Southeastern Tibet

Zuogong County is located in the southeast of Tibet, which is rich in hot spring geothermal resources, but its development and utilization degree are low, and the genetic mechanism of the geothermal system is not clear. Hydrogeochemical characteristics of geothermal water are of great significance in elucidating the genesis and evolution of geothermal systems, as well as the sustainable development and utilization of geothermal resources. The hydrogeochemical characteristics and genesis of the geothermal water in Zuogong County were investigated using hydrogeochemical analysis, a stable isotope (δD, δ18O) approach, and an inverse simulation model for water–rock reactions using the PHREEQC. The results indicated that the Zuogong geothermal system is a deep circulation heating type without a magmatic heat source. The chemical types present in the geothermal water from the Zuogong area are HCO3 and HCO3·SO4, and the main cations are Na+ and Ca2+. The groundwater is replenished by atmospheric precipitation and glacier meltwater. The salt content of geothermal water mainly comes from the interaction between water and surrounding rocks during the deep circulation process. The reservoir temperature of geothermal water in Zuogong is 120–176 °C before mixing with non-geothermal water and drops to 62–98 °C after mixing with 58 to 79% of non-geothermal water. According to the proposed conceptual model, geothermal water mainly produces water–rock interaction with aluminosilicate minerals in the deep formation, while in shallow areas it interacts mainly with sulfate minerals. These findings contribute to a better understanding of the geothermal system in Zuogong County, Tibet.

Decarbonising primary industries with geothermal heat – a pathway to greater direct use

ABSTRACT This paper discusses the opportunities and policy levers to increase the use of low-temperature geothermal resources in New Zealand for decarbonising primary industries, in particular, covered crops. Geothermal heat (geoheat) is a local, reliable, resilient and sustainable energy source. Low-temperature geothermal energy (220°C) is available in the Taupō Volcanic Zone with low awareness of the nationwide availability of lower temperature resources. Covered crop growers in New Zealand, needing to decarbonise their operations, are investigating the potential of utilising geoheat, following the example of the Netherlands. The Netherlands has strategically invested in low-temperature geothermal energy, utilising 80 °C water resources, from ∼ 2 to 3 km below the surface to heat greenhouses. Internationally, risk mitigation schemes and insurance programmes have proven pivotal policy instruments for fostering geothermal adoption. This paper discusses the opportunities that the adoption of using low-temperature geothermal provides to New Zealand drawing upon successful models from other countries.

Imaging and modelling the subsurface structure of the Rungwe Volcanic Province in SW Tanzania with aeromagnetic data: An improved structural map to support geothermal exploration

The Rungwe Volcanic Province (RVP) in the East African Rift System, SW Tanzania, provides a unique opportunity to investigate geothermal resources in the context of particularly complex continental rifting processes. To support geothermal resource targeting in the RVP, we present a revised neotectonic structural map based on an interpretation of aeromagnetic data constrained by 2D-forward modelling of magnetic anomalies integrated with the distribution of previously reported faults, seismic epicentre locations, 3D magnetotelluric resistivity models and surface geothermal manifestations. Magnetic anomalies in the RVP, including the nationally prominent Mbeya anomaly, are related to the high magnetic susceptibility or remanent magnetism of Precambrian rocks and Cretaceous carbonatite intrusions buried in the rift under a varying thickness of non-magnetic sediments and volcanic rocks. Magnetic lineaments are related to structures controlling the geometry of the Precambrian rocks and concealed dikes and the thickness of the sediments and volcanics. The recent Ngozi and Rungwe trachyte volcanics have relatively low magnetic susceptibility comparable to the low susceptibility of the sediments in the rift basins. The revised neotectonic structural map shows prominent NW, NE and NS-trending magnetic lineaments that correlate with previously reported faults and alignments of seismic epicentres in the study area and with the regional trend of the rift segments. The NE-trending magnetic lineaments are consistent with interpretations of the current stress field in the RVP. The main volcanoes in the RVP, Ngozi, Rungwe and Kiejo (also known as Kyejo and Kieyo), are aligned with the NW-trending linear magnetic feature joining the Lupa and Livingstone rift border faults. This lineament is intersected and frequently displaced by the NE and NS-trending lineaments, suggesting that the NE to NS-striking structures are younger. The Rungwe and Ngozi volcanoes as well as numerous ‘’monogenetic’’ eruption centres and the Mwakaleli caldera, which originated ca. 2 Ma ago (Ebinger et al., 1989) following a large explosive eruption emplacing widespread ignimbrite deposits, are located within a zone of low-intermediate magnitude magnetic features forming a basin-like structure surrounded by magnetic high anomalies of the Precambrian basement structures. We interpret the intersections between the NW-trending intra-rift faults and the NS and NE-trending faults as favourable locations for wells to target high permeability within the geothermal resource conceptual models previously constructed using 3D MT resistivity imaging integrated with supporting geoscientific data. The intersections provide a focus area for follow-up ground mapping of subtle features that may be associated with very recent fault movement.

Designing and multi-objective optimization of a novel multigenerational system based on a geothermal energy resource from the perspective of 4E analysis

Over the past few years, a growing emphasis has been placed on providing sustainable energies to reduce carbon emissions and promote energy efficiency. This paper delved into energy, exergy, exergoeconomic, and exergoenvironmental investigation for a system that combines the Kalina cycle, a double-effect absorption chiller with a vapor compression refrigeration system coupled with an air handling unit driven by a geothermal renewable energy resource. This innovative system generated four distinct outputs: electricity, potable water, cooling load, and hot water. Key system performance variables, such as net power output, coefficient of performance, sum unit cost of the product, energy and exergy efficiencies, the temperature of supply air to the cold store, and potable water production in the base mode, are measured at 63.45 kW, 0.83, 56.74 $/GJ, 62.28 %, 45.67 %, 268.7 K and 20.82 lit/h, respectively. This research explored the impact of various parameters on the output variables, the exergy destruction and environmental impact rate of all components, and the net percent value of the proposed system. The multi-objective optimization significantly improved energy and exergy efficiencies by 6.83 % and 1.8 % from its base mode. Exergy and exergoenvironmental analysis revealed that the highest exergy destruction occurs in Re-injection, and the highest environmental impact rate associated with exergy belongs to the HPG component. Moreover, the geothermal section has the largest share of exergy destruction, approximately 58.5 % of the total exergy destruction of the system.

Heat in the news: Geothermal energy in Chilean newspaper coverage

Although Chile has abundant geothermal resources and is home to the first geothermal power plant in South America, the country faces uncertainties regarding the future development of geothermal energy. Lack of economic incentives, insufficient regulatory framework, and social opposition to geothermal power plant projects are some of the main challenges faced in the last years. To reflect on the pitfalls of the geothermal energy public debate and promote the integration of social aspects in the geothermal energy discussion, this study examines how geothermal energy has been portrayed in two influential Chilean newspapers from 2008 to 2021. Based on the idea that the mass media plays a critical role in public perception, this paper presents a framing analysis of 259 newspaper press to reflect on the public discourse of geothermal energy. The study shows that the media focused mainly on deep, high-enthalpy geothermal projects and the energy concession market. Geothermal energy has been mostly part of the finance discussion, and the coverage has been primarily event-driven, with limited visibility beyond specific events. Two events, the controversial exploration project in El Tatio (2009) and the successful commissioning of the first geothermal plant Cerro Pabellón (2017) attracted significant attention and presented geothermal energy from contrasting perspectives. Geothermal energy is mainly portrayed as an abundant, clean, and renewable energy source. However, geothermal development is described as a “business” or a “resource to be exploited”. There is a notable absence of discussion regarding the success of Latin American geothermal initiatives. Instead, European cases are the most prevalent in the discourse, serving as exemplars for potential future action. This result calls for the promotion of a new geothermal narrative and relationship with geothermal energy that acknowledges the experience from Latin American countries such as Costa Rica or El Salvador, the importance that geothermal energy has had for Indigenous peoples and promotes its use in the light of social demands for a more sustainable relationship with the environment, instead the main geothermal frame reproduces the commodification of natural resources in Chile.

Region specific economic model for solid sorbent direct air capture using geothermal energy resources (S-DAC-GT)

Low temperature geothermal resources, ranging from 80° to 120 °C, may substantially lower both the cost and the CO2 emissions footprint of CO2 direct air capture (DAC) systems. This paper provides a model for determining a region-specific economic analysis for DAC with solid sorbent (S-DAC) using geothermal resources (S-DAC-GT).This paper provides a methodology and program for calculating estimated cost and carbon emissions for potential S-DAC facilities on a region-specific basis. The paper outlines the necessary region-specific characteristics required as parameters for the techno-economic model. The region-specific characteristics are then applied to an S-DAC energy and cost model based on existing literature to calculate the levelized cost per tonne of CO2 captured and stored. Further, the model provides a reasonable approximation of the carbon intensity of the S-DAC-GT system. These calculations allow selecting and prioritizing regions appropriate for potential S-DAC-GT facilities operating at a scale of ∼1 Mt CO2 captured and stored per year.This paper presents a novel approach that addresses several gaps in current DAC techno-economic analyses found in literature. First, the model is highly customizable, allowing the user to apply their own proprietary sorbent properties and region specific parameters to determine precise costs and carbon emissions for their hypothetical S-DAC-GT facility. Second, the overwhelming majority of DAC techno-economic analyses in literature assume away variability of ambient conditions, presuming stable temperature and humidity during operations. This paper directly integrates these large local ambient effects on sorbent performance and evaluates S-DAC-GT costs and carbon emissions based on specific and variable conditions dictated by the user. Third, the flexibility of the model allows the user to rapidly compare S-DAC-GT costs and carbon emissions in different user selected regions, with custom sorbent characteristics. The model provides visualizations of the sensitivity of S-DAC-GT costs and carbon emissions to different parameters and provides visualizations of the cost and carbon emissions due to variability in ambient conditions.Existing techno-economic analyses are either region agnostic or constrain their results to a specific region. The novelty of this paper and its model is the deeper technical and economic analysis of using geothermal energy as the thermal resource, coupled with customizability and visualizations that enable accelerated differentiation of S-DAC-GT costs and carbon intensity by region.

Review of Reservoir Damage Mechanisms Induced by Working Fluids and the Design Principles of Reservoir Protection Fluids: From Oil–Gas Reservoirs to Geothermal Reservoirs

Various working fluids are applied during geothermal reservoir development, and geothermal reservoir damage induced by contacts between working fluids and reservoir formations are inevitable. Reservoir damage mechanisms, including solid and colloidal plugging, fluid sensitivity, stress sensitivity, and water locking, provide guidance for designing reservoir protection working fluids. In this paper, based on the design principles of reservoir protection working fluids applied in oil–gas reservoirs, four design principles of reservoir protection working fluids are proposed to eliminate potential geothermal reservoir damage for geothermal reservoirs, containing solid-free, facilitated flowback, temporary plugging, and inhibition. Solid-free is achieved by replacing solids with polymers in working fluids. Surfactant and materials with low affinity towards rock surfaces are applied for the facilitated flowback of working fluids from reservoir formations. Temporary plugging is achieved by using temporary plugging materials, some of which are polymers that also apply to solid-free working fluids. Besides, some of the temporary plugging materials, such as surfactant, are applicable for both the facilitated flowback and inhibition of working fluids. The inhibition of working fluids include the inhibition of clay minerals, which can be attributed to clay mineral inhibitors or activity regulators in working fluids, as well as the inhibition of mineral precipitations. This review aims to provide insights for geothermal reservoir protection working fluids, contributing to achieving an efficient development of geothermal resources.

Repurposing idle wells in the North German Basin as deep borehole heat exchangers

This study investigates the feasibility to repurpose wells from gas production for geothermal closed-loop application in the North German Basin (NGB). The objective for this research topic is to extend the value-added chain of idle wells by re-completion as coaxial deep borehole heat exchangers as an efficient way to produce green energy without drilling new wells by saving the carbon emission and costs of building a new geothermal well. With numerical models of two typical geological settings of the NGB and two different completion schemes, it is possible to simulate the thermal performance over a lifetime of 30 years. The calculated heat extraction rates range from 200 to 400 kW, with maximum values of up to 600 kW. Sensitivity analyses demonstrate that re-completion depth and injection temperature are the most sensitive parameters of thermal output determination. The heat demand around the boreholes is mapped, and heat generation costs are calculated with heating network simulations. The initial production costs for heat are comparable to other renewable energy resources like biomass and competitive against gas prices in 2022. This study highlights available geothermal resources’ environmental and economic potential in already installed wells. The application has almost no geological and no drilling risks and may be installed at any idle well location.

Analysis of thermal production effect of multi-horizontal U-shaped well

The multi-horizontal section hot dry rock (HDR) heat extraction system is proposed for efficient deep geothermal resources mining in this study. The thermal-hydraulic numerical model of the multi-horizontal section geothermal exploitation system is set up, the space-time evolution of temperature field is analyzed. The sensitivity factors including completion schemes, horizontal well diameter, quantity of horizontal sections and spacing of horizontal sections are investigated. The simulation results show that the production temperature and heating power of the multi-horizontal HDR production system decrease with the development of mining, and the decreasing speed gradually slows down. The open hole completion can be preferred when the formation conditions permit. The variation of horizontal well diameter has little effect on heat production when other conditions remain unchanged. The quantity of horizontal sections to be 3 or 4 for better heat extraction performance under the spacing of horizontal section remains 300m and the spacing of the horizontal section to be 150m is recommended within the scoped of this study. The results of this study can provide guidance for HDR mining research.

A multiphysics simulator for stope-coupled heat exchanger operation in deep underground mines

The ever-increasing mine depth offers unprecedented opportunities to access high-grade geothermal resources. By pre-installing pipeline systems in mined-out cavities before waste tailings placement, the stope-coupled heat exchanger (SCHE) has drawn growing attention for its superior socio-economic advantages. However, despite the extensive focus on energy efficiency, the system stability during heat production has been typically overlooked. This study therefore introduces a novel high-fidelity simulator for replicating practical SCHE operation. By embedding non-isothermal pipe flow into an evolutive thermo-poromechanics framework for cemented tailings, the outlet water temperature and multiphysics backfill response in diverse production settings are meticulously studied. Our calculations reveal for the first time that circulating chill fluid within mine backfill can substantially alleviate pressure development, suggesting enhanced system stability with heat-exchanger implementation. We also demonstrate that albeit targeting higher-grade geothermal resources, prioritizing cold-season operation, and pre-charging heat exchangers with production delays could spur heat productivity, the companion thermal pressure generation might still impose significant overloading risks. Conversely, while fast circulation would diminish the end-utilization temperature, the rapid heat removal could indeed facilitate superior efficiency and stability performance for the geothermal system. We believe these new findings hold critical implications for better positioning SCHE as a safely sustainable pathway towards hybrid utilization of deep resources.

Influence of design parameters on heat production of a multilateral butted closed loop geothermal system

To efficiently develop hot dry rock and other geothermal energy, a multilateral butted closed loop geothermal system (MBCLGS) is presented in this paper to replace the U-shaped closed-loop geothermal system (UCLGS). Besides, a casing-cement-formation transient heat transfer model is established to investigate the influences of key factors on the heat production of MBCLGS. After thermal-fluid-structural coupling analysis, we can find that higher injected rate and lower fluid temperature can improve heat power but reduce output temperature. In addition, the output temperature and heat power do not increase continuously with the increasing of branch well number. There is an optimal value of branch well number. Longer well pair distance can improve both output temperature and heat power. Considering the drilling technology level and design purpose, the recommended injected flow rate of MBCLGS is 90 m3/h, the injected fluid temperature is 42.5 °C, the number of branch wells is 10 and the well pair distance is 200m. Finally, by comparing MBCLGS and UCLGS, it is found that MBCLGS has a lower temperature decline rate and higher output temperature than UCLGS under the same conditions. It works more stable and has better economy. Overall, the proposal of MBCLGS is expected to promote the efficient development of deep geothermal resources.

Geothermal distribution and evolution of fault-controlled Linyi geothermal system: Constrained from hydrogeochemical composition and numerical simulation

This study explores the Linyi geothermal field, located in Shandong Province, China, characterized by its non-magmatic, active fault-controlled geothermal system. Utilizing a combination of geochemical analyses, temperature measurements, and numerical simulations, a detailed genetic model of the geothermal system has been developed. The analysis included extensive water geochemical and isotopic characterization to determine reservoir temperature, depth, and origin of the geothermal waters. The thermal-hydro coupling model was integrated with these data to refine the thermal distribution and assess the evolutionary dynamics of the geothermal system. Our findings indicate that the geothermal anomalies in the Linyi field are predominantly controlled by hydrothermal convection within the Ordovician and Cambrian carbonate layers, facilitated by the high permeability of the Yishu Fault. The fault acts as a crucial conduit for meteoric water recharge, which undergoes significant heating due to the geothermal gradient in deeper rock formations. Isotopic analyses of hydrogen and oxygen revealed the meteoric origin of the geothermal waters, with recharge likely originating from the nearby Yimeng Mountains. Furthermore, the study established a conceptual evolutionary model to understand the mechanisms driving the geothermal resource development in the area. It was determined that the geothermal resources are typically fault-controlled, with significant potential for further exploration due to the identified hydrothermal anomalies at the fault's footwall. The model predicts the preservation of heated meteoric water in the reservoir rock for periods ranging from 10 to 50 thousand years, providing a sustainable source of geothermal energy. This comprehensive approach not only enhances the understanding of the heat accumulation mechanism but also highlights the potential for optimizing geothermal exploration strategies within fault-controlled geothermal systems.

The characteristics of S-wave velocity and mineralization of the “Double Domes” structure in the eastern Tethys Himalaya

The Tethys Himalayan belt in the southern Qinghai–Tibet Plateau has been intruded by a large amount of leucogranite due to collisional orogeny. In addition, strong tectonic movements since the Cenozoic era have led to the formation of a series of dome structures accompanied by various types of mineralization. The Cuonadong Dome and Yalaxiangbo Dome, forming the “double dome” structure in the eastern part of the Tethys Himalayan Belt, are affected by different geological processes, resulting in differences in their deep structures and affecting the formation of polymetallic minerals. At present, geophysical research on the fine structure of the crust of the “double dome” structure is limited, making it difficult to fully understand the formation of different deep structures in the Tethys Himalayan dome belt. This hinders the progress of research on the genesis of dome structures and large-scale mineralization mechanisms in continental collisional environments. In this study, the ambient noise tomographic method was used to obtain the S-wave velocity structure of the upper crust of the Cuonadong Dome and the Yalaxiangbo Dome, and the following results were found: 1. there is a significant difference in the velocity structures of the two domes, with the core velocity structure of the Yalaxiangbo Dome showing an overall high velocity, extending downward for more than 9 km, while the core of the Cuonadong Dome exhibits low-velocity characteristics, with some high-velocity bodies occurring locally, which may be related to the later intrusion of leucogranite and extensional activity of the Cuona Rift. 2. There are significant differences in the S-wave velocities between the lead–zinc deposits and rare metal deposits in the study area; the lead–zinc deposits occur in basins and graben margins and have large variations in the S-wave velocity, which may be related to the involvement of basin brine in mineralization; below the tungsten–tin–beryllium deposits, the S-wave velocity exhibits high-velocity protrusions, with mineralization occurring at the front ends of the protrusions, which may be caused by crystallization differentiation of leucogranite. 3. The study area has abundant geothermal resources and obvious geothermal structural features. The low-velocity basin in the upper part of the upper crust is a heat storage layer, the low-velocity channel in the middle is a heat-conducting layer, and the lower part is a low-velocity heat source area that continuously supplies heat, forming a special geothermal structural model for the Cuonadong Dome and Yalaxiangbo Dome.

Geothermal resources of Hungary: a play-based review

In this paper we review the geothermal resources of Hungary using the geothermal play concept and its scale-dependent hierarchical categorization. The Pannonian Basin belongs to an extensional domain play type, with two main plays: the porous Neogene basin fill sediments and the fractured-karstified Palaeozoic and Mesozoic basement rocks. Both plays can be divided into hydrostatic and overpressured play segments. The most widely utilized play level in the hydrostatic segment of the porous Neogene sediment play comprises laterally extended highly permeable sandstone layers storing low salinity thermal water with average flow rate around 900 l/min and temperatures between 50 °C and 100 °C in the depth range of 1–2 km. The other prosperous play level is represented by the fractured-karstified Mesozoic carbonates in the hydrostatic segment of the basement play having elevated temperatures (90–120 °C) and several thousand l/min flow rates. The play level related to fractured Palaeozoic rocks is less important due to its limited extent. The overpressured segment of the basement play may have high flow rates, but still an untapped resource, where exploitation is limited by high overpressure, high temperature (170–200 °C), and highly saline hot waters.