Mantle Heat Flow Research Articles

The Curie Surface and Lithospheric Thermal Structure in Mongolia‐Baikal Region

AbstractThe Mongolia‐Baikal region, located between the Siberia, North China, and Tarim cratons, exhibits the most pronounced lithospheric accretion and extension since the Phanerozoic. Despite its distance from plate boundaries, the region's notable tectonic activity underscores its importance for studying intraplate lithospheric deformation. However, its lithospheric thermal structure, particularly at high resolution, remains inadequately characterized. By integrating magnetic anomaly constraints with heat flow measurements, we have obtained a high‐resolution lithospheric thermal structure for the Mongolia‐Baikal region, revealing lithospheric thicknesses ranging from 60 to 180 km. The Curie depth and mantle heat flow also show diverse variations across different regions. Our results suggest that elevated mantle heat flow in the Baikal Rift Zone, coupled with a uniform Curie depth and minimal lithospheric thinning, likely reflects lithospheric weakening from mantle upwelling, facilitating rifting in the early stages of the rift's formation. Additionally, some localized lithospheric thermal variations identified in our results may be closely linked to the formation of the Hangai Plateau and the low magnetic anomalies observed in the Mongolia‐Okhotsk suture.

Continental subduction and exhumation of the lower crust in a hot orogen: Insights from high-pressure (ultra) high-temperature granulite in the Pouso Alto Nappe, Southeast Brazil

The Pouso Alto Nappe (PAN) is part of the Southern Brasília Orogen (SBO) hinterland and primarily comprises K-feldspar + garnet + kyanite + rutile-bearing paragneiss, interpreted as a residual high-pressure (HP) granulite. The PAN granulite was studied by combining detailed microstructural and petrographic descriptions with monazite petrochronology, thermodynamic modeling, and trace element thermometry. The P–T–t trajectory of the PAN granulite reveals that it experienced HP, and possibly ultrahigh temperature (UHT), metamorphic conditions during the SBO evolution. The prograde subsolidus metamorphic conditions occurred between ca. 670 and 620 Ma. Subsequently, the granulite underwent water-undersaturated partial melting during heating and burial, reaching peak conditions of ≥1000 °C and 18–19 kbar at a maximum age of ca. 620 Ma. The proposed prograde path indicates that the granulite was involved in the continental subduction channel, reaching depths of ca. 70 km, corresponding to the interface between the lower crust and lithospheric mantle in a double-thickened crust. The granulite facies metamorphic conditions would have been attained primarily through the accumulation of heat production elements and mantle heat flow. Decompression and cooling of the melt-weakened rocks commenced after the delamination of denser material of lithosphere. Subsequently, the previously melt-weakened granulite initiates the in-sequence ductile flow, driven by gravitational force exerted by the weight of the orogen. The PAN granulite likely records the transition from a wedge-shaped orogenic belt to an orogenic plateau during continental collision development.

Constraints on Growth and Stabilization of the Western Superior Craton From Inversion of Magnetotelluric Data

AbstractA data set consisting of 376 broadband and long‐period MT measurements was used to generate the first ever 3D resistivity model of the Archean western Superior Craton. The modeled resistivity structure is compared to coincident seismic reflection data. The observed geophysical signatures are interpreted within the context of the late stages of crustal growth and cratonization of the region via the progressive accretion of terranes against the initial cratonic core. The northern‐most terranes comprising the cratonic core exhibit a nearly homogenous highly resistive crust. The lower crust of the southern terranes contains largely continuous low resistivity bands which run subparallel to major terrane boundaries and corresponding fault systems. In some cases, low resistivity features are coincident with dense packages of sub‐horizontal to listric reflections within the mid‐ to lower crust. These resistivity structures are inferred to represent preserved geoelectric signatures of late to post‐orogenic magmatic pulses likely related to delamination of locally overthickened crust. Increased mantle heat flow resulted in partial melting of the lower crust and upper mantle and upward migration of CO2‐rich melts and fluids through crustal weak zones corresponding to shear and/or suture zones formed during terrane amalgamation. Thermal softening of the mid‐ to lower crust led to orogenic collapse and reactivation of the crustal shear zones, resulting in formation and interconnection of graphitic films which were preserved within the stable craton. These results have implications for the tectono‐magmatic history of the western Superior Craton, as well toward the understanding of the geodynamic regime of the Archean Earth.

Heterogeneities of the lithospheric thermal structure and rheology control Cenozoic intracontinental deformation in southeast China

It still remains elusive how the rheology of the lithosphere influences intracontinental deformation. We constructed a thermo-rheological model of the lithosphere in southeast China, a typical intracontinental deformation area, to address this issue. The thermal model was derived from updated heat flow data assuming steady-state heat conduction, using xenoliths and Pn seismic velocity data as constraints. This thermal model was integrated with a compositional and structural model of the lithosphere to estimate the strength distribution. Remarkable heterogeneities in the thermo-rheological structure were obtained. Most of southeast China is characterized by a large mantle heat flow and high temperature, thin and weak lithosphere, except for the western Yangtze Craton where a cold and rigid lithosphere exists. The lithosphere thins southeastward from 200 km in the craton interior to 70 km in the northern South China Sea. Both the ‘jelly sandwich’ and ‘crème brûlée’ rheological profiles for the continental lithosphere exist in southeast China, depending on the geothermal condition. The seismicity in southeast China is restricted to areas cooler than 600 °C, which are rheologically weak and characterized by strength transition zones. The Mesozoic flat-slab subduction of the Paleo-Pacific Ocean and far-field effects of the Cenozoic Indo-Asia collision influence the thermo-rheological pattern in southeast China, and the thermo-rheological heterogeneities control the Cenozoic intracontinental deformation.

A high geothermal setting in the Linyi geothermal field: Evidence from the lithospheric thermal structure

The lithospheric thermal structure has a profound indicative significance for the potential evaluation and exploration of geothermal resources. The Linyi geothermal field, located in the southern section of the Yishu fault in Shandong Province, boasts abundant geothermal resources. However, its origin is still unclear. This study analyzed the characteristics of terrestrial heat flow using the temperature logging of geothermal wells and measurements of thermal conductivity and heat production. Combined with the geophysical information of the Xiangshui (Jiangsu Province)-Mandula (Nei Mongol) geoscience transect and the lithology revealed by the geothermal wells, this study built a conceptual model of the lithospheric thermal structure using the one-dimensional steady-state heat conduction equation. Based on this model, the heat flow is 64.9 mW/m2, indicating a high geothermal setting in the study area. Furthermore, the ratio of crustal to mantle heat flow is < 1 (0.67), implying that surface heat flow originates predominantly from the mantle. The Yishu fault probably acts as a pathway for heat transfer from the mantle. The temperature of the Moho boundary in the study area was estimated to be 614.8 °C. The Curie depth was calculated to be 29.5 km (585 °C), which is consistent with the depth estimated using the aeromagnetic data. In sum, the Linyi geothermal field has a high geothermal setting, which contributes to the formation of geothermal resources.

Characteristics of geothermal field and evaluation of geothermal resource potential in the Yingjiang Basin

Geothermal resource, a green and sustainable energy resource, plays an important role in achieving ‘emission peak’ and ‘carbon neutrality’ targets. The Yingjiang Basin is located in the eastern branch of the Mediterranean-Himalayan high-temperature geothermal belt and exhibits considerable potential for geothermal resources. However, current investigations into the distribution of deep geothermal resources in this region are somewhat limited. In this paper, the transient plane source (TPS) method is used to measure the thermal conductivity parameters of 31 rock samples within the study area. Additionally, the one-dimensional steady-state heat conduction equation is employed to calculate the deep geothermal field, considering the constraints of rock thermal properties and terrestrial heat flow in the study area. Furthermore, the “stripping method” is used to determine the contribution rate of sedimentary layer to terrestrial heat flow, while the volume method is applied to estimate the geothermal resources at burial depths of 3000–5000 m. The results show that (1) The heat generation rate of granite is the highest with an average value of 4.52 μW/m3, followed by gneiss with an average value in the range of 2.0–3.5 W/(m·K), mudstone and sandstone being the lowest with an average value between 1.0 and 2.0 W/(m·K). (2) The main contributor of terrestrial heat flow in the study area is mantle heat flow, and the contribution of sedimentary layers to terrestrial heat flow only accounts for about 2%. (3) The geothermal resources in Yingjiang Basin within the depth range of 3000–5000 m is 93.6 × 1015 kJ, or 3.2 × 109 tonnes standard coal equivalent (SCE).

Crust-mantle differentiation and thermal accumulation mechanisms in the north China plain

The North China Plain, which is the central part of the lithospheric thinning in the North China Craton, is rich in clean geothermal energy. However, a current lack of understanding about the thermal accumulation mechanisms of the deep geothermal resources in this area is hindering the exploration, exploitation, and utilization of these resources and the achievement of the carbon reduction targets. Based on deep drilling and the tests of thermal property parameters at different depths, this study calculated the terrestrial heat flow and the heat flux at different depths of the lithosphere in the North China Plain and revealed the lithosphere thermal structure characteristics and the thermal accumulation mechanisms in the plain, obtaining the following results. The North China Plain has widely varying terrestrial heat flow of 33.5–92.1 mW/m2 (average: 62.1 ± 17.04 mW/m2). The average mantle heat flow and crustal heat flow in the plain are 42.05 ± 13.90 mW/m2 and 20 mW/m2, respectively, which account for approximately 67% and 33% of the total surface heat flow in the plain, respectively. This plain has a greatly varying Moho depth of 30–40 km and a Moho temperature of 420–920 °C mostly. The thermal lithosphere in the North China Plain has a thickness of 80–100 km and a thermal structure of the cold crust and hot mantle type. It has thinned on a large scale due to the extensional process, and the mantle-derived materials have migrated upward along the weak structural plane (e.g., deep faults) after pressure release and remelting. The resultant high mantle heat flow serves as a stable heat source for the formation of layered medium-low temperature geothermal fields.

Longitudinal structure of Earth’s magnetic field controlled by lower mantle heat flow

Longitudinal structure of Earth’s magnetic field controlled by lower mantle heat flow

Electrical Moho and upper mantle metasomatism in the Archaean Bundelkhand craton of the Indian peninsular shield

The Bundelkhand Craton (BKC), one of the Archaean nuclei in the north central part of the Indian shield, has a lesser surface exposure compared to other cratons. Recent magnetotelluric (MT) study in the Central Ganga Basin (CGB) showed NNE-SSW extension of the cratonic block as a transverse ridge and delineated a shear zone within the buried section of the BKC. In the present study, we extend the MT profile to further south with 19 broadband MT sites in the exposed BKC to complement the lithospheric electrical resistivity architecture. Two-dimensional (2-D) geoelectric structure down to 100 km is obtained from inverse modelling of the distortion corrected MT impedance tensors together with the 31 sites in the CGB. The resulting geoelectric model reveals a flat and sharp resistivity contrast at 40–42 km depth, the electrical Moho (e-Moho), separating highly resistive Bundelkhand massif and moderately conductive upper mantle. The 2-D model also brings out two shear zones represented by near-vertical moderately conductive zones within the massif, indicating zones of amalgamation of different fragments of the pre-Bundelkhand craton. In contrast to other major cratons of the Indian shield, the present MT study has delineated a moderately conductive upper mantle beneath the BKC. In view of the estimated low mantle heat flow along with relatively flat topography, we infer metasomatism of the mantle lithosphere by percolation of fluids. We hypothesize that infiltration of fraction of water (H2O) in nominally anhydrous mantle minerals as hydrogen (H) bonded to structural oxygen (O) originated from the subducted oceanic slab has altered the mantle rheology and metasomatized the lithosphere.

Plutonic-subvolcanic connection of the Himalayan leucogranites: Insights from the Eocene Lhunze complex, southern Tibet

The Lhunze region of southeast Tibet uniquely juxtaposes Cenozoic granitic plutons with subvolcanic rocks in the Tethyan Himalayan Sequence. In this study, the potential petrogenetic connection between two-mica granite and subvolcanic rhyolite porphyry from the Lhunze area is investigated using petrology, geochronology, and geochemistry. Monazite Th Pb ages imply the two-mica granite crystallized during the mid-Eocene at c. 43.5–43.1 Ma, consistent with previous zircon U Pb isotope data. Monazite in the porphyry also records Th Pb ages of c. 44.5–42.9 Ma , suggesting contemporaneous emplacement with the two-mica granite. Porphyritic structure, feldspar aggregates and comb alignment demonstrate that the two-mica granite resulted from transient melt flow associated with melt extraction. Some plagioclase phenocrysts from the porphyry have consistent An contents with the two-mica granite, indicating that both the two-mica granite and the porphyry probably originated from a similar melt. However, the porphyry has a higher SiO 2 concentration (72.2–75.9 wt%) than the two-mica granite (69.0–73.0 wt%). In addition, the porphyry is characterized by lower TiO 2 , MgO, CaO, Ba, Sr, and Zr contents as well as Zr/Hf, Sr/Y, Nb/Ta ratios than the two-mica granite. Moreover, strontium and REE contents of monazite in both the two-mica granite and porphyry also imply that crystal fractionation dominated melt evolution. Whole-rock Sr Nd and in situ monazite Nd isotope compositions indicate that the porphyry is slightly more radiogenic than the two-mica granite, implying that the porphyry likely assimilated more ancient country rocks during its evolution. We interpret the two-mica granite and porphyry as comagmatic intrusives linked by fractional crystallization of a cognate magma mush, in which the crystals accumulated to form the two-mica granite, and the complementary high silicic melt segregated to form the porphyry. Plagioclase accumulation is responsible for the generation of the high Sr /Y adakitic geochemical feather within two-mica granite. The scenario of complementary melt extraction and crystal fractionation might also have been an important process in forming the Himalayan leucogranites. Regionally, Neo-Tethyan slab breakoff during the Eocene could have increased mantle heat flow and triggered the generation and extraction of large volumes of silicic melt. • Two-mica granite and subvolcanic rhyolite porphyry have a coeval crystallization age at 44–43 Ma . • Two-mica granite represents cumulate and the porphyry as its complementary highly fractionated melt. • Magma differentiation via melt extraction from crystal mush is an effective mechanism to produce Himalayan leucogranites.

Geothermal regime and implications for basin resource exploration in the Qaidam Basin, northern Tibetan Plateau

• Geothermal field characteristics of the Qaidam Basin, northeastern Tibetan Plateau, were analysed. • The crustal contribution to the surface heat flow was approximately 55%. • The existence of abnormally high-temperature zones significantly dominated the hydrocarbon distribution. • The Qaidam Basin is favourable for low- and medium-temperature geothermal resources development. • Certain deep high-temperature geothermal resource is prospective if using abandoned oil wells. The Qaidam Basin was formed under the background of the continuous uplift of the Tibetan Plateau, and its tectonic location imparts unique geothermal regime. The geothermal regime of the Qaidam Basin was studied based on oil-test static temperatures from 60 wells, 195 thermal conductivities measured by the optical scanning method, and 142 radiogenic heat production values. The geothermal gradient in the Qaidam Basin is 17.1–47.6 °C/km, with an average of 31.3 °C/km, and the thermal conductivity is 0.523–4.379 W/m‧K. The heat flow is 28.3–83.1 mW/m 2 , with an average of 59.6 mW/m 2 , and it is “high in the west and low in the east.” The heat flow can exceed 70 mW/m 2 in the northern marginal fold-and-thrust belt of western Kunlun and Nanyishan and generally exceeds 65 mW/m 2 in the Mangya Depression. The average radiogenic heat production rate (HPR) is 2.53 μW/m 3 , which is close to the HPR of granite in northern Tibetan Plateau. The crustal and mantle heat flows in the Qaidam Basin are 32.9 mW/m 2 and 26.7 mW/m 2 , respectively. The crustal contribution to the surface heat flow was approximately 55 %. The geothermal regime may be dominated by lithospheric thickness, HPR of sedimentary cover, and extra heat production related to late Cenozoic tectonic movement. The proven hydrocarbon reserves are primarily distributed around hydrocarbon-generating kitchens, and the existence of abnormally high-temperature zones significantly influences hydrocarbon distribution. The Qaidam Basin satisfies the fundamental temperature conditions for the development of low- and medium-temperature geothermal resources using abandoned oil and gas drilling wells.

The thermal state of Volgo–Uralia from Bayesian inversion of surface heat flow and temperature

SUMMARY Volgo–Uralia is the easternmost segment of the East European Craton. It accommodates the Volga–Ural petroleum province where the maturity of source rocks is tightly related to the temperature distribution in the crust. Numerous heat flow and temperature measurements have been reported for this region. However, no consistent geothermal model was presented for the Volgo–Uralian crustal block so far. In this study, we present a novel model of the Volgo–Uralian geothermal field where we aim to reconcile the reported heat flow and temperature data. The main goal of the study is to explore lateral variations of the unknown thermal parameters within Volgo–Uralia. For this purpose, we applied a Bayesian Markov Chain Monte Carlo approach where we used the known surface heat flow, surface temperature, lithosphere–asthenosphere boundary temperature and thicknesses of the Earth's lithospheric and crustal layers as input and investigated the possible lateral variations of crustal and lithospheric mantle thermal conductivities, crustal heat production and mantle heat flow. We implemented this methodology for a single-layer and multilayer crust and validated the obtained geothermal models with existing subsurface temperature measurements for the region. The results show that the Volgo–Uralian subcraton is characterized by significant lateral variations of crustal radiogenic heat production (RHP) and mantle heat flow. The variations of crustal and lithospheric mantle thermal conductivities are less pronounced. According to our model, the surface heat flow distribution is controlled mostly by crustal RHP which accounts for more than half of Volgo–Uralian surface heat flow. Validation of the models shows that single-layer and multilayer crustal models give roughly the same fit of measured and modelled temperatures. This implies that a single-layer crust with constant RHP can be considered a sufficient approximation for regional-scale geothermal modelling.

Seismic tomography of the mantle and primary hydrogen deposits in the Dnieper-Donetsk basin

According to the three-dimensional P-velocity model of the mantle under Eurasia obtained by the Taylor approximation method, the analysis of the velocity structure of the mantle (to depths of 2500 km south of 50° N and 1700 km north) in the territory of the Dnieper-Donetsk depression was carried out in order to determine the possible areas of primary hydrogen release. Primary hydrogen is formed in the core and lower mantle, can be transferred to the surface (according to I.L. Gufeld). According to seismotomography, nine superdeep mantle fluids are isolated on the territory of Ukraine, the routes of which are defined as subvertical columns of alternation of high-speed and low-speed anomalies. In addition to the presence of superdeep mantle fluids in the study area, the following characteristics were analyzed: the depth of the main geodynamic boundary, the influence of the high-velocity transition zone of the upper mantle (propagating northward into the low-velocity transition zone of the upper mantle of the East European platform), the depth of the Moho boundary, gravity mantle anomalies and heat flow. The totality of the studies performed allowed us to conclude that, according to seismic tomography data, the Izyumsky and the eastern part of the Lokhvitsky segment of the Dnieper-Donetsk depression are promising areas for detecting primary hydrogen in the territory of the Dnieper-Donetsk depression.

Heat source model for Enhanced Geothermal Systems (EGS) under different geological conditions in China

A heat source is the basis for Enhanced Geothermal Systems (EGS) and is the most important factor for the site selection for EGS development. In this paper, we analyze regional variation patterns of mantle heat flow, study crustal thermal states, construct models of crustal steady-state temperature fields, and discuss the heat source mechanism of EGS in different zones, including the strongly tectonic activity zone of the Tibetan Plateau, North China sedimentary basin, and the highly radiogenic rock distribution zone of southeastern China. The results show that differences in the crustal thermal structure of different regions control their deep thermal conditions and EGS heat sources. The intense tectonic activity zone of the Tibetan Plateau, represented by the Gonghe Basin, shows an anomalously heated crustal thermal structure, and the low-velocity layer in its thickened crust provides the most important intracrustal heat source in the region. The local area in southeastern China is influenced by both highly radiogenic rocks and good sedimentary cover insulation, indicating a hot crust-cold mantle type of crustal thermal structure, thus reflecting the role of heat production from highly radiogenic rocks in controlling the shallow crustal temperature field in the area. The North China Plain has a typical cold crust-hot mantle type of crustal thermal structure, and the development of EGS in the area must consider the undulating bedrock pattern in the sedimentary basin and whether there is a deep fracture that connects the nearby mantle heat source. The results are of scientific significance for guiding future target site selection and EGS development in different regions.

Genetic Mechanism of Geothermal Anomaly in the Gaoyang Uplift of the Jizhong Depression

The Gaoyang uplift is rich in geothermal resources, but there are few studies on the regional geothermal genetic mechanism. A large number of geothermal wells fail in position calculation because of a shortage of basis. By using the methods of P-wave velocity structure imaging and magnetotelluric sounding, it draws the following conclusions: 1) The crustal thickness in the Gaoyang uplift area is relatively thin, about 32 km; 2) The cutting depth of the Gaoyang East fault exceeds 28 km and has reached the bottom of the lower crust. It is a large tensile fault that provides a channel for mantle heat flow into the shallow crust; 3) The Gaoyang uplift and its surrounding depressions form a concave-convex base fluctuation mode, which is conducive to the accumulation of heat flow to the uplift; 4) The deep carbonate thermal reservoir in the Gaoyang uplift is overlaid with Cenozoic sand and mudstone strata, with a thickness of more than 3000 m and low thermal conductivity, which is conducive to the preservation of thermal storage heat. Therefore, the shortening of the heat conduction path caused by regional crustal thinning, convective heat conduction of large faults, concave-convex structure, and thick Cenozoic caprock are the reasons why the heat reservoir temperature in the Gaoyang uplift is higher than that around, which provides a theoretical basis for geothermal development and utilization.

Surface Heat Flow, Deep Formation Temperature, and Lithospheric Thickness of the Different Tectonic Units in Tarim Basin, Western China

Abstract Herein, the new collected well-testing temperature as well as continuous steady-state temperature logs were achieved for the analysis of deep thermal structural characteristics and current thermal states of various tectonic units in Tarim Basin. Generally, geothermal gradient fluctuates in 14.6-31.1°C/km, the heat flow ranges between 31.6 and 59.2 mW/m2 with the average heat flow of 43.2 mW/m2, and these values are typical of low heat flow background in Precambrian craton basins. Furthermore, estimated formation temperature spatial distributions at 6~8 km depth are the same and are mainly under the control of basement structural pattern. At 6000 m depth, temperature is 99-188°C, which become 126-242°C and 113-215°C at 7000 m and 8000 m depths, respectively. These findings confirmed that heat flow in Tarim Basin was relatively low with similar geothermal regimes to other Precambrian craton basins around the globe. In addition, 1D theoretical crustal thermal structures in Tarim Basin were established based on the solution of the equation of steady-state heat conduction. The findings revealed that “thermal” lithosphere maximum thickness in Tarim Basin is witnessed in Manjiaer sag. Tazhong uplift thermal state differs from those of Tabei uplift and Manjiaer sag. Tazhong mantle heat flow is 23.9 mW/m2, which accounts for 48.8% of surface heat flow. Hotter thermal states of Tazhong uplift generated temperatures as high as ∼690°C in Moho. Tarim Basin heat flow distribution reveals that crustal heat flow plays a more significant role in surface heat flow and possesses typical “hot crust and cold mantle” model thermal structure properties.

Has the tectonic regime of the Baltic Shield always remained the same?

ABSTRACT Recent theories on the growth of continental crust stress its formation in pre-Archean and Archean times with minor additions at later times. The Earth has gone through a unidirectional evolution including surface changes, the genesis of life and an important loss of energy. The energy loss drives tectonic processes, but at a rate declining with available energy and thus with time. Semiquantitative modelling of energy-changes and transport indicates important differences between today’s Earth and the Paleoproterozoic Earth. Actualistic but non-uniformitarian arguments suggest that principal tectonic processes have changed over time. The Baltic Shield displays a fundamental difference in conditions between the c. 0.9 Ga high-pressure metamorphism including the occurrence of eclogite in the western Sveconorwegian Orogen and c. 2 Ga low-pressure metamorphism in the eastern Svecokarelian Orogen. This suggests that modern platetectonic processes were operative at c. 0.9 Ga but leaves the question whether it was active during the Svecokarelian orogeny open. The lack of eclogite in the Svecokarelian Orogen is explained with a change with time of the geotherm slope. The occurrence of two generations of granitic rocks of different compositions in the Svecokarelian is easily explained by an increased mantle heat flow in a stratified continental crust. In contrast to calc-alkaline platetectonic compositions, alkali-calcic rocks occur in a quarter-circle around the Svecokarelian core. The question arises whether modern plate-processes successively replaced proto-plate processes during Paleo- and Mesoproterozoic times.

Heat Aggregation Mechanisms of Hot Dry Rocks Resources in the Gonghe Basin, Northeastern Tibetan Plateau

AbstractHot dry rock (HDR) is an important geothermal resource and clean energy source that may play an increasingly important role in future energy management. High‐temperature HDR resources were recently detected in deep regions of the Gonghe Basin on the northeastern edge of the Tibetan Plateau, which led to a significant breakthrough in HDR resource exploration in China. This research analyzes the deep temperature distribution, radiogenic heat production, heat flow, and crustal thermal structure in the Qiaboqia Valley, Guide Plain, and Zhacanggou area of the Gonghe Basin based on geothermal exploration borehole logging data, rock thermophysical properties, and regional geophysical exploration data. The results are applied to discuss the heat accumulation mechanism of the HDR resources in the Gonghe Basin. The findings suggest that a low‐velocity layer in the thickened crust of the Tibetan Plateau provides the most important source of constant intracrustal heat for the formation of HDR resources in the Gonghe Basin, whereas crustal thickening redistributes the concentrated layer of radioactive elements, which compensates for the relatively low heat production of the basal granite and serves as an important supplement to the heat of the HDR resources. The negative effect is that the downward curvature of the lithospheric upper mantle caused by crustal thickening leads to a small mantle heat flow component. As a result, the heat flows in the Qiaboqia Valley and Guide Plain of the Gonghe Basin are 106.2 and 77.6 mW/m2, respectively, in which the crust‐mantle heat flow ratio of the former is 3.12:1, indicating a notably anomalous intracrustal thermal structure. In contrast, the crust‐mantle heat flow ratio in the Guide Plain is 1.84:1, which reflects a typical hot crust‐cold mantle thermal structure. The Guide Plain and Zhacanggou area show the same increasing temperature trend with depth, which reflects that their geothermal backgrounds and deep high‐temperature environments are similar. These results provide important insight on the heat source mechanism of HDR resource formation in the Tibetan Plateau and useful guidance for future HDR resource exploration projects and target sites selection in similar areas.

Geochemical Characteristics of Hydrothermal Volatiles From Southeast China and Their Implications on the Tectonic Structure Controlling Heat Convection

Hot springs and igneous rocks are present widely in southeast China, influenced by the subduction of the Western Pacific and Philippine Sea Plates. This study reports on new data of chemical compositions and He–Ne–C isotopes for gas samples from representative hot springs and wells in the Guangdong and Fujian provinces to identify the origin of hydrothermal volatiles and provide insight into geothermal tectonic affinities. The primary hydrothermal volatile component from southeast China is atmospheric N2, with a volumetric percentage of 82.19%–98.29%. It indicates medium-low temperature geothermal systems where geothermal fluids suffered a shallow circulation in closed fracture systems. Low CO2 and CH4 contents and their depleted δ13C values confirmed the small number of deep-derived components in the study area. However, spatially discernible geochemical characteristics imply enhanced hydrothermal fluid convection in the adjacent area of the two provinces, including the Fengshun, Zhangzhou, Longyan, and Sanming geothermal fields. Specifically, the He–Ne isotopes from this area exhibit mantle He contribution of more than 10% and mantle heat flow accounts for more than half of the total heat flow. Moreover, according to the thermal background calculations, the highest heat flow value of 77.7 mW/m2 is indicated for the Zhangzhou geothermal area and the lowest value of 54.7 mW/m2 is indicated for the Maoming geothermal area. Given the epicenter distributions and the corresponding earthquake magnitudes, the NE-trending faults are heat-control tectonic structures and their intersections with the NW-trending faults provided expedite channels for geothermal fluids rising to the surface. Therefore, the preferred development potential of geothermal resources can be expected in the adjacent area of the two provinces where two sets of active faults crossed. This study provides critical information on understanding the geothermal distribution controlled by the tectonic structure in southeast China.

Characteristics of Terrestrial Heat Flow and Lithospheric Thermal Structure in Typical Intermountain Basin at the Eastern Foot of Yanshan Mountain, North China

The Yanshan area is rich in geothermal resources. However, limited research has been done on the geothermal resources of intermountain basins in the area, which restrict the exploration and development of geothermal resources. In this study, the Yanheying Basin, a typical intermountain basin located in the eastern foothills of Yanshan Mountain, is selected to perform a comprehensive analysis regarding heat flow and lithospheric thermal structure, to have a better understanding of the geothermal background and resource utilization potential of the area. The methods of deep borehole temperature logging, and rock sampling and testing were applied. With geological and geophysical data collected in the surrounding basins, the thermophysical parameters of rock formations, terrestrial heat flow and temperature distribution on a crustal-scale around the basin were analyzed. Results show that the ratio of crust heat flow to that of the mantle in the Yanheying Basin is 0.68, which falls in the range of that of the North China Plain (0.6–0.8), showing an obvious result of lithospheric thinning. The results also show that both crust and mantle heat flows in the Yanheying Basin are far lower than those of the North China Plain. it indicates that the crust of the Yanheying Basin and the entire Yanshan area has experienced a low degree of damage. That provides a piece of good thermodynamic evidence for the spatial variation of North China Craton destruction. The depth of the Curie surface in the study area is estimated to be about 24 km, which is consistent with the results of aeromagnetic data analysis. It confirms the results of lithospheric thermal structure and deep temperature distribution in the Yanheying Basin. The Yanheying Basin has certain potential for geothermal resources utilization in the depth of 2–6 km, where probably exist several carbonate thermal reservoirs with medium-temperature geothermal water. The above results can provide new insights into the geothermal research and exploration of intermountain basins in the Yanshan area.