High Heat Flow Research Articles

Characteristics and genesis of geothermal systems in the southern Junggar Foreland Basin, NW China

Complex structural styles of foreland basins and limited temperature data hinder our understanding of the characteristics and genesis of geothermal systems in these basins. Characteristics and genesis of the present thermal regime in the southern Junggar Foreland Basin are discussed and a conceptual model of the geothermal system is established based on steady-state temperatures, well-testing temperatures, thermal conductivities, radiogenic heat production, and thermal structures. Thermal conductivities of mudstone, sandstone, and volcanic rocks exhibit normal distribution patterns, with their average thermal conductivities in a consistent order. Heat production varies according to lithologic assemblages and uranium anomalies, being higher in mudstones and tuffs and lower in sandstones and coal measures. The geothermal characteristics are predominantly controlled by tectonic patterns, including geodynamic process and current basement structure. Surface heat flow is decreased from the first structural belts in the south to the third structural belts in the north and is converged from sub-depressions to sub-uplifts or anticlines, whose distribution matches well with positions of three structural belts. The generally low geothermal characteristics are attributed to thick thermal lithosphere and crust, as well as the thermal structure of “cold crust and cold mantle”. Groundwater and fault activities also influence heat flow. Additionally, uranium anomalies at the Cretaceous and Jurassic strata in the first structural belts enhance radiogenic heat production and result in continuously-distributed high heat flow. The heat generated by uranium anomalies helps explain the heat flow distribution in the first structural belts, which cannot be fully accounted for by tectonic-related thermal genesis alone.

C/C-(Hf0.5Zr0.3Ti0.2)C-W-Cu composites: Long-term ablation resistance based on active-passive protection at 2600 °C

Compared with the traditional C/C composites modified by ultra-high-temperature ceramics (C/C-UHTCs), those modified by metal/medium-entropy ceramics have excellent mechanical properties, thermophysical properties, and long-term ablation resistance. These composites have great potential towards improving the high-temperature resistance and service life of thermal protection systems for spacecraft. In this study, a new type of (Hf0.5Zr0.3Ti0.2)C-W-Cu cermet-modified C/C composites (C/C-(Hf0.5Zr0.3Ti0.2)C-W-Cu) was prepared at 1500 °C. Compared with C/C-UHTCs, the bending strength and fracture toughness of C/C-(Hf0.5Zr0.3Ti0.2)C-W-Cu increased by 70% and 110% to 364.25 MPa and 14.64 MPa·m1/2, respectively. Due to the high thermal conductivity of Cu and W, the thermal conductivity of this new composite was 106% higher than that of C/C-(Hf0.5Zr0.3Ti0.2)C (44.26 versus 21.53 W/m·K). Under a high heat flow of 4.18 MW/m2, this material exhibited very low mass and linear ablation rates (−0.163 mg/s and −0.193 μm/s, respectively). Active and passive protection occur during ablation due to the evaporative cooling of Cu, CuO, and WO3 as well as a dense outer oxide layer that inhibits oxygen diffusion. The internal oxide layer forms a Hf-Zr-Ti-C-O framework mingled with Ti-rich Ti-Hf-Zr-C-O and an unoxidised W-Cu structure, effectively reducing the osmotic oxygen content. This work provides a new direction for developing thermal protection materials capable of long-term service in ultra-high-temperature environments.

Acceleration of Antarctica glaciers at high subglacial heat flow

High subglacial heat flow and volcanic activity in West Antarctica contribute to instability and accelerated flow into the ocean of the West Antarctic ice sheet. In this case, a catastrophic rise in sea level by tens of centimeters – the first meters can occur in a very short geological time (years-decades) due to the rapid sliding of large masses of ice in West Antarctica into the ocean. If the Pine Island (50 cm sea level rise) or Thwaites (65 cm sea level rise) glaciers slide into the ocean, the West Antarctic Ice Sheet will lose support from these glaciers and may begin to collapse. In this case, the sea level will rise by a few meters. Based on Glen’s rheological law for a two-dimensional model of the movement of ice as a nonlinear viscous fluid, the flow velocities of a 3000 m thick glacier were calculated under conditions of adhesion to the bed (~20 m/year) and under conditions of sliding along the bedrock when the lower edge of the glacier melts due to increased heat flow from below (~3000 m/year). These velocities are in good agreement with the velocities of the Pine Island, Thwaites, Amery, Denman and Totten glaciers. The rapid movement of some outlet glaciers in East Antarctica is also likely caused by melting of their bases, suggesting increased subglacial heat flow in these areas of East Antarctica.

Numerical simulation study of boiling heat transfer of R290 flow in horizontal microtubes

Abstract R290 is considered to be an excellent alternative refrigerant for domestic air conditioners in the future. In this paper, CFD numerical simulation was used to obtain the flow field distribution of R290 in a micro-fine circular tube with an inner diameter of 2mm under a specific range of working conditions, and the effects of saturation temperature, mass flow density, heat flow density and tube type on the boiling heat transfer characteristics of R290 tube were investigated. The results show that the boiling heat transfer coefficient increases with the increase of saturation temperature, and the maximum value of the heat transfer coefficient increases by 8.1% when the saturation temperature increases from 284K to 286K. The boiling heat transfer coefficient increases with the increase of mass flow density, and the maximum value appears in the medium dryness range. The boiling heat transfer coefficient in the tube increases and then decreases when the heat flow density increases from 10 kW/m2 to 20 kW/m2 and increases faster at high heat flow density conditions. In addition, compared with the circular tube, the boiling heat transfer coefficient in the elliptical tube with an aspect ratio of 1.56 increases by 2.78% for R290 under the same flow area.

Tectono-thermal evolution from the proximal to hyperextended domains of the northern South China Sea margin since initial rifting

The Pearl River Mouth Basin (PRMB) is located on the northern margin of the South China Sea (SCS). Heat flow measurements indicate that the PRMB is a typical ‘hot basin' characterized by a high background heat flow. However, the tectono-thermal evolution of the PRMB and the mechanisms involved are still controversial due to the different input parameters used in tectono-thermal models, small datasets and the limited area of the basin studied. We used tectono-thermal modelling with a multi-stage finite stretching model, constrained by extensive well data, to systematically analyse the tectono-thermal evolution of the PRMB since the onset of rifting. The study area was expanded relative to previous studies to cover both the proximal and hyperextended regions of the northern SCS margin, providing a more comprehensive understanding of its tectono-thermal history. Numerous wells and seismic data covering the entire basin were used, along with appropriate input parameters, to address the gaps in previous studies and to enhance the accuracy of the results. Our findings indicate that the PRMB underwent two phases of heating, primarily due to thinning caused by lithospheric extension during rifting. By the end of rifting, the Northern Depression Zone and the Kaiping Sag had reached peak heat flow, while the Panyu Lower Uplift and Baiyun Sag saw their highest heat flow since the initial rifting. The PRMB experienced thermal decay during the post-rift stage, but a significant reheating event occurred from 23.03 to 13.82 Ma, likely due to northwards lower crustal flow from the Baiyun Sag. The Panyu Lower Uplift and the Baiyun Sag had reached their peak heat flow by 13.82 Ma and the heat flow generally increased by 1–3 mW m −2 in the other studied areas during this stage. The basin's thermal decay slowed at 5.33 Ma and localized heating events linked to magmatic activities in the southern Dongsha Uplift were observed. In general, the proximal domain of the northern SCS margin reached peak heat flow by the end of rifting, whereas the hyperextended domain reached peak heat flow by 13.82 Ma. The heat flow in the hyperextended domain was generally higher than that in the proximal domain as a result of the thinner crust of the hyperextended domain caused by intense multiple lithospheric detachment–extensional thinning processes. During the rifting stage, the lithospheric extensional thinning process was the most important factor influencing the tectono-thermal evolution of the northern SCS margin, while lower crustal flow and magmatism were the most important factors during the post-rift stage.

An updated terrestrial heat flow data set for the Junggar basin, northwest China: implications for geothermal resources

SUMMARY Terrestrial heat flow plays a vital role in determining the present thermal regimes of sedimentary basins, offering a robust foundation for understanding hydrocarbon maturation processes and the geothermal resource potential. The Junggar basin is one of the largest and most petroliferous superimposed petroleum basins in China. However, research on heat flow is scarce. In this study, 94 new high-quality heat flow values are derived from through borehole temperature analysis and thermal conductivity measurements of rocks. The results indicate that (1) the geothermal gradient in the basin varies from 11.4 to 28.3 °C km−1, with a mean value of 20.9 ± 3.4 °C km−1, and the heat flow varies from 23.4 to 64.5 mW m−2, with a mean value of 45.1 ± 8.4 mW m−2. The overall low geothermal gradient and heat flow are attributed to the continuous cooling during the Meso-Cenozoic. (2) At basin scale, the high heat flow values are primarily concentrated in areas characterized by basement uplift, whereas the low heat flow values are mainly located in the depressions. This suggests that thermal refraction is the primary factor influencing the heat flow variations. (3) Although large-scale development and utilization of geothermal resources face challenges, certain local areas in the basin show promise for geothermal resource utilization.

Formation of a Large Cold Groundwater Mantle Helium Anomaly and High Temperature Geothermal Resources in Response to Bimodal Magmatism Near Roosevelt Hot Springs and Utah FORGE, Milford Valley, Southwest Utah

AbstractA large mantle helium anomaly and separate domains of high heat flow are the predominant manifestations of bimodal magmatic activity in the Milford valley. The mantle helium anomaly (1.9–2.6 R/Ra) covers 270 km2 and is subdivided into two separated domains: a cold shallow groundwater regime and high temperature hydrothermal activity. The zone of anomalous heat flow covers >100 km2 and is also subdivided into two adjacent domains, comprising hydrothermal activity at Roosevelt Hot Springs (RHS) (3–7 W/m2) and conductive heat flow (100–180 mW/m2). While the transfer of heat and mantle helium at RHS are coupled, heat and helium transfer are decoupled in the adjacent cold groundwater regime to the west. Both the mantle helium and geothermal anomalies are attributed to recent mafic‐felsic magmatic intrusions of >400 km3, however, the absence of volcanic eruptions <500,000 years indicates magmas stall before rising to shallow crustal level <10 km depth. Deep level magmatism produces a felsic composition melt, which is inferred to be responsible for the widespread and near uniform range of diluted mantle helium values. A thick and impermeable mass of crystalline granitic basement rock at the mid‐crustal level divides the ascent of mantle helium into separate flow paths. It may also impede the rise of buoyant magma trapping thermal energy that facilitates partial melting, slow cooling, and development of a thick thermal aureole. Partitioning of convective and conductive thermal regimes and independent flow paths supplying deeply derived helium characterize the development of a large long‐lived magma‐related geothermal system.

Effect of the inclination angles of the capillary tube on the natural evaporation of absolute ethanol

Microchannel heat transfer plays an important role in microelectronics technology for heat dissipation, due to its high efficiency and low heat transfer temperature difference and flow resistance. To underpin the fundamental understanding of this technology, the natural evaporation process of absolute ethanol in a capillary tube at inclination angles ranging from 0° to 90° was investigated experimentally by exploring a spectrum of properties, such as Marangoni flow patterns, evaporation rate, heat flux, and temperature distribution. We found that the morphology of the meniscus is similar under different inclination angles, but the liquid and the tube wall slip to varying degrees due to the pressure difference at the liquid–vapor interface during evaporation. Therefore, the force distribution of the meniscus interface is different, and the resultant force is Fmax(60°) > Fmax(0°) > Fmax(30°) > Fmax(90°). We found that the morphology of the meniscus is independent of the inclination angle when absolute ethanol evaporates naturally. And the evaporation rate, heat flux and temperature distribution of meniscus at the initial stage of evaporation follow the law of resultant force distribution. That is, when the inclination angle is 60°, the evaporation rate and heat flux reach the maximum, i.e. 1.64 μm/s and 10.96 W/cm2, respectively, and the temperature between the center of the meniscus and the wedge region reaches 1.5 ℃. We used μ-PIV to observe the Marangoni vortex morphology of the vertical section of the meniscus, and found that there are different degrees of deformation at different inclination angles. When the inclination angle is 90°, the Marangoni vortex structure is destroyed.

Investigations on the heat transfer performance of phase change material (PCM)-based heat sink with triply periodic minimal surfaces (TPMS)

During the operational process of electronic components, excessive heat generation results in significant temperature elevation. This elevated temperature poses a significant risk to their service life. Regarding the issue of efficient thermal management of electronic devices in enclosed spaces experiencing high heat flow, a thermal management scheme for electronic equipment using TPMS and a PCM-based heat sink is proposed. The apparent heat capacity method is employed to simulate the melting process of the PCM-based heat sink. The effects of structural parameters w1, w3, and C of TPMS structures on the heat transfer characteristics (including base temperature, liquid fraction, average cell temperature, and average heat transfer coefficient) of the PCM-based heat sink during the melting process are discussed. A temperature testing platform is established. Experimental research is performed to investigate the effect of TPMS structures with two different printing prototypes (Sample 1, and Sample 2) on the heat sink during the intermittent cycle. The results indicate that increasing the parameters C and w1 significantly improves the average heat transfer coefficient (HTC) of the heat sink. When C increases from 0.3 to 0.7, the average HTC increases from 307 W/(m2·K) to 358 W/(m2·K). When w1 increases from 1 to 3, the average HTC increases from 284.5 W/(m2·K) to 321.3 W/(m2·K). Sample 1, possessing superior thermal conductivity, exhibits better heat transfer performance. When the temperature achieves a stable periodic variation, the base temperature of Sample 1 stabilizes within the range of 310 K-340 K. And Sample 2 stabilizes within the range of 315 K-350 K.

Three-stages tectonic evolution controls the differential distribution of hydrocarbons in the West Java backarc basin

The West Java Basin is a typical back-arc basin in Southeast Asia and one of Indonesia's main petroleum provinces. In the past ten years, it has been found that the new hydrocarbon reserves are on the rise, and a amount of resources to be discovered is significant. The distribution of hydrocarbon resources and the tectonic evolution characteristics of the basin are systematically explored, and the differences in hydrocarbon distribution and its main controlling factors in the back-arc basin of West Java are analyzed. The uneven distribution pattern of hydrocarbon is mainly controlled by the differential distribution of source rocks in the subsidence period. The distribution of the main source rocks is influenced by the "three-stage" tectonic development process that governs the distribution of sedimentary facies in various sedimentary environments throughout the tectonic subsidence period. Second, the weakening of the crust and magmatism facilitates the production of high heat flow values in the shallow strata of the back-arc area, thereby accelerating the pyrolysis and hydrocarbon generation of source rocks. The study delineates the formation and distribution of various types of oil and gas across various blocks. Prospective basin exploration sites include the shallow-deep water zones in the basin's south-central sector, as well as underexplored terrestrial regions. The exploration history and hydrocarbon resources identified within the West Java back-arc basin support these findings.

Source and U-Pb Chronology of Diagenetic Fluids in the Permian Maokou Formation Dolomite Reservoir, Eastern Sichuan Basin, China

The hydrothermal dolomitization, facilitated by basement fault activities, had an important impact on the Permian Maokou Formation dolomite in the Sichuan Basin, which experienced complex diagenesis and presented strong reservoir heterogeneity. The source and age of diagenetic fluids in this succession remain controversial. In this study, various analyses were implemented on samples collected from outcrops and wells near the No. 15 fault in the eastern Sichuan Basin to reconstruct the multi-stage fluid activity and analyze the impact on reservoir development, including petrology, micro-domain isotopes, rare earth elements, homogenization temperature of fluid inclusions, and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U-Pb dating. The homogenization temperature of primary brine inclusions in fine-grained matrix dolomite and saddle dolomite is concentrated between 100 and 150 °C, which indicates that the impacts of abnormally high temperatures of other geological bodies. The δ13C and δ18O value and low 87Sr/86Sr value indicate that the diagenetic fluid of fine-grained matrix dolomite is mainly Permian seawater. The U-Pb ages of fine-grained matrix dolomite are ~260 Ma, which coincides with the age of the main magmatism of Emeishan Large Igneous Province (ELIP), and hydrothermal fluid provided a favorable high-temperature environment in the penecontemporaneous stage. While highly radiogenic 87Sr/86Sr compositions suggests those of saddle dolomite, the high-temperature Sr-rich formation fluid. The U-Pb ages of saddle dolomite are 245–250 Ma, which coincides with the age of the 255~251 Ma magmatism of ELIP. This indicates that those should be the diagenetic products of the ELIP hydrothermal fluid in the shallow burial stage. The U-Pb age of coarse-grained calcite is 190–220 Ma, and it should be the diagenetic product of the deep burial stage. Brine inclusions associated with primary methane inclusions were developed in coarse-grained calcite, with a homogenization temperature range of 140.8–199.8 °C, which indicates that the formation fluid activities were related to hydrocarbon charging. The Permian Maokou Formation dolomite was firstly formed in the penecontemporaneous shallow burial stage, and then it was subjected to further hydrothermal dolomitization due to the basement faulting and the abnormally high heat flow during the active period of ELIP. Hydrothermal dolomitization contributed to the formation and maintenance of intercrystalline and dissolution pores, whereas it also formed saddle dolomite to fill the pores, and reduce the pore space. The influence of deep fluid activities on reservoir evolution is further distinguished.

Research on melon cascade drying technology to improve food safety

Abstract The aim of the study is to study the process of cascade drying of melons. The prospects for the implementation of the melon drying process using IR convective heat supply are substantiated. Intensification of moisture transfer occurs due to pre-pulse IR treatment of high density power heat flow. The effect of heat flux emitted by IR lamps on the object of study was studied. Analyses have shown that in the proposed method, under the influence of IR rays, there is an intensive removal of moisture from the entire volume of the material. A decrease in air temperature leads to an increase in the duration of the drying process. And an increase in the density of the heat flux leads to overheating of the surface of the material layer.

Two-station Lg wave attenuation tomography in Eastern Asia

SUMMARY Utilizing over 31 000 Lg waveforms from 136 crustal earthquakes recorded at 346 regional stations, we conduct detailed tomographic mappings of the Lg Q structure across Eastern Asia in a frequency range from 0.5 to 4.0 Hz. By improving the standard two-station (TS) method, we effectively correct non-unity site response ratios using site responses estimated at individual stations. This innovative approach combines the flexible recording geometry of the TS method with the precision of reversed two-station (RTS) and reversed two-event (RTE) methods, producing a comprehensive data set devoid of source and site effects for Q tomography. To address unsolvable 3-D structural effects in the Lg spectral amplitude modelling, we justify these as modelling errors with a Gaussian distribution. This approach supports our SVD-based tomographic method, allowing for effective inversion of attenuation parameters and quantitative assessment of model resolution and errors. Our results reveal a complex relationship between Lg Q and the tectonic characteristics of Eastern Asia. In well-resolved regions, low Qo (1-Hz Q) values correspond to areas with high heat flow, partial melt, thick sediment and recent tectonic-thermal activities, in contrast to high Qo values in stable, ancient crusts lacking recent tectonic activity. Rift basins are characterized by low Lg Qo, whereas flexural basins generally have high Qo basements. We also note that post-formation factors, such as sedimentation and crustal flow intrusion, significantly impact Qo values. Furthermore, Lg Q shows a complex frequency relationship, though the power-law approximation with positive power η remains useful. The frequency dependence power η is inversely related to Qo: the regions with low Qo typically have high η and vice versa. This study provides reliable attenuation tomographic and relative site response models for Lg waves in Eastern Asia, pertinent for relative geophysical studies.

Geothermal energy appraisal and subsurface structural mapping of the Rafin Rewa warm spring region, Precambrian basement complex of Nigeria

This research work aims at evaluating the geothermal energy potentials of the Rafin Rewa warm spring (RRWS) of the Precambrian Basement Complex in Nigeria as an alternative energy source using integrated aeromagnetic geophysical techniques. Four aeromagnetic dataset were acquired, assemblage, analyzed, and interpreted using integrated geophysical processing techniques of spectral analysis and Euler deconvolution. Qualitative interpretation of the residual anomalous map reveals a distribution of positive anomalies (> 53 nT) majorly in the central and southeastern regions, which are traced to the granitic rocks, while the low anomalies (< − 1.5 nT) have been traced to the RRWS location emanating from the coastal plain sands of the Pliocene, Pleistocene, Oligocene, and Miocene ages. Quantitatively, the depth to the top (DTT) of the anomalous bodies reveals a depression that is almost intersecting with the Curie point depth (CPD) plot at the RRWS location, which indicates high heat flow in the RRWS region. The Spectral Analysis results reveal that the DTT and the CPD in this area ranges from 0.512 to 0.761 km and 6.504 to 10.582 km, respectively while the average CPD is 8.543 ± 0.325 km. It is observed that the DTT and CPD decrease as one move away from the RRWS region. The computed heat flow average was 160.76 ± 19.09 mW/m2 within the RRWS region. The Euler deconvolution result reveals the presence of geological structures, which were interpreted as faults and fractures. The major fractures trend in the east–west (E-W) directions, while the minor fractures trend northeast-southwest (NE-SW) directions. The geochemical result presented shows that iconic compositions impact the convective heat transfer processes associated with geothermal systems. It was conclusively believed that regions with comparable shallow CPDs could be viable for further geothermal energy investigations.

High temperature heat flux sensor with ITO/In2O3 thermopile for extreme environment sensing

Hypersonic vehicles and aircraft engine blades face complex and harsh environments such as high heat flow density and high temperature, and they are generally narrow curved spaces, making it impossible to actually install them for testing. Thin-film heat flux sensors (HFSs) have the advantages of small size, fast response, and in-situ fabrication, but they are prone to reach thermal equilibrium and thus fail during testing. In our manuscript, an ITO–In2O3 thick film heat flux sensor (HFS) is designed, and a high-temperature heat flux test system is built to simulate the working condition of a blade subjected to heat flow impact. The simulation and test results show that the test performance of the thick-film HFS is improved by optimizing the structure and parameters. Under the condition of no water cooling, the designed HFS can realize short-time heat flux monitoring at 1450 °C and long-term stable monitoring at 1300 °C and below. With a maximum output thermopotential of 17.8 mV and an average test sensitivity of 0.035 mV/(kW/m2), the designed HFS has superior high-temperature resistance that cannot be achieved by other existing thin (thick) film HFSs. Therefore, the designed HFS has great potential for application in harsh environments such as aerospace, weaponry, and industrial metallurgy.

Experimental and numerical investigations on the intermittent heat transfer performance of phase change material (PCM)-based heat sink with triply periodic minimal surfaces (TPMS)

The excessive heat generated during the operation of electronic components leads to significant temperature increases, posing a significant risk to their service life. For the problem of efficient thermal management of electronic devices in confined spaces experiencing high heat flow, a scheme using triply periodic minimal surfaces and a phase change material-based active–passive cooling heat sink is proposed to control the temperature of electronic equipment. The apparent heat capacity method is employed to simulate the intermittent process of the phase change material-based heat sink. The optimization based on Box-Behnken Design and Nondominated Sorting Genetic Algorithm II is analyzed to obtain an improved triply periodic minimal surface structure. The effect of thermal performance (including base temperature, liquid fraction, and Grashof number) of an intermittent heat sink based on an improved structure is discussed. Visualization and temperature testing platforms are established. Through visualization experiments, the internal temperature and liquid fraction distribution of the heat sink are obtained, and the simulation results are in good agreement with the test results. The results show that the base temperature, liquid fraction, and Grashof number achieve a steady periodic variation during the intermittent process. Specifically, the base temperature remains stable in the range of 314 K to 340 K, the liquid fraction stabilizes between 0.8 and 1.0, and the Grashof number stabilizes between 100 and 1000. At the heating power of 30 W or below, the base temperature of the heat sink exhibits a steady periodic variation. At the heating power of 40 W, the maximum base temperature of the heat sink exceeds 370 K.

Predicting heat flow in the Iranian plateau and surrounding areas based on machine learning approach

While Surface Heat Flow (HF) is an important constraint unveiling the Earth interior's thermal structure, estimates over the Iranian plateau are sparse. In the presence of sparse estimates, machine learning provides a statistical-based prediction of HF based on a supervised predictor trained in the far-field regions. Here, we imply the machine learning technique of Gradient Boosting Regression Tree (GBRT) which has been proved to be efficient for predicting HF projecting complexities and nonlinearities of input features into predicted HF. Our results provide a robust map of HF with resolution of one degree and uncertainty of up to ±6 mW/m2 over Iran and surrounding regions. The predicted HF has an average value and minimum standard deviation of 59 and 10 mW/m2, respectively. The quality of the algorithm performance is 16%, indicated by normalized Root-Mean-Square Error (RMSE), and linear correlation of predicted HF with validation set is 97%. Total number of trees considerably prevents overfitting which is believed to be solely controllable by shrinkage factor, maximum tree depth and cross-validation scheme. The three most important features, having the highest influence on the output HF, are thermal Lithosphere-Asthenosphere Boundary (LAB), distance to volcanoes and distance to trenches. The extreme importance of LAB in HF prediction of Iran indicates that the lithospheric thermal structure is significantly controlled by lithospheric thickness in the Iranian plateau. Selection of petrologically and seismologically consistent LAB guarantees the precision of the predicted HF. Our results imply that high HF in central Iran is in agreement with extensive magmatism since the Paleozoic. Additionally, the high HF in Zagros keel (originally Proterozoic as the Zagros keel appears to be the Arabian plate front) indicates the tectonically active system of the Arabia-Eurasia collision zone, high likely, in the form of lithospheric mantle deformation.

Timing of hydrocarbon charge in the Axial Zone of the Eastern Cordillera, Colombia

The petroleum potential of onshore basins in Colombia has been partly controlled by the Andean Orogeny since the end of the Cretaceous. Its Axial Zone has at least one understudied active petroleum system with a rather low petroleum potential and few commercial medium to heavy oil accumulations, raising questions about how the Andean deformation influenced the petroleum system and the possible undiscovered accumulations. We examine the timing of this petroleum system in the Axial Zone through oil–source correlations and two 2D petroleum system models across the Boyacá and Soápaga faults based on cross-sections. Modelling reveals the direct control of deformation on generation–accumulation in the Axial Zone, where the Lower Cretaceous source rocks, due to high heat flows during the synrift phase, started generation so early (100 to 60 Ma) that no reservoirs or traps were yet available to allow hydrocarbon entrapment and accumulation. Equally, for the younger Upper Cretaceous source rocks, the tectonic inversion of the basin between 33 and 23 Ma along the Boyacá and Soápaga faults interrupted burial and the maturation in most parts of the basin, leaving only local pods of active source rocks where maturation continues today due to the tectonic overburden along the footwall of the Soápaga Fault. The latter is thus the major kitchen, contributing more than 50% of the liquid hydrocarbons trapped mainly in Upper Cretaceous and Paleocene sandstones. Hydrocarbons migrate upwards where biodegradation and water washing occurred in the near-surface, giving rise to the many tar sand occurrences in the Eocene sandstones.

Geothermal parameter assessment in the Southwestern Sokoto Basin, Nigeria, using spectral analysis (centroid method)

This study utilized spectral analysis (centroid method) to assess geothermal parameters in the southwestern part of the Sokoto Basin, Nigeria. The high-resolution airborne data comprised forty-nine (49) overlapping blocks, and each block was divided into 55x55 km to evaluate essential parameters such as depth to the top boundary (Zt ), centroiddepth (Zo), and magnetic source bottom (Zb = 2Zo-Zt ). The analysis revealed variable Curie points depths (CPD), ranging from 3.89 km to 26.56 km. The lowest CPD is primarily associated with basement rocks within anomalies A, B, C, D, E, F, G, H, and I, with an average CPD of 9.16 km. Furthermore, the thermal gradients ranged from 21.84 ◦C/km to 149.10 ◦C/km, with an average thermal gradient of 73.30 ◦C/km. The heat flow exhibited variations between 54.81 mW/m² and 374.24 mW/m², with average heat flow of 180.4 mW/m², indicating significant geothermal potential zones. The high thermal gradients and heat flow regions were identified, around anomalies A, B, and C. Additionally, temperature gradients identified at shallow depths ranged from 110 ◦C/km to 150 ◦C/km. The results reveal the presence of high-temperature points and anomalous geothermal potentials, particularly within anomalies A, B, and C, thus requiring further for sustainable geothermal energy generation in the study area.

Curie point depth, thermal gradient and heat flow along the Ethiopia Rift System and adjacent plateaus using spectral evaluation approach: implications for geothermal resources

The Ethiopia Rift System (ERS) is a section of the East African Rift System within Ethiopia extending from the Afar in the northeast to the Kenya border in the southwest. It is apparent that magmatism and magmatic intrusions influence the crustal shape in the ERS resulting in its thinning and the shallowing of magmatic sources at various locations within it. As a consequence, more than 31 volcanoes hosting hydrothermal structures with a conceivable potential to generate massive quantities of geothermal energy have been identified along the ERS. In this study, we map the Curie Point Depth (CDP) over the ERS based on the analysis of aeromagnetic data extracted from the World Digital Magnetic Anomaly Map. Spectral evaluation method was used to estimate the boundaries (top and bottom) of the magnetized crust. Reduced-to-pole (RTP) aeromagnetic records have been divided into 105 (50% overlap) square blocks of 200 × 200 km size. The Curie temperature (580 °C) of magnetite was used to determine the thermal gradient and the heat drift in the area. The depths obtained for the bottom of the magnetized crust are assumed to correspond to the Curie Depths, where the magnetic layer loses all its magnetization. The determined values of Curie Point Depth, geothermal gradient and heat flow for the 50% overlapped 105 blocks, respectively, range from 8.85 to 55.85 km, 10.38 to 65.54 °C/km and 25.96 to 163.84 mW/m2. Lower CPD (< 20 km) in the ERS was obtained between Mille and Gewane (southwest Afar), between Adama (Nazret) and Yerer (NMER) and between Wendo Genet and Koti (SMER) localities. These areas, showing low CPD, exhibit excessive geothermal gradient and high heat flow all of which indicate the presence of significant geothermal potential.