Geothermal resources in the middle and deep layers of the Fenwei Graben exhibit considerable development, yet their genetic mechanism remains elusive. A thorough understanding of the geological background and the cause of thermal convergence is essential for improving exploration and exploitation efficiency. Building on previous research, this paper provides a comprehensive analysis of the deep thermal structural characteristics, structural evolution, genetic mechanisms, and the source, migration pathways, reservoirs, and sealing conditions of the Fenwei Graben. Additionally, it explores the mechanisms of driving thermal convergence in the region. The formation of middle and deep geothermal resources in the Fenwei Graben is rooted in a complex geological framework, with Cenozoic tectonic processes playing a pivotal role in the development of medium- and high-temperature reservoirs. The Cenozoic extension of the Fenwei Graben is primarily driven by the distant effects of the Indian-Eurasian plate collision. Key factors contributing to the formation of geothermal resources in the region include asthenospheric diapir upwelling, the development of low-velocity, high-conductivity zones in the middle and shallow layers, crustal stretching and thinning, and solid-shear ductile deformation. Mantle heat conduction serves as the primary dynamic heat source for the target geothermal reservoir, with shallowly embedded low-velocity, high-conductivity layers within the upper mantle and crust acting as efficient heat conductors and energy accumulation centers. These layers function as direct heat sources and focal points for medium- and deep-thermal reservoirs. The significant extension and tension during the Cenozoic era, combined with distinct structural patterns, provide favorable thermal control structures. Marginal faults and basin-controlling faults, characterized by deep incisions and active Cenozoic tectonics, exhibit excellent heat conduction properties, playing a crucial role in the formation and distribution of geothermal resources. These faults act as efficient pathways for heat conduction and release. The thick Cenozoic loose sediments with extensively developed pores, along with volcanic rocks characterized by low thermal conductivity and excellent heat retention, serve as high-quality thermal capping layers. The metamorphic basement, marked by ductile shear deformation, functions both as the target layer for dry hot rock geothermal resources (solid heat energy) and as an effective heat source layer for shallow hydrothermal geothermal systems. As a result, the Fenwei Graben boasts an exceptional thermal accumulation system, integrating heat sources, pathways, reservoirs, and capping layers, which collectively support the enrichment of high-quality geothermal resources.

This paper characterized the spatio-temporal differences in rock rapid cooling events during the Meso-Cenozoic through frequency analysis and phased interpolation based on systematically collected apatite fission track ages, U-Th/He ages, and fission track length data from the Tianshan Mountains and northern Central Asia. And it also discussed the relationship between rock rapid cooling events and the dynamics of plate boundaries by considering tectonic deformation in different regions across various stages. The results indicate that the Tianshan Mountains experienced four primary rapid cooling events, which occurred in the Late Triassic, Late Jurassic-Early Cretaceous, Late Cretaceous-Paleogene, and Middle-Late Cenozoic periods. The rapid cooling event in the Late Triassic, mainly observed in the western segment of the Tianshan, is linked to rock uplift and exhumation resulting from reverse thrusting, potentially controlled by the collision between the western Turan block and the paleo-Asian continent. During the Late Jurassic-Early Cretaceous, rapid cooling was primarily found in the western Kyrgyz Tianshan and the easternmost Tianshan, where both events were associated with thrusting-controlled rock uplift and exhumation. The uplift in the western Kyrgyz Tianshan is probably connected to the far-field effects of the collision between the southern Lhasa block and the paleo-Asian continent, while uplift in the easternmost Tianshan was likely influenced by the far-field effects of the closure of the northern Mongol-Okhotsk Ocean. The rapid cooling event during the Late Cretaceous-Paleogene is primarily characterized by thermal cooling along major faults. In the western Kyrgyz Tianshan, western Chinese Tianshan, and the Jueluotage region in the southern part of the eastern Tianshan, this rapid cooling due to faulting mainly occurred in the latest Cretaceous-Paleogene and can be attributed to the accretion of island arcs such as Kohistan-Dras, as well as the final collision between the Indian and Eurasian plates. But in the Harlik Mountains, located in the northern part of the Eastern Tianshan, this rapid cooling mainly happened in the middle Late Cretaceous, slightly earlier than in other regions but was synchronised with the post-collision extensional collapse of the northern Mongolia-Okhotsk orogenic belt. The faulting associated with this rapid cooling in the Harlik Mountains demonstrates a dextral transtensional movement within a northeast-southwest tensile stress field, suggesting a dynamic link between the dextral transtension in the Harlik Mountains and the post-collision collapse in the northern Mongolia-Okhotsk orogenic belt. The strong uplift and exhumation event in the mid to late Cenozoic is mainly observed in the Pamir and the western segment of the Tianshan, reflecting the far-field effects of intense intracontinental compression caused by the rise of the Tibetan Plateau and its northward expansion following the collision between the Indian and Eurasian plates. In summary, the rapid cooling events in various parts of the Tianshan Mountains during different stages of the Meso-Cenozoic era were the result of the combined effects of various plate boundary dynamics, including multi-block collisions and the subsequent rise of the Tibetan Plateau in the southern Tethys tectonic domain, as well as the closure of the Mongol-Okhotsk Ocean and the resulting post-collision extensional collapse in the northern tectonic domain.

Geochemical field sampling is a critical component of geochemical exploration. There has long been a significant lack of specialized software support for information technology in geochemical field sampling. With the rapid development of information technology, traditional field geochemical survey models are accelerating their transformation towards intelligence, convenience, and modernization. Therefore, it has become an inevitable trend to informatize the entire process of geochemical field sample collection. This article systematically summarizes the key development directions and core technical characteristics of geochemical field investigations and geological survey informatization based on the latest progress in geological survey informatization both domestically and internationally. It also delves into the functional requirements and characteristics of future geochemical field survey systems. The research aims to promote the digitalization and informatization of geochemical field sample collection, laying the foundation for constructing an information product system that covers the entire geochemical exploration process while also enhancing the overall service capacity of geological survey informatization. This will ultimately help establish a product system for the informatization of the entire geochemical exploration process and improve the quality of geological survey informatization services.

Photosynthesis is the primary determinant of crop yield, with the current energy conversion efficiency of crop photosynthesis being only about 2%, which significantly limits the yield of grain and vegetable crops. Earth Science Frontiers is dedicated to advancing global scientific and technological frontiers and addressing primary economic concerns, having reported on a series of our scientific research findings over nearly three decades. Recently, Earth Science Frontiers has continuously been reporting on groundbreaking research on mineral-enhanced biological photosynthesis and its breakthrough applications in solving the international challenge of improving crop yield and quality in agriculture. Our latest studies have further confirmed that the manganese clusters (Mn₄CaO₅) in plant chloroplasts have an evolutionary and genetic relationship with birnessite in the mineral membrane on the surface of soils and rocks, and both exhibit similar functions in photocatalytic water splitting. The infrared emission spectra of minerals can affect the function of water and promote the function of photocatalytic water splitting. Classical plant photosynthesis is confined to the absorption and conversion of sunlight by manganese clusters in chloroplasts. In contrast, mineral-based non-classical photosynthesis outside of chloroplasts can expand the utilization range of the solar spectrum through functionalized water; that is, by altering the functionality of irrigation water, the efficiency of solar energy conversion can be improved. This has opened up a new way to improve the efficiency of plant photosynthesis. Based on this theory, we have proposed the innovative “mineral-water-photosynthesis” technology, which has achieved a 20%-50% increase in crop yields in field trials, significantly enhancing the yield and quality of various crops. This represents a pioneering example of how natural minerals can influence water functionality to promote biological photosynthesis.

Boron (B) is a new strategic mineral widely used in modern high-tech industries. In recent years the exploration of boron mineral resource has received increasing attention as the demand for boron contineous to rise. The overall distribution characteristics of boron in China is very important for boron prospecting. Based on analyses of the 3380 deep soil samples collected by the China Geochemical Baseline (CGB) project, this paper reveals the geochemical and anomaly distribution characteristics of boron in China. We found that the average boron concentration in deep sediments/alluvial soil of China was 46.4 mg/kg, showing a trend of high in the south and low in the north, with contiguous distribution across five geochemical zones: northeastern China and eastern Inner Mongolia (Ⅰ); northwestern China (Ⅱ); northern China (Ⅲ); Qinghai-Tibet (Ⅳ) and southern China (Ⅴ). Taking 70.9 and 52.4 μg/g (cumulative frequency 85%) as the lower anomaly thresholds in the south and the north, respectively, we identified a total of 37 geochemical anomalies, which were classified into ten geochemical provinces and nine individual anomalies. According to the spatial distribution of boron anomalies, combined with the geological background and distribution of boron deposits, we further delineated nine metallogenic prospective areas. We suggest that more efforts should be made to explore boron-rich salt lake deposits, and that hard rock (marine sedimentary) boron deposits should be the next exploration target.

The Big Science Program on CHEMICAL EARTH was first proposed by Wang et al. in 2008. An initiative was lunched in 2016 by the UNESCO International Centre on Global-scale Geochemistry and accepted by the UNESCO in 2023. The goal was to establish a digital CHEMICAL EARTH presenting all naturally occuring chemical elements on Earth to provide data services for sustainable global development; the scientific and technical aims were to understand the spatiotemporal distribution and cyclying of key elements on Earth, and to develop high-quality laboratory chemical analysis and big data mining technology. This article summaries the major achievements to date. (1) A Global Geochemical Baselines Network is established covering 33% of the world’s land area. It provides spatial distribution patterns and geochemical baselines of 76 chemical elements, allowing delineation of REE, Li, Cu and Au super-enrichment targets and, whereby, the discovery of giant HREE deposits in Yunnan. (2) A global distribution map of eight toxic heavy metals in soil is completed. It finds that Europe has the highest pollution risks compared to China and the United States, with 48% of its land area exceeding the pollution risk limits for the studied heavy metals. This results from Europe’s long history of industrial development without early pollution control technology, allowing large-scale toxins release into the environment. (3) China Geochemical Observation Network is established based on three rounds of resampling campaigns throughout China. It finds significant increase of Cd, Hg, As, and Ca in the past 30 years, and that cycling of Hg occurs in the form of nano cinnabar (HgS) grains, not mercury vapor as traditionally recognized. (4) The program promotes public access to geochemical big data by providing QR codes, which allow anyone to query big data through websites and mobile phones. Geochemical big data show that farmlands in China’s major grain-produing regions overall are of good quality in terms of food safety.

VMS deposits from thePaleo-Tethys stage are only exposed in the Sanjiang region of China. Whether this type of deposit exists in other parts of the Tethys or its metallogenic potential remains critical scientific and practical issues of interest. The Pamir region of Tajikistan, located between the Qinghai-Tibet Plateau and the Iranian Plateau, is an important component of the Tethys domain. The region remains underexplored due to limited geological work, a lack of systematic geological surveys and investments, and the absence of significant breakthroughs in mineral exploration to date. Geochemical surveys serve as an effective method for analyzing the distribution characteristics of metallic elements such as copper, lead, and zinc, while also enabling the rapid identification and prioritization of promising exploration areas and targets.

Based on the geochemical survey data at scales of 1∶1000000 and 1∶250000 jointly conducted by the China Geological Survey and the Tajikistan Geological Survey, this study focused on 1∶50000 geochemical surveys in anomalous areas and conducting anomaly verification, followed by anomaly verification and genetic analysis of the discovered mineralized bodies, while also exploring the regional mineralization potential. The research findings are as follows: (1) The primary anomalous element associations in the Tokhtamesh area of the Pamirs include Fe, Cu, Pb, Zn, Ag, Sb, Au, and As. The anomalies are large in scale, high in intensity, and show distinct zonation in concentration, with anomalies clearly controlled by strata and fault structures. Two prospective exploration target zones, labeled Z01 and Z02, were identified. These zones show potential for discovering massive sulfide copper-lead-zinc deposits and hydrothermal vein-type gold deposits. (2) Anomaly verification revealed six iron-copper polymetallic mineralization bodies, with three phases of mineralization identified. The first phase is the main mineralization period, forming VMS-type copper-lead-zinc mineralization bodies within Permian strata (Z01 target zone: Mineralization bodies I and II). The second phase is a hydrothermal reformation period involving deformation and metamorphism, forming bed-parallel and cross-layer vein-like iron-copper mineralization bodies (Mineralization bodies III, IV, V, and VI) and modifying the preexisting VMS-type copper-lead-zinc bodies. The third stage corresponds to the supergene oxidation period, during which weathering and erosion oxidized the previously formed mineralized bodies, resulting in zoning phenomena. It is inferred that the Z02 prospecting target area still holds potential for discovering VMS-type copper-lead-zinc deposits. (3) The Pamir-Tianshuihai area of Tajikistan-China demonstrate good metallogenic potential for VMS copper-lead-zinc deposits, with nine prospective exploration areas predicted. It is proposed that the Permian strata of the Paleo-Tethys stage within the Tethys region offer promising prospects for the exploration of VMS massive sulfide deposits, representing an important direction for future exploration efforts.

The density of soil water exhibits significant variation, yet no comprehensive theory currently exists to fully explain this pattern. In this study, quartz tubes with micrometer-scale diameters were used to simulate the pore systems of porous media, and the mass-volume method was employed to measure the density of water in eight quartz tubes with diameters ranging from 50 μm to 530 μm. The results indicate that when the diameter of the quartz tube is less than 75 μm, the density of water exceeds that of bulk water, reaching a maximum of 1.19 g/cm. Conversely, when the diameter ranges between 100 μm and 250 μm, the density of water is slightly lower than that of bulk water, with a minimum of 0.98 g/cm. The variation in water density with quartz tube diameter can be described using an empirical formula similar to the Lennard-Jones potential. The findings suggest that conventional mechanisms such as hydration effects, water-solid interfacial interactions, capillary effects, or cavitation cannot fully account for the observed changes in water density within the quartz tubes. Instead, the analysis indicates that the complex hydrodynamics and rheology within the capillaries: particularly shear thickening at the tube nozzle and its reverse process may be the primary physical mechanism driving the changes in water density across quartz tubes of different diameters. This mechanism represents a departure from traditional theories used to explain variations in soil water density and offers a novel perspective for understanding the phenomenon. It becomes possible to predict the density of water in soils with varying water contents by integrating the observed variation in water density within quartz tubes with soil water content models based on the concept of capillary bundles in porous media. Future research should focus on the fundamental principles of rheology to establish quantitative relationships between shear rate and viscosity, as well as between viscosity and density. Such efforts would enable the theoretical construction of models to describe the density variation of capillary water and soil water.

Sulfur gas geochemical detection has long been applied in mineral exploration. However, this method has not been widely used due to the high activity and reactivity of sulfur gases, low reproducibility of test results, and high cost. Today, as mineral exploration shifts from near-surface, easy-to-discover ore deposits to deep concealed ones, and with the successful development of portable, economical, efficient, real-time gas detection systems, a new opportunity arises to improve and promote this method. This paper reviews research progress, challenges, and future development directions regarding to concealed sulfide-rich deposits. Equilibrium thermodynamic models, simulation experiments on weathering and oxidation of sulfide minerals, and field studies suggest that gas geochemical anomalies of concealed sulfide-rich ore deposits are influenced by their mineral compositions, cover characteristics, geochemical landscapes, and physicochemical characteristics of sulfur gases. In regolith-covered terrains, portable multi-component gas analyzers can be used to obtain on-site, real-time measurements of soil gases including sulfur gases; more importantly, sulfur gas anomalies in soils tend to appear directly above the blind deposits if the blind deposits are covered by regolith directly. In bedrock outcrops, sulfur gases can be measured by rock thermal desorption; and the spatial relationship between the blind deposits and sulfur gas anomalies is primarily influenced by the development of permeable channels such as faults and fractures. Case studies indicate the sulfur gas geochemical detection is effective for mineral exploration in semi-arid and arid terrains and has great potential for mineral exploration in semi-humid and humid terrains. Future research directions should focus on three aspects: the formation and evolutionary process of sulfur gases in surface environment to ascertain the dominant controlling factors; the effectiveness of geochemical detection of sulphur-containing gases under different geochemical landscapes, especially in semi-humid and humid terrains; and the miniaturization and intelligent upgrading of portable soil gas detection equipment.

Pakistan, which is located between the Tibetan and Iranian Plateaus, is an important part of the Tethys Domain, where some lead-zinc deposits and ore occurrences have been revealed. The metallogenic pattern and the extend of lead-zinc mineralization zones, however, are unclear due to lack of systematic geological investigation, and the metallogenic potential of lead and zinc in Pakinstan remains undetermined. The low-density geochemical survey is an effective method to address the above issues. Based on the results of the 1∶1000000 low-density geochemical survey in Pakistan, this paper describes the geochemical background and geochemical anomaly distribution characteristics of lead and zinc in Pakistan. Combined with the regional geology and metallogeny, types, and key ore-controlling factors of lead-zinc deposits, favorable prospective areas are delineated and potential ore deposit types are proposed, providing the foundation for lead and zinc prospecting and exploration. The results show that the content of lead in stream sediments in the bedrock outcrop area of Pakistan ranged between 0.37-155.90 μg/g, with an average value of 13.44 μg/g, which is higher than the Clark value of the crust. The content of zinc varied from 1.78 to 288.70 μg/g, with an average value of 52.10 μg/g, which is lower than the Clark value of the crust. According to 92% cumulative frequency as the lower limit of anomaly (Pb = 18.4 μg/g, Zn = 76.0 μg/g), a total of 18 lead geochemical anomalies, 24 zinc geochemical anomalies, nine lead-zinc prospective areas were delineated, and three main metallogenic series were identified. It is suggested that the Khuzdar-Rasbela and Quetta areas of south-central Pakistan have great prospecting potential for SEDEX and MVT lead-zinc deposits. This region—connecting with the Sanandagi-Sirjan lead-zinc metallogenic belt of Iran to the west, extending to the Tianshuihai-Sanjiang lead-zinc metallogenic belt of China to the east—is an important component of the giant metallogenic belt of the Tethys hosting sedimentary lead-zinc deposits, and this type of lead-zinc deposits may also be found in other metallogenic belts and areas of the Tethys belt.

The strategic mineral resources contain 56 critical elements, most of which have low crustal abundance and require 10-1000 folds of enrichment to form ore deposits. This results in extremely uneven distribution of mineral resources. Thus the delineation of super enrichment area is the key to the resource prospecting and discovery of large-sized ore deposits. The enrichment intensity of elements can be quantitatively expressed by the metallogenic acumulatioin index (m.a.i), the tonnagea acumulatioin index (t.a.i) and the anomalous concentration index (a.c.i). Statistical analyses of 35 strategic mineral species, including precious, non-ferrous, ferrous, rare and dispersed elements, rare earth elements and radioactive metals, revealed that (1) elements with a m.a.i greater than 1000 were antimony, bismuth, rhenium and gold; a m.a.i of >100-1000 were silver, tungsten, tin, chromium, lithium, cesium, tellurium, indium, uranium and platinum group elements; and a m.a.i of >10-100 were copper, nickel, chromium, beryllium, rubidium, scandium, niobium, tantalum, zirconium and primary rare earth elements. Iron, aluminium, titanium and ion-adsorbed rare earth elements had a m.a.i ≤10. (2) Large-sized ore deposits should have a t.a.i greater than 10⁷, generally 10¹⁰, and a a.c.i greater than 2.0. Indicators for element super enrichment also included anomaly greater than >100-1000 km², with anomalous hierarchical structure across more than three layers, and with occurence of at least four associated elements. The element enrichment factor and potential resources in a geochemical block may be estimated using areal and cubic metal contents. The qualitative and quantitative geochemical characteritics of element super enrichment provide evaluation criteria for the assessment and discovery of large-sized mineral deposits.

High-temperature geothermal reservoirs with temperature above 150 ℃ have been successively discovered in China—mainly in southern Tibet, Yunnan and Sichuan in the Mediterranean-Himalayan geothermal belt, and Taiwan in the Pacific Rim geothermal belt. In recent years breakthroughs in high-temperature geothermal prospecting have also been made in cental and eastern North China. For example, in 2019 in Hebei, granite dry hot rock mass with a temperature of 151 ℃ was drilled at a depth of 4000 m in Matouying. In 2020, a geothermal fluid of 167 ℃ in high temperature gneiss fissure reservoir was drilled at 1586 m depth in Tianzhen County, Shanxi Province. And in 2023 in Shandong, a high-temperature Ordovician limestone karst reservoir with a temperature of 167.5 ℃ was drilled at 4283 m depth in Zhuanxi area, Dongying City. It is therefore an urgent task to systematically study the formation of high-temperature geothermal reservoirs in this region as well as related exploration technologies. Taking the above three high-temperature geothermal fields as examples, this paper analyzes the dynamic process underlying the effect of regional crust-mantle structure, deep geological processes—such as crust-mantle upwelling and Moho uplift-on the shallow high-temperature thermal anomalies in the Earth’s crust. Combined with geophysical and geochemical studies and exploration results, this paper explains how deep geodynamic processes shape the Earth’s shallow geothermal field and constrain high-temperature thermal anomalies, and discusses technologies to identify deep heat sources, upwelling channels and thermal energy gathering structures. The paper also explores the formation mechanism of high-temperature geothermal reservoirs in typical locations and its significance for high-temperature geothermal exploration in central and eastern North China. Briefly, (1) under the far field effect of the India-Eurasia plate collision and subduction retreat of the Western Pacific plate, the destruction of the North China Craton (NCC) leads to deep geodynamic processes—such as lithospheric thinning, asthenospheric upwelling and thermal erosion, extensional rift basin and deep strike-slip fault development—which are the main driving forces behind the upwelling of mantle-derived molten material to the shallow crust. (2) There is a good corresponding relationship between a high conductivity-low velocity-low resistivity body, geochemical evidence and high-temperature geothermal resource distribution. Therefore, it is believed that the upward infiltration of molten materials causes shallow thermal anomalies, and the molten/semi-molten magma sac in the crust provides a stable heat source to form high-temperature geothermal reservoirs. The weak lithospheric structures-such as plate margin zones and deep strike-slip faults—cut into the lithosphere, constituting the main channels for the upward infiltration of the molten material. (3) The concave-convex tectonic pattern and groundwater flow field mainly control the heat distribution in the shallow crust. Under the “thermal refraction” effect driven by the difference in thermal conductivity of shallow rocks, heat flow accumulates from the sag to the uplift, forming high-temperature thermal anomalies in ancient buried hills.

Lithium (Li) and beryllium (Be) are strategic metal resources with significant applications in emerging industries such as new materials and information technology. Pakistan is located at the convergence of the Eurasian, Indian and Arabian tectonic plates with favorable Li/Be mineralization conditions. However, due to limited geological investigations the full scope of Li/Be resource potential in Pakistan remains unknown. Low-density geochemical survey (1∶1 million scale) is an effective method for the study of Li/Be mineral distribution and rapid delineation of Li/Be prospective areas. In this paper, the geochemical background of Li/Be in Pakistan is analyzed based on a 1∶1 million low-density geochemical survey. Combined with analysis of the geological background of Li/Be mineralization, the paper aims to determine the prospective areas of Li/Be ore deposits to provide a basis for the prospecting and exploration of rare metal resources in Pakistan. In stream sediments of outcrop areas throughout Pakistan, Li concentrations ranged from 1.56 to 118.2 μg/g, with an average of 20.06 μg/g, while Be concentrations ranged from 0.07 to 7.16 μg/g, averaging 1.22 μg/g. Using 92% cumulative frequency data, 18 lithium and 12 beryllium geochemical anomaly areas were delineated, and prospective areas were selected accordingly. The Karakorum terrane and the Himalayan Fold Belt were identified as prospective areas for pegmatite-type lithium ore deposits, while the eastern part of the Chagai magmatic arc was identified for saline brine-type lithium ore deposits. The Karakorum terrane was found to be the most favorable area for further exploration of lithium and beryllium mineral resources.

The Sino-Mongolian border area has excellent geological conditions for ore formation and is one of the world’s most important metal mineralization provinces. The area is situated on one of the three largest porphyry copper-gold-molybdenum metallogenic belts in the world with enormous resource potential—it is a hotspot for international and domestic geoscience research and exploration. Based on the 1∶1 million geochemical mapping data of the Sino-Mongolia border areas, the geochemical parameters and regional geochemical distribution of gold in the catchment sediments are discussed in this paper. The median and average gold anomaly values of the catchment sediments were 0.79×10^-9 and 1.34×10^-9, respectively. The North China Block and the Altay Tectonic Belt had the highest gold contents, with the regional concentration coefficients of 1.43 and 1.36, respectively, consistent with regions faverable for gold enrichment. The outer, middle and inner zones of gold geochemical anomalies were identified according to cumulative frequencies of 85% (1.55×10^-9), 92.5% (2.22×10^-9) and 97.5% (4.03×10^-9), respectively. A total of 28 geochemical prospective areas were delineated, providing important exploration targets for gold and other precious metal deposits in this area. The paper fills the gap in the study of gold geochemical distribution, and provides important data for comparing precious metal deposits in the Sino-Mongolia border area.

The Tibetan Plateau is the most active geothermal area in China, and its northeastern region is traditionally considered to be on a relatively stable landmass with average geothermal endowment conditions. Within this region, Qinghai Province possesses a complete range of geothermal resources. Previous studies have been mainly focused on the areas with high levels of exploration or with high-temperature hot springs, yet the overall distribution characteristics of geothermal resources and the heat sources are poorly understood. In this paper, the hot springs are divided into 11 districts from NE to SW according to the main heat-control activity fractures and hot springs areas, and the distribution characteristics and formation of hot springs are comprehensively studied by means of hydrogeochemistry and isotope analysis. The results showed that atmospheric precipitation and snow/ice melt were the source of hot springs recharge. The chemical characteristics of hot spring water were related to the stratigraphy of the hot springs. In granite, chert and sandstone hot springs the dominant cation/anions were Na+/ {\mathrm{SO}}_4^{2-}-Cl^-, Ca²⁺-Mg²⁺/ {\mathrm{HCO}}_3^{-} and Ca²⁺-Na⁺-Mg²⁺/Cl^-- {\mathrm{SO}}_4^{2-}- {\mathrm{HCO}}_3^{-}, respectively. Hot springs were mainly distributed along the fracture lines-resembling a string of beads, and concentrated at intersections of different tectonic units, or at bends of tectonic units. Areas between the primary and secondary fractures had the largest thermal-storage depth, the longest runoff path, and more adequate water-rock reactions; whilst the opposites were found along the ternary fractures. From NE to SW, the temperatures of geothermal reservoirs were high in the central areas and SW, and low in the S and NE, and the medium- and high-temperature reservoirs mainly distributed in Gonghe, Guide, Wulan and Tanggula Mountain areas, with the reservoir temperatures ranging from 89.0 ℃ to 139.0 ℃, averaging 117.7 ℃. The heat sources of hot springs included heat gain by conduction of Earth heat flow; heat from the decay of radioactive elements; residual heat from magma; frictional heat from fault ruptures; and heat from low-velocity-high-conductivity melts and mantle channel flow. With focuses on the distribution pattern of hydrothermal resources and heat source of hot springs, this study can provide a reference basis for the later development and utilization of geothermal resources in Qinghai.

The thermal state of a region is crucial for understanding the main source of geothermal heat flow in the region, which help to solve the basic problem of regional heat source, and provide a basis for the study of the regional geothermal resources. Based on the regional geothermal measurements and deep borehole temperature logging carried out in China in recent years, this paper analyzes the crust-to-mantle heat flow ratio in China’s land area and divides the land area into four geothermal zonal types, namely high-temperature geothermal zone with a crustal heat source, medium- and low-temperature geothermal zone with a mantle heat source, low-temperature geothermal equilibrium zone with a crust-mantle heat source, and medium- and high-temperature geothermal equilibrium zone with a crust-mantle heat source. On this basis, typical geothermal zones—such as the northeastern Tibetan Plateau, the Tengchong area, the southeastern coastal area, and the North China Basin—are selected to systematically analyze the basin-scale regional thermal state and its main controlling factors, such as the characteristics of the regional geothermal field, the distribution of heat flow, and the crustal-mantle thermal structure. The paper summarizes the deep and shallow geologic factors affecting the regional thermal state—including crust-mantle architecture, tectono-thermal events, stratigraphic lithology, fracture structure, etc.—and establishes multilevel controlling factors of regional thermal states, providing a scientific basis for the geothermal resource exploration and heat source condition analysis in different regions.

Terrestrial heat flow is a key parameter in geothermal researches. Building upon the analyses of previously compiled terrestrial heat flow data, this paper examines the newly measured (260 sets), collected and screened (112 sets) data by authors since 2016. The added heat flow data effectively filled large data gaps in the southwest, northwest and northeast and improved the data density in the eastern region of China mainland. The proportion of high-quality data was improved to 86.3%. Using the latest data the calculated average terrestrial heat flow in China was 63.8 mW/m², higher than the national average value in the fourth compilation, with higher average values found for most of the primary and secondary tectonic units of China and lower values for the Qinghai-Tibet Plateau. The statistics of heat-flow data of typical geothermal systems showed that high average heat flow conditions could significantly improve the distribution range of conductive geothermal resources and the output temperature of hot springs, but were not a controlling factor for the formation of the two types of geothermal resources. Based on the latest terrestrial heat flow data and contour map of China related phenomena and problems were discussed, such as the increase of low heat flow area in the Qinghai-Tibet Plateau, the “overestimation” of early heat flow data in the North China Plain, and the existence of heat flow indicator magma sacs in the Changbai Mountain. It was noted that heat flow monitoring stations in China were still relatively few, and, with the continuous updating and standardization of the measurement methods, plus further improvements in data quantity/quality and sampling locations, the previously assessed regional heat flow characteristics might need to be re-examined. This study deepens the understanding of the status of terrestrial heat flow in China, and can provide better support for regional geothermal basic research and resource exploration.

Multifield coupling interactions have significant effects on hydrothermal cycles and geothermal fluid chemistry in hydrothermal systems. In this paper, a hydraulic-thermal-chemical (isotope) multifield numerical simulation model is developed using COMSOL-Multiphysics, and the simulation method for lithium isotope fractionation is validated by a simplified profile model. On this basis, a multifield coupling model of the hydrothermal cycle in a typical profile of Yangbajing is established based on the understanding of the hydrothermal cycling process in the Yangbajing geothermal field. Futher, the hydrothermal cycling of the Yangbajing geothermal system and lithium isotope fractionation under water-rock reactions are reproduced, and the influence of the main model parameters on the effect of thermal energy convergence is discussed. The results indicated that high fracture-zone permeability accelerated temperature decline in wall rock near the deep fracture zone, while low permeability limited near-surface hydrothermal activity. After constraining the fracture-zone permeability by surface drainage, it was found that long-lived (nearly 150 ka) high-temperature geothermal features could form near the surface, but only when the fracture zone made direct contact with the deep melt. Provided that such contact occurred and the temperature of the melt heat source remained constant, the depth of the melt had little effect on hydrothermal activity. Prolonged water-rock interactions could lead to significant lithium depletion in the fracture zone, and only when the deep melts provided a continuous source of material for the fracture system could it guarrantee sustained high lithium concentration in geothermal fluids. Based on the lithium isotope fractionation process, the estimated mass fraction of lithium in the involved rocks was ~25—35 mg/kg, and the value of δ⁷Li_rock was ~-2.0‰—0.5‰. The research results contribute to the further understanding of the formation of typical high-temperature geothermal systems.

Strategic coal-associated mineral resources hold significant importance for national economic development and security. These minerals, often referred to as coal-type minerals, include not only coal seams enriched with critical metals but also partings, coal seam roofs and floors, other enriched layers within coal measures that do not contain coal seams, and even acid mine waters from coal mines enriched with metals. Based on a systematic review of domestic and international literature on coal-type minerals, this paper organizes and analyzes strategic coal-type mineral resources throughout China’s geological history, listing the main periods during which coal-type strategic minerals were formed. It compiles maps showing the spatial distribution of coal mining resources and strategic key minerals during major geological periods nationwide. Using gallium and germanium as examples, the study dissects typical deposits, delving into the geological background and ore-forming mechanisms of coal-type deposits represented by gallium and germanium, and summarizes key prospecting information such as the enrichment sites of gallium and germanium within these deposits. The results show that during various geological periods, strategic critical metal resources, represented by gallium, germanium, and other “four scarcities” and bulk minerals, are the main products. Since the Phanerozoic Eon, “four scarcities” minerals and bulk minerals have been produced. Gallium and germanium deposits in China are mainly concentrated in coal-bearing basins of the North China Platform and Yangtze Platform during the Carboniferous-Permian, Triassic-Jurassic, Early Cretaceous, and Neogene periods. The formation of coal-type germanium deposits is closely related to magmatic activity and associated hydrothermal processes. The enrichment of elements such as gallium and germanium has specific locations within coal-bearing strata: gallium is typically found at the top of coal-forming cycles, such as in the Ga-enriched No.6 coal seam of the Shanxi Formation in the Carboniferous-Permian coal-bearing basin of North China, exemplified by the Heidaigou deposit. The Benxi Formation at the base of the coal cycle also contributes to some extent. Germanium, on the other hand, is usually enriched at the beginning or base of coal cycles, as seen in the Bangmai germanium deposit in Lincang. The gallium and germanium resources in China’s coal have great potential.

The most representative samples were collected three times at 30 points in the Qingshui River Basin in Ningxia in level period(May), wet period(July) and dry period(December) of 2022 in order to explore the hydrochemical control factors and the causes of high-fluorine water in the Qingshui River Basin. The spatial and temporal distribution characteristics of hydrochemical components and fluorine was analyzed, the formation and enrichment mechanisms of high fluorine water were analyzed, and the contribution of different factors to the hydrochemical components of surface water in the basin was calculated by APCS-MLR. The results show that the surface water in Qingshui River Basin is weakly alkaline, the anion concentration was {\mathrm{SO}}_4^{2-}>Cl^-> {\mathrm{HCO}}_3^{-}, and the cation concentration was Na⁺>Mg²⁺>Ca²⁺>K⁺. The F^- concentration was dry period > wet period > level period, tributary > reservoir > trunk stream. The main hydrochemical type of surface water is SO₄-Cl-Na type, followed by SO₄-Cl-Ca-Mg type. The formation of high fluorine water is controlled by evaporation and concentration, rock weathering, mineral dissolution and precipitation, cation exchange and adsorption, and the enrichment of high fluorine water is controlled by climate, terrain and hydrochemical composition. Natural factors are the key driving factors for the hydrochemistry of surface water in Qingshui River Basin, contributing 77.56% to the hydrochemical components of surface water in the study area, and human activities mainly contribute TP (59%), {\mathrm{SO}}_4^{2-} (10%) and Ca²⁺ (10%).The contribution of natural sources to the hydrochemical components of surface water in the study area is as follows: sulfate mineral weathering > silicate mineral weathering > carbonate mineral weathering > rock salt weathering, and the main contribution source of F^- is sulfuric acid rock mineral weathering (56%).

Climate change significantly impacts the formation of water resources and the transformation of hydrological elements within basins. Accurately quantifying river runoff responses to climate change is crucial for the sustainable development and efficient utilization of water resources. However, research on hydrological climate elasticity under non-stationary conditions remains relatively limited. This study focuses on eight sub-basins in the mountainous region of the Baiyangdian Lake Basin, employing a newly developed non-stationary runoff elasticity coefficient analysis method based on the Budyko model to examine the annual runoff response to climate change. The proposed method is validated in a Chinese basin, broadening its applicability, and is compared with results obtained using the Budyko model-based elasticity method under multi-year stationary conditions. The results reveal the following: on an annual scale, the annual evapotranspiration ratio and water storage change ratio exhibit a strong linear correlation with the annual aridity index; runoff is more sensitive to changes in precipitation at both annual and multi-year time scales; the annual runoff elasticity coefficient is smaller than the coefficient calculated under multi-year stationary conditions, highlighting the significant regulatory role of basin water storage in runoff responses to climate change. Furthermore, the annual elasticity coefficient is strongly correlated with basin area. This study validates the effectiveness of the newly proposed non-stationary runoff elasticity coefficient method based on the Budyko model and extends its applicability from humid regions to semi-humid and semi-arid areas. These findings provide valuable guidance for the sustainable management of water resources in the Baiyangdian Lake Basin and the Xiong’an New Area.

The Archean basement of the Jiyang Depression has emerged as a key target for oil and gas exploration; however, an unclear understanding of the reservoir formation mechanisms has severely limited exploration and discovery efforts. This paper systematically studies the diagenesis of Archean basement rock in the Jiyang Depression and its influence on reservoir development through field geological investigation, core observation, thin section identification, cathodoluminescence, X-ray diffraction (XRD), scanning electron microscopy, and fluid inclusion analysis. Diagenetic characteristics are identified based on core analysis, flake and elemental analysis results, and fluid inclusion homogenization temperatures. The impacts of these characteristics on reservoir development are characterized through flake face rates and physical property logging data. The results indicate that the lithology of the basement rock in the study area is primarily divided into two categories: magmatic and metamorphic rocks. Magmatic rock has undergone four successive diagenetic stages: condensation consolidation, post-magmatic hydrothermal alterations, weathering denudation leaching, and buried rock formation. During these stages, magmatic rock has experienced processes such as condensation consolidation, compaction, dissolution, filling and cementation, as well as alteration and metasomatism. Eventually, metamorphic rock is formed through metamorphic deformation. Condensation consolidation can create a small number of primary matrix pores, while corrosion processes generate corrosion pores and fractures, contributing to up to 80% of the porosity, which is crucial for enhancing reservoir quality. Conversely, compaction, alteration, and metasomatism tend to destroy these pores, as calcite, clay minerals, and other secondary minerals fill and cement fractures, with a filling degree ranging from 30% to 70%, adversely affecting reservoir space. A comprehensive analysis reveals that the physical properties of gneiss reservoirs are superior to those of granite. Favorable reservoirs are mainly located in the weathering crust and the inner fracture zone. The weathering crust, which is situated at the top of the buried hill of the basement rock, displays longitudinal zoning and is primarily influenced by weathering, leading to the development of I and II reservoirs. The inner fault zone, located in the middle section of the buried hill and aligned along fault lines, predominantly develops II and III reservoirs. The findings of this study provide valuable insights into the genetic research of basement rock reservoirs.

Peru, as an important part of the Andean metallogenic belt, is located on the west coast of South America. It is rich in mineral resources, and its copper reserves and copper production ranks second in the world. This paper carried out a global scale geochemical mapping project in Peru for the first time, and obtained a total of 416 catchment sediment samples. Copper contents in catchment sediments in Peru ranged from 2.38 to 495 μg/g, with a background (median) value of 24.0 μg/g. The average copper content in the surface (deep) catchment sediments of the whole Peruvian region and of the coastal zone, the Andes mountains and the Amazon plain were 31.4 (31.6), 45.6 (32.2), 47.5 (48.2) and 21.3 (24.9) μg/g (μg/g), respectively. The geochemical map showed that the spatial distribution of copper in Peru as a whole had a trend of high in the west and low in the east, with higher copper content in the western coastal zone and the central Andes mountains and lower copper content in the eastern Amazon plain. Using a cumulative frequency of 75% as the lower limit of anomaly, five copper geochemical anomalies were delineated, two of which reached the scale of geochemical giant province, and another two of geochemical province. The paper also discusses the source and influencing factors of copper geochemical anomaly and the impact on mineral resources. The favorable tectonic evolution environment of Peru provide favorable conditions for the formation of large and super-large copper deposits. The continuous subduction and transformation of the Nazca plate of the Pacific Ocean to the South American continent led to partial melting of the oceanic crust, resulting in strong and extensive medium-acidic magmatic activity. In addition, the copper content in the magma is enriched on a large scale, and the local area is enriched and metallogenic under specific environment. This tectonic movement led to several geochemical blocks in the spatial distribution of Cu elements in Peru, which may also be one of the reasons for the formation of Cu geochemical anomalies. In future studies these geochemical blocks can be used to search for copper ore concentration areas or large and super-large copper deposits, delineate prospective areas, reduce prospecting risks, improve the prospecting efficiency and shorten the prospecting period. Geochemical prospecting conducted in the research area can provide basic information and data for the exploration, development and utilization of copper deposits in Peru.

Under the Belt and Road initiative China and Laos have carried out national-scale 1∶1000000 geochemical mapping in Laos. This study marked the first national-scale geochemical study of gold, a dominant mineral species, in Laos, where the geochemical background and spatial distribution characteristics of gold in Laos were preliminarily investigated, and the geochemical anomaly and prospective areas of gold in Laos were delineated. A total of 2079 geochemical samples were collected and analyzed for gold element, using foam adsorption-graphite furnace atomic absorption spectrometry (FAS-GAAS), a high-precision analytical technique, and strict quality control measures. Gold contents in Laos aquatic sediments ranged between 0.10-913.70 ng/g, with mean and median (background) values of 2.44 and 1.00 ng/g, respectively. Gold occurred across the country with scattered distribution, mainly along extended large fractures affected by tectonic activities and magmatism. Using 85% quantile (1.99 ng/g) as the anomaly detecton limit, 17 gold anomaly areas were identified, with eight reaching a geochemical province scale (>1000 km²); seven prospective gold mineralization zones were classified according to anomaly identification, taking into consideration the spatial distribution of gold, geologic background, regional tectonics and mineral distribution. The results provide basic information for gold exploration in Laos and fill the gap of geochemical mapping for gold exploration in Laos.

Buried-hill reservoirs are the primary geothermal reservoirs widely developed in northern China. They are characterized by significant heat storage capacity, shallow depth, and easy re-injection. The reservoirs, constrained by their physical properties, spatial distribution, and geological structures, have diverse heat control mechanisms and complex heat transfer processes, and recent research is focused on the heat transfer and accumulation mechanisms. In this paper, based on the analysis of geothermal exploration wells constructed in Xiong’an, we propose a theory of dominant heat transfer in the buried-hill geothermal field of North China. According to this theory, the heat source of the buried-hill reservoirs originates mainly from the deep mantle, while the crustal heat flow is less than 30 mW/m. The enhanced mantle convection from the destruction of the North China Craton (NCC) leads to dominant heat flow from the deep mantle to shallower depths, and with the tensile thinning of the lithosphere in the NCC the surface heat flow increases significantly. The high thermal conductivity buried-hill reservoirs creates conductive dominant heat flow, vertically and horizontally, towards the carbonate reservoirs, while fluid circulation in the highly porous carbonate reservoirs creates convective dominant heat flow. Faulting exacerbates the conduction and convection heat gathering effect along the fault direction. The temperature profiles of boreholes at various sites in the buried hill exhibit five types: conduction, conduction-convection-conduction, conduction-convection-weak convection, conduction-strong convection, and conduction-weak convection. The percentage of thermal convection in groundwater in the Rongcheng Fault was calculated to be 29.2%. Through comprehensive analysis of the influencing factors of the dominant heat flow and heat accumulation in the buried-hill geothermal field, this research provides new insights into the heat transfer mechanism in North China.

Geothermometers are used to estimate the reservoir temperatures in hydrothermal systems. To clarify the limitations and validity of traditional chemical geothermometers we conduct a comprehensive review in this study. We found that certain chemical geothermometer types (Na-Li, Li-Mg, Ca-Mg, SO₄-F) were not widely usable, as hydrochemical equilibrium systems in some areas were influenced by the regional geological conditions. Meanwhile, the use of Na-K-Ca type(β=1/3) was constrained by a variety of hydrochemical factors, thus it should be used with caution in low-medium-temperature geothermal systems. The types more suitable for estimating the reservoir temperatures were Na-K, K-Mg, and SiO₂. The Na-K type gave relatively accurate estimates for the high-temperature reservoirs (>200 ℃) where extensive water-rock reactions occurred; while the K-Mg and SiO₂ types were more suitable for the low-medium-temperature reservoirs. In sedimentary geothermal systems, chemical geothermometers were not recommended for estimating the equilibrium temperature of geothermal waters directly. Besides, determining the occurrence state and the hydrothermal equilibrium status of a geothermal reservoir was prerequisite for selecting chemical geothermometers; yet, even within a suitable application range, the measurement results should be compared and validated against the calculation results. In high-temperature geothermal systems the accuracy of chemical geothermometers could be verified by the mixing processes; in low-medium-temperature systems the measurement uncertainty increased due to lack of extensive water-rock reactions, thus validation by various methods became even more important. Results from this study can be used to guide the selection of chemical geothermometers.

Shandong Province possesses abundant geothermal resources with widespread distribution of geothermal reserviors of different types. However, the occurrence rules and accumulation mechanism of geothermal resources are not well understood. In this paper, based on previous geothermal well temperature logging, geothermal exploration, well drilling, pumping test and long-term dynamic monitoring data, we explain the distribution characteristics of geothermal resources in Shandong, and delineate the geological structure that controls the geothermal flow and water conduction. The heat and water sources and accumulation mechanisms and the occurrence of thermal reservoirs were explored. Four geothermal resource areas were delineated: eastern Shandong, Yishu fault zone, western Shandong uplift and northwestern Shandong depression. Combining the characteristics of major ore-controlling factors such as geothermal water source, heat source and occurrence of thermal reservoir, the geothermal systems were divided into three models: open-convection-cavity tubular; weakly open-convection/conduction-banded stratified; and closed-convection/conduction-banded stratified. Insights on the heat/water sources and accumulation mechanisms under different types of geothermal systems and the occurrence law of hydrothermal accumulated reservoirs provide a basis for targeted geothermal exploration and well drilling.

This paper presents a comprehensive summary of exploratory experimental research conducted by the ‘Industry-college-institute Cooperation’ technology innovation talent team in Guizhou Province, focusing on a novel intelligent exploration model leveraging big data. Utilizing a collaborative innovation system integrating industry-college-institute cooperation, the team undertook a retrospective analysis of mineral exploration processes employing big data for the famous ‘Datangpo’ manganese ore concentration area in China, as well as several concealed giant manganese deposits. Their research aimed to explore intelligent predictive methodologies and digital exploration techniques for deep-seated mineral resources, with the goal of cultivating and developing new quality productivity in the field of geological and mineral exploration. The team developed a big data-based metallogenic schema and exploration model, established a comprehensive geological big data resource system. They refined and widely promoted digital exploration technologies system, created a province-wide three-dimensional glass earth in Guizhou Province, and developed multi-scale, multi-objective progressive mineral prediction techniques. These efforts have significantly accelerated the digital transformation of geological and mineral exploration in Guizhou Province. Their efforts led to the discovery of multiple concealed exploration targets, including manganese, phosphate, bauxite, lead-zinc (germanium), barite, and newly identified altered limestone-type lithium deposits, contributing to significant advancements in Guizhou new round of prospecting breakthrough strategic action. The key outcomes indicate that the team’s research not only accelerates the digital transformation of geological mineral exploration but also fosters a deep integration with big data, cultivating and developing new quality productivity in the field of geological and mineral exploration and supporting breakthroughs in the exploration of concealed minerals. To further advance this digital transformation and develop a digital economy in geology, it is crucial to continue initiatives aimed at enhancing ‘Data cloud service, Deep integration of big data, and Enterprise intelligent transformation’ in exploration, strengthen the key technology research and development, and vigorously promote these applications, while continuously exploring, improving, and developing in practice.

China has made some progress in recent years in the exploration and development of hot dry rock (HDR) resources and drilling technology, but is relatively lacking in basic research on high-temperature HDR fracturing technology. For enhanced geothermal systems, hydraulic fracturing is generally used to inject high-pressure fluid into the reservoir to expand and extend natural fractures, in order to increase the reservoir permeability and heat exchange area. Thus, reliable in-situ stress data are important for guiding the stimulation of reservoir reconstruction. Taking the Qinghai Gonghe HDR pilot project as an example, this paper first obtains the in-situ stress state by combining the anelastic strain recovery (ASR), diametrical core deformation analysis (DCDA), core cake, and image logging methods. Next, the influence of the in-situ stress state on the development of HDR reservoirs is discussed. Finally, to evaluate the effectiveness of reservoir fracturing under the current in-situ stress state, a three-dimensional fracture geological model of the hydraulic fracturing zone is established using the discrete fracture network (DFN) method. The sliding tendency (T_s) and dilation tendency (T_d) of each fracture are calculated through numerical simulation, and fracturing activities under different injection pressures are analyzed. According to the results, (1) the main type of in-situ stress state was the thrust faulting regime developed within the granite reservoir range (3500—4000 m) in the Gonghe HDR reservoir, with the horizontal compressive stress being the dominant stress. (2) The average direction of the maximum principal stress at 3500—4000 m depth was 39.35°±14.23°, predominantly oriented in the NE direction, consistent with the notion that the compressive stress was associated with the NE-trending compression movement on the northeastern rim of the Qinghai-Tibet Plateau. (3) The suitable fracturing pressure for the Gonghe HDR field area was 46—55 MPa, and most fractures tend to open after shear activation (high-dilation tendency), which was conducive to increasing the area of heat exchange and improving extraction efficiency. (4) Results of in-situ stress measurement and microseismic monitoring showed that natural fractures expanded horizontally and vertically under hydraulic fracturing, ultimately forming a horizontal-vertical fracture network. The research results provide a reference for future in-situ stress measurement and its application in the assessment of hot dry rock development in China.

The depth of well drilling has been continuously rising in recent years with the increasing demands for energy resources development and earth systems research. Problems encountered in deep drilling include high formation temperature, high rock hardness, low drilling efficiency, high cost and frequent accidents. Key drilling technologies such as downhole motors, efficient drill bits, measurement-while-drilling tools and mud cooling systems have been researched abroad to address the above problems; the research results have been applied in the fields of oil and gas drilling, high-temperature geothermal exploration, etc. Relevant researches have also been conducted in China, but gap exists compared to the level of research abroad. This paper analyzes the technical difficulties in drilling high-temperature hard rock well in China and summarizes the technical requirements. A new drilling method, along with its technical characteristics and application results, are also introduced. The new method, in principle, seeks to utilize the existing equipments to achieve directional drilling of deep wells. It uses a bottom hole assembly (BHA) consisting of high-speed, strong diameter-retaining tri-con drill bits, high-temperature resistance positive displacement motor (PDM) and measurement-while-drilling (MWD) technique, and combines with high-temperature resistance drilling fluid, mud cooling system and segmented circulating cooling technology. However, future researches are needed in the areas of durable drill bits (e.g., polycrystalline diamond compact (PDC) and impregnated diamond drill bits), all metal downhole motors, impact drilling tools and high-temperature resistance MWD.

The strategic value of nickel (Ni) continues to rise with the increase in demand for nickel from China’s new energy industries and infrastructure projects. Quantitative evaluation of nickel content and distribution is critical for nickel prospecting and for alleviating nickel shortage in China. The China Geochemical Baselines project (CGB) has established the geochemical baseline of Ni in China from 3382 top and 3380 deep catchment sediment/alluvial soil samples and 11602 rock samples. The Ni baseline (median value) and background levels in rock were 12.1×10^-6 and 22.2×10^-6, respectively, comparable to the Ni abundance level in exposed crust in eastern China, where ultrabasic and basic rocks had respectively baseline levels of 1317×10^-6 and 63.4×10^-6, much higher than intermediate (17.5×10^-6) and felsic (3.19×10^-6) rocks. In surface and deep layers of catchment sediment/alluvial soil the Ni baseline levels were 23.6×10^-6 and 22.4×10^-6, respectively, slightly lower compared to other continents (countries) and close to the average Ni level obtained from the Regional Geochemistry National Reconnaissance project (RGNR). Parent rock types, especially ultrabasic-basic rocks, predominantly controlled the distribution of Ni-enriched catchment sediments/alluvial soils. Nickel-enrichment areas (> 85th percentile) were mainly in regions with widespread ultrabasic-basic outcrops, such as ophiolite belts, large igneous provinces, and black shales along the middle-lower Yangtze River. Nickel anomalies correlated well with magmatic Ni deposits. The geological setting mainly controlled Ni geochemical baselines in the sampled environments, whereas strong chemical weathering and well developed carbonate rocks could also contribute to Ni enrichment. The geochemical baseline of nickel provide a reference and data basis for further quantitative resource evaluation and establishment of environmental baselines.

Robustness is a fundamental scientific concern in low-density geochemical mapping, which has long garnered close attention from mapping researchers. However, quantitative understanding of robustness has been lacking due to the lack of effective quantitative assessment methods. In this study, using cobalt element data from two low-density mapping sources—the China Geochemical Baselines project (CGB) and the Regional Geochemical National Reconnaissance project (RGNR)—robustness is quantitatively assessed based on 1546 representative catchments through the utilization of local spatial correlation coefficients; the spatial distribution features and influencing factors are also discussed. On a national scale, robustness was influenced by sediment cobalt (Co) content and geochemical landscape conditions; on a local scale, it was affected by differential erosion in cobalt-rich and Co-poor source areas. In Co-poor environments (sediment Co<13 μg/g) the robustness index (R) value fluctuated around 0.4, while in Co-rich environments (sediment Co>13 μg/g) it increased from 0.4 to above 0.6 with rising Co content. Regions such as karst terrains, tropical rainforests, and semi-arid low hills had R values as high as 0.58 to 0.74, whereas alluvial plains and forested swamp regions had R values below 0.32. This study provides a reference for quantitative evaluaton of low-density mapping, deomonstrating that low-density geochemical mapping has good robustness and promising prospect in the global-scale geochemical mapping.

Mexico is a major economic power in Latin America and an important mineral producer in the world. Based on data obtained from Mexico global-scale geochemical mapping using 287 deep soil (C layer) samples, this paper produced a C-layer copper geochemical map with a scale of 1∶8000000. The geochemical background and spatial distribution characteristics of copper in soil were studied from a global-scale perspective, and the major copper geochemical anomalies of Mexico were delineated. The main findings are: (1) the copper content in soils of Mexico ranged from 3.6 to 129.0 μg/g, with the mean and median values being 20.3 and 15.9 μg/g, respectively, and the background value being 15.6 μg/g. The Chiapas Plateau and the Southern Madre Island Arc had significantly higher median copper content than other tectonic units, and had the highest background copper value in the whole country. (2) The geochemical map showed uneven distribution of copper content in soil, with the general trend of high in the south, low in the north, and high in the west, low in the east. (3) The geochemical map identified ten copper geochemical anomalies, eight of which reached mega-province scale and two reached province scale. Based on the fit between copper geochemical information and existing mineral deposits, it is considered that the Sierra Madre del Sur and Chiapas Mountains in southern Mexico are important prospective areas for copper in Mexico.

In order to enhance the geoscientific collaboration between China and Peru using China’s advanced geochemical investigation and research methods, the China Geological Survey (CGS) and Peru Instituto Geológico, Minero y Metalúrgico (INGEMMET) jointly conducted a multipurpose geochemical survey in the Mantaro Basin of central Peru. The samples were collected and analyzed in Chinese laboratory according to applicable Chinese national standards. According to the results, the soil of the study area was in general weakly alkaline, with strong enrichment of Au and relatively enriched indicators such as I, C, C_org, Cd, and N. The soil nutrient indicators N and P were relatively abundant, but K was lacking. The comprehensive nutrient grade was mainly “relatively rich” (Grade 2), accounting for 74.1% of the total area, indicating good soil fertility. In terms of soil environmental assessment, Zn and Pb showed slight to severe pollution in a small number of areas, while Cd and As contamination was widespread. The comprehensive grade of soil environment was predominantly “slightly to lightly polluted”, with the polluted areas mainly concentrated within 5 km from either side of the Mantaro River, while the heavily polluted areas were mainly distributed close to the Mantaro River and Huancayo City with large population density. The heavy metal pollution was serious, and the spatial distribution of pollution was closely related to the Mantaro River. The comprehensive geochemical grade of soil quality was mainly “moderate” to “severe”, constituting 83.18% of the area, with only 16.82% of the area graded “good to high quality”. In summary, the Mantaro Basin was found to have relatively rich soil nutrients, severe heavy metal pollution, and a moderate to poor overall soil quality. Recommendations to relevant agencies include strengthening environmental management and control of heavy metal pollution sources in the Mantaro River and its upstream areas.

The paper utilizes the geochemical data of stream sediments based on the national-scale (1∶1000000) geochemical mapping project in the outcrop area across Pakistan for the first time. This study aims to determine the geochemical background of copper in the study area, as well as the regional geochemical characteristics and geochemical anomalies associated with large porphyry copper deposits in Pakistan. The geochemical features of the main stratigraphic units and magmatic rocks within this region were examined. The average copper concentration in the outcrop areas of Pakistan is 23.48×10^-6, with a background value of 18.6×10^-6. This is comparable to the copper abundance found in northwest regions of China and the Tibetan Plateau. The magmatic rocks related to mineralization in porphyry systems are mainly Cenozoic and Mesozoic acid magmatic rocks, with average copper concentrations of 39.09×10^-6 and 28.28×10^-6, respectively, indicating that copper-rich porphyries are the main source of material. A modeling analysis of the elemental association of Cu, Au, Mo, Ag, Pb, Zn, Co and Cr has been conducted based on the national-scale geochemical data, indicating that the national-scale geochemical anomalies serve as indicators of large and super-large porphyry copper deposits. Based on the theory of geochemical block, the Pfd (Prospecting Favoralble Degress) and Qm (Quality of Mineral) were calculated and sorted by applying the principle and technical innovation of mineral resource potential prediction. On the basis of the geochemical model of typical porphyry copper deposits, with Cu, Mo, Au, Ag as primary indicator elements, and Pb, Zn, Co, Cr as secondary reference indicator elements, combined with the geological background, four prediction areas for porphyry copper deposits were identified. Furthermore, an analysis of the metallogenic potential of these identified prospecting areas was conducted.

Papua New Guinea (PNG), which is located at the convergence edge between the Pacific plate and the Indo-Australian plate, consists of three tectonic units. There are two main types of gold mineralization in PNG: epithermal and porphyry. National-scale geochemical mapping was conducted in PNG between 2015-2018, using 1399 stream sediment samples collected from the Highland Region, Papua Peninsula, and New Guinea Islands. In this preliminary study we analyzed the geochemical background, spatial distribution characteristics and metallogenic potential of gold in PNG. The gold concentration ranged between 0.2-6188.0 ng/g, with a median value of 1.5 ng/g, which is higher than the gold upper crustal aboundance, and slightly lower than the gold geochemical baselines of China and Australia. The Central Arc-Land Collision Zone—consisting of the Papuan Fold Belt, the New Guinea Thrust Belt, Finisterre Terrane, the Aure Fold Belt, the Eastern Fold Belt, the Eastern Papuan Composite Terrane, and the Finisterre Terrane, with widespread development of medium-acidic intrusive rocks, alkaline intrusive rocks, and alkaline volcanic rocks—has a higher median value of gold than the Melanesian Arc. The calc-alkaline intrusive complex of the New Guinea thrust belt, and the calc-alkaline intrusive complex and the potassium-rich volcano-intrusive complex of the Melanesian magmatic arc strongly correlate with higher gold concentration. Altogether seven gold geochemical provinces and nine gold anomalies with epithermal or porphyry mineralization potential are delineated.

Natrophilite is a rare phosphate mineral that has not been reported in China, especially its primary mineral, which has not been discovered both domestically and internationally. The literature with a few data suggests that natrophilite is formed by sodium replacement of lithiophilite as a secondary mineral. Lithiophilite is a common mineral in pegmatite, which is generally believed to be a product of the magmatic stage in phosphate rich pegmatites as a primary mineral. In this article, natrophilite and lithiophilite developed on natrophilite were found in the Chakabeishan rare-metal pegmatite. Natrophilite is characterized by euhedral mineral particles without any metasomatism, and has primary mineral features of apatite alteration. And the lithiophilite is irregular and develops on the natrophilite, showing typical metasomatic characteristics. Moreover, electron probe data showed that the Mn/Fe values of natrophilite were 1.692-1.875, and the Mn/Fe values of lithiophilite were 2.519-2.548. This also indicates that the formation of natrophilite occurred earlier than that of lithiophilite. Natrophilite should be the primary mineral, and the lithiophilite should be the secondary mineral. The higher manganese content of the parent magma in the pegmatite area may be a possible reason for the occurrence of natrophilite. The alteration of lithiophilite and fluoroapatite developed on the natrophilite reflect the later oxidation and metasomatism of Li, Mn, Ca, and F rich fluids. Meanwhile, combined with the alteration of spodumene in this area, it is indicated that there is a geochemical cycle of lithium in the Chakabeishan deposit.

The Moroccan High Atlas tectonic belt is located at the west end of the Tethyan metallogenic domain with favorable geological conditions for mineralization. Numerous Mississippi Valley-type lead-zinc deposits (MVT) have been discovered in this region. However, the mineralization potential of lead and zinc is unclear due to lack of long-term, high-level geological investigation. Medium- to large-scale geochemical surveys are effective tools for resource exploration, as detailed geochemical anomaly information can help to quickly delineate prospective mineralization areas, thereby improving the exploration efficiency and success rate. In this study, a 1∶100000 geochemical survey was conducted over an area of more than 10000 km² in the eastern section of the Moroccan High Atlas tectonic belt. The results revealed that the lead content in stream sediments ranged from 5.7 to 43,210.0 μg/g, averaging 45.0 μg/g, and the zinc content ranged from 12.2 to 75,420.0 μg/g, averaging 86.4 μg/g. Both values are higher than the Clarke values of the Earth’s crust. Using the 92% cumulative frequency as the anomaly threshold (Pb=36.9 μg/g, Zn=78.3 μg/g), a total of 73 lead and 68 zinc geochemical anomalies were delineated. By analyzing the regional geochemical distribution characteristics of lead and zinc, combined with the regional geological background and mineralization conditions, three major lead-zinc metallogenic belts were identified, and nine lead-zinc ore prospective areas were delineated. This study suggests that the region has significant potential for discovering MVT deposits, providing important directions for future mineral exploration efforts.

The Lhasa terrane is located in the southern part of the Tibetan Plateau and is one of the regions with the greatest crustal thickness globally. However, the timing and process of crustal thickening in the Lhasa terrane remain debated. Zircon trace element characteristics are controlled by the co-existing relationships between zircon and other trace element carrier minerals, meaning different minerals have varying partition coefficients, thus zircon trace elements can be used to quantitatively reconstruct crustal thickness. This study conducted U-Pb geochronological and trace element geochemical research on zircons from igneous and sedimentary rocks in the Dangra Yongcuo area of the central Lhasa terrane. Using zircon europium anomalies to quantitatively reconstruct crustal thickness, the results reveal that the central Lhasa terrane experienced two crustal thinning events (150-130 Ma and 85-65 Ma) and two crustal thickening events (130-85 Ma and 65-15 Ma) during the Jurassic to Neogene periods. During 150-130 Ma, crustal thinning in the central Lhasa terrane was primarily related to slab retreat of the Bangong-Nujiang Ocean. Between 130-85 Ma, the central Lhasa terrane underwent crustal thickening due to northward subduction of the Neo-Tethys Ocean and southward subduction of the Bangong-Nujiang Ocean. During 85-65 Ma, slab retreat of the Neo-Tethys Ocean and back-arc extension led to another crustal thinning event. From 65-15 Ma, collision and subsequent compression between the Indian and Eurasian plates caused the central Lhasa terrane to thicken again.