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Intelligent geoscience information mining and knowledge discovery using big data analytics: A case study of the Shangfanggou Mo (Fe) mine in Henan Province WANG Luofeng, WANG Gongwen, XU Wenhui, XU Senmin, HE Yaqing, WANG Chunyi, YANG Tao, ZHOU Xiaojiang, HUANG Leilei, ZUO Ling, MOU Nini, CAO Yi, LIU Zhifei, CHANG Yulin Earth Science Frontiers    2023, 30 (4): 317-334.   DOI: 10.13745/j.esf.sf.2022.2.85 Abstract （367）   HTML （14）    PDF（pc） （8487KB）（3143）       Knowledge map    Save Industry 4.0 of the 21st century has given birth to smart mines. The multidisciplinary datasets of smart mines-such as geology, exploration, mining, geometallurgy, environment and survey/map datasets-constitute big data of mines, and they play an important role for the rapid advancements of geoscience in areas of geoscience digitization and application of information/Al technology in geoscience. Taking the Shangfanggou Mo (Fe) mine, a 5G+ smart mine, in Henan Province as an example, using big data of mines, this paper carried out geoscience information mining to highlight emerging engineering research with integrated multidisciplinary approach. Innovative results and geological knowledge discoveries from this study are summarized as follows: (1) According to theories on porphyry-associated skarns and mineralogical approach to minera resources prospecting, using borehole datasets and large-scale open-pit mapping and microscopic identification analysis, a 3D temporo-spatial model of the identified key minerals and predicted minerals in the study area was established, and a NE trending ore-bearing fault section and a penetration-type ore-bearing section were discovered. (2) Using UAV remote sensing and ground hyperspectral short-wave/long-wave infrared techniques, more than 20 types of key altered minerals in the study area were delineated, and a 3D multi-parameter mineral model was constructed. (3) Using geochemical techniques such as XRF and in-situ microscopy, a rock dataset with matching hyperspectral interpretation was established, and a dual-matrix mapping software for useful/harmful elements of rocks/ores in the study area was developed. In addition, mathematical modeling combining traditional geostatistics (gauss simulation, kriging interpolation) with machine learning (deep learning) was realized, and the composition of ore blends used between March-April 2021 was identified and the cause of the resulting low recovery rate was clarified. (4) Based on process mineralogy practice in the study area, multi-stage, multi-type mineral processing datasets (>1800 data on quarterly/monthly/daily processing of rock powder, mud powder, concentrate, tailings, etc.) were used to develop rock/mineral powder testing techniques and analysis methods, and the types of refractory ores and harmful minerals in the Shangfanggou Mo mine were identified. The multivariate, multi-type datasets of mines have the “5V” (volume, variety, velocity, veracity, value) characteristics of big data. The accurate management control of dynamic correlation measurement/analysis and rapid/efficient evaluation of big data of mines is conducive to intelligent mining decision-making and improvement of economic benefit (recovery rate). Among them, high-precision multi-parameter 3D modeling can be applied not only to deep mining of geological, structural, alteration and mineralization information models of rocks/ores as well as reserve/resources verification, but also to facilitating 4D control on real-time mining of fourth generation industrial 5G+ mines, such as 3D visualization of geological and mineral resources prediction/evaluation/storage expansion, virtual simulation of “year-quarter-month-day” dynamic ore blending and mining, and real-time digital twin for mine beneficiation. The research results provide a reference for in-depth geoscience research on mineral exploration and mineral resources assessment in smart mines. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Overview of magmatic differentiation and anatexis: Insights into pegmatite genesis ZHOU Qifeng, QIN Kezhang, ZHU Liqun, ZHAO Junxing Earth Science Frontiers    2023, 30 (5): 26-39.   DOI: 10.13745/j.esf.sf.2023.5.8 Abstract （512）   HTML （86）    PDF（pc） （3044KB）（2527）       Knowledge map    Save The origin of granitic pegmatites is significant for the understanding of their formation processes and rare-metal metallogenesis. Granitic pegmatites are mainly formed by fractional crystallization of granitic magmas or by anatexis. In discussing pegmatite genesis, pegmatite classification and its mineral assemblage characteristics can provide the preliminary evidence, whilst parental granite plutons provide the final proof of origin. Studies have shown that granite pluton and its pegmatite swarm are nearly coeval, with less than 10 km apart in location and continuing to differentiate, and they have a common material source. To determine the degree of fractional crystallization and to decipher the formation process of granite magmas major element/trace element/REE/stable isotope Rayleigh fractional crystallization models have been used. Current evidences for an anatexis origin include regional metamorphic-tectonic events; metamorphism features; close spatial and chemical compositional relationships and consistent isotopic compositional relationships between pegmatites and metamorphic rocks; formations of unique mineral assemblages and mineral inclusions in pegmatites; and similar chemical components between the parental granite magma and partial melt. The following research approaches have been used to discuss the partial-melting process and melt-extraction history and to clarify the pegmatite-forming process via anatexis: determining protolith by elemental comparison, isotope tracing, and trace-element simulation; clarifying major melting model using Rb/Sr-Ba diagram; and determining the melting condition and melt production based on mineral composition of protolith and element partitioning between mineral and silicate melt. Researchers have found that rare-metal pegmatites mainly formed from extreme fractional crystallization of highly evolved granitic magmas and, in rare cases, from low-degree partial melting of fertile metasediments. Besides, rare-metal pegmatite swarm could be formed from magmatic differentiation without a parental pluton, or from further differentiation of anatectic granite. Future researches need to gain a deeper understanding of the partial melting and fractional crystallization controls on granitic magmas, explore the physical and chemical processes during the formation of granitic magmas—especially melt escaping and migration mechanisms and their affects on rare-metal enrichment, and establish petrogenetic discrimination criteria for granitic pegmatites. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Helium: Accumulation model, resource exploration and evaluation, and integrative evaluation of the entire industrial chain TAO Shizhen, WU Yiping, TAO Xiaowan, WANG Xiaobo, WANG Qing, CHEN Sheng, GAO Jianrong, WU Xiaozhi, LIU-SHEN Aoyi, SONG Lianteng, CHEN Rong, LI Qian, YANG Yiqing, CHEN Yue, CHEN Xiuyan, CHEN Yanyan, QI Wen Earth Science Frontiers    2024, 31 (1): 351-367.   DOI: 10.13745/j.esf.sf.2024.1.71 Abstract （1084）   HTML （12）    PDF（pc） （4043KB）（1701）       Knowledge map    Save China's helium industrial chain needs scientific and technological support, but there lack a systematic theoretical understanding of helium geology, along with the lacks of targeted helium resource evaluation methods and parameter selection standard, comprehensive accurate detection of helium content, helium prospecting methods, cost index system, as well as methodology for integrative evaluation of the entire helium industrial chain. To address these knowledge/technology gaps we developed a helium accumulation model and three key technologies for helium resource and asset evaluation, using interdisciplinary research methodology and experimental techniques involving geology, geochemistry, gravity-aeromagnetic-electrical-seismic, and investment and economics. Through detailed investigation of typical helium-rich gas reservoirs, combined with analysis of “helium-natural gas-water” phase equilibria and phase-potential coupling in underground fluids, we revealed three helium occurrences—water-dissolved, gas-dissolved, free-particle; three migration mechanisms—mass-flow, seepage, diffusion; and four dispersion-enrichment controlling factors—proximity to source, adjacent faults, low-pressure zone, high-location. We developed a theoretical framework for the understanding of helium geology, recognizing high-quality source, efficient migration, suitable gas-carrier are the three key controlling factors of effective helium accumulation. To overcome a series of challenges in helium detection, such as variable detection techniques, low accuracy, large discrepancies with foreign data, and no targeted resource evaluation methods, we developed a comprehensive, accurate detection technique for helium content, with helium source and content at the core, and established 10 resource evaluation methods under four categories, solving the technical bottleneck in helium resource classification and evaluation. A normalized gravity/magnetic downward extension scheme was created to address challenges in helium source-rock distribution, lithofacies identification, source-fault characterization, and reservoir evaluation. An intelligent identification technique for multi-scale faults based on deep learning and a simulation method for acoustic properties of gas reservoir under different helium contents were developed, laying the foundation of predicting source-rock distribution, characterizing source-faults, logging interpretation, and evaluating helium-bearing gas reservoirs. By establishing a multi-process helium control model for helium-rich gas zones and target optimization methodology, the problem of target optimization for helium-rich gas zones is solved. Facing the reality of helium deficiency in China, with the goal of promoting cost-effective investment in helium extraction equipment, we developed a methodology for integrative evaluation of the entire helium industrial chain by adopting response surface methodology to build a nonlinear regression model between optimization target and various main process parameters, which preliminarily addressed the technical demand for cost-effective helium extraction from natural gas. Results from this research provide effective support for China's long-term, safe, and large-scale utilization of its natural helium asset. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Distribution characteristics and causes of arsenic in shallow groundwater in the Pearl River Delta during urbanization LÜ Xiaoli, ZHENG Yuejun, HAN Zhantao, LI Haijun, YANG Mingnan, ZHANG Ruolin, LIU Dandan Earth Science Frontiers    2022, 29 (3): 88-98.   DOI: 10.13745/j.esf.sf.2022.1.26 Abstract （624）   HTML （7）    PDF（pc） （7479KB）（1614）       Knowledge map    Save A high level of arsenic (As) in groundwater (ρ(As)>10 μg/L) is a potential threat to safe drinking water and the ecological environment. The sources of As in groundwater derived from coastal urbanized areas are complex, which mainly include various anthropogenic and geogenic sources. The rapidly urbanized Pearl River Delta was selected as the study area. The occurrence of and key driving factors for As enrichment in the shallow aquifers in areas with different urbanization levels in the Pearl River Delta were evaluated via mathematical statistics and principal component analysis. According to the results, the total dissolved As concentration in shallow groundwater ranged from below the detection limit to 420 μg·L-1 in the study area, with As(Ⅲ) as the main form. ρ(As) was found to be generally higher in porous aquifers than in fractured or karst aquifers. The proportion of As in the groundwater of urbanized areas was more than five times that of non-urbanized areas. Among the 1567 groups of groundwater samples collected from the study area, 89 high As groups, or 5.7% of total, had high level of As (ρ(As) >10 μg·L-1). Among them, 82 groups were from shallow porous aquifers, 4 groups from fissure aquifers, and 3 groups from karst aquifers, accounting for 7.8%, 0.8%, and 9.7% of total, respectively. Compared with historical hydrochemical data collected from 2005 to 2008, the average ρ(As) in shallow high As groundwater of newly added construction areas increased by 30% in 10 years. The chemical type of high As groundwater mainly included HCO3-Ca and Cl-Na types, characterized by high pH, low redox potential (Eh), low {\mathrm{NO}}_3^{-} concentration, and positive correlation between ρ(As) and concentrations of {\mathrm{NH}}_4^{+}, Fe, and Mn or oxygen consumption. Under microbial degradation and mineralization of organic matter, reductive dissolution of As-bearing iron (oxygen) hydroxide in the Quaternary basement muddy sedimentary strata in the Delta plain was identified as the cause of As mobilization. The leaking and infiltration of As-containing industrial wastewater produced during the urbanization process were also important sources of As in groundwater in Shunde District, southern Foshan City. Due to the dual effects of the original sedimentary environment and human input, the neutral to weakly alkaline, closed to semi-closed reducing environment that is rich in organic matter formed in the Delta plain, was the main cause of the occurrence of high As in groundwater. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Geophysical approaches to the exploration of lithium pegmatites and a case study in Koktohay HE Lanfang, LI Liang, SHEN Ping, WANG Sihao, LI Zhiyuan, ZHOU Nannan, CHEN Rujun, QIN Kezhang Earth Science Frontiers    2023, 30 (5): 244-254.   DOI: 10.13745/j.esf.sf.2023.5.14 Abstract （511）   HTML （44）    PDF（pc） （5404KB）（1504）       Knowledge map    Save Lithium is a critical metal widely used in Li-ion batteries for energy storage. The demand for lithium resource in a low-carbon economy is immense and rapidly growing, where a jump between 2015 to 2050 is predicted by Science. Currently more than half of lithium production comes from pegmatite lithium deposits. However, due to similar rock property between pegmatites and granite, lithium pegmatite prospecting by geophysical methods has proven difficult. Nevertheless, with the advancements in instrumentation and method developments, geophysical approaches have become increasingly widely used in lithium exploration. In this paper we briefly review the status of lithium resource as strategic raw material, and discuss and summarize the art of geophysical exploration for pegmatite lithium deposits, including rock physics, space remote sensing, gravity and magnetic prospecting, and geoelectrical exploration. A case study of the Koktokay rare-metal pegmatite by audio-frequency magnetotelluric (AMT) method is presented. Pegmatites and leucogranites are characterized by low magnetic susceptibility, low density, low polarizability and high velocity, and the electrical resistivity of pegmatites is affected by hydrophilic minerals and can vary by several orders of magnitude. As the host schist and gneiss in comparison have higher magnetic susceptibility and density, regional gravity and magnetic data are often used to delineate granite bodies. Recent reports show that micro-gravity in some cases can be used to identify pegmatite in host granite. With relatively high resolution and penetration depth, geoelectrical exploration plays an important role in the exploration of concealed pegmatite lithium deposits. In Koktokay, the rock formation and rock mass in the mining district are generally characterized by high resistivity by AMT method, but many low resistivity anomalies are detected. Based on the known ore deposits and geological survey results, the low-resistivity anomalies most likely reflect hidden pegmatites and indicate a good rare-metal resource prospect in the southern Koktokay mining district. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Aeolian deposits in the Yarlung Zangbo River basin, southern Tibetan Plateau: Spatial distribution, depositional model and environmental impact XIA Dunsheng, YANG Junhuai, WANG Shuyuan, LIU Xin, CHEN Zixuan, ZHAO Lai, NIU Xiaoyi, JIN Ming, GAO Fuyuan, LING Zhiyong, WANG Fei, LI Zaijun, WANG Xin, JIA Jia, YANG Shengli Earth Science Frontiers    2023, 30 (4): 229-244.   DOI: 10.13745/j.esf.sf.2022.9.7 Abstract （326）   HTML （14）    PDF（pc） （8436KB）（1379）       Knowledge map    Save Situated in the suture zone formed by the India-Euroasia collision, the Yarlung Zangbo River (YZR) basin in the southern Tibetan Plateau is a hotspot for Earth systems research, where Middle-Pleistocene aeolian deposits not only provide an important window into the history of climate change and atmospheric circulation in the Tibetan Plateau, but also help us to gain a deeper understanding of the link between tectonics, climate and landscapes in general. However, a systematic understanding of the distribution, depositional model, and environmental effects of aeolian sediments in this region is still lacking. Here, we construct a new atlas and a depositional model of aeolian sediments in the YZR basin based on extensive field investigation as well as laboratory analyses of typical sediment samples collected across the region, combined with existing research results. In general, aeolian sand and loess are distributed in patches and usually occur together. A close provenance relation between loess and nearby loose sediments such as sand dunes and river sands indicates that aeolian sediments cycle locally, hence they record spatial changes of regional climate; in contrast, the valley sediments not only receive dust from distant sources but also contribute dust materials to the world via upper-level westerly winds. Middle-Pleistocene aeolian dust activity in the YZR basin was controlled combinedly by tectonic movement and global climate change; whereas aeolian dust activity during the Holocene was relatively complex under the river valley environment, and regional climate change was generally influenced by the synergistic effect of the mid-latitude Westerlies and the Indian summer monsoon. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Overview of magmatic-hydrothermal evolution of and rare element super enrichment in NYF pegmatites RAO Can, WANGWU Mengyu, WANG Qi, ZHANG Zhiqi, WU Runqiu Earth Science Frontiers    2023, 30 (5): 106-114.   DOI: 10.13745/j.esf.sf.2023.5.6 Abstract （194）   HTML （18）    PDF（pc） （4067KB）（1244）       Knowledge map    Save NYF pegmatites as an important strategic mineral resource have not been widely studied. Compared to LCT pegmatites, NYF pegmatites have poor internal structural zonation and regional zonation but contain large amounts of Nb, Y, F and other rare minerals. The geochemical characteristics of columbite-/mica-group minerals and tourmaline can accurately reveal the magmatic-hydrothermal evolutionary process and reflect the degree of internal differentiation of NYF pegmatites; whereas volatile components such as F, B, P and H2O not only affect the degree of internal differentiation of the pegmatites but also play a crucial role in the super enrichment of rare elements. The enrichment, migration and crystallization of rare elements take place through all stages of magmatic-hydrothermal evolution; and the mineralization of rare metals (Nb, Be, Rb, Zr, Th, U) and rare earths (Y, Ce, Sc, etc.) may occur in the highly evolved pegmatites. In future, alkaline rocks/granites should be key exploration targets for NYF pegmatites; and researches on NYF pegmatites should be strengthened to guide ore prospecting. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Soil screening levels in the United States and implication for soil evaluation in China WANG Xiaoyu, QU Yajing, ZHAO Wenhao, MA Jin Earth Science Frontiers    2024, 31 (2): 64-76.   DOI: 10.13745/j.esf.sf.2023.11.50 Abstract （458）   HTML （12）    PDF（pc） （1829KB）（1108）       Knowledge map    Save Soil evaluation guidelines are essential for soil evaluation and soil environmental protection. The United States (USA) was one of the developed countries first paid attention to contaminated sites protection and soil pollution control, and it has since developed fairly comprehensive guidelines such as the Soil Screening Guidance (SSG) for soil evaluation, whilst China is still in its infancy in this regard. In this paper we review research results on soil screening levels (SSLs) in the USA, focusing on the laws and regulations and technical specifications for soil protection and remediation, and discuss the methodology of SSL formulation based on five health hazard types: direct ingestion, dermal absorption, ingestion of contaminated groundwater, inhalation of outdoor volatiles/particulates and vapor intrusion. On this basis, we propose that researches on soil evaluation in China should be conducted based on soil environmental conditions in China, with emphasis on establishing regional and national soil parameter databases, standardizing national soil evaluation guidelines and carrying out combined research on soil and groundwater evaluation criteria, so as to provide a reference for formulating soil evaluation criteria in China. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Research progress on zircon from pegmatites and insights into rare-metal mineralization—a review SUN Wenbo, LI Huan Earth Science Frontiers    2023, 30 (5): 171-184.   DOI: 10.13745/j.esf.sf.2023.5.2 Abstract （234）   HTML （29）    PDF（pc） （4644KB）（1021）       Knowledge map    Save With increasing global demand for rare metals rare-metal pegmatites have attracted much attention due to their widespread distribution and great metallogenic potentials. Zircon as an important accessory mineral in pegmatites is important for the understanding of pegmatite genesis regarding the ore-forming source material, fluid properties/evolution, and rare-metal enrichment mechanism. This paper summarizes the latest research progress on pegmatite-hosted zircons and insights into rare-metal mineralization in pegmatites. Recent studies show that pegmatite-hosted zircons have multiple origins and often undergo hydrothermal transformation, which result in complex zircon age spectrum, where rare-metal mineralization is related to older zircons. Geochemical anomalies of trace elements in zircons can indicate complex rare-metal mineralization in pegmatites, constrain magmatic evolution process and reveal ore-forming fluid properties. The REE tetrad effect is a special mode of rare-earth distribution in magmatic rocks. Such distribution mode also exist for pegmatite-hosted zircons revealing complex melt-fluid evolution. Hf-O isotopic composition of pegmatite-hosted zircons is highly variable where Hf isotopes are a good tracer for pegmatite source areas and oxygen for fluids. Pegmatite-hosted zircon is rich in fluid and mineral inclusions, thus future key research should focus on using fluid inclusion temperature measurement and composition analysis to delineate the magmatic evolution stages, using high-U zircons to track the source of U-rich fluids, and using zircon Li/Zr isotopes to reveal the ore-forming processes. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Lithium isotope geochemistry—a review CHEN Yu, XU Fei, CHENG Hongfei, CHEN Xianzhe, WEN Hanjie Earth Science Frontiers    2023, 30 (5): 469-490.   DOI: 10.13745/j.esf.sf.2023.2.51 Abstract （738）   HTML （41）    PDF（pc） （4298KB）（962）       Knowledge map    Save Lithium (Li) as a non-traditional stable isotope is a strategic and critical metal for the development of emerging industries. This review summarizes the geochemical properties of Li as well as its isotope distribution characteristics, analytical techniques, and fractionation mechanisms, and provides a comprehensive discussion on the latest research application of Li isotopes in plate subduction, crust-mantle material evolution, metallogenic mechanism, surface weathering, carbon cycle, and human activities. The relative mass difference between the two stable isotopes, 6Li and 7Li, can reach 17%. Significant Li isotopic fractionation occurs due to changes in environmental conditions (both physical and chemical) during tectonic evolution, and δ7Li can vary up to 60‰ between different reservoirs. Lithium stable isotopes have great potential for ore prospecting and geochemical tracing. Lithium as a lithophile element with strong fluid activity is widely distributed in the crust, where 7Li is more likely to enter the aqueous phase as tetravalent cations during fluid migration, which results in higher δ7Li in natural reservoirs. Lithium isotopic fractionation is significant at low temperature by forming secondary clay minerals, and it is less likely to occur at high temperature, where Li diffusivity and partition coefficient in minerals are the controlling factors. The rapid development of Li isotope detection techniques such as MC-ICP-MS and in-situ microanalysis greatly improves the accuracy of Li isotopic analysis (up to 0.2‰) and promotes use of Li isotopes in geoscience research. One example is in the study of dehydration and metasomatism during plate subduction. The preferential partitioning of 7Li in the aqueous phase affects Li isotopic composition of mantle wedge fluid and island arc lavas, where the absence of Li isotopic fractionation in the deep, high temperature environment causes low δ7Li values in the deep fluids, similar as in the subduction plate; whilst Li isotopic variations in mantle-derived xenoliths reflect different degrees of metasomatism. Li isotopes are also effectively used to study the genesis of ore deposits and ore prospecting. Lithium in salt brine are mainly sourced from weathering of Li-rich parent rocks and transported by bottom-up hydrothermal fluids, and the dissolution of sediments further promotes Li enrichment. The low δ7Li granopegmatite type lithium deposits mainly formed during late-stage magmatic differentiation. Rivers, rainwater, aerosols, and clay formation jointly affect Li isotopic fractionation via epigenetic effects. This review provides a reference for the geochemical application of Li stable isotopes. Lithium isotopic analysis can be more broadly applied in geological studies as the accuracy of isotopic measurements is further improved and the mechanism of Li isotopic fractionation under complex conditions is further clarified. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Carbon sequestration assessment methods at home and abroad for terrestrial ecosystems: Research progress in achieving carbon neutrality XIE Lijun, BAI Zhongke, YANG Boyu, CHEN Meijing, FU Shuai, MAO Yanchao Earth Science Frontiers    2023, 30 (2): 447-462.   DOI: 10.13745/j.esf.sf.2022.2.78 Abstract （1367）   HTML （92）    PDF（pc） （3170KB）（865）       Knowledge map    Save The purpose of this paper is to differentiate the characteristics of different mainstream carbon sink accounting methods developed in the past 30 years for the four main terrestrial ecosystems—forest, grassland, farmland, and wetland—in order to accurately assess the current status of the carbon sink capacity and future carbon sink potential of terrestrial ecosystems. Through literature review, comparative analysis, and induction we show that 1) the existing carbon sink accounting methods are mainly based on formula model calculations, and are affected by sample size, measurement and parameter errors, inconsistent data sources, and model universality when analyzing the spatial pattern of vegetation carbon sinks, which lead to great uncertainty in the calculated result; thus, China urgently needs to establish an unified standard terrestrial ecosystem carbon sink monitoring system. 2) Accurate carbon sink calculation for terrestrial ecosystems requires reliable data sources, reasonable calculation methods and models, multi-channel cross-validation, appropriate error analysis, and interpolation corrections. 3) Methods such as site survey, model construction, micrometeorology, and remote sensing monitoring should be effectively integrated to solve the problem of multi-scale coupling. Future research should be based on a large number of measured data, explore differentiated carbon sink accounting methods according to ecosystem types, regions, and climates, and establish a full-scale, generalized carbon sink calculation model to provide reference for a carbon sink accounting standard for terrestrial ecosystems in China. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Marine science in China: Current status and future outlooks WU Lixin, JING Zhao, CHEN Xianyao, LI Caiwen, ZHANG Guoliang, WANG Shi, DONG Bo, ZHUANG Guangchao Earth Science Frontiers    2022, 29 (5): 1-12.   DOI: 10.13745/j.esf.sf.2022.4.60 Abstract （2232）   HTML （156）    PDF（pc） （4828KB）（847）       Knowledge map    Save Oceans as the cradle of life, the treasure trove of resources, and the protective barrier for national security play an important strategic role in the future sustainable development of mankind. Until now only 5% of oceans have been explored. For the national development it is vital to accelerate the marine science and technology innovation, improve the marine resources exploration capability, and protect the marine ecological environment. However, due to its inherent complexity, the “ocean problem” cannot be solved within a single discipline. Presently marine study in China is gradually catching up with the world, yet research originality is still lacking. This paper reviews the domestic marine research progresses and trends, points out the gaps between China and advanced countries, and proposes future directions. Focusing on the major scientific frontiers e.g., multiscale inter-ocean interaction, climate change, healthy ocean, marine life cycle, cross-sphere fluid-solid interaction, rapid changing polar system, and sustainable development of coastal zone-this paper proposes that China should strengthen its top-level design and strategic planning, carries out cross-scale, cross-sphere interdisciplinary research, and pursues leadership roles in major international scientific programs. These efforts are essential to enhancing China's influence in international marine research, effectively improving its national security capability, supporting its socioeconomic development, and providing scientific and technological support in achieving maritime power and building a global community with a shared future. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Developing structural control models for hydrothermal metallogenic systems: Theoretical and methodological principles and applications YANG Liqiang, YANG Wei, ZHANG Liang, GAO Xue, SHEN Shilong, WANG Sirui, XU Hantao, JIA Xiaochen, DENG Jun Earth Science Frontiers    2024, 31 (1): 239-266.   DOI: 10.13745/j.esf.sf.2024.1.40 Abstract （1371）   HTML （27）    PDF（pc） （5137KB）（810）       Knowledge map    Save A defining feature of a hydrothermal metallogenic system (HMS) is strong structural control on ore mineralization. A systematic analysis of the geometry, kinematics, thermodynamics, and rheology of multiscale ore control structures is crucial for understanding the genesis of HMSs and for ore prospecting. The main challenges include: transitioning from static to multiscale spatiotemporal analysis of the 4D dynamical system involving ore-control structural frameworks, permeability structures, ore-forming fluid pathways, and mineralization deformation networks; identifying key influencing factors of fluid pathways that control ore deposition; and unraveling the mechanism of structure-fluid coupling control of ore formation and localization. This study presents the theoretical and methodological principles and application for developing structural control models for HMSs in the following aspects. (1) The theoretical core. It states that fluid, not structure, is at the core of a structural control model. Fluid flow and ore formation within a hydrothermal system are influenced by the fault zone architecture and permeability structure, where permeability, in linking fluid flow and fluid pressure variation, is key to understanding ore control structures. (2) Stress and pressure dynamics. It considers that differential stress and fluid pressure difference result in diverse combinations of ore control structures, while differences in regional stress field and host rock strength result in variations in mineralization type. (3) Growth of fluid pathways. It considers that fluid pathways initiate from isolated microfractures within the upstream host rocks of overpressured fluid reservoirs which evolve along the direction of the steepest pressure gradient to form new extended fractures through growth and interconnection. These extended fractures eventually interconnect to form fluid pathways. As ore deposition takes place during brief periods of high fluid flux when repeated fault sliding induces rapid changes in fluid pressure, flow velocity, and stress, rapid pressure release—caused by a disruption of dynamic equilibrium in the fluid system due to fluid pathways growth—is a key factor driving metal precipitation. (4) Integrated research. Methodology involves integrating macro and microscopic examination of ore control structures, integrating geological history and stress analysis, combining local and regional analyses, adopting shallow and deep perspectives, and employing a multidisciplinary, multiscale approach to study various ore-controlling factors. (5) Geological mapping. Methodology involves using structure-alteration-mineralization network mapping to characterize alteration-mineralization rock blocks in terms of geometric parameters for ore control structures (such as type, shape, size, occurrence, spacing), and performing quantitative analyses (such as topological analysis of hydrothermal vein-fracture systems, 3D geometric analysis of ore bodies) to determine ore-control structural frameworks and permeability structures and reveal the connectivity of mineralization deformation networks and their ore-forming potential. (6) Numerical modeling. Methodology involves developing geological models, selecting appropriate thermodynamic parameters and dynamic boundary conditions, and utilizing methods such as HCh and COMSOL to perform quantitative simulation of spatiotemporal variations in fluid flow, heat-mass transfer, stress deformation, and chemical reactions during ore formation. This is an effective approach to unveil the mechanism of ore formation controlled by structure-fluid coupling and ore localization pattern, predict ore-forming centers, and identify mineral exploration targets. Based on the above principles, this paper proposes a research methodology for model building, focusing on deriving metallogenic models and ore deposition patterns based on structure-fluid coupling control. Briefly, hydrothermal veins-fracture systems and structure-alteration-mineralization networks are selected as primary research subjects. Research methods include geometric description, kinematic assessment, rheological/dynamic analyses, and thermodynamic synthesis, seeking to delineate ore-control structural frameworks, identify mineralization centers, trace the developments of ore-forming fluid pathways and various mineralization styles, and reveal the spatiotemporal evolution patterns of permeability structures. Additionally, the causal relationship between tectonic reactivation and ore localization is explored. Finally, a metallogenic model based on structure-fluid coupling is constructed to support strategic mineral exploration. This research methodology was applied for mineral prediction in the Jiaojia gold field, Jiaodong Peninsula; its validity and effectiveness were tested and approved. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Prospects for submarine hydrogen exploration and extraction technologies JIANG Zhaoxia, LI Sanzhong, SUO Yanhui, WU Lixin Earth Science Frontiers    2024, 31 (4): 183-190.   DOI: 10.13745/j.esf.sf.2024.6.10 Abstract （564）   HTML （8）    PDF（pc） （5779KB）（725）       Knowledge map    Save In the current context of the dual-carbon policy, the national demand for clean energy, such as hydrogen, is growing significantly. Serpentinization of peridotite is one of the most widespread water-rock interactions on the seafloor, and hydrogen gas, a primary product of this process, serves as a crucial pathway for the formation of marine hydrogen energy. Therefore, the deep oceanic crust holds highly promising hydrogen energy reserves, representing a vital breakthrough for alleviating current dual-carbon pressures and driving the development of new productive capacities. However, global technologies for detecting and extracting marine hydrogen energy are still in their infancy, presenting a significant opportunity for future seafloor energy exploration and growth. This paper systematically reviews the formation principles and distribution characteristics of marine hydrogen energy, outlining potential detection technologies and extraction methods. We propose that comprehensive geophysical exploration methods, such as multibeam bathymetry, magnetic surveys, gravity measurements, and multi-component seismic exploration, hold promise for detecting potential hydrogen reservoirs on the seafloor. Additionally, methods like hydraulic fracturing and microwave heating could be utilized for extracting hydrogen from these reservoirs. However, due to the limited understanding of marine hydrogen energy and the unique challenges associated with hydrogen storage and transport, there is a pressing need to develop specialized detection and extraction technologies tailored to marine hydrogen energy. Advance layout in this direction will provide the necessary technical support for the exploitation and utilization of marine hydrogen energy and spur revolutionary breakthroughs in various technological fields. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Tectonic evolution and Cenozoic deformation history of the Qilian orogen WU Chen, CHEN Xuanhua, DING Lin Earth Science Frontiers    2023, 30 (3): 262-281.   DOI: 10.13745/j.esf.sf.2022.12.20 Abstract （785）   HTML （48）    PDF（pc） （14534KB）（687）       Knowledge map    Save The Qilian orogen—formed along the northern margin of the eastern Tethys as results of pre-Cenozoic multi-phase subduction, continental collision and punctuated orogeny involving the North China craton and the Qaidam paleocontinent—develops widespread ophiolitic mélange belts and (ultra-) high pressure metamorphic and arc igneous rocks. The present Qilian Mountains, a key tectonic zone undergoing plateau uplift/expansion along the northern margin of the Tibetan Plateau, with complex intracontinental deformation and deep structures, records the histories of tectonic deformation and basin-mountain evolution during different stages of plateau growth in the Cenozoic. This paper, on the basis of comprehensive analysis of regional geological data, discusses the nature of Proterozoic metamorphic basement, paleo-oceanic evolution during the Neoproterozoic-Paleozoic, and Mesozoic-Cenozoic structural deformation, and explores the tectonic evolution of the Qilian orogen and the intracontinental deformation history of the Qilian Mountains. The Early-Neoproterozoic and Early-Paleozoic arcs represent respectively subduction-collision events took place in the Paleo-Qilian and (South/North) Qilian oceans. Basement structure beneath the North China craton suggests that the Qilian ocean is not the ocean separating the Gondwana and Laurasia continents, but rather a relatively small embayed sea along the southern margin of the Laurasia continent. The northeastern margin of the Tibetan Plateau experienced two-stage tectonic deformation and basin-mountain evolution in the Cenozoic, while transition from Early-Cenozoic thrust activity to joint action of strike-slip/thrust faults occurred in the Miocene, where, with rapid uplift of the Eastern Kunlun Range, a large Paleogene basin split into two basins—the current Qaidam Basin and the Hoh Xil Basin. Since the Middle-Late Miocene the tectonic framework along the margin has been mainly controlled by the development and clockwise rotation/lateral growth of two large near-parallel transpressional tectonic systems, of Eastern Kunlun and Haiyuan. The growth process and development mechanism of the large-scale strike-slip fault system in the Qilian orogen is a central issue of research on intracontinental deformation and requires in-depth quantitative examination. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Opportunities and challenges in deep hydrogeological research WEN Dongguang, SONG Jian, DIAO Yujie, ZHANG Linyou, ZHANG Fucun, ZHANG Senqi, YE Chengming, ZHU Qingjun, SHI Yanxin, JIN Xianpeng, JIA Xiaofeng, LI Shengtao, LIU Donglin, WANG Xinfeng, YANG Li, MA Xin, WU Haidong, ZHAO Xueliang, HAO Wenjie Earth Science Frontiers    2022, 29 (3): 11-24.   DOI: 10.13745/j.esf.sf.2022.1.49 Abstract （752）   HTML （39）    PDF（pc） （4206KB）（664）       Knowledge map    Save Rapid social and economic development requires a steady supply of energy and natural resources. Such resources are markedly abundant in the deep earth. “Marching into the deep earth”, therefore, is an inevitable trend in energy supply such that the current resource exploration and development technology, cost, and financial prospects are compatible with meeting the resources needs. Owing to the “carbon peak and carbon neutrality” campaign, green, low-carbon, high-quality development has become a shared goal for society. To meet the major demands for energy, resource security, and ecological environmental protection, it is particularly important to accelerate the clean energy exploration and development, enhance the carbon storage capacity, and strengthen research on geological energy storage. These tasks are closely related to the study of deep hydrogeological process and such study requires immediate attention. By analyzing several literature reports, a comprehensive comparative study was conducted on the course of research discipline development and its relevant hot issues. This study sought to summarize and assess the current situation and future trends in deep hydrogeological research related to the distribution and circulation of deep groundwater, the accumulation of geothermal and lithium resources under the control of deep groundwater, the development of clean energies such as deep geothermal, hot-dry rock, and shale gas, the geological sequestration of CO2 in the deep saltwater layers, and geological energy storage in the aquifer. Deep and systematic studies were found to be needed in such areas owing to the dynamic mechanism of groundwater circulation, the material and energy conversion process, water-rock interaction, the thermal accumulation mechanism, and the accuracy and precision of monitoring technology in deep hydrogeology under the conditions of high temperature and high pressure. In addition, the characterization of reservoir heterogeneity, the heat source mechanism, the sustainable development technology of deep resources and energy, the evolution characteristics of deep resources and environment under human intervention, the earthquake induced by hydraulic fracturing, the sensitivity of faults triggered by fluids, and the evolution of the triggering process will continue to remain as key research topics. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Petrogenesis of Paleoproterozoic granites in the Dondo area, northern Angola block: Geological response to the assembly of Columbia Supercontinent LIU Wei, ZHANG Hongrui, LUO Dike, JIA Pengfei, JIN Lijie, ZHOU Yonggang, LIANG Yunhan, WANG Zisheng, LI Chunjia Earth Science Frontiers    2024, 31 (4): 237-257.   DOI: 10.13745/j.esf.sf.2024.2.15 Abstract （842）   HTML （10）    PDF（pc） （7995KB）（657）       Knowledge map    Save The Paleoproterozoic Eburnean orogenic granites are widely exposed in the western part of Angola, offering an ideal setting to study the magmatism and tectonic evolution of the Angola Block. This paper presents systematic studies of petrology, petrogeochemistry, and zircon U-Pb geochronology on the exposed granites in the Dondo area, northern Angola Block. The results indicate that the emplacement ages of porphyritic biotite monzonite granite and biotite monzonite granite in the Dondo area are 1983.3±7.7 Ma and 1956.6±7.5 Ma, respectively, both products of middle Paleoproterozoic magmatic activity. The whole-rock samples are characterized by high SiO2, ALK, 10000Ga/Al, FeOT/(FeOT+MgO), and Zr+Y+Nb+Ce, and low MgO, TiO2, CaO, and P2O5. Trace elements are enriched in Rb, K, Th, U, Zr, and Hf, and depleted in Sr, Nb, Ta, P, and Ti. All samples are enriched in LREE and depleted in HREE, with no significant negative Eu anomaly. The crystallization temperature, calculated using zircon saturation thermometry, ranges from 757 to 889 ℃. Based on these geochemical characteristics, the granites in the Dondo area are classified as A2-type granite. Mineralogical and geochemical features suggest that the porphyritic biotite monzonite granite and biotite monzonite granite were generated by the mixing of crust-derived melts and mantle-derived mafic magma. The similar formation ages within analytical error, identical mineral assemblages, and consistent variations in major and trace elemental compositions indicate that their parental magma originated from a common magma chamber, with lithological differences resulting from melt extraction processes. It is proposed that the magma producing the potassium feldspar porphyry resided in the deep crust for an extended period, leading to stable crystallization of potassium feldspar, increased viscosity and density, and a frozen state of the magma. Subsequent thermal disturbance and volatile enrichment from mantle-derived magma injection rapidly reactivated the frozen magma chamber, resulting in crystal-melt separation. The extracted melt formed biotite monzonite granite, while magma mixed with pre-existing crystals formed porphyritic biotite monzonite granite. Combining regional and global tectonic evolution, it is suggested that the granites from the Dondo area formed in a post-collision tectonic environment between the São Francisco Craton and the Congo Craton. The Paleoproterozoic magmatic events in the Angola Block are likely responses to the Columbia Supercontinent assembly. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Can hydrocarbon source rock be uranium source rock?—a review and prospectives LIU Chao, FU Xiaofei, LI Yangcheng, WANG Haixue, SUN Bing, HAO Yan, HU Huiting, YANG Zicheng, LI Yilin, GU Shefeng, ZHOU Aihong, MA Chenglong Earth Science Frontiers    2024, 31 (2): 284-298.   DOI: 10.13745/j.esf.sf.2023.5.33 Abstract （480）   HTML （8）    PDF（pc） （3706KB）（649）       Knowledge map    Save The coexistence of hydrocarbon source rocks and sandstone-hosted uranium (U) deposits in the same basin has been widely reported. Hydrocarbon source rock contributes to uranium precipitation and enrichment by providing oil and gas; whereas, whether it can be a source of uranium supply is of great relevance as to weather uranium prospecting should expand deep into the basin. This study reviews relevant domestic and international studies and offers perspectives on this topic, focusing on three key issues: migration potential of uranium in source rock, possible ways of uranium transport by formation fluids, and mechanisms of uranium precipitation and accumulation. Hydrothermal modeling results show that uranium migration can occur during hydrocarbon generation and expulsion, and the migrated-uranium, probably a mix of U(IV) and U(VI), is likely transported by both hydrocarbon-bearing formation water and oils. The transported-uranium precipitates due to a decrease of uranium solubility and decomposition of the transport fluids caused by a decrease of temperature and pressure and change of pH and Eh; the uranium precipitates can also redissolve in oxygen-rich formation water. The main perspectives are: (1) the amount of migrated-uranium is uncertain, and the mechanism and laws of U migration are still unclear, thus further modeling experiments on source rock-uranium system is recommended to understand the kinetics of uranium migration. (2) Up to now, little is known about the dominant U mobile forms and their thermodynamic properties and distribution between hydrocarbon-bearing formation water and oil, thus, in-situ thermal testing via thermal simulation experiments is recommended to address this issue. (3) During uranium upward transport, changes in temperature, pressure, Eh, and organic/inorganic components of the transport fluids control uranium geochemistry, thereby, in order to understand uranium geochemistry and its controlling factors under different conditions, multi-variable simulation experiments on hydrocarbon-uranium transport is suggested. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Toxicity thresholds (ECx) for Cr in soils and prediction models SUN Xiaoyi, WANG Meng, QIN Luyao, YU Lei, WANG Jing, CHEN Shibao Earth Science Frontiers    2024, 31 (2): 121-129.   DOI: 10.13745/j.esf.sf.2023.11.55 Abstract （463）   HTML （3）    PDF（pc） （2958KB）（643）       Knowledge map    Save The lack of toxicology data is the main factor hindering the ecological risk assessment of Cr contamination in soils and the revision of soil environmental quality standards in China. In this study, we conduct toxicology tests on seven soil types (with different soil properties) in China, using earthworm biomass, cabbage biomass, and microbial matrix induced respiration (SIR) as measurement endpoints. We determined the effective concentration (ECx) values under different soil types based on the Log-logistic dose-effect relationship and low-dose stimulus effect function model. On this basis we developed predictive models for estimating toxicity thresholds of Cr under different soil properties. Chromium toxicity in earthworms, Chinese cabbage, and soil microorganisms under different soil types showed significant inhibitory effect with increased soil Cr concentrations, and the dose-response (D-R) relationship was clearly sigmoid in shape. Under different soil types, the EC10 values for soil microorganisms (SIR), earthworms, and Chinese cabbage ranged between 22.1-53.7, 65.0-137.2, and 82.1-220.2 mg/kg, respectively, and the EC50 values between 50.3-103.7, 103.9-369.0, and 159.9-441.9 mg/kg, respectively. The Cr toxicity thresholds for the tested species, from high to low, followed the order of Chinese cabbage>earthworms>soil microorganisms, with soil microorganisms being the most sensitive to Cr toxicity. Under low Cr concentrations (<112 mg/kg), the tested species showed significant hormesis effects, among which earthworms had a maximum hormesis between 102%-108% under different soil types, and Chinese cabbage between 105%-112%, while soil microorganisms showed relatively small effect at 104%. Chromium toxicity thresholds under different soil types can be well predicted based on soil pH and clay/CEC contents. The research results provide a scientific basis for the ecological risk assessment of Cr in soils and for the formulation and revision of environmental quality standards for Cr in soils. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Geological features and formation mechanism of pegmatite-type rare-metal deposits in the Renli orefield, northern Hunan, China—an overview LI Jiankang, LI Peng, HUANG Zhibiao, ZHOU Fangchun, ZHANG Liping, HUANG Xiaoqiang Earth Science Frontiers    2023, 30 (5): 1-25.   DOI: 10.13745/j.esf.sf.2023.5.24 Abstract （333）   HTML （56）    PDF（pc） （22668KB）（636）       Knowledge map    Save The Renli orefield in northern Hunan is a newly discovered pegmatite Li-Ta-Nb orefield in eastern China. It is located in the middle Jiangnan orogenic belt and consists mainly the Renli Nb-Ta-Be deposit, Yongxiang-Chuanziyuan Li-Be-Nb-Ta deposit and Huangbaishan Li-Be-Nb-Ta deposit. Pegmatite dikes in the northern orefield distribute along the southwestern margin of the Mufushan complex, forming distinct pegmatite zonation. Outwards from the complex, the pegmatite types are divided into microcline, microcline albite, albite and albite spodumene. Among the pegmatite dikes, Renli No.5 is the largest Nb-Ta ore body, which exhibits two-stage magmatic-hydrothermal mineralization characteristics; Yongxiang-Chuanziyuan No.206 is the largest spodumene dike in the area, where spodumene occurs mostly as pseudomorph due to strong late-stage metasomatism; and Huangbaishan No.603 is a newly discovered spodumene dike characterized by high-grade Li2O and weak metasomatism. Hydrothermal fluid played an important role in the rare-metal mineralization of Renli No.5, which is evidenced by the occurrence of quartz-hosted fluid inclusions. Fluid inclusion microthermometry reveals the Renli No.5 core formed at ~550 ℃ and ~350 MPa. According to existing data, the Renli orefield formed during the Yanshanian intracontinental orogeny (~130 Ma). The data show that during intracontinental orogeny granitic melts formed from basement rocks, i.e. the anatexis of the Neoproterozoic Lengjiaxi Group; then during multi-stage granitoid intrusion the late-stage two-mica granitic melts fractionated into pegmatite-forming melt; finally the hydrothermal metasomatism resulted in Nb and Ta enrichment and Li depletion in pegmatites. Thus, rare-metal mineralization in pegmatites in the Renli orefield can be characterized by metapelite anatexis during intracontinental orogeny, granitic magma differentiation, and two-stage magmatic-hydrothermal mineralization. Table and Figures | Reference | Related Articles | Metrics | Comments（0）