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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 （307）   HTML （13）    PDF（pc） （8487KB）（2028）       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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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 （534）   HTML （7）    PDF（pc） （7479KB）（1585）       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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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 （369）   HTML （62）    PDF（pc） （3044KB）（780）       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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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 （1082）   HTML （79）    PDF（pc） （3170KB）（689）       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 （1740）   HTML （103）    PDF（pc） （4828KB）（636）       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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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 （621）   HTML （41）    PDF（pc） （14534KB）（561）       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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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 （217）   HTML （49）    PDF（pc） （22668KB）（552）       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）

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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 （632）   HTML （37）    PDF（pc） （4206KB）（543）       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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Crustal-scale plate interactions beneath the dominant domain in the India-Eurasia collision zone—a tectonogeophysical study GUO Xiaoyu, LUO Xucong, GAO Rui, XU Xiao, LU Zhanwu, HUANG Xingfu, LI Wenhui, LI Chunsen Earth Science Frontiers    2023, 30 (2): 1-17.   DOI: 10.13745/j.esf.sf.2022.11.7 Abstract （473）   HTML （168）    PDF（pc） （11297KB）（523）       Knowledge map    Save Since the Early-Cenozoic onset of the Indian plate subduction beneath the Eurasian plate along the Yarlung-Zangbo suture zone (YZSZ), the subduction process has gained wide interests among geologists. However, crustal-scale vertical interactions between the two plates beneath the dominant domain in the collision zone remains unclear owing partly to the lack of high-resolution datasets, which has severely limited the understanding of the crustal thickening mechanism of the dominant collision domain and its deep geodynamic processes. In this study, fine structural interpretation of two deep seismic reflection profiles—180 km and 100 km long cutting through the middle and eastern part of the YZSZ, respectively—revealed the crustal-scale lateral and vertical contact relationships between the subducting Indian plate and the overriding Lhasa terrane. (1) Laterally, the Indian lower crust subducts northward, with limited subduction front beneath the southern margin of the Lhasa terrane (SLT) which is shown as non-reflective crust, while the Central Lhasa terrane (CLT) is north-dipping. (2) Vertically, the Indian lower crust undergoes subduction, while crustal duplexing occurs in the middle-upper crust. Nearly three quarters of the SLT crust are non-reflective crust, while the rest, the SLT upper crust, is south-dipping. The CLT crust can be divided into two domains: north-dipping lower crust and concave-downward upper crust. Differential vertical zonation is observed in all three tectonic units. (3) The upper crust of the dominant collision domain has a consistent deformation pattern, where a sequence of break-backward imbricate structures is present. This break-backward imbricate system can be traced from the Luobadui-Mila fault of the northern edge of SLT, beyond YZSZ, to the northern edge of the North Himalaya dome belt. Combing with the previous findings based on coincident magnetotelluric data on the southward migration of high conductive barrier of SLT thrusting along the main Himalayan into the northern Himalayas, we believe the episodic magmatism in the Tethyan Domain beneath SLT generated juvenile crust that is prone to anomalous thickening. Meanwhile, during India-Eurasia plate interaction, mantle-sourced magmatism in SLT—generated from northward subduction of the Neo-Tethyan oceanic slab and subsequent collision between the India and Eurasia plates—caused southward thermal migration, which induced anatexis in the northern Himalayas and weakened the crustal strength of the region. The ongoing crustal-scale duplexing therefore leads to antiformal stacking and causes crustal thickening. Rapid exhumation of the North Himalayan dome by the increasing antiformal stacking, meanwhile, exerts sudden northward compression to the overlying Tethyan Himalayan sequence, which eventually creates fault-propagation folds following a break-backward sequence in the upper crust through the whole dominant collision domain. Overall, vertical and lateral tectonic interactions within the dominant collision domain in the India-Eurasia collision zone played an important role in producing such anomalous thick crust, but the break-backward imbricates system in the upper crust lowered topographic relief in the dominant collision domain as well. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Multi-cycle superimposed sedimentary basins in China: Formation, evolution, geologic framework and hydrocarbon occurrence HE Dengfa Earth Science Frontiers    2022, 29 (6): 24-59.   DOI: 10.13745/j.esf.sf.2022.8.1 Abstract （292）   HTML （23）    PDF（pc） （11062KB）（509）       Knowledge map    Save Understanding basin's geological structure and tectonic evolution and exploring its oil and gas distribution pattern is key to revealing the geological features of China, and the energy resources distributions, environmental changes, and potential hydrocarbon exploration targets in China. Based on the new data of recent petroleum exploration and using the methodology of comparative geo-tectonics, this paper studies the superimposed sedimentary basins in China from the view point of mobile geo-tectonic history, focusing specifically on the basin's tectonic evolution, tectonic subdivision, geologic framework, and pool-formation models, and explores the basin's oil and gas distribution patterns. According to our analysis, the superimposed sedimentary basins in China evolve through four tectonic cycles during the Meso- to Neo-Proterozoic, Cambrian-Devonian (or Middle Devonian), (Late Devonian-) Carboniferous-Triassic, and Jurassic-Quaternary Periods. The sedimentary basins in China can be subdivided into ten sedimentary basin areas: northern Xinjiang, inner Mongolian, Songliao, Tarim-Alax, Ordos, Bohai Bay, Qinghai-Tibet, Sichuan, southern China, and oceanic area. They can be further characterized by eight structural styles as foreland/cratonic-basin, foreland/sag, sag/faulted-depression, faulted-depression/sag, inverted faulted-depression, passive margin, or strike-slip superimposed basins, or as modified residual basins. Twelve types of hydrocarbon pool-formation are developed, which are represented by the Anyue rift trough, northern Tarim, Sulig composite delta, Mahu sag, Luliang uplift, Kuqa thrust belt, Daqing anticline, paleo-buried hill, central canyon channel, eastern Qaidam biogas, Sichuan intra-source rock, and Qinshui syncline coalbed gas. Within a sag/faulted-depression superimposed basin, oil and gas distributions are typically ordered spatially, with the interface area most favorable for hydrocarbon accumulation. However, oil and gas distribution patterns are highly heterogeneous across different structural styles. For example, in the foreland/cratonic-basin superimposed basins of central and western China, oil and gas distribute separately in isolation, whilst in the passive-margin/faulted-depression superimposed basins of the oceanic area, oil and gas zones distribute respectively along the inner and outer sedimentary belts. The multi-cycle superimposed basins in China generally have a distinctive ‘three ring-like’ oil and gas distribution pattern within each basin area. 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 （455）   HTML （33）    PDF（pc） （4298KB）（498）       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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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 （237）   HTML （12）    PDF（pc） （8436KB）（492）       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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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 （398）   HTML （38）    PDF（pc） （5404KB）（490）       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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What forces are driving the Indian subcontinent to drift northward? LIANG Guanghe, YANG Weiran Earth Science Frontiers    2023, 30 (2): 68-80.   DOI: 10.13745/j.esf.sf.2022.11.5 Abstract （384）   HTML （62）    PDF（pc） （12046KB）（470）       Knowledge map    Save It is widely recognized that the Indian continental plate splits and drifts from Gondwana in the southern hemisphere to its current location, but the driving force behind such movement has been under debate ever since the theory of continental drift was put forward. Quantitative estimation of the driving force may help to resolve the issue. We collected two deep reflection seismic exploration profiles in the passive continental margin basin area of the southern Indian subcontinent. We interpreted the data structurally, estimated the dip angle of Moho surface in detail, and obtained the magnitude of crustal gravity slip shear force which was used to explain the dynamic mechanism of the Indian plate movement. The results show that the Indian continental plate can produce enough gravity slip force on the inclining interface formed by mantle upwelling to drive the Indian subcontinent to drift northward. Hence, a “mantle upwelling and gravity slip” dual-drive continental-drift model is proposed. That is, continental plate can drift by relying on continuous mantle thermal upwelling and gravity slip force. This model can reasonably explain the continental fragments in the Indian Ocean and the genetic mechanism of left rotation in the northward drift of the Indian continent. The gravity-slip driving mechanism provides a new dynamic model for plate motion and more accurate constraints for understanding the driving force behind plate motion. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Formation and distribution potential of global shale oil and the developments of continental shale oil theory and technology in China ZOU Caineng, MA Feng, PAN Songqi, ZHANG Xinshun, WU Songtao, FU Guoyou, WANG Hongjun, YANG Zhi Earth Science Frontiers    2023, 30 (1): 128-142.   DOI: 10.13745/j.esf.sf.2022.8.29 Abstract （516）   HTML （45）    PDF（pc） （5107KB）（466）       Knowledge map    Save The global unconventional shale formations contain rich oil and gas resources, and worldwide there are four major shale formations namely Upper Jurassic, Oligocene-Miocene, Cretaceous and Upper Devonian formations of the Laurasia and Tethys tectonic domains. In this study, the relationship between production and Ro value of typical North America shale oil is identified by cross-analysis, and a Ro value of 0.7% is proposed dividing the low-maturity and medium-high maturity shale oil. In addition, systematic evaluation is performed on low and high maturity shale oil from 157 shale formations in 116 basins around the world, which involves 251.2 billion tons of technically recoverable resources distributed mainly in North America, South America, North Africa and Russia, where the dominant strata are Miocene formations of foreland basins, Paleozoic formations of cratonic basins, and Mesozoic formations of rift basins and passive continental margin basins. Affected by marine transgression since the Phanerozoic marine shale oil is enriched in stable craton and foreland basins with large-scale stable distribution and moderate maturity; whilst due to greenhouse effect continental shale oil developed mainly in depression and fault-depression basins, where micro and nano inorganic pores and micro laminate fractures serve as the main channels for hydrocarbon migration/accumulation characterized by rapid sedimentary transformation and local enrichment in “sweet spots”. China’s petroleum industry is undergoing a transition from “continental shale oil generation” to “continental shale oil production”, with the initial developments of the geological theory on “in-source exploration” of oil/gas source rocks and the technical system for ‘high-efficiency exploration and low-cost development’ of continental shale oil, seeking major breakthroughs in continental shale oil development in China. Future research should focus on the basic applied theories and key technologies, geology-engineering integration, and “full life cycle” management, aiming to accelerate industrial development of “artificially fractured reservoirs” of medium-high maturity shale oil, enhance technical research and industrial testing on in-situ thermal conversion of low-maturity shale oil, promote “continental shale oil revolution” in China, and solidify resource foundation achieved by stabilizing oil production while increasing gas production. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Research methods for the deep extension pattern of rock/ore-controlling structures of magmatic-hydrothermal ore deposits—a preliminary study HAN Runsheng, ZHAO Dong Earth Science Frontiers    2022, 29 (5): 420-437.   DOI: 10.13745/j.esf.sf.2021.11.1 Abstract （236）   HTML （11）    PDF（pc） （14978KB）（466）       Knowledge map    Save The lack of understandings about the deep distribution pattern of rock/ore-controlling structures of magmatic-hydrothermal ore deposits and the spatial positioning pattern of deep deposits (or orebodies) is the main problem holding back deep mineral exploration deployment and hindering ore prospecting breakthroughs. This paper discusses first the main research methods for the deep extension patter of the controlling structures of magmatic-hydrothermal orefields (or deposits). Based on the discussed methods and following the idea that hydrothermal polymetallic ore deposits controlled by regional metallotectonics are associated with geophysical and geochemical anomalies, this paper, taking the Huangshaping-Baoshan copper-tin polymetallic orefield in southern Hunan as an example, constructs a theoretical framework for analyzing the rock/ore-controlling structures and their extension patterns as well as a comprehensive evaluation index system for assessing the depth extension of the controlling structures. Using these methods, through comprehensive analyses of the rock/ore-controlling structures as well as mineralization alteration zoning pattern for magmatic-hydrothermal porphyry in the orefield, this paper predicts the depth extension patterns of the rock/ore-controlling structures and favorable prospecting target sites (within the controlling structures) for the Huangshaping and Baoshan deposits. This paper provides a new method for deep exploration deployment and ore prospecting in the Huangshaping-Baoshan copper-tin polymetallic orefield, and, without doubt, this method can be referenced for advancing the theories of rock/ore-controlling structures and deep prospecting and exploration for other hydrothermal ore deposits. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Mesozoic-Cenozoic tectonic evolution and buried hill formation in central Bohai Bay ZHOU Qijie, LIU Yongjiang, WANG Deying, GUAN Qingbin, WANG Guangzeng, WANG Yu, LI Zunting, LI Sanzhong Earth Science Frontiers    2022, 29 (5): 147-160.   DOI: 10.13745/j.esf.sf.2022.3.36 Abstract （376）   HTML （26）    PDF（pc） （17469KB）（454）       Knowledge map    Save The Bohai Bay Basin is a Late Mesozoic-Cenozoic faulted basin in the eastern North China Craton. Located in the continental active margin of the western Pacific Ocean, the Bohai Bay Basin experienced multi-stage tectonic movements of various types. Currently there is still much controversy over the divisions of tectonic stages and stress fields for each tectonic movement in the Bohai Bay Basin during the Meso-Cenozoic. Buried hill is a palaeogeomorphologic feature formed before the basin filled and then buried by new sedimentary cover. The pre-existing faults inside the buried hill and the contact relationship between the buried hill and the overlying new strata provide an evidence basis for studying the tectonic movement in the basin. Choosing the Bozhong 19-6 buried hill as an example, this paper proposes a new structural model for the buried hill, based on the 3D seismic interpretation and systematic structural analysis of coherent seismic profile and drilling data, and discusses the regional tectonic evolution of the eastern North China Craton. The current structural characteristics of the Bozhong 19-6 buried hill are: (1) The buried hill is bounded by a series of S-N-trending normal faults, which separates it to the east and the Shanan Depression to the west. The buried hill first appeared in the Late Triassic and formed in the Early Cretaceous. (2) The S-N-trending boundary faults and the E-W-trending faults within the buried hill are formed by the transpressive strain due to the regional strike-slip faults along either sides of the buried hill, which are the important controlling factors for the structural reservoir in the buried hill. (3) The buried hill, impacted by the scission-type collision between the North China and Yangtze Plates and the NNW-ward subduction of the Paleo-Pacific Plate, underwent six-stage tectonic evolution since the Mesozoic era: the Early Indosinian compression, the Late Indosinian extension, the Early Yanshanian sinistral transpression, the Middle Yanshanian sinistral transtension, the Late Yanshanian sinistral transpression, and the final Himalayan transtension. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Mesozoic tectonic evolution of the southwestern Bohai Sea and its dynamic mechanism: Implications for the destruction of the North China Craton YE Tao, NIU Chengmin, WANG Deying, WANG Qingbin, DAI Liming, CHEN Anqing Earth Science Frontiers    2022, 29 (5): 133-146.   DOI: 10.13745/j.esf.sf.2021.9.22 Abstract （216）   HTML （12）    PDF（pc） （10842KB）（436）       Knowledge map    Save Mesozoic of the southwestern Bohai Sea experienced multi-stage tectonic activities and records in detail the destruction process of the North China Craton. Here, to clarify the relationship between Mesozoic tectonic evolution in the southwestern Bohai Sea and regional tectonic setting, the structural characteristics of the Mesozoic are determined, its formation and evolutionary processes are restored, and its dynamic mechanism and response to the destruction of the North China Craton are discussed based on the 3D seismic and deep drilling data, combined with regional tectonic background. As results show, (1) differing from the NEE-trending structure of the onshore oil area of the Bohai Bay Basin, the southwestern Bohai Sea develops multi-strike, multi-type structures. The 3D seismic data reveal negative-inversion, strike-slip thrusting, and folding structures that are different from the Cenozoic extensional structures; among them, the NWW-trending negative-inversion structure dominates. (2) Mesozoic of the Bohai Sea undergoes multi-stage deformation, which includes formation of the Indonesian thrust fold, sino-lateral thrust transformation in the Early Yanshan period, negative inversion in the Middle Yanshan period, and fold in the late Yanshan period; among them, thrust fold during the Indosinian movement was the key stage for the buried-hill formation, and the middle Yanshan negative-inversion stage was the key stage for the tectonic transformation. (3) Formation of the NWW-trending structure is related to the South-North China collision during the Indonesian period. The sinistral strike-slip in the early Yanshan period is the result of the NWW-ward subduction of the Pacific plate, which signifies the replacement of the Paleo-Tethys domain by the Pacific domain for controlling the deformation of the North China plate. The negative inversion in the middle Yanshan period corresponds to the large-scale regional magmatic activity, which is the shallow response to the large-scale destruction of the North China Craton. The proposed model of a NWW-trending negative-inversion towards the preexisting structure of the Indosinian in the middle Yanshanian enriches the simple traditional structural model for the destruction of the North China Craton to form the NEE-trending basins. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Carbon dioxide storage in China: Current status, main challenges, and future outlooks DENG Yirong, WANG Yonghong, ZHAO Yanjie, GU Peike, XIAO Jin, ZHOU Jian, LI Zhaohui, YU Zhiqiang, PENG Ping’an Earth Science Frontiers    2023, 30 (4): 429-439.   DOI: 10.13745/j.esf.sf.2023.2.70 Abstract （599）   HTML （34）    PDF（pc） （3840KB）（431）       Knowledge map    Save Excessive fossil fuel consumption and land misuse lead to continuous increasing emissions of carbon dioxide and other greenhouse gases, causing a series of environmental problems such as global warming. To effectively control carbon emissions underground carbon storage is developed and it plays an important role in China’s efforts to achieve carbon neutrality while ensuring its energy supplies. Here, we systematically summarize the technical principles and characteristics of typical terrestrial (such as CO2-EOR and CO2-ECBM) and marine carbon sequestration techniques (such as natural gas hydrate sequestration and marine sediment sequestration), and present an overview of China’s carbon emission profile and storage potential, characteristics of domestic carbon-storage pilot projects at different capacities (10000 s to million tons), gaps between China and foreign countries, and main challenges in carbon sequestration. In view of China’s carbon-storage status and goal of carbon peaking/carbon neutrality, we suggest to improve policy support, storage evaluation standards, and relevant laws and regulations, explore suitable storage sites and high-potential areas, strengthen scientific research and access to advanced technology, increase CCS/CCUS infrastructure investments and construction scales, and develop model pilot projects and industrial clusters. As Guangdong Province possesses industrial (trillion ton) carbon-storage potential ahead of carbon peaking, its coastal areas with the greatest carbon storage potential should take the lead in the industrial application of underground carbon-storage technology as well as in the developments of industrial carbon-storage clusters and trillion-ton carbon-storage industry towards achieving China’s carbon neutral target. Table and Figures | Reference | Related Articles | Metrics | Comments（0）

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Carbon sequestration, transport, transfer, and degassing: Insights into the deep carbon cycle CHEN Xueqian, ZHANG Lifei Earth Science Frontiers    2023, 30 (3): 313-339.   DOI: 10.13745/j.esf.sf.2022.12.51 Abstract （461）   HTML （31）    PDF（pc） （7116KB）（410）       Knowledge map    Save Carbon plays a fundamental role in subduction zones in melting enhancement, magma genesis and evolution, and petrological/thermodynamic processes in the deep Earth. The occurrence state of carbon in the deep Earth is controlled by temperature, depth (pressure), oxygen fugacity, and fluid property. When carbon of various occurrence states is transported to the deep Earth via subducting slab and then returns to the atmosphere through degassing, the so-called ‘deep carbon cycle’ is realized. Carbonation/decarbonation reactions are the main mechanisms affecting carbon transfer between the solid Earth, the atmosphere, and the oceans. Carbonation processes include silicate weathering, hydrothermal alteration, trench outer-rise serpentinization, organic carbon burial, and reverse weathering; while carbon transport is achieved by subduction of depositional and metasomatic sediments. Surface carbon, when transported to the Earth’s interior, may be retained within the subducting slab, transferred into the upper mantle wedge, or recycled into the deep Earth depending on the depth and redox state under specific tectonic settings; that carbon is then returned to the atmosphere via decarbonation mechanism through volcanic degassing, diffuse degassing in the forearc, dissolution, metamorphism, and melting to maintain a carbon balance at subduction zones. This systematic review summarizes the carbon occurrence states, carbon movements and change of carbon-bearing phases during carbon sequestration, transport, transfer, and degassing relevant to deep carbon cycling and the related carbon fluxes, analyzes the reasons for the inconsistencies in carbon-flux estimates, and discusses future research directions. Since the industrial revolution anthropogenic CO2 emission has contributed greatly to global warming, exerting extra pressure on Earth as a self-regulating system. In the context of transition to a low-carbon economy, China adheres to energy conservation, carbon emission reduction, and forest growth, and aims to peak CO2 emissions by 2030 and achieve carbon neutrality by 2060 to address the world climate crisis. Table and Figures | Reference | Related Articles | Metrics | Comments（0）