Geoscience

The Oxidation of the Big Mantle Wedge Beneath Eastern China

LI Xinyi, DONG Xuhan, HUANG Hui, DENG Yangfan, WANG Shuijiong

2025, 39(02): 239-247. DOI: 10.19657/j.geoscience.1000-8527.2025.026

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The Big Mantle Wedge (BMW), since first proposed in eastern China, has been extensively studied. The deep volatile cycling in the BMW system has a great impact on the redox state of the mantle. Here, we review geochemical data of the Cenozoic intraplate basalts and enclosed mantle xenoliths from eastern China, and find that the intraplate basalts are highly oxidized, with their oxygen fugacity higher than the lithospheric mantle as represented by the mantle xenoliths, based on metal stable isotope geochemistry, V-in-olivine oxybarometry, and bulk rock Fe³⁺/∑Fe. Therefore, we propose that the BMW has experienced one or multiple oxidation events, whose trigger mechanism is closely linked to the deep carbon cycle. The subduction of western Pacific slab has delivered a large amount of sedimentary carbonates into the deep mantle, facilitating carbon-iron redox reaction in the mantle transition zone. The diamond produced during the carbon-iron redox reaction in mantle transition zone due to its high density, making the resulting melts highly enriched in Fe³⁺/∑Fe, and the forming the highly oxidized mantle endmember (HOME), likely serving as a crucial medium for the transportation of precious metals and sulfides in the deep mantle.

Deciphering Microbial-Mediated Uranium Mineralization via FIB-TEM Nanotomography: A Case Study from the Hailijin Deposit, Songliao Basin

JIN Weiguo, YIN Shuo, WANG Qingfei, PAN Jiayong

2025, 39(02): 248-262. DOI: 10.19657/j.geoscience.1000-8527.2024.133

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Resolving the evidentiary gap in microbe-mineral interactions within sandstone-hosted uranium systems, this study presents nanoscale evidence elucidating the biogeochemical controls on uranium mobilization.Focusing on uranium-bearing monazite in the Lower Yaojia Formation of the Hailijin deposit, we integrate FIB-TEM nanotomography with EPMA geochemical mapping to decode dissolution-uranium release coupling mechanisms.Three pivotal findings emerge: (1) Quartz-encapsulated monazite preserves pristine surfaces, whereas exposed grains exhibit 75% uranium depletion with intense dissolution features; (2) FIB-TEM nanotomography reveals epitaxial overgrowths of chernikovite and uraninite nanoparticles along dissolution fronts, forming characteristic U-P biogeochemical halos; (3) The established biofilm catalytic kinetics model shows that the microbe-mediated interfacial reaction activates uranium to precipitation.This study not only provides critical microscopic-scale evidence elucidating synergistic mineralization mechanisms between microorganisms and nano-minerals, but also holds significant implications for advancing uranium deposit geology research into refined microscopic domains.

Thermodynamic-Geochemical Signatures of Ore-Forming Fluids in the Gudui Sb-Polymetallic District, Southern Tibet: Implications for Sb Enrichment and Deposit Genesis

LOU Yuanlin, CHENG Ming, CHEN Wu, TANG Yao, ZENG Hao, CHEN Kun, YUAN Yongsheng, YANG Tao

2025, 39(02): 263-266. DOI: 10.19657/j.geoscience.1000-8527.2024.115

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The Gudui area of southern Tibet is situated in the mid-Himalayan segment of the Tethys-Himalayan tectonic domain, adjacent to the Yarlung Tsangpo suture zone in the north. A series of Sb-polymetallic deposits have been newly discovered in this region, though limited scientific research currently constrains understanding of their genesis and regional metallogenic controls. This study investigates three representative deposits (Qiaga, Naqiong, and Zhuomuri) through detailed geological characterization and systematic analysis of ore-forming fluids to constrain physicochemical conditions (composition, temperature, salinity, pressure) and metallogenic depth. Our results reveal that Sb-dominated ores contain primarily liquid-rich fluid inclusions, whereas Pb-Zn ores host three-phase (liquid-vapor-solid) inclusions. Stibnite mineralization temperatures (180-208 ℃) are slightly lower than Pb-Zn mineralization (203-230 ℃), with salinities of 3.0%-9.9% NaCl eq. The CO₂-dominated gas phase contains minor N₂, CH₄, and H₂O, consistent with a medium-low temperature, low-salinity NaCl-H₂O hydrothermal system. Calculated pressures (33-71 MPa) and depths (1.2-2.6 km) indicate shallow crustal mineralization. Hydrogen and oxygen isotopes reveal mixed fluid sources: δD_(V-SMOW) values (-64.6‰ to -70.2‰ and -135.2‰ to -129.4‰) and δ¹⁸ $O H 2 O$ values (+2.9‰ to +5.2‰ and +6.6‰ to +9.9‰) suggest formation water dominance with shallow crustal contributions. These findings demonstrate that the Gudui Sb-polymetallic deposits represent shallow epithermal systems dominated by formation waters, with vertical zonation implying potential Au-Sb and Pb-Zn-Sb mineralization at depth beneath existing Sb ores.

Petrogenesis and Tectonic Implications of Granite Porphyry Veins in the Shangjiao Uranium Deposit, Eastern Nanling Range

LAI Jing, LIU Wenquan, ZHONG Fujun

2025, 39(02): 277-293. DOI: 10.19657/j.geoscience.1000-8527.2024.062

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To further constrain the Mesozoic geodynamic background and tectonic evolution of South China, this study investigates zircon U-Pb geochronology, Hf isotopes, and geochemical characteristics of granite porphyry from the Shangjiao Uranium Deposit in the Longyuanba pluton.Zircon U-Pb dating yields weighted mean ²⁰⁶Pb/²³⁸U ages of (190.6±2.2) Ma (MSWD=0.11) and (190.6±1.3) Ma, indicating Early Jurassic emplacement.Bulk-rock analyses reveal the granite porphyry is characterized by high silica (SiO₂=68.97%-69.56%), alkali enrichment (Na₂O+K₂O=9.12%-9.28%), and depletion in calcium (CaO=0.50%-1.22%), magnesium (MgO=0.09%-0.11%), and phosphorus (P₂O₅=0.05%), classifying as high-K calc-alkaline (σ=3.16-3.27) metaluminous to weakly peraluminous rocks (A/CNK=0.98-1.09).Geochemically, the rocks show enrichment in large-ion lithophile elements (Rb, Th, U), depletion in high-field-strength elements (Zr, Hf, Nb, Ta, Ti), light rare earth element enrichment with negative Eu anomalies, and heavy rare earth element depletion, collectively indicating an A-type granite affinity.Zircon ε_Hf(t) values range from+5.39 to+9.07 (average+6.91), corresponding to two-stage model ages (T_DM2) of 652-887 Ma, suggesting derivation primarily from Neoproterozoic juvenile mafic crust formed through mantle magma differentiation.The granite porphyry formed in an intraplate extensional setting during Paleo-Pacific Plate subduction, with the Longyuanba pluton serving as critical evidence for the tectonic transition between the Paleo-Tethyan and Paleo-Pacific regimes.Combined with the chronological characteristics of regional magmatic rocks and the tectonic setting of South China, it was concluded that the transition from the Tethy orogenic regime to the Paleo-Pacific tectonic regime already started before 190 Ma.

Genesis and Environmental Response of Siliceous Rocks in the First Member of Longjiayuan Formation of Mesoproterozoic, Western Henan

LI Qianqian, ZHENG Deshun, SUN Fengbo, WANG Xin

2025, 39(02): 294-311. DOI: 10.19657/j.geoscience.1000-8527.2024.075

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Siliceous rocks in different geological periods have complex genesis, and their sources of silica are influenced by various factors such as microorganisms, terrestrial debris, seawater conditions, and hydrothermal fluids.Siliceous rocks serve as important indicators of sedimentary environments at different stages of tectonic evolution.The concentration of dissolved form of silicic acid is high in the Precambrian ocean, but the silica source of the siliceous rocks and the formation process of siliceous sediments in the southern margin of the North China Craton have not been extensively studied.The siliceous rocks of the first member of the Longjiayuan Formation in the Mesoproterozoic Guandaokou Formation in Western Henan are of various types and show continuous development.Based on their petrological characteristics and combined with analyses of major and trace elements, the silica sources, formation processes, and mechanisms of the Longjiayuan siliceous rocks were studied.The results show that the Longjiayuan siliceous rocks are uniformly distributed in the section and can be classified into bedding-banded, deformed stratified, nodule-massive, and chrysanthemum-like forms.Geochemical analyses including discriminant diagrams of Al/(Al+Fe+Mn) values as well as Ce/Ce^* and Eu/Eu^* values suggest two sources of silica components: hydrothermal and dissolved silica from seawater.The formation process of the siliceous rocks can be divided into three stages: sedimentary, early diagenetic, and diagenetic stages.During the sedimentary stage, silica components in seawater are mainly deposited in the form of siliceous colloids.During the early diagenetic stage, unconsolidated siliceous sediments aggregate in low-lying areas under the influence of gravity, forming some storm-induced siliceous rocks under the action of external forces such as storms.During the diagenetic stage, siliceous sediments are gradually consolidated under the pressure of diagenesis, forming layered siliceous rocks in gently sloping areas and massive siliceous rocks in low-lying areas.The siliceous rocks of the first member of the Longjiayuan Formation record the Mesoproterozoic sedimentary environment of the southern North China Craton, indicating a stable, open shallow marine setting in western Henan, conducive to silica enrichment and preservation.

Properties and Distribution of Diagenetic Fluids in Ordovician Carbonate Reservoirs in Tazhong Region of Tarim Basin

HAN Huiping, MA Jia, ZHANG Yi, PAN Yinglu

2025, 39(02): 312-326. DOI: 10.19657/j.geoscience.1000-8527.2022.067

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The Ordovician carbonate rocks in Tarim basin, which located in the northwestern China, are considered as important reservoirs. Observation of cores and slices indicates that the buried fluid plays an important role in controlling the reservoir. The dissolved pores and secondary minerals during the burial period (calcite, pyrite, etc.) are all related to the activity of the buried fluid. Taking the Ordovician carbonate rock fillings and surrounding rocks in the Tazhong area as the research objects, the research on the properties of buried fluids in the study area was carried out using the methods of carbon, oxygen, strontium isotope, rare earth elements, trace elements and inclusions temperature. It was found that the main fluid types in the study area were normal formation waters, and there were hydrothermal fluid activities in some areas. Due to the slightly different geochemical characteristics, hydrothermal fluids were divided into two types: magmatic hydrothermal fluids and deep circulating hot brines. The geochemical characteristics of normal formation water fluids are that the homogenization temperature of inclusions is lower than the highest burial temperature (120 ℃) in this area, the oxygen isotope composition is from -6.64‰ to -4.23‰, and the strontium isotope value is ⁸⁷Sr/⁸⁶Sr<0.709. The distribution pattern of rare earth elements is consistent with the surrounding rock, and the variation range of δEu is from 0.627 to 0.921. The geochemical characteristics of hydrothermal fluids are the homogenization temperature of the inclusions is higher than the maximum burial temperature of surrounding rocks by more than 5 ℃(125 ℃) and it is of the lighter oxygen isotope composition (from -15.18‰ to 7.09‰). The distribution pattern of rare earth elements is different from the surrounding rock limestone. Some of the hydrothermal fluid samples have ⁸⁷Sr/⁸⁶Sr values (from 0.707,82 to 0.709,03) consistent with the international Ordovician sedimentary carbonate rock standard, with obvious Eu positive anomaly (δEu varies from 1.24 to 20.906), and has a low Th/U value (<0.45). This part of the hydrothermal fluid is magmatic hydrothermal fluid. Others hydrothermal fluid samples have a high ⁸⁷Sr/⁸⁶Sr value (>0.709), and inclusions have high salinity (≥15%NaCl). The main intrusive rocks of the Ordovician in the Tazhong area are diabase, and the diabase should have a lower ⁸⁷Sr/⁸⁶Sr value, which conflicts with the higher ⁸⁷Sr/⁸⁶Sr value in the sample. It is considered that the fluid with the high strontium isotope value in the clastic rock formation is circulated to the carbonate rock formation under the influence of magmatic heat and geothermal gradient, causing some samples to have higher ⁸⁷Sr/⁸⁶Sr values (from 0.709,185 to 0.709,853). This part of the hydrothermal fluid is hot brine circulating in deep. The movement of hydrothermal fluids is mainly controlled by deep faults. Magmatic activities lead to the formation of hydrothermal fluids directly or indirectly.

Provenance Analysis and Sedimentary Facies Distribution of Jingjingzigou Formation in the Southeastern Margin of the Junggar Basin

WEI Chaofan, ZHANG Zhijie, WAN Li, CHENG Dawei, LI Shunli, SUN Hongwei

2025, 39(02): 327-350. DOI: 10.19657/j.geoscience.1000-8527.2025.011

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The Lower Permian Jingjingzigou Formation, a significant oil and gas reservoir in the southeastern margin of the Junggar Basin, has been a key research focus due to its complex sedimentary characteristics and provenance system. This study investigates the Jingjingzigou Formation exposed in the Sigonghe, Jingjingzigou, Hongyanchi, and Aiweiergou sections of the southeastern Junggar Basin. Detailed field descriptions and sedimentary facies interpretations, combined with provenance tracing techniques including heavy mineral associations, the ZTR index, Q-type cluster analysis of heavy minerals, and zircon U-Pb dating, were employed to investigate the provenance system and sedimentary characteristics of the formation in the study area. The results indicate that during the sedimentary period of the Jingjingzigou Formation in the eastern Bogda Peak area, East Bogda Mountain served as the primary provenance, with the Beisantai Uplift as the secondary source. In this region, low-relief, broad paleogeomorphic settings favored the development of distal braided river slope deposits. The Bogda Peak area, characterized by local uplifts, exhibited a primary provenance and developed proximal braided river and turbidite deposits. The Aiweiergou section was primarily sourced from Yilinheibiergen Mountain and was marked by the development of a proximal fan delta under the influence of tectonic uplift. By integrating the provenance and sedimentary system studies, this research clarifies the presence of a bidirectional (east-west) provenance system in the Jingjingzigou Formation along the southeastern margin of the Junggar Basin. This study refines the understanding of the sedimentary distribution patterns and successfully established a comprehensive tectonic-sedimentary model for this region during the Early Permian, providing a theoretical basis for oil and gas exploration in the region.

Microstructure and Paleoenvironmental Significance of Dinosaur Egg Fossils from the Late Cretaceous Lianhe Formation in Zhanggong District, Ganzhou City, Jiangxi Province

LI Jing, SHI Guo, LOU Fasheng, YANG Ling, XU Mengyuan, YU Juan

2025, 39(02): 350-360. DOI: 10.19657/j.geoscience.1000-8527.2024.104

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As the most important late Cretaceous dinosaur egg fossil producing area in China, Ganzhou’s fossil record has unique value in revealing dinosaur breeding behavior and paleoenvironmental evolution.In this study, multi-scale analysis (polarizing microscope, scanning electron microscope and sedimentology) was used to systematically study the newly discovered dinosaur egg fossils in the Lianhe Formation (K₂l) in Zhanggong area.The results showed that: (1) The egg body was elongated in appearance, with a long diameter of 165-184 mm (mean 174 mm) and an equatorial diameter of 65-79 mm (mean 73 mm).The egg body was ridged in shape, and the ratio of the thickness of the shell columnar layer to the pyramidal layer was about 6:1, which was confirmed as Elongatoolithus magnus.(2) Under the scanning electron microscope, the pyramidal layer was intact and neatly arranged, the interior was dense, and the mastoid space was small, indicating that the nest of dinosaur eggs should be in the early stage of embryo hatching.The columnar layer mainly develops vertical micro-pores, which is conducive to the exchange of gas and water.There is a loose layer with large pores on the columnar layer, which can protect the eggshell.The large eggshell thickness may be affected by the arid-semi-arid climatic conditions at the end of the Late Cretaceous.(3) According to the lithology and structure of the strata containing dinosaur eggs, the study area belongs to the sedimentary facies of the middle-distal braided channel of the alluvial fan, and from the preservation state of the egg nest, it can be seen that the egg fossils are buried in situ.

Sedimentary Filling Processes of Quaternary Deposits in the Dachang Depression, North Hebei Plain

ZHANG Jinlong, PAN Zhilong, ZHANG Yunqiang, ZHANG Huan, HOU Dehua, SHI Guangyao

2025, 39(02): 361-370. DOI: 10.19657/j.geoscience.1000-8527.2024.016

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The establishment of the Quaternary sedimentary framework in the Hebei Plain provides fundamental constraints for regional stratigraphic correlation and depositional environment studies. To further elucidate the sedimentary characteristics of Quaternary unconsolidated deposits in the Dachang Depression of northern Hebei Plain, this study integrates sedimentological analysis and paleomagnetic investigations with previous data from the Sanhe standard borehole (San9) in Langfang City. Eight Quaternary boreholes aligned along the NNE-trending axis of the depression were systematically analyzed through stratigraphic subdivision, sedimentary facies discrimination, and cross-section correlation, enabling comprehensive reconstruction of the three-dimensional geological architecture and fluvial-alluvial fan migration history. Analytical results demonstrate that the Quaternary deposits originated from synergistic interactions among the Baoqiu River, Ju River, and Duanjialing alluvial fan system. The San9 borehole reveals Early Pleistocene dominance by alluvial fan deposition under arid conditions. During the middle Pleistocene, warmer climate promoted enhanced drainage development, characterized by fluvial sedimentation with localized alluvial fan activity. Late Pleistocene witnessed gradual attenuation of north-south topographic relief, leading to alluvial fan contraction and widespread floodplain deposition by paleo-Ju and paleo-Baoqiu rivers. Holocene climate amelioration triggered pronounced fluvial incision, particularly along the paleo-Baoqiu channel. The current geomorphic configuration reflects stabilization phases of the Baoqiu-Ju river system and Duanjialing alluvial fan complex since the Late Quaternary.

Sedimentary Environmental Evolution and Stratigrphic Division of the Hinterland of Huang-Huai-Hai Plain Since 750 AD

TIAN Chenlong, XU Fenglin, TIAN Pengfei

2025, 39(02): 371-383. DOI: 10.19657/j.geoscience.1000-8527.2024.015

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Lake Liangshanpo is located in the hinterland of Huang-Huai-Hai Plain, the detailed stratigraphic correlation division and regional sedimentary environment analysis can help to construct the project in Lake Liangshanpo.Based on the lithology, grain size, and sporopollen analysis of sediments in ZK1-ZK4 drilling cores of Lake Liangshanpo, along with the results of ¹⁴C dating, a new stratigraphic division scheme was established and the sedimentary environment evolution process during the past 1,000 years was reconstructed of Huang-Huai-Hai plain.The Lithostratigraphy, Biostratigraphy, Chronostratigraphy are selected to multiple classify and correlate the strata of Lake Liangshanpo, the results showed that the Ⅰ stratigraphic and Ⅱ stratigraphic belong to Baiyunhu formation; the Ⅲ stratigraphic, Ⅳ stratigraphic and Ⅴ stratigraphic are divided into the Juye formation.The elimate of the Ⅰ stratigraphic (formed in 750-900 AD) of Lake Liangshanpo relatively cool and dry, which was a sedimentary marsh environment; the sedimentary environment of the Ⅱ stratigraphic (formed in 900-1,200 AD) was a deep lake facies, and the climate became warm and humid; during the formation period of the Ⅲ stratigraphic (formed in 1,200-1,300 AD), the climate was warm and humid, and the sedimentary environment was fluvial facies; the sedimentary characteristics found in the Ⅳ stratigraphic (formed in 1,300-1,500 AD) indicate that the sedimentary environment is a disturbed and stable deep lake environment, and the climate changes from warm and humid to cool and dry; the sedimentary environment of the Ⅴ stratigraphic (formed in 1,500 AD till now) changed from lake facies to fluvial facies, and the climate was cold and dry.

Reflections on Building a Comprehensive Observation Network for Natural Resource Components: A Case Study of the Middle and Lower Yangtze River Basin

REN Jijun, XIAO Yuexin, SUN Zelong, ZHAO Yuan, CHENG Ming, CHEN Panpan, LAN Jianmei

2025, 39(02): 384-395. DOI: 10.19657/j.geoscience.1000-8527.2024.145

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Building on the strategic guidance provided by the “Development of Scientific and Technological Innovation in Natural Resources”, this study explores the innovative development of a multi-technology integrated observation system for natural resource elements, focusing on the core area and ecological barrier of the middle and lower Yangtze River Basin.The research systematically addresses three critical constraints affecting regional observation network effectiveness: Ⅰ) Lack of systemic coupling due to single-element monitoring; Ⅱ) Data heterogeneity hindering cross-domain integrated analysis; Ⅲ) Lagging intelligent technology application limiting dynamic assessment capabilities.Breaking through traditional monitoring paradigms byintroducing the innovative “three-level gradient observation system”, the study pioneers a dimensional station network framework of “1+12+52”(comprehensive central station-regional stations-specialized stations), effectively bridging the research gap in basin-scale natural resource system coupling.Taking Huangshan Observation and Research Station for Land-water Resources as an example, multi-element collaborative monitoring has significantly enhanced data collection efficiency, enabling synchronous dynamic monitoring of hydrological, soil, and vegetation parameters.The innovation in the technical system leads to the development of a “coupling of elements-process simulation-effect assessment” observation paradigm, which markedly improves the analysis of ecological processes and the prediction of system responses.Practical applications demonstrate that the comprehensive observation network effectively resolves fragmentation issues in traditional monitoring, providing full-element, multi-scale data support for dynamic resource management in the Yangtze Economic Belt.The innovative design offers a scalable reference for building a “mountain-water-forest-farmland-lake-grassland-desert” life communities.The research outcomes substantially enhance regional ecological security early-warning capabilities and scientific decision-making levels, providing crucial technical support for modernizing China’s natural resource governance system.Implementation results show significant improvements in cross-departmental data interoperability and ecological risk prediction accuracy compared to conventional methods.

County-Scale Spatiotemporal Dynamics and Drivers of Habitat Quality in the Capital Economic Zone

ZHU Meitao, XING Liyuan, NIU Xueyao, LIU Xiaohuang, WU Jie, SONG Dongyang, GONG Lun, AN Hongyan

2025, 39(02): 396-409. DOI: 10.19657/j.geoscience.1000-8527.2024.124

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To assess the spatiotemporal dynamics of habitat quality and its drivers in the Capital Economic Zone (CEZ) from 1990 to 2020, we integrated multi-source, heterogeneous remote sensing data and biophysical models to evaluate habitat quality trends. Spatial autocorrelation analysis revealed distinct spatial clustering patterns, while a spatiotemporal geographically weighted regression (GTWR) model quantified the temporally and spatially heterogeneous impacts of natural, socio-economic, and landscape configuration factors. Key results indicate: (1) Habitat quality distribution strongly correlates with land-use types, with forests exhibiting the highest quality and built-up/agricultural lands the lowest. Despite relative spatial stability, the CEZ experienced a 3.51% mean decline in habitat quality, concentrated in rapidly urbanizing Tianjin (-23%) and Langfang (-21%); (2) Habitat quality displayed persistent positive spatial autocorrelation (Moran’s I), with high-high clusters in northwestern districts (ecologically stable zones) and low-low clusters in southeastern districts (urban/agricultural cores), consistent with regional urbanization gradients; (3) Driver impacts diverged spatiotemporally: precipitation, NDVI (vegetation cover), elevation, and landscape connectivity metrics (NP, PD, IJI, SPLIT) enhanced habitat quality, whereas temperature, GDP, population density, and fragmentation indices (SHAPE, PARA_MN, PRD, SHDI) degraded it. Patch cohesion (COHESION) exhibited spatially balanced positive/negative effects. This work provides a mechanistic framework to disentangle urbanization-ecology trade-offs, supporting spatially targeted policies for sustainable development in metropolitan regions.

H-O Isotope Signatures of Three Water Bodies in the Lhasa-Nyang River Basin, Tibetan Plateau: Source Discrimination and Hydrologic Connectivity

ZHANG Xunxun, WEN Lang, YANG Bin, ZHAO Yanggang, XING Liyuan, DUAN Yanghai, PU Chun

2025, 39(02): 410-419. DOI: 10.19657/j.geoscience.1000-8527.2024.127

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To investigate isotopic variability and hydrological processes in the Lhasa-Nyang River Basin, 278 water samples (including precipitation, surface water, and groundwater) were collected between April and November 2021.Stable isotopes of hydrogen (δ²H) and oxygen (δ¹⁸O) were analyzed using laboratory experiments and statistical methods.Key findings include: (1) Precipitation isotopes in the basin reflect a shared atmospheric circulation background dominated by summer monsoon moisture.The Nyang River sub-basin exhibits narrower isotopic variability and greater enrichment in heavy isotopes compared to the Lhasa River sub-basin.Temperature and precipitation amount exert significant positive correlations (P<0.05) with precipitation δ¹⁸O, whereas relative humidity and elevation show negative correlations.(2) Surface water and groundwater δ¹⁸O values exhibit progressive depletion with increasing elevation, demonstrating distinct altitudinal gradients of -0.27‰ per 100 m (‰/hm) and -0.29‰/hm, respectively.(3) Both surface water and groundwater are predominantly recharged by atmospheric precipitation, as evidenced by overlapping isotopic ranges and bidirectional isotopic exchanges indicative of hydraulic connectivity.This study provides critical baseline isotopic data for clarifying basin-scale hydrological cycling, including moisture sources, recharge mechanisms, and surface-groundwater interactions.The findings advance understanding of water resource sustainability and ecohydrological resilience in the Yarlung Zangbo River system, with implications for managing freshwater availability and mitigating climate-driven hydrological risks on the Tibetan Plateau.

Retrieval of Chlorophyll-a Concentration in the Yellow Sea Based on a BP Neural Network Model

LIU Zihua, YOU Zhongyi, LIU Jiufen, LIU Xiaohuang, ZHAO Xiaofeng, LI Ziqi, ZHANG Wenbo, LI Hongyu, YIN Yonghui, SHI Lianwu

2025, 39(02): 420-428. DOI: 10.19657/j.geoscience.1000-8527.2024.128

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The concentration of chlorophyll-a in marine waters is one of the key indicators for assessing the ecological environment and water quality of oceans, which plays a crucial role in marine resource management and protection.Focusing on the Yellow Sea, this study constructs a chlorophyll-a concentration inversion model based on 2022 VIIRS remote sensing data using a BP neural network machine learning method.The model features a three-hidden-layer architecture with 4-6-4 nodes and takes multi-band remote sensing reflectance and sea surface temperature during the same period as input data.The results are compared with commonly used models, such as OC2, OC3, linear, and cubic models.The comparison shows that all five models can be used for chlorophyll-a concentration inversion in the Yellow Sea, but the model designed in this study exhibits smaller inversion errors (with relative errors generally less than 12%, and an average relative error of 8.2%), outperforming the other models.To further assess the model’s performance, a comprehensive evaluation index was applied, demonstrating that the inversion results (MAE=0.122, RMSE=0.153, R²=0.937) meet the expected accuracy.Additionally, the model’s generalization ability was tested using VIIRS remote sensing data and sea surface temperature data from February 2021.The validation shows that the model has good generalization ability and can be used for inversion tasks in other periods within the same region.This study demonstrates the feasibility of using a BP neural network model based on VIIRS data for monitoring ocean chlorophyll-a, which provides a foundation for related practices and research.

Hydrochemistry and H-O Isotopic Constraints of Geothermal Fluids in the Guantao Formation in the Eastern Hebei Plain: Implications for Geothermal Reservoir Dynamics

XU Yiming, LI Aoyu, CHENG Liqun, DU Lixin, ZHANG Yanshuai, HAO Wenhui, LIU Liang

2025, 39(02): 429-439. DOI: 10.19657/j.geoscience.1000-8527.2023.056

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The Neogene Guantao Formation geothermal reservoir in the Eastern Hebei Plain represents a clastic porous layered heat reservoir characterized by superior geothermal geological conditions. To facilitate the scientific conservation and rational utilization of these geothermal resources, this study presents comprehensive analysis of the chemical and H-O isotopic compositions of 16 geothermal water samples collected from various geological units within the Eastern Hebei Plain. Experimental results reveal that the primary hydrochemical types of the Guantao Formation geothermal water are HCO₃· SO₄-Na, HCO₃·Cl-Na, SO₄·Cl-Na, with pH values ranging from 7.78 to 8.62 and salinity levels between 722.3 and 2619 mg/L. The geothermal water exhibits elevated concentrations of F^-, SiO₂, TDS, Sr, Zn, Br, I, Fe, Mn, and HBO₂. However, concentrations of certain elements associated with magmatic hydrothermal activities (such as F, B, As, Li, etc.) are significantly lower compared to those found in Yangbajing and Dagejia in Tibet. H-O isotopic analysis indicates δD values ranging from -71‰ to -73‰ and δ¹⁸O values from -7.6‰ to -9.8‰, suggesting a recharge elevation of 800 to 1300 meters. The geothermal water primarily flows from northwest to southeast, with minimal interaction with overlying shallow strata water. It is predominantly recharged by lateral flow within the same layer and the upward migration of Ordovician hot fluids from the Paleozoic erathem, classifying it as deep-circulation heated groundwater. Atmospheric precipitation from the Yanshan area percolates downward along fault structures under gravitational force, flowing southeastward. As the groundwater is progressively heated by deep crustal thermal sources, water-rock interactions intensify, leading to a significant increase in mineral content. With increasing circulation depth and distance, the geothermal water environment becomes more confined, resulting in a gradual reduction in water renewal rates. Desulfation processes occur within the geothermal water, which also mixes with underlying deep geothermal fluids, altering the primary ion composition. This study provides a scientific foundation for understanding the formation and evolution of geothermal water in the Guantao Formation.

Hydrochemical Characteristics and Genesis analysis of Shallow Groundwater in the Lower reaches of Nanfei River, Anhui Province

WANG Runtao, QIAN Jiazhong, WANG Xiuxuan, MA Haichun, WANG Xiaoyong

2025, 39(02): 440-446. DOI: 10.19657/j.geoscience.1000-8527.2022.028

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In order to explore the hydrochemical characteristics and genesis of shallow groundwater in the lower reaches of Nanfei River, Anhui Province, 87 groups of shallow groundwater samples were collected. By using Piper trigram, Shukalev classification, Gibbs model, ion ratio method and mathematical statistics, the hydrochemical characteristics and genesis of shallow groundwater in the lower reaches of Nanfei River were analyzed, and their genesis were further revealed. The results show that the average pH value of the shallow groundwater in the lower reaches of Nanfei River is 7.61, showing weak alkalinity. The average value of cation content is in the order of Na⁺ >Ca²⁺ >Mg²⁺ from high to low, and the average value of anion content is in the order of $\mathrm{HCO}_{3}^{-}>\mathrm{SO}_{4}^{2-}>\mathrm{Cl}^{-}$ from high to low. Na⁺ and $\mathrm{HCO}_{3}^{-}$ are the dominant ions in cations and anions respectively. In addition, the distribution of shallow groundwater chemical types in the lower reaches of Nanfei River is relatively rich, with a total of 15 hydrochemistry types, and the main hydrochemistry types can be divided into HCO₃-Na·Ca, HCO₃·Cl-Ca·Na, HCO₃-Ca·Na·Mg, HCO₃·SO₄-Ca·Na, HCO₃·SO₄·Cl-Na·Ca. By considering the influence of water-rock interaction, we find that the hydrochemical composition of the shallow groundwater in the lower reaches of Nanfei River is mainly controlled by rock weathering and dissolution and affected by dissolution of carbonate mineral. Meanwhile, cation exchange plays an important role in the hydrochemical characteristics of shallow groundwater.

Multi-dimensional Drivers of Wetland Evolution in the Yellow River Delta Since 1980 and Sustainable Management Strategies

BA Yinji, PANG Guotao, LIU Xiaohuang, DOU Wenjun, LI Chuang, GAO Jinhua, MA Ruqiang

2025, 39(02): 447-455. DOI: 10.19657/j.geoscience.1000-8527.2024.125

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The Yellow River Delta wetland is the largest and most well-preserved wetland in the Yellow River Basin.However, issues such as soil salinization and fragile ecological environment caused by seawater intrusion have not been completely resolved, necessitating further strengthening of monitoring and research on relevant resource and environmental indicators of wetland resources.This study takes the modern Yellow River Delta wetland as the research area and employs a combination of remote sensing interpretation and soil and vegetation surveys to systematically analyze the wetland resources of the Yellow River Delta.The study quantitatively analyzes the changes in wetland area since 1980 and the influencing factors of wetland resource evolution, and proposes scientific protection and restoration strategies.The results show that: (1) The wetland area has shown a trend of first decreasing and then increasing.Before 2000, the wetland area decreased, and it began to increase after 2000.The center of gravity of wetland area changes shifted from the southeast to the northwest.(2) The evolution of wetland resources is driven by a combination of factors, including Yellow River runoff, sediment load, and precipitation.With the reduction of Yellow River water supply, the water cycle of the Yellow River Delta wetland is in a precarious situation.Human industrial activities have a significant impact on wetlands, but the establishment of nature reserves has played a positive role in the protection and restoration of wetland resources.(3) The soil salinity variation during the evolution of wetland resources shows that soil salinity decreases from the coast to the inland, and the influence of groundwater on soil salinity increases with depth.Combined with the study of wetland vegetation distribution characteristics, it is further confirmed that soil and water salinity changes are important factors affecting the structure of wetland vegetation communities.Yellow River runoff, sediment transport, and human activities are the driving factors of wetland resource evolution.Therefore, suggestions for rational water and sediment regulation, protection and utilization, and publicity and education are proposed to support the protection and restoration of Yellow River Delta wetland resources.

Spatiotemporal Dynamics, Zoning, and Sustainable Utilization of Soil Salinization in the Yellow River Delta

WANG Bing, DOU Wenjun, CHEN Jie, CHEN Jingwen, LAI Jianbin

2025, 39(02): 456-466. DOI: 10.19657/j.geoscience.1000-8527.2024.070

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It is of strategic significance in the Yellow River Delta (YRD), whether it is ecological protection or agricultural development.The layout of the agricultural structure based on the salinity of soil resources is the prerequisite for the high-quality development of agriculture in the YRD.Based on soil sampling in 4 areas with different sedimentary histories in the YRD and along with statistical data, the spatial distribution characteristics and seasonal dynamics of soil salinity characteristics in this area were investigated.Various land types were involved, such as coastal beaches, saline-alkali wastelands, forests and grasslands, and agricultural land.The results showed that the farmland productivity in the YRD was significantly lower than the average level of Shandong Province, and the grain yield on the north bank of the Yellow River was significantly lower than that on the south bank.The spatial difference of soil salt content is obvious.The soil conductivity can reach as high as 20 mS/cm in the tidal flat, and the farmland far away from the coast is about 0.5 mS/cm.The longitudinal distribution of salinity is mostly upper-accumulated or average distributed, accounting for 78.6%.Affected by rainfall and evaporation, the shallow soil salinity and pH value have seasonal changes, and the increase in vegetation coverage can weaken the seasonal changes in soil salinity.The soil organic matter content (OM) is generally low, most of the OM in the soil within 1m of depth is between 0.4% and 0.8%, and the organic matter of the surface soil is slightly higher.In farmland soils far away from the coast, the organic matter content in the surface layer has increased significantly, reaching more than 1.5% or 2.0%.Given the temporal and spatial changes of soil salinity characteristics and new national strategic needs, further suggestions for the development and utilization of the Yellow River Delta were proposed.The study provide a scientific reference for the green development of saline-alkali land, the efficient use of agricultural water and soil resources, and the healthy development of grass and animal husbandry in this area.

Spatiotemporal Dynamics and Multiscale Drivers of Agricultural Soil Erosion in the North China Plain from 1990 to 2020

LI Zhiheng, LIU Xiaohuang, XIA Xueqi, XIAO Yuexin, ZHANG Wenbo, WANG Ran, LUO Xinping, XING Liyuan

2025, 39(02): 467-476. DOI: 10.19657/j.geoscience.1000-8527.2024.123

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As China’s primary grain production base, the North China Plain’s soil erosion dynamics hold strategic significance for agricultural ecological security.This study integrates multi-source remote sensing data, digital terrain models, and climate observations to develop an erosion-driving mechanism framework using an AHP-Geodetector integrated model.Through time-series analysis (1990-2020 at 5-year intervals), key findings reveal that: (1) Erosion intensity exhibits marked spatial gradients, with non-significant erosion areas expanding annually by 1.7%, showing strong spatial concordance with alluvial fan frontal zones (Kappa=0.68); (2) Policy interventions reduced moderate-to-severe erosion by 64.3%, with differential response patterns observed across geomorphic units under conservation measures; (3) Topographic interactions demonstrate critical threshold effects, where elevation (q=0.0833) and slope (q=0.0638) synergistically amplify explanatory power by 40.1% (Δq=0.0335), delineating erosion hotspots in transitional zones (150-300 m elevation, 10°-15° slope).The results advance the “topographic energy gradient” theory, establishing the piedmont hills of central Shandong as priority areas for contour farming systems.This work provides a mechanistic foundation for spatially explicit soil conservation strategies in agro-ecosystems.

Spatiotemporal Dynamics and Drivers of Soil Erosion in the Mountainous Areas of South Anhui from 1990 to 2020

XIAO Yuexin, SUN Zelong, MIN Yingzi, YANG Pengzhi, TIAN Zhaofei, CHENG Ming, LAN Jianmei

2025, 39(02): 478-494. DOI: 10.19657/j.geoscience.1000-8527.2025.025

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Based on GIS technology and CSLE model, this paper quantitatively evaluated the spatiotemporal variation characteristics of soil erosion in the study area in 1990, 2000, 2010 and 2020, and focused on the relationship between soil erosion and land use, slope and altitude.The results showed that the amount of soil erosion in the study area in the four phases from 1990 to 2020 was 57.19 million t, 48.93 million t, 66.69 million t and 65.65 million t respectively, and the average soil erosion modulus was 1336 t/(km²·a), 1,143 t/(km²·a), 1,558 t/(km²·a)and 1,558 t/(km²·a), respectively.The degree of soil erosion was mainly slight and mild, and the overall spatial distribution was low in the north and high in the south.The mountainous areas of Chizhou, Huangshan and Xuancheng were the key areas for soil erosion prevention and control.The spatial distribution of soil erosion was closely related to land use, slope and altitude, and the degree of soil erosion in woodland was higher than that in cultivated land, which was related to the distribution degree of land use patterns.Soil erosion modulus increased with the increase of slope and altitude, and the soil erosion was the largest in the area with slope of 25-35, with an annual average of 9,609,200 t, accounting for 32.79%, and the largest in the area with altitude of 200-500 m, with an annual average of 13,067,500 t, accounting for 39.24%.Therefore, it is necessary to further strengthen the ecological restoration and soil and water conservation in these areas in the future.The results of this study can provide scientific basis for comprehensive control of soil erosion in mountainous areas of Southern Anhui.

Ecological Risk Evaluation of Soil Heavy Metal Contamination in a Typical Coal-mining Area from Qujing, Yunnan Province

WEI Zong, JIANG Xin, HUANG An, YANG Chaolei, ZHAO Junsheng, HE Feng, TIAN Yufeng, YAN Liu, XIA Xin, ZHANG Qiuyu, JIANG Aihua

2025, 39(02): 495-503. DOI: 10.19657/j.geoscience.1000-8527.2024.059

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Heavy metal contamination constitutes a critical component of ecological risk evaluation. Concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were measured in 135 surface soil samples (0-20 cm)from a typical coal-mining area in Qujing, Yunnan Province, where a dual-index-dual-criteria evaluation system was developed to characterize pollution patterns. Key findings reveal that: (1)According to China’s Soil Environmental Quality Standard for Agricultural Land (GB 15618-2018), only localized Cd concentrations exceeded regulatory thresholds, while Cr, As, Hg, and Pb levels remained below risk control values; (2)The 2021 Nemerow comprehensive pollution index averaged 2.80 (moderate pollution), contrasting with a GB 15618-2018-based index mean of 1.58 (monitoring threshold). While regulated zones under GB 15618-2018 aligned with severe ecological risk areas identified by potential risk indices, discrepancies emerged in lower-risk classifications between ecological hazard indices and Nemerow evaluations. Traditional risk assessment methods, initially derived from case studies without standardized protocols, demonstrate limited compatibility with GB 15618-2018 frameworks, suggesting their validity requires further scrutiny; (3)Elevated pollution levels near coal gangue stockpiles necessitate prioritized regulation of coal production activities in high-risk zones, particularly targeting Cd contamination mitigation.

Variation of Vegetation During the Growing Season and Its Response to Human Activities in Ningxia During 2000-2020

LUO Xinping, LIU Xiaohuang, YAN Yuxiang, HE Zhenfang, XING Liyuan, WANG Ran

2025, 39(02): 504-513. DOI: 10.19657/j.geoscience.1000-8527.2024.078

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It is of great significance to research the dynamic variation of vegetation and its response to human activities in Northwest China, which can promote the protection and restoration of regional ecological environment, as well as continuously consolidating and deepening the achievements of ecological construction.Based on the MOD13Q1-NDVI data and meteorological data from 2000 to 2020, the dynamic variation of vegetation NDVI during the growing season in Ningxia were analyzed and its response to human activities were discussed in this paper using methods such as trend analysis, correlation analysis and residual analysis.The results showed that the vegetation NDVI during the growing season has exhibited an increase trend as a whole with a linear regression trend of 0.008 in recent 20 years.Also, the spatial distribution of vegetation NDVI shows significant regional differences, generally characterized by higher values in the southern and northern regions and lower values in the central area.The area with an improving vegetation trend is significantly larger than that with a degrading trend, with proportions of significantly increased and decreased vegetation NDVI areas being 65.34% and 3.05%, respectively.Residual analysis indicates that the average contribution rate of human activities to vegetation changes is approximately 33%.In the last 20 years, the mean values of NDVI residual and their trend are 0.17 and 0.007 per year, respectively, indicating that the positive effect of human activities on vegetation have gradually strengthened.Ecological restoration projects have played a crucial role in significantly enhancing the NDVI of vegetation in Ningxia.

Research on Mobile Ultrasonic Rapid Electromagnetic Exploration Technology

RUAN Hongyu, WANG Meng, LIN Zucan, ZHANG Xiyuan, WANG Xinchang, ZHOU Keyu, ZHANG Hui, ZHANG Kuiyuan, ZHANG Rongbo, WANG Yongqing, ZHANG Qisheng

2025, 39(02): 514-522. DOI: 10.19657/j.geoscience.1000-8527.2025.010

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The controlled source radio magnetotelluric method (CSRMT) is an innovative frequency-domain electromagnetic sounding technique designed for near-surface exploration.Building upon the traditional Magnetotelluric (MT) method, CSRMT employs an artificial transmitter source and measures various components of the electromagnetic field at a distance to infer subsurface structures.This paper introduces a mobile ultra-high-frequency rapid electromagnetic exploration technology based on CSRMT.This technology leverages existing artificial field sources, such as AM signals from radio broadcast stations, very low frequency (VLF) electromagnetic signals from naval communication stations, and electromagnetic signals from national time service centers, to conduct electromagnetic surveys.By equipping a vehicle with an ultra-high-frequency controlled-source electromagnetic receiver, mobile exploration can be achieved without on-site deployment of artificial field sources, as required in traditional Controlled Source Magnetotellurics (CSMT).This significantly enhances exploration efficiency and reduces the costs associated with deploying and maintaining transmitters.The mobile ultra-high-frequency controlled-source electromagnetic receiver developed for this technology features a bandwidth range of 1 Hz to 600 kHz, a sampling rate of up to 2.5 MHz, a dynamic range of 138 dB, and an apparent resistivity measurement accuracy better than 3%.

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