Table of Content

20 August 2026, Volume 32 Issue 04

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Tectonic Magnetic Fabric Characteristics and Finite Strain Analysis of Southern Margin of the Western Sichuan Plateau

ZHANG Jiakai, JIA Dong, ZHONG Cheng, ZHANG Yong, LI Wei

2026, 32(04):  471-487.  DOI: 10.16108/j.issn1006-7493.2025043

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Through anisotropy of magnetic susceptibility (AMS) analysis, it is investigated that the superposed structural characteristics and tectonic evolution of the southern margin of the Western Sichuan Plateau, including the Longmen Shan Fault Zone, the Songpan-Ganzi Block, and portions of the Qiangtang Block. The findings offer new constraints on the strain patterns and tectonic history of the study area. Focusing on the Triassic Xikang Group strata, six distinct types of magnetic fabrics were identified across 87 sampling sites, representing progressively increasing deformation intensity. These magnetic fabric types include: sedimentary fabric, incipient deformation fabric, pencil fabric, weak foliation fabric, strong foliation fabric, and stretching lineation fabric. Notably, the incipient deformation fabric is quantitatively dominant. Furthermore, a significant proportion of the magnetic fabrics exhibit superimposed characteristics, recording the overprinting of tectonic stresses and revealing two major phases of tectonic deformation: Late Triassic and Cenozoic. The magnetic fabrics record Late Triassic deformation characterized by widespread NE-SW oriented tectonic shortening (compression). Additionally, along the eastern margin of the Songpan- Garzê Terrane, this shortening exhibits a gradual decrease in intensity from SE to NW. The Cenozoic deformation recorded by the magnetic fabrics is superimposed upon the pre-existing Late Triassic fabrics and is primarily controlled by Cenozoic faultrelated shear deformation. Regionally, the Late Triassic deformation is pervasive, displaying marked characteristics of penetrative deformation. In contrast, the Cenozoic deformation is predominantly localized around major fault zones, exhibiting a nonpenetrative deformation pattern at the regional scale.

Analogue Modelling of Two-phase Tectonic Superposition in the Kekeya Fold-and-thrust Belt, West Kunlun Piedmont

LUO Qiang, CHEN Jiuzhou, AZMAT Mirhalim, ZHONG Cheng, LIU Chang, WANG Wei, LI Yiquan, YIN Hongwei, JIA Dong

2026, 32(04):  488-500.  DOI: 10.16108/j.issn1006-7493.2025044

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The Kekeya fold-and-thrust belt (Kekeya FTB) at the front of the West Kunlun Range underwent multiple phases of
tectonic deformation and reworking during the Caledonian, Indosinian, and Himalayan periods. Unraveling the mechanisms of superimposed deformation in the southwestern Tarim Basin could provide crucial constraints for seismic interpretation and structural modeling. This study systematically investigates the two-phase superimposed deformation of the Kekeya FTB using analogue modeling. We designed experimental series with varying décollement configurations to evaluate the effects of tectonic superposition, décollement rheology, and Cenozoic syntectonic growth strata. The main conclusions are: (1) Syntectonic growth strata facilitate the propagation of deformation toward the foreland by inhibiting the surface breakthrough of deep-seated faults. This process enhances the decoupling effect of shallow décollements, allowing for more efficient strain transmission to the distal foreland; (2) Second-phase faults exhibit strong structural inheritance, preferentially reactivating pre-existing first-phase faults; (3)
Comparisons between experimental results and geological cross-sections demonstrate that a coupled model involving a deep brittle and shallow ductile décollement under two-phase compression accurately reproduces the structural geometry of the Kekeya FTB. This deformation results in a stratified architecture comprising a deep basement imbricate fan system and a shallow passive-roof thin-skinned system. 


Research on Interpretating Electrical Resistivity Tomography (ERT) for Rock-Soil Structures in Typical Karst Limestone Slopes

TANG Zhanyu, JIANG Weiwei, PENG Tao, DAI Deqiu

2026, 32(04):  501-513.  DOI: 10.16108/j.issn1006-7493.2025040

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The distribution of soil and epikarst zones in karst areas is highly heterogeneous. Depicting the characteristics of rocksoil structures is crucial for regional hydrological research and key zone model construction. Taking typical limestone slopes in central Guizhou as an example, this study uses high-density electrical method as the main exploration means. Geotechnical structures are characterized based on electrical resistivity tomography (ERT), , and combined with soil probing method and typical profiles for comparative verification, the rock-soil structures of limestone slopes are analyzed under complex geological conditions. The results show that the resistivity of the soil layer ranges from 0 to 89.4 Ω·m; the average resistivity values of karst fractures are less than 585.3 Ω·m for thick-layer limestone and less than 292.8 Ω·m for thin-layer limestone; The performance of the high-density electrical method is better for interpreting soil area than for karst fracture area in, and better under single structure conditions than under complex structure conditions, and the interpreted lithological boundary l is clear; the average soil thickness of the entire limestone slope is about 0.495 m, and the average thickness of the epikarst zone is about 3.921 m; the soil and karst fractures show high spatial heterogeneity, and the epikarst zone is discontinuous. The results can help further apply the high-density electrical method to detect and characterize the rock-soil structures under complex lithological conditions in karst areas, providing data support for constructing models for karst critical zones. 


Constraints of Dissolution Rates on the Anaerobic Decomposition of Sulfate Minerals

DU Mengmeng, CHEN Tianhu, KONG Dianchao, ZHOU Yuefei, XIE Qiaoqin

2026, 32(04):  514-521.  DOI: 10.16108/j.issn1006-7493.2025038

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In this study, three representative sulfate minerals (gypsum, anhydrite, and celestite) were co-cultured with a strain
of sulfate-reducing bacteria (SRB). The process of and constraints on anaerobic decomposition of typical sulfate mineral were investigated by monitoring dynamic changes in solution pH, oxidation-reduction potential, protein content, acid-volatile sulfur, and SO₄^2- concentration during the 360-hour incubation period, combined with post-cultivation analysis of mineral surface micromorphology. The results show that oxidation-reduction potential levels follows the order: gypsum system < anhydrite system < celestite system. Concentrations of proteins, SO₄^2-, and acid-volatile sulfur exhibited: gypsum system > anhydrite system > celestite system. SRB growth rates decrease sequentially as: gypsum system > anhydrite system > celestite system. Post-experiment analysis reveals that the formation of etch pits and dissolution micropores on the surfaces of anhydrite and celestite occurs at sites where bacterial cells and their metabolic byproducts made contact. The study demonstrates that anaerobic decomposition process of sulfate mineral is fundamentally constrained by their solubility and dissolution rates. Gypsum with the fastest dissolution rate facilitates robust SRB growth through readily available dissolved SO₄^2-, thereby accelerating its own decomposition. Anhydrite with the moderate dissolution rates supports SRB growth primarily through dissolved SO₄^2- utilization, while bacterial adhesion and metabolic byproducts on mineral surfaces provide additional decomposition enhancement. Celestite possessing both low solubility and slow dissolution rates relies predominantly on bacterial adhesion to promote mineral breakdown, with SRB growth sustained by the limited SO₄^2- released during this gradual decomposition process.

Study on the Reaction-Curing Synergistic Mechanism of Geopolymer in-situ Sealing of AMD

LIU Yingao, MAO Hengqi, YE Tao, ZHOU Lai, QI Zenggang, WU Jianfeng, ZHANG Kaikai

2026, 32(04):  522-533.  DOI: 10.16108/j.issn1006-7493.2025047

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In-situ injection of reactivity geopolymers can effectively seal Acid Mine Drainage (AMD), achieving the goals of
source control and quality improvement of AMD. The reactivity and solidification performance of the grouting material are key parameters for the in-situ sealing of AMD using reactive geopolymers. This study aims to elucidate the synergistic mechanisms of the reactive geopolymers in AMD sealing and conducted experiments including grouting the material curing stability tests, dynamic AMD sealing experiments, and microscopic mechanism characterization. The results indicate that the grouting material exhibits good chemical stability and durability, with heavy metal leaching levels meeting national standards; the erosive effect of AMD can promote the formation of silicate and silicoaluminate substances, then effectively enhance the compressive strength of the nodule body to 6.37 MPa; under dynamic water conditions in an AMD environment, the dynamic blocking rate exceeded 90%. After grouting and blocking reactions, the final effluent pH increased from 3.6 to a range of 6.8 to 8.3. The removal rates of total Fe, Mn, and SO₄^2- were above 98.8%, 52.1%, and 33.3%, respectively. The increase in C-(A)-S-H and N-A-S-H gel products enhanced the ability of the solidified grouting body to solidify and stabilize heavy metals, while SO₄
^2- was converted into more sulfur-containing minerals; The geopolymer was used as a grouting agent injected into aquifers or filling zones, and the cement hydration, the generation of geopolymer, and the formation of the cement polymer were enhanced. hydration, the generation of geopolymer and the formation of hydrophobic film three reaction processes at the same time, under the erosion of acidic mine water, to promote the solidified body surface and the internal C-(A)-S-H, N-A-S-H gel products and Ca₆Al₂(SO₄)₃(OH)₁₂(H₂O)₇, FeS, CaSO₄ and other minerals, and at the same time, curing the heavy metals, formation of colloidal precipitates containing CaCO₃, H₂SiO₃, Fe(OH)₃, and Mn(OH)₂ to meet the needs of green grouting. The synergistic mechanism of “grouting-reactingsolidifying-reducing” of the geopolymer grouting materials was clarified, which provides a scientific basis and practical guidance for the in-situ green management of AMD. 


Analysis of Pore Development Characteristics and Controlling Factors in Shale of the Da’anzhai Member, Northeastern Sichuan

PENG Jun, YANG Yuqiu, JIA Yunqian, HUANG Lei, ZHOU Yongshui, LEI Ming, YAO Suping

2026, 32(04):  534-546.  DOI: 10.16108/j.issn1006-7493.2025039

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Exploration practice indicates that the Jurassic Da’anzhai Member shale oil and gas in northeastern Sichuan show
broad exploration prospects, yet in-depth research on shale pore development and its controlling factors remains lacking. This study investigates the co-evolutionary process of hydrocarbon generation, diagenesis, and reservoir formation in the Da’anzhai shale through source-reservoir coupled pyrolysis experiments. The research demonstrates that: organic matter degradation and hydrocarbon generation, alkaline mineral dissolution, clay mineral transformation, and quartz mineral dissolution constitute the primary pore-enhancing factors during the evolution of the Da’anzhai shale, while alkaline mineral recrystallization, organic matter aromatization, and quartz secondary enlargement represent the main pore-reducing factors. Based on the organichydrocarbon generation evolution curve and mineral alteration characteristics during thermal evolution, a semi-quantitative analysis was conducted on the contributions of organic hydrocarbon generation and mineral transformation to shale pore development throughout the thermal evolution process. Furthermore, a co-evolution model for diagenesis-hydrocarbon generationreservoir formation of the Da’anzhai Member shale was established, dividing the pore evolution processes of the Da’anzhai shale into four stages: The Middle Diagenetic substages A1 (Ro=0.79%-1.09%), A2 (Ro=1.09%-1.28%), B1 (Ro=1.28%-1.47%), and B2 (Ro=1.47%-2.02%) exhibit distinct evolutionary characteristics. Significant shale porosity increment primarily occurs during the Middle Diagenetic Substage A2, which corresponds to the peak oil generation stage of organic matter. This demonstrates that hydrocarbon generation from organic matter substantially contributes to pore development in the Da’anzhai Member shale, providing critical insights into understanding the reservoir evolution patterns in northeastern Sichuan’s Da’anzhai Formation.

Extraction and Distribution Patterns of Grain-size End-members for the Surface Sediments in the Qiantang River Estuary District

YU Lihan, FAN Daidu, WANG Jun, LIN Chunming, WANG Bo, SU Jianfeng, ZHANG Xia, WANG Jin, NAN Feng

2026, 32(04):  547-560.  DOI: 10.16108/j.issn1006-7493.2025042

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The surface sediment grainsize data from the Qiantang River estuary is investigated using the End-member Modeling
Algorithm and a non-parametric estimation decomposition algorithm. In order to characterize the compositional features and planar distribution patterns of different grainsize endmembers, and explore their coupling relationships with sediment provenance and environmental changes. Results show that the data obtained by algorithms have good consistency, however, the End-member Modeling Algorithm demonstrate superior performance in accurately identifying unimodal distributions of each endmember. Surface sediments of the Qiantang River estuary can be divided into five grain-size end-members: EM1 (clay and silt), EM2 (coarse silt and very coarse silt), EM3 (very fine sand and fine sand), EM4 (fine sand and medium sand), and EM5 (medium sand and coarse sand). EM1 and EM2 represent the suspended sediments transported over long distances, primarily derived from the Yangtze River (Changjiang). EM3, distributed in the estuary mouth, indicates the reworking of residual sands from the Yangtze River estuary. EM4 denotes fluvial sandy sediments transported over a relatively long distance, while EM5 represents very coarse fluvial sand transported over a short distance; both primarily originate from the upper reaches of the Qiantang River and its tributaries. This study demonstrates that for estuarine sedimentary environments with complex source-to-sink systems, the End-member Modeling Algorithm enhances the resolution and efficiency of grain-size analysis and can sensitively indicate hydrodynamic conditions, source-to-sink processes, and event deposits. Therefore, this method holds promise for application in analyzing diverse and complex source-to-sink systems and hydrodynamic conditions in similar estuarine regions worldwide.

Human Settlement in the Yangtze River Delta over the Past 7000 Years: Response to Delta Formation and Climate Change

ZHANG Yuchen, ZHANG Zhiping, WANG Jieren, ZHENG Duo, XU Jiahao, HU Zhujun, SHANG Zhiyuan, YANG Lin, Harry F. Lee, JIA Xin

2026, 32(04):  561-576.  DOI: 10.16108/j.issn1006-7493.2025041

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Complex geomorphological evolution in the lower reaches of the Yangtze River during the Holocene has been jointly driven by frequent human activities and hydrological changes, which affected the continuity of sedimentary processes
and complicated accurate understanding of the relationship between the origin and development of prehistoric cultures and environmental evolution in the region. In this study, we collected sedimentary samples from the Xingang site in the lower reaches of the Yangtze River and established a chronological framework for natural sedimentary strata based on archaeological stratigraphy and AMS14C dating of natural cores. Multiple proxy indices-including magnetic susceptibility, Mn/Ti, Fe/Mn, and grain-size parameters were analyzed to reconstruct regional environmental evolution and its linkage to cultural development. The results show a shift from an aquatic to a terrestrial sedimentary environment near the site around 7 ka BP. Together with sedimentary hiatuses identified in multiple cores across the region, this suggests the contemporary formation of the Yangtze River Delta. The emergence of the delta provided new habitats and agricultural space for prehistoric settlements. The drier climate after 7 ka BP led to further expanded arable land. This coupled geomorphic-climatic effect enhanced land productivity and supported substantial population growth, thereby laying the spatial foundation for the development of the Majiabang-Songze archaeological cultures and ultimately contributing to the rise of early state societies in the region.


Ground Subsidence Monitoring and Analysis of Influencing Factors in Ganzhou City Based on SBAS-InSAR

JIANG Wentao, DONG Shaochun, PENG Zhengquan, SUN Jianhao, LI Houyu

2026, 32(04):  577-589.  DOI: 10.16108/j.issn1006-7493.2025045

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Urban ground subsidence can lead to building cracks and tilting, damage to underground infrastructure, and secondary disasters, posing a serious threat to the sustainable development of cities. Therefore, accurately understanding the spatiotemporal evolution characteristics of ground subsidence and identifying its dominant driving mechanisms are of great significance for developing effective monitoring strategies and mitigation measures. This study utilized the Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technique and analyzed 154 scenes of Sentinel-1A satellite imagery from January 2020 to March 2025 to obtain the spatiotemporal distribution characteristics of ground subsidence in the central urban area of Ganzhou City. The results show that 80% of the study area has subsidence rates between -2 and 2 mm/y; localized areas exhibit significant subsidence, primarily concentrated in Ganzhou County , with the highest annual average subsidence rate reaching -26.4 mm/y. Some subsidence centers exhibit distinct seasonal fluctuations, primarily influenced by variations in precipitation infiltration recharge and the intensity of groundwater extraction. Additionally, human activities such as the perturbation of the new construction loads and river sediment deposition also triggered significant ground subsidence in localized areas. This study contributes to understanding the spatiotemporal evolution characteristics of ground subsidence in Ganzhou City, further optimizes urban ground subsidence monitoring methods, and provides scientific support for enhancing the city’s geological hazard risk management capabilities.


Microscopic Pore Structure Analysis of Glutenite Reservoir in the Baikouquan Formation, Mahu Sag

YAO Wenli

2026, 32(04):  590-603.  DOI: 10.16108/j.issn1006-7493.2025046

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In light of the strong microscopic heterogeneity and varied development outcomes in the low-permeability glutenite
reservoir of the Baikouquan Formation in the Mahu Sag, Junggar Basin, this study carried out an integrated investigation of core description, thin-section observation, CT scanning, and constant-rate mercury injection techniques to quantitatively characterize and classify the microscopic pore structure of the reservoir. The results show that reservoir pores in the study area are dominated by residual intergranular pores and intragranular dissolved pores, exhibiting overall “small pores, fine throats” characteristic. The connectivity of pore-throat networks is generally poor, with coordination numbers concentrated in the range of 1-3. The reservoir can be classified into four pore structure types ( Ⅰ , Ⅱ , Ⅲ , and Ⅳ ), corresponding to sandy small conglomerate, gravel-bearing coarse sandstone, sandy fine conglomerate, and argillaceous fine conglomerate, respectively. Type Ⅰ reservoirs show large throat radii (average 5.94 μm), low pore-throat radius ratios (average 45.85), and optimal configuration, resulting in the strongest seepage capacity. In contrast, Type Ⅳ reservoirs are characterized by the smallest throat radii (average 2.62 μm), the highest pore-throat radius ratios (average 79.33), and poor configuration, leading to extremely weak seepage capacity. The development of the throat system is identified as the key factor controlling reservoir quality and seepage capability, while the influence of pore size is relatively limited. Pore structure, within the glutenite reservoir are the main cause of severe pore-throat configuration imbalance, forming a seepage “bottleneck” that contributes to low permeability, significant productivity variations, and low recovery efficiency in the reservoir.