地质力学学报

Composition, tectonic framework, and evolution of the Luxi Orogenic Belt in the North China Craton during the Late Neoarchean

WANG Dongming, HU Jianmin, ZHAO Yuanfang, YAN Jiyuan, GONG Wangbin, ZHANG Zhigang

Objective The growth and evolution of the early Earth’s crust are hot topics in Precambrian research. As one of the oldest cratons in the world, the North China Craton (NCC) has undergone a complex cratonization process accompanied by crustal growth and reworking. Methods Existing petrological, geochemical, chronological, and structural geological studies are summarized to reveal the tectonic evolution of the Luxi granite–greenstone belt in the eastern NCC. Results Multiple lines of evidence indicate late Neoarchean crustal growth, including continental arc and arc magmatic rocks represented by the Feicheng‒Tengzhou magmatic arc and late Neoarchean volcanic rocks, post-collisional crustal-derived magmatism represented by the Lushan‒Yishui magmatic belt, sedimentation in a back-arc basin defined by late Neoarchean metamorphic sedimentary rocks, and the strike-slip shear deformation caused by the oblique convergence of plates. The >2.60 Ga tonalite, trondhjemite, granodiorite (TTG) suite and the supracrustal rock belt exposed in the central part of the Luxi area represent an ancient microcontinent with apparent affinity to the Jiaoliao Block. Conclusions Therefore, the Luxi granite–greenstone belt is an accretionary orogenic belt located on the western margin of the Jiaoliao Block, namely the Luxi Orogenic Belt. High-angle oblique arc-continent collision and underplating of large volumes of mantle-derived magma represent two crustal growth modes in horizontal and vertical directions, respectively. This orogenic belt has undergone multi-stage evolution, including the formation of initial oceanic crust, subduction, and intracontinental extension from the Neoarchean to the end of the Paleoproterozoic. [Significance] In the late Neoarchean, extensive crustal growth occurred around the Jiaoliao Block in the eastern NCC, which was controlled by an early plate tectonic regime characterized by hot subduction.

Tectonic evolution of the Sumatran Fault: synthesis and perspective

GUO Lin, CHU Yang, LIN Wei, LEI Yiyang, LIU Tanjie, GUO Yilin, MENG Lingtong

Objective Oblique convergence between the Indo-Australian Plate and the Eurasian Plate produced a ~1,900-km-long dextral strike-slip fault—the Sumatran Fault—within the overriding plate. While previous studies have extensively examined its geometry, kinematics, and seismicity, the tectonic evolution of the fault remains poorly constrained. Methods This study integrates multidisciplinary evidence from structural geology, geomorphology, seismicity analysis, geodesy (GPS), low-temperature thermochronology (apatite and zircon (U-Th)/He dating), and volcanic distribution mapping. We systematically synthesize data on fault segmentation, slip rates, cumulative displacement, magmatic-tectonic relationships, and regional geodynamic models to evaluate the fault’s spatiotemporal evolution. Results The Sumatran Fault is a highly segmented dextral strike-slip system that can currently be divided into 19 segments based on geometric complexity and seismic activity. Slip rates along the fault are relatively uniform from south to north, with an average around 15 mm/yr, and a total cumulative displacement of approximately 20~25 km. Regionally, the distribution of active arc magmatism closely aligns with the trace of the fault, indicating a dynamic interaction between faulting and magmatism: while magma-induced crustal weakening facilitates fault development, extensional zones associated with normal faulting in turn influence the volcanic activity. Despite its tectonic significance, low-temperature thermochronological studies on the Sumatran Fault remain limited. Existing thermochronological data reveal a period of rapid uplift at ~2 Ma, likely driven by dip-slip motion along the fault. Conclusions A three-stage model is proposed. Before 2 Ma, oblique convergence was primarily accommodated by forearc faults (e.g., Mentawai Fault) and shear zones. Around 2 Ma, the Sumatran Fault initiated contemporaneously with the Mentawai Fault, manifesting strain localization in the overriding plate. At present, the Sumatran Fault accommodates the majority of the strain, while strike-slip motion on the Mentawai Fault has significantly diminished. The uplift phase correlates with the initial timing of the Sumatran Fault inferred from present-day slip rates and cumulative offsets, suggesting that the current through-going structure of the fault and the modern tectonic framework were established at the same time. [ Significance ] This study provides a comprehensive synthesis of multidisciplinary constraints on the Sumatran Fault and establishes a unified spatiotemporal framework for its tectonic evolution. By integrating fault segmentation, slip rates, thermochronological data, and magmatic–tectonic interactions, this study clarifies the timing of fault initiation and the development of the present-day tectonic architecture. The results offer new insights into strain partitioning and the formation of trench-parallel strike-slip faults at obliquely convergent margins, providing a valuable reference for understanding similar plate boundary systems and their associated seismic hazards.

Geochemical characteristics of Late Paleozoic–Early Mesozoic volcanic rocks in Heiyingshan, Beishan Orogenic Belt: evidence of the transition from subduction to collision of the Paleo-Asian Ocean

DING Yiwen, SHAO Zhaogang, CHEN Yanfei, CHEN Xuanhua, LI Bing, YU Wei, XU Daxing, HAN Lele

Objective It is generally accepted that the Paleo-Asian Ocean in the northern part of the Beishan Orogenic Belt was in the stage of ocean–continent evolution during the Carboniferous–Permian. However, the timing of the closure of the Paleo-Asian Ocean remains controversial. The Heiyingshan area, located at the northern margin of the Beishan Orogenic Belt, is a key area for studying the evolution of the Paleo-Asian Ocean. This study analyzes the geochemical characteristics of tuffs in this area to reveal their tectonic setting and further constrain the evolution of the Paleo-Asian Ocean in the northern Beishan Orogenic Belt. Methods Late Carboniferous and Late Triassic volcanic tuffs exposed in the Heiyingshan area were analyzed using petrological and geochemical methods. Major, trace, and rare earth elements concentrations were determined to obtain the geochemical characteristics of the volcanic tuffs. Combined with published regional volcanic rock ages and geochemical data, the petrogenesis and tectonic setting of the volcanic tuff are discussed. Results The Late Carboniferous volcanic tuff belongs to the peraluminous calc-alkaline series; it is enriched in large ion lithophile elements (LILE; i.e., Rb, Ba, Th and U) and depleted in high field strength elements (HFSE; i.e., Nb, Ta, Zr, Hf and Ti). The total rare earth element content (ΣREE) ranges from 74.64×10⁻⁶ to 142.45×10⁻⁶, with significant fractionation between light and heavy REEs (LREE/HREE=5.14–7.49, (La/Yb)_N=4.58–6.36). The chondrite-normalized REE distribution pattern is right-leaning, with a weak negative Eu anomaly (δEu=0.35–0.66). These characteristics are indicative of I-type granite. The Late Triassic volcanic tuff belongs to the peraluminous high-K calc-alkaline series. It is enriched in silicon and alkali but depleted in aluminum and magnesium. This tuff exhibits a strong negative Eu anomaly (δEu=0.02–0.22). Its chondrite-normalized REE distribution pattern is a slightly right-leaning ‘seagull type’. This tuff is enriched in LILE, (e.g., Rb, Th and U), depleted in incompatible elements (e.g., Ba, Nb, Zr and Ti), and depleted in HFSE, (e.g., Hf and Zr). These characteristics are typical of S-type granite. The Th content of the Late Carboniferous and Late Triassic rock samples in the Heiyingshan area ranges from 7.66 to 32.2 μg/g, with an average of 19.24 μg/g, which is much higher than the average mantle abundance and closer to the crust. The Nb/Ta ratios of the rock samples range from 8.01 to 12.78, with an average of 10.36, which is much lower than the mantle average of 60 and closer to the crust average of 11. In addition, the Ba/La ratios of the Late Carboniferous volcanic rocks range from 19.19 to 24.09, with an average of 21.64, slightly higher than the continental crust average of 15.63. Conclusions The Late Carboniferous and Late Triassic volcanic tuffs in the Heiyingshan area formed in the subduction and collision setting of the Paleo-Asian Ocean, respectively, indicating that the tectonic environment in the Hongshishan-Heiyingshan area transitioned from subduction to collision between the Late Carboniferous and the Late Triassic. The volcanic magma in this area was mainly derived from partial melting of the crust, with the Late Carboniferous volcanic rocks possibly mixed with a small amount of mantle-derived materials. [ Significance ] The geochemical characteristics of the Late Carboniferous and Late Triassic volcanic tuffs in the Heiyingshan area provide evidence for the subduction–collision processes of the Paleo-Asian Ocean in the Beishan Orogenic Belt. The results constrain the timing of the tectonic environment transformation in the Hongshishan–Heiyingshan area in the northern Beishan Orogenic Belt, which is of great significance for understanding the closure of the Paleo-Asian Ocean.

Characteristics of current in-situ stress field and engineering zoning evaluation in complex structural areas: A case study of the Longmaxi shale reservoir in the southeastern margin of the Sichuan Basin

MA Shunting, LI Ruixue, CHEN Xinhao, DU Yifei, DENG Hucheng, HE Jianhua, YANG Hong, WEI Limin

Objective The Dingshan–Dongxi area, located on the basin margin in southeastern Sichuan, lies at the junction of the eastern Sichuan fault–fold zone and the northern Guizhou fault–fold zone on the east side of the Luzhou–Chishui tectonic superposition zone. Due to multiple tectonic movements, the geological structure in this area is complex. The Longmaxi Formation in the study area is rich in shale gas resources, characterized by superior geological and reservoir conditions, and holds great potential for exploration and development. Clarifying the current in-situ stress state and its distribution is conducive to improving shale gas development efficiency. However, the complex in-situ stress field in this area leads to less accurate planar predictions and significant differences in the fracturing stimulation effects and production among horizontal wells. Methods This study provided a detailed interpretation of the in-situ stress direction in the well profile of the study area by integrating multi-source data, including core tests, well logging, and microseismic monitoring. Furthermore, the distribution characteristics of in-situ stress magnitudes among the well profile were clarified through hydraulic fracturing, acoustic emission experiments, and well logging. Refined geological modeling was performed on the structural deformation and fracture characteristics of the study area, and heterogeneous rock mechanical properties were assigned. Numerical simulation software was then applied to simulate the current in-situ stress distribution characteristics of the study area. Finally, based on the analysis of the influence of in-situ stress characteristics on fracturing stimulation effects, an in-situ stress zoning evaluation standard was constructed. Using the simulated in-situ stress field results, in-situ stress zoning was carried out in the Dingshan–Dongxi area, and the zoning results were verified through a retrospective evaluation of the fracturing effects of new wells. Results The results show that the current in-situ stress direction in the study area is mostly near east –west, with local deflections caused by fractures and structural deformations. The maximum horizontal principle stress, minimum horizontal principle stress, and vertical principal stress range from 58.4 to 167.0 MPa, 38.6 to 135.4 MPa, and 54.7 to 148.2 MPa, respectively, indicating a strike-slip stress state. The stress difference (maximum minus minimum horizontal principal stress) mainly ranges from 5 to 30 MPa. The magnitude of in-situ stress and the stress difference are generally controlled by burial depth. In areas with high structural deformation, both in-situ stress and stress difference are lower. Near faults, in-situ stress is lower, but the stress difference is higher. Zoning was performed using a minimum horizontal principal stress of 80 MPa and a stress difference of 20 MPa as thresholds. [ Conclusions ] It is recommended that areas with low stress difference and low in-situ stress be selected for fracturing stimulation. These areas are mainly located in the high-structural parts of the gentle slope area in the middle of Dingshan, the slope area of Dongxi, and the northern part of the Dongxi fault and anticline area.[ Significance ] This study advances the understanding of the current in-situ stress field of the Longmaxi Formation on the southeastern margin of the Sichuan Basin and has significant practical value for optimizing fracturing stimulation.

Study of disaster-prone geological structures and instability modes of typical goaf landslides in mountainous areas of southwest China

ZHANG Haoxiang, ZHU Sainan, YAO Leihua, GAO Feng, ZHANG Limei, YANG Long, TAN Weijia, DAI Xusheng, GAO Yu

Objective Landslides occur frequently in the goaf areas of mountainous areas in Southwest China. This study aims to explore the commonalities and differences among such landslides to support the development of scientific disaster prevention and mitigation measures. Methods A comparative study was conducted using three research objects: the Jiguanling Landslide in a limestone area, the Zhaojiagou Landslide in a clastic rock area, and the Shanyang Landslide in a metamorphic rock area. Methods included data collection and analysis, on-site investigation, multi-phase remote sensing interpretation, physical and mechanical testing of rock and soil masses, and numerical simulation. These methods were employed to analyze similarities and differences in disaster-prone geological structures and instability mechanisms among the selected landslides. Results Landslide disasters are prone to occur on slopes characterized by steep terrains, favorable overhanging conditions, and binary structures. Numerical simulations indicate that under goaf conditions, the displacement of each landslide increases, the maximum shear strain increments concentrate on the potential sliding surface and the goaf roof area, and the overall stability of each landslide decreases. Conclusions The limestone mountainous area is characterized by thick layers of hard rock interbedded with thin layers of soft rock, presenting high rock mass strength. The Jiguanling Landslide belongs to the toppling–sliding failure mode. The clastic rock mountainous area is affected by interbedding of thin layers of fragmented soft and hard rock, with overall rock mass strength weakened. The Zhaojiagou Landslide belongs to the creep–tensile fracture failure mode. The metamorphic rock mountainous area exhibits hard rock at the top and soft rock at the bottom, with significant differences in strength. The Shanyang Landslide belongs to the slipping-collapse failure mode. [ Significance ] This study provides an important scientific basis for the early identification of goaf landslides and for studying goaf-related disaster formation patterns.

Cover Page

2026, 32(2).

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Contents

2026, 32(2): 1-2.

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Tectonic System & Structural Geology

Composition, tectonic framework, and evolution of the Luxi Orogenic Belt in the North China Craton during the Late Neoarchean

WANG Dongming, HU Jianmin, ZHAO Yuanfang, YAN Jiyuan, GONG Wangbin, ZHANG Zhigang

2026, 32(2): 169-195. doi: 10.12090/j.issn.1006-6616.2025033

Abstract (491) HTML (127) PDF (8707KB)(225)

Tectonic evolution of the Sumatran Fault: synthesis and perspective

GUO Lin, CHU Yang, LIN Wei, LEI Yiyang, LIU Tanjie, GUO Yilin, MENG Lingtong

2026, 32(2): 196-216. doi: 10.12090/j.issn.1006-6616.2025067

Abstract (591) HTML (147) PDF (6290KB)(264)

Geochemical characteristics of Late Paleozoic–Early Mesozoic volcanic rocks in Heiyingshan, Beishan Orogenic Belt: evidence of the transition from subduction to collision of the Paleo-Asian Ocean

DING Yiwen, SHAO Zhaogang, CHEN Yanfei, CHEN Xuanhua, LI Bing, YU Wei, XU Daxing, HAN Lele

2026, 32(2): 217-232. doi: 10.12090/j.issn.1006-6616.2025017

Abstract (496) HTML (110) PDF (3299KB)(192)

Crustal Stress & Tectonic Stress Field

MA Shunting, LI Ruixue, CHEN Xinhao, DU Yifei, DENG Hucheng, HE Jianhua, YANG Hong, WEI Limin

2026, 32(2): 233-250. doi: 10.12090/j.issn.1006-6616.2025057

Abstract (186) HTML (52) PDF (8043KB)(51)

Analysis of the three-dimensional in-situ stress state and underground cavern stability of a pumped storage hydropower station in Xinjiang, China

ZHANG Xiaofei, WANG Jiming, ZHANG Peng, LI Zhengzheng, LI Changhu, OUYANG Jiangquan

2026, 32(2): 251-266. doi: 10.12090/j.issn.1006-6616.2025076

Abstract (392) HTML (86) PDF (2580KB)(203)

The stress changes of the 2025 Dingri M 6.8 earthquake on the surrounding areas

ZHANG Chenchen, WAN Yongge, GUAN Zhaoxuan, ZHAO Jiebin, WANG Runyan, ZHOU Mingyue

2026, 32(2): 267-280. doi: 10.12090/j.issn.1006-6616.2025072

Abstract (240) HTML (75) PDF (4609KB)(191)

A refined evaluation method for in-situ stresses in orthotropic shale formations

ZENG Bo, GUI Junchuan, HUANG Haoyong, MA Tianshou, CUI Shuai, ZHONG Guanghai, XU Ersi

2026, 32(2): 281-297. doi: 10.12090/j.issn.1006-6616.2025002

Abstract (124) HTML (55) PDF (1581KB)(55)

Refined characterization and analysis of shallow crustal stresses based on hydraulic fracturing data

XIONG Sijie, MA Xiaodong, YANG Yuehui, WU Bangchen, LI Awei, SUN Dongsheng

2026, 32(2): 298-310. doi: 10.12090/j.issn.1006-6616.2025096

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Numerical simulation of the influence of normal stress on sub-instability synergy of strike-slip faults

DAI Shuhong, SUN Zhaoyang

2026, 32(2): 311-322. doi: 10.12090/j.issn.1006-6616.2025022

Abstract (440) HTML (155) PDF (2028KB)(46)

Analysis of structural plane stability in the Panlong lead–zinc mine, Guangxi, China and its engineering implications

HUANG Xiaopan, WANG Chenghu, YANG Chengwei, LIU Jikun, XIAO Haifan

2026, 32(2): 323-335. doi: 10.12090/j.issn.1006-6616.2025083

Abstract (384) HTML (109) PDF (2440KB)(188)

Energy Resources Geology

The evolution of the Sinian–Early Cambrian E’xi Trough in the Central Yangtze region and its geological significance for natural gas

CHEN Ke, LU Yanxin, WANG Yuluo, LI Fei

2026, 32(2): 336-352. doi: 10.12090/j.issn.1006-6616.2025048

Abstract (119) HTML (40) PDF (5028KB)(51)

Research on high-precision one-dimensional geomechanical modeling of shale oil reservoirs

HOU Shuoyang, WANG Xiaoqiong, XIAN Chenggang, GE Hongkui, ZHONG Yi

2026, 32(2): 353-364. doi: 10.12090/j.issn.1006-6616.2025094

Abstract (149) HTML (50) PDF (2489KB)(81)

A calculation method of the reservoir Biot coefficient based on the Griffith criterion and the equivalent inclusion theory

ZHANG Hui, PEI Chenyang, WANG Zhimin, LIU Lei, LI Jing, LIU Yishuai, WU Zekun

2026, 32(2): 365-374. doi: 10.12090/j.issn.1006-6616.2025086

Abstract (203) HTML (59) PDF (1169KB)(164)

Geo-hazards & Engineering Geology

Study of disaster-prone geological structures and instability modes of typical goaf landslides in mountainous areas of southwest China

ZHANG Haoxiang, ZHU Sainan, YAO Leihua, GAO Feng, ZHANG Limei, YANG Long, TAN Weijia, DAI Xusheng, GAO Yu

2026, 32(2): 375-390. doi: 10.12090/j.issn.1006-6616.2025047

Abstract (352) HTML (74) PDF (3145KB)(178)

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Symmetric and asymmetric deformation from plate-margin orogeny to intracontinental tectonics: formation mechanisms of lithospheric tectonic vergence

ZHANG Yipeng, xie liubiao, JIN Ruizhi, SHEN Xuzhang, HE Xiaohui, JING Hulu, LIU Kang, WANG Yang, WANG Weitao, ZHANG Peizhen

doi: 10.12090/j.issn.1006-6616.2026026

[Abstract](2) [PDF 2593KB](3)

Abstract:
[Objective] Tectonic vergence records the geometric asymmetry and kinematic directionality of shortening during orogenic thickening, and provides a key link between surface deformation and lithospheric-scale geodynamics. Although vergence is widely used in structural geology, its expression at the scale of entire orogenic belts remains insufficiently clarified, especially in intracontinental settings where stable plate-boundary subduction is absent. This study aims to compare vergence patterns from plate-margin orogens to intracontinental mountain belts and to identify the mechanisms controlling their formation, maintenance, weakening, and transformation. [Methods] We synthesize five representative orogenic systems: the Central Andes, Taiwan, the Alps, the Qilian Shan, and the Tianshan. Surface structural styles, fold–thrust belt geometry, orogen–foreland basin coupling, geomorphic evolution, modern crustal deformation, seismicity, and lithospheric architecture constrained by Moho/LAB geometry and geophysical imaging are integrated to evaluate vergence at multiple scales. [Results] Plate-margin convergent systems commonly develop stable one-sided tectonic vergence. In the Central Andes, long-lived subduction of the Nazca slab provides persistent asymmetric forcing, causing shortening to be localized above the subduction interface and transmitted eastward toward the retroarc and foreland. The Altiplano Plateau, with crustal thickness locally reaching 60-75 km, records progressive Cenozoic crustal thickening, uplift, and eastward propagation of deformation. Taiwan, as a young arc–continent collision system, locally records early-stage bidirectional deformation around the Central Range and arc-side backthrusting near the Longitudinal Valley–Coastal Range system. However, foreland basin evolution, westward migration of the frontal fold–thrust belt, and modern shortening concentrated along the western Taiwan thrust system indicate that its long-term, orogen-scale, dominant vergence remains west-directed. The Alps demonstrate that tectonic vergence is time-dependent. During early subduction and continental collision, deformation was localized along a single subduction interface, producing a north-vergent simple-shear-dominated architecture. After collision, slab break-off, eclogitization of the orogenic root, and thermomechanical reorganization weakened the earlier interface-controlled deformation and promoted strain redistribution across both flanks of the orogen, leading to paired north- and south-vergent thrust systems and a more symmetric collisional structure. In intracontinental orogens, stable one-sided vergence is not guaranteed. The Qilian Shan and Tianshan lack compelling evidence for a continuous, long-lived, single-sided lithospheric subduction interface. Their deformation is mainly expressed by distributed crustal thickening, high-angle reverse faulting on opposing flanks, and near-symmetric shortening. Recent studies from the Qilian Shan further show that lithospheric-scale tectonic wedges may develop along basin-mountain transition zones, where relatively rigid basin lithosphere wedges into the weakened lower crust of a thickened orogen. Such wedge structures are best interpreted as local expressions within a pure-shear, vertically coherent deformation framework rather than as large-scale simple-shear intracontinental subduction. [Conclusions] Lithospheric-scale tectonic vergence is controlled by the coupling among boundary conditions, negative-buoyancy forcing, and lithospheric strength–buoyancy structure. Persistent single-sided slabs or effective negative-buoyancy sources favor stable simple-shear vergence, whereas slab break-off, loss of one-sided forcing, and mechanically strong opposing blocks favor distributed pure-shear thickening and weak or near-symmetric vergence. [Significance] This study provides a unified framework for interpreting tectonic vergence from plate margins to continental interiors. It highlights vergence as a geometrically testable indicator for linking surface deformation, basin–orogen coupling, and lithospheric-scale geodynamic processes.

Geomorphic indices response to segmentation activity characteristics of the Kouquan fault on the western boundary of the Datong Basin

TianShu CHU, REN JunJie

doi: 10.12090/j.issn.1006-6616.2024134

[Abstract](20) [PDF 2403KB](9)

Abstract:
To investigate whether geomorphic indices can reflect the segmentation-related differences in fault activity, the Kouquan fault—a typical active normal fault located between mountain and basin on the western boundary of the Datong Basin—was selected as the study object. Based on 12.5 m resolution ALOS-PALSAR DEM data, 55 upstream drainage basins on the footwall of the fault were extracted. Several typical geomorphic indices were calculated, including basin slope, mountain front sinuosity (Smf), hypsometric integral (HI), valley-floor-width-to-height ratio (Vf), basin asymmetric factor (Af), basin elongation ratio (Re), and normalized channel steepness index (ksn). The spatial distribution of these indices across different fault segments was analyzed. Influences of non-tectonic factors such as lithology and climate were evaluated, and the results were compared with late Quaternary slip rate data. The findings reveal that the geomorphic indices primarily controlled by tectonic uplift exhibit clear spatial segmentation, with significantly higher values in the central segment than in the southern and northern segments, consistent with the spatial variation in fault slip rates. Some indices are more affected by lithological and climatic factors, showing lower tectonic sensitivity. This study confirms the effectiveness and objectivity of geomorphic indices in identifying segmentation of active faults and proposes a high-resolution, quantitative geomorphology-based approach for fault segmentation analysis.

Study on the cooling history of Pliocene basalt columns in Kanchanaburi，Thailand

ZHOU Enxiong, YAN Yonggang, LAI Zhenyang, LI Danxin, FU Yalan, DENG Xiaotai, ANCHANA Thanakan, VEERAVINANTANAKUL Apivut, CHARUSIRI Punya, WANG Weitao, HUANG Baochun, ZHANG Peizhen

doi: 10.12090/j.issn.1006-6616.2025169

[Abstract](35) [PDF 5062KB](18)

Abstract:
[Objective] Columnar joints in basalt are typical structures formed during magmatic cooling and contraction. However, their formation mechanisms, internal structures, and cooling histories remain debated. This study aims to constrain the internal structure and cooling history of large basalt columns using integrated rock magnetic and paleomagnetic methods. [Methods] Detailed rock magnetic and paleomagnetic analyses were conducted on 49 oriented samples collected from two Pliocene basalt columns (up to 1.5 m in diameter) in the Bo Phloi section, Kanchanaburi, Thailand. Rock magnetic experiments include hysteresis loops, isothermal remanent magnetization (IRM) acquisition, first-order reversal curve (FORC) analysis, anisotropy of magnetic susceptibility (AMS), and temperature-dependent magnetic susceptibility measurements. Stepwise thermal demagnetization was used to isolate stable remanent magnetization components. [Results] Hysteresis loops and IRM acquisition curves show saturation below ~300 mT and a two-stage increase with increasing field, indicating contributions from magnetic components with different coercivities. FORC diagrams confirm pseudo-single-domain (PSD)-dominated magnetic domain states, with systematic differences between column margins and interiors. AMS results show that both basalt columns are characterized by sub-vertical minimum susceptibility axes (K₃) and sub-horizontal maximum (K₁) and intermediate (K₂) axes, with generally low anisotropy degrees (Pj < 1.05), indicating a primary near-horizontal magma flow fabric during emplacement and no evidence for vertical melt migration or internal convection. AMS parameters further reveal systematic spatial variations: marginal samples exhibit lower magnetic susceptibility (Km), lineation (L), and anisotropy degree (Pj), with predominantly oblate fabrics (T > 0), whereas interior samples show higher Km, L, and Pj values and predominantly prolate fabrics (T < 0). These differences reflect contrasting cooling conditions, with rapid cooling at the margins and slower cooling in the interiors. During magma solidification, the margins of the basalt columns experienced faster cooling, resulting in shorter time available for crystallization and preferred orientation of magnetic minerals, and consequently lower magnetic susceptibility and anisotropy. In contrast, the interior portions cooled more slowly and likely remained in a high-temperature plastic or partially molten state for a longer period, allowing magnetic minerals to crystallize more completely, become concentrated, and align under thermal contraction stress. Paleomagnetic results indicate that thermal demagnetization isolates stable single-component remanence carried by PSD titanomagnetite. Six marginal samples from basalt column A exhibit more scattered virtual geomagnetic pole (VGP) distributions and anomalous directions, whereas the remaining 43 samples show relatively clustered VGPs after tilt correction. Systematic variations in remanent magnetization directions and VGPs indicate that cooling did not proceed symmetrically or uniformly from the margins toward the cores, but rather followed an asymmetric, unidirectional regional cooling pattern, which was likely influenced by a localized heat source. [Conclusions] Based on integrated rock magnetic and paleomagnetic analyses, the main conclusions are summarized as follows. (1) The basalt columns from Kanchanaburi are dominated by pseudo-single-domain (PSD) titanomagnetite, and AMS fabrics with sub-vertical K₃ and sub-horizontal K₁ and K₂ axes indicate a primary near-horizontal magma flow during emplacement. (2) Marginal zones cooled faster, producing finer magnetic grains, lower anisotropy, and oblate fabrics, whereas interior zones cooled more slowly, allowing stronger magnetic alignment and higher anisotropy with predominantly prolate fabrics. (3) Systematic variations in paleomagnetic directions and VGPs from 49 samples indicate that post-jointing cooling was not uniform or symmetric, but instead proceeded as an asymmetric, unidirectional process across the basalt columns. [Significance] This study contributes to a better understanding of the cooling process of basaltic lava and provides new insights into geomagnetic secular variation.

Tectonic uplift and geomorphic evolution of the East Tianshan from the Late Cretaceous to Cenozoic

JING Hulu, WANG Weitao, liu kang, LI Zhigang, ZHANG Yipeng, lu lejun, ZHANG Peizhen

doi: 10.12090/j.issn.1006-6616.2025177

[Abstract](36) [PDF 2026KB](17)

Abstract:
[Objective] As an intracontinental orogenic belt reactivated since the Cenozoic by the far-field effect of the India-Asia collision, the Tianshan’s Cenozoic tectonic evolution is key to understanding intracontinental deformation mechanisms. [Methods] Based on stratigraphic sedimentary characteristics and provenance tracing of a section on the northern margin of the Turpan Basin (south of the Bogda Shan), the Late Cretaceous—Cenozoic tectonic and geomorphic evolution of the East Tianshan and its adjacent region has been constrained. [Results] Field investigations reveal that the Paleocene and lower Oligocene strata in this area consist predominantly of red mudstones, indicating a lacustrine environment and stable tectonic conditions. The uppermost Cretaceous and Eocene strata contain conglomerate deposits with relatively small thickness and clast diameters, suggesting tectonic uplift of the Bogda Shan but with weak intensity. In contrast, the upper Oligocene to Pliocene strata are composed of extremely thick, coarse conglomerates, reflecting long-term and intense tectonic activity. Detrital zircon U-Pb ages show that from the Late Cretaceous to the Oligocene, the northern Turpan Basin continuously received detrital material from the West Tianshan, implying low topographic relief of the Bogda Shan during this period. Since the Miocene, however, the Bogda Shan has become the primary sediment source, indicating its rapid tectonic uplift. [Conclusions] In summary, the Bogda Shan remained tectonically stable with low relief during the Late Cretaceous—Oligocene. Since the late Oligocene, it has undergone intense deformation and rapid uplift, becoming the sole provenance area for the northern Turpan Basin. [Significance] This study refines the Cenozoic tectono-geomorphic evolution of the East Tianshan, thereby contributing to a better understanding of the intracontinental deformation processes resulting from the India-Asia collision.

A Study of Diffusion Coefficients and Multi-scale Diffusion Models for Oil and Gas Transport in Shale

ZHANG Mingdi

doi: 10.12090/j.issn.1006-6616.2025140

[Abstract](30) [PDF 794KB](13)

Abstract:
[Objective] Diffusion governs fluid transport and production behavior in shale oil and gas reservoirs with nano–microscale pore–fracture systems. However, strong nanoscale confinement and multiscale structural complexity make the underlying mechanisms unclear, and existing models lack cross-scale predictive capability. This study aims to clarify diffusion mechanisms and develop a model applicable to multiscale porous media. [Methods] High-temperature and high-pressure diffusion experiments were conducted, combined with fractal modeling and nanoscale confinement analysis. A fractal–confinement diffusion model was established and validated against experimental data. [Results] Nanoscale confinement significantly affects phase behavior and diffusion capacity. (1) Confinement induces phase-diagram contraction and a leftward shift of the critical point, leading to a reduction of effective diffusivity by approximately five orders of magnitude compared with bulk fluids. (2) Porosity and permeability are the primary structural controls. When porosity increases from 5.68% to 10.53%, diffusion coefficients increase by about one order of magnitude. When bedding-fracture permeability increases from 1.69 mD to 404.88 mD, diffusion coefficients rise by 3–4 times, indicating enhanced transport pathways. (3) Pressure and temperature exert different effects: increasing pressure (10–36 MPa) suppresses gas-phase diffusion but promotes liquid-phase diffusion, whereas increasing temperature (80–115 °C) enhances diffusion for both phases. (4) Diffusion capacity in fractures exceeds that in the matrix by 1–2 orders of magnitude, demonstrating the dominant role of fractures in large-scale transport. (5) The proposed model matches experimental results well and captures multiscale diffusion behavior, enabling structural sensitivity analysis and cross-scale prediction. [Conclusions] Diffusion in shale reservoirs is jointly controlled by nanoscale confinement, pore–fracture structure, and thermodynamic conditions. Confinement reduces diffusivity and alters phase behavior, while fractures significantly enhance transport capacity. The proposed model effectively integrates these effects and provides accurate cross-scale predictions. [Significance] This study establishes a practical framework for modeling shale-fluid diffusion and provides theoretical support for quantitative evaluation of fluid transport and optimization of reservoir development.

Magnetostratigraphy of the Late Cenozoic sediments of the West Kunlun foreland and its tectonic implications

ZHANG Lijuan, ZHANG Zhiliang, REN Zhikun, BAO Guodong, NING Yutao

doi: 10.12090/j.issn.1006-6616.2025163

[Abstract](46) [PDF 3631KB](40)

Abstract:
[Objective] The West Kunlun Mountains, located on the northwestern margin of the Tibetan Plateau, is a key area for studing the tectonic uplift and outward growth of the plateau. However, the Cenozoic uplift of the West Kunlun Mountains is still controversial. [Methods] This study focuses on the well-exposed late Cenozoic sediments on the Pusika aticline, West Kunlun foreland. Using high-resolution magnetostratigraphy to constrain the base of the growth strata, we further define the uplift timing of the West Kunlun Mountains from the perspective of mountain-basin coupling. [Results]The results indicate that the magnetic minerals of the sediments in this study are hematite and magnetite. The high-resolution magnetostratigraphic results show that the age range of the Pusika section is between ~6.8 Ma and ~2.4 Ma, and the base age of growth strata is ~5.3 Ma, indicating that the deformation of this anticline initiated at ~5.3 Ma. [Conclusion] Integrating previously published results of sedimentation, tectonics, and low-temperature thermochronology in the West Kunlun foreland, we propose that the West Kunlun Mountains have subjected an intensive uplift since ~5.3 Ma, suggesting that the Tibetan Plateau experienced a significant uplift since the beginning of the Pliocene, with tectonic stress began to propagate toward the Tarim Basin. [Significance] This study provides new perspectives and evidence for understanding the complex relationship between the uplift of the Tibetan Plateau and the sedimentary responses in its periphery, contributing to a further unraveling of the comprehensive impact of the Tibetan Plateau.

Reactivation Mechanism and Stability Trend Prediction of the Huangci 2# Landslide

DOU Xiaodong, LI Yushan, MENG Yateng, CONG Kai, ZHANG Yongjun, JIA Qiang

doi: 10.12090/j.issn.1006-6616.2026014

[Abstract](158) [PDF 2310KB](137)

Abstract:
[Objective] To investigate the disaster-causing mechanism, dynamic evolution process, and post-disaster stability trend of the reactivation of the Huangci No. 2 landslide in Heifangtai, Gansu Province on December 10, 2025. [Methods] Field surveys and the Transient Electromagnetic Method (TEM) were comprehensively applied to analyze the deep structure of the landslide. A back-analysis was conducted based on Massflow numerical simulation, and the 3D limit equilibrium method was utilized to perform quantitative stability evaluation for the post-disaster deposit and the high-steep rear wall. [Results] (1) The landslide reactivation is the result of toe excavation, long-term irrigation, and special meteorological conditions. The freezing-induced water retention effect acted as the direct trigger, where surface freezing blocked seepage channels, causing an accumulation of pore water pressure and inducing a loess-mudstone bedding slide. (2) The entire sliding process lasted for 22 hous, with a cumulative displacement of 310 m. The Massflow analysis reproduced the four-stage evolution process of "creep-acceleration-deceleration-consolidation", and the IoU of the deposition morphology reached 85.85%. (3) Quantitative calculations shows that the current deposit has a safety factor greater than 1.15, indicating a stable state of settlement and consolidation; however, under extreme saturation conditions, the potential collapse volume of the high-steep rear wall could reach 40.9×10⁴ m³, with a maximum sliding distance of approximately 640 m. [Conclusion] The analysis suggests that the reactivation of the landslide is controlled by freezing-retained water and multiple disturbance mechanisms. Although the main body has currently stabilized, secondary instability of the high-steep rear wall is highly likely to occur, necessitating the establishment of a long-term dynamic monitoring system to strictly prevent high-position disasters. [Significance] The understanding of the reactivation mechanisms of loess landslides in seasonal freeze-thaw zones was deepens, providing a scientific basis and technical support for prevention and mitigation of such landslides.

Tectonic evolution of the WesternYangtze Block during the Ediacaran–Cambrian: Evidence from detrital zircon U-Pbgeochronology

Zhiqiang SHI, Le SUN, ZHANG Hong, PEI Jinyun, LI Wei

doi: 10.12090/j.issn.1006-6616.2025065

[Abstract](92) [PDF 2116KB](122)

Abstract:
[Objective] The Yangtze Block was a crucial component of the Gondwana supercontinent. During the Ediacaran-early Cambrian, its western margin underwent a marked transition from carbonate-dominated to siliciclastic-dominated depositional environments. However, the tectonic dynamics controlling this sedimentary facies shift of early Cambrian sedimentation remain poorly constrained. The exposed thick Early Cambrian terrigenous clastic rocks on the western Yangtze Block are key archives for tracing sediment sources and studying the geotectonic background of the Early Cambrian .[Method] This study carried out systematic detrital zircon U-Pb geochronology and whole-rock element analysis on the lower Cambrian Qiongzhusi Formation on the western Yangtze Block to study above question. [Results] The results indicate: (1) The clastic rocks exhibit high-field-strength elements (HFSEs) and large-ion lithophile elements (LILEs; e.g., Th, Zr, Hf, Ba, Pb) consistent with upper crustal compositions, whereas Sr, Sc, V, Cr, Cu, Ni, and Zn show depletion relative to upper continental crust (UCC)-particularly pronounced for Sr, Cr, V, and Cu. The immobile elements (Th, Sc, Hf, Zr, Ho) and rare earth elements (RREEs; e.g, La, Ce, Yb) suggest a dominantly felsic igneous provenance of the upper continental crust; (2) Primary age clusters of detrital zircon U-Pb ages in the Qiongzhusi Formation are ca.590-500Ma and ca.880-720 Ma, with subordinate groups at 1900-1500 Ma and 2500-2400 Ma. [Conclusions]Integrated with regional data and prior studies, we propose that the early Cambrian detritus was largely derived from the Ediacaran-Early Cambrian magmatic rocks in the Longmenshan tectonic belt (Ediacaran-early Cambrian), and the late Neoproterozoic felsic magmatic rocks of the Panxi-Hannan magmatic arc, Ailaoshan Magmatic Arc and the Jiangnan Orogen. The Proto-Tethyan Ocean's subduction beneath the western Yangtze during the Ediacaran-early Cambrian converted the western Yangtze from a passive to an active continental margin, and formed a late Ediacaran-early Cambrian magmatic arc. This arc supplied voluminous early Cambrian detritus, ultimately shifting the western Yangtze margin to a siliciclastic-dominated depositional system. [Significance]These findings reveal the provenance linkages between the western Yangtze and adjacent orogenic belts, thereby providing critical constraints for reconstructing the tectonic and paleogeographic evolution of the South China Block during the Ediacaran-Early Cambrian.

A 4400-Year-Old Extreme Paleo-Storm Surge Recorded in the Dongzhai Port Chenier, Hainan Island, China

ChaoQun WANG, DongXia SUN, YaoLing ZHANG, XiaoXiao YANG, Lei ZHANG, DaoGong HU

doi: 10.12090/j.issn.1006-6616.2025073

[Abstract](119) [PDF 3542KB](163)

Abstract:
Identifying paleo-storm surge deposits and extreme storm surge events holds significant scientific and practical importance for understanding the recurrence patterns of super typhoon-induced surges and predicting future storm hazards. Current research predominantly focuses on historical and modern storm surges, with less attention given to prehistoric extreme surges. This study investigates a 3.2-m-thick chenier at Wushu Village, Dongzhai Port, Hainan Island. Analyses of sedimentary structures, shell provenance, accelerator mass spectrometry (AMS)¹⁴C dating, and estimates of overtopping deposit elevation demonstrate that this chenier records an extreme storm surge event approximately 4400 years ago. The chenier's overtopping deposits accumulated on a Late Pleistocene alluvial plain landward of the Holocene highstand paleo-shoreline. Nine AMS ¹⁴C dates on shells range from 4402 to 6647 cal yr BP, exhibiting age reversals and co-occurrence of younger and older shells. The deposit is well-sorted and displays sedimentary structures diagnostic of high-energy deposition, including hummocky cross-stratification, current cross-stratification, and erosional scours. Comparative analysis of shell assemblages and ages between the chenier and underlying paleo-lagoon deposits within Dongzhai Port indicates that the chenier shells were reworked from these older lagoon sediments. The reconstructed paleo-elevation of the overtopping deposits indicates a storm surge height of 5.5 m above modern sea level. This exceeds the 4.58 m surge documented during the 2014 Super Typhoon Rammasun along the Dongzhai coast. Considering the potential influence of astronomical tides on total water levels, we infer that the extreme storm surge height 4400 years ago was likely superimposed on a contemporaneous high astronomical tide.

Evaluation of Source Rocks and Oil Source Correlation in Chang 7-Chang 6 Member of Yanchang Formation in Jingbian Area, Ordos Basin

SiWei TANG, Hui XUE, YouJun TANG, ShuMin WANG, GuangMing HU, Geng LI, FangTingYu SHI

doi: 10.12090/j.issn.1006-6616.2025050

[Abstract](115) [PDF 2632KB](159)

Abstract:
Objective The Chang 7 and Chang 6 Members of the Yanchang Formation in the Jingbian Area of the Ordos Basin constitute significant source rock intervals. However, systematic studies on their hydrocarbon generation potential and contributions to petroleum accumulation remain limited, which constrains further exploration efforts in this region. Therefore, this study integrates geochemical analytical methods to systematically characterize the distribution and the geochemical properties of the Chang 7 and Chang 6 source rocks in the Jingbian area, as well as the geochemical signatures of the crude oils from the Yan 9 and Chang 2 reservoirs in the Jingbian Oilfield. Methods By comparing the geochemical parameters between the local Chang 6 and Chang 7 source rocks and the Zhangjiatan Shale in the center of the basin, the potential sources of the oils in the Yan 9 and Chang 2 reservoirs were identified. Results The results demonstrate that the Chang 7 source rocks are high quality, with widespread distribution and considerable thickness. They are characterized by Type I-II₂ kerogen and are in the mature stage. The biomarker characteristics indicate mixed organic matter inputs, deposited in a reducing environment with low salinity. The low Pr/Ph and high C₂₇/C₂₉ regular sterane ratios further suggest that the organic matter is predominantly derived from aquatic algae and other lower organisms, consistent with a reducing, fresh to brackish water depositional environment. In contrast, the Chang 6 source rocks are of medium to high quality, containing Type II₂-III kerogen and are generally in the low-to-mature stage. The moderate Pr/Ph and low C₂₇/C₂₉ regular sterane ratios reflect a predominance of terrigenous higher plant input, deposited under a weakly reducing environment. The oil-source correlation results reveal that the Yan 9 and Chang 2 oils are of the same origin, primarily derived from the Chang 7 source rocks, with a minor contribution from the Chang 6 Member. Conclusion (1) the Chang 7 Member is the primary, high-quality source rock in the Jingbian area, superior to the Chang 6 Member in terms of thickness, lateral distribution, organic richness, and hydrocarbon generation potential. (2) Distinct biomarker signatures differentiate the Chang 7 (aquatic/algal, reducing), Chang 6 (terrigenous, weakly reducing), and distal Zhangjiatan (highly aquatic, strongly reducing) source rocks. (3) The Yan 9 and Chang 2 crude oils share a common origin and are primarily sourced from the local Chang 7 source rocks, with a possible minor contribution from the Chang 6 Member. The oils show no direct genetic link to the Zhangjiatan Shale in the basin center, supporting a predominantly local hydrocarbon sourcing model for the Jingbian area. Significance This study provides crucial geochemical evidence for a local hydrocarbon system within the Jingbian area, resolving previous ambiguities regarding oil sources and assessing the resource potential in the Jingbian Area, Ordos Basin.

Research on mechanical parameter prediction and modeling methods based on statistical regression and prestack inversion—Taking a particular area in the Bonan Depression as an example

Bin WANG, Han XIAO, XueMin NIU, RuiXuan ZHANG, Xing GE

doi: 10.12090/j.issn.1006-6616.2025084

[Abstract](162) [PDF 1153KB](235)

Abstract:
Abstract: [Objective] In the development of unconventional oil and gas, there exist problems such as complex reservoir structure and unclear rock mechanical properties. During the design of horizontal well trajectories and fracturing schemes, it is necessary to rely on rock mechanical models for segment and cluster division and design, thereby increasing the modification volume, reducing the risk of set changes, and achieving efficient development of unconventional oil and gas. The rock mechanics model can simultaneously reflect the continuous changes of mechanical parameters in the longitudinal and transverse directions with high resolution in the target area of the horizontal well trajectory. Therefore, in response to the model requirements, this paper provides a mechanical parameter prediction and modeling method based on statistical regression and prestack inversion. [Methods] Basing on the core test data and logging data, the quantitative relationship between elastic parameters and rock mechanical parameters is established and analyzed. Then, three-dimensional prestack inversion is performed using both drilling data and seismic data to obtain precise elastic parameters, including longitudinal wave velocity, density, Poisson's ratio, and Young's modulus. [Results] The application of this method in the tight glutenite reservoirs of the Bonan Sag has yielded significant and practical results. First, a robust quantitative relationship between mechanical and elastic parameters was established. The statistical regression relationship between Young's modulus and Uniaxial Compressive Strength (UCS) demonstrated a strong correlation (e.g., R² > 0.75), validating the feasibility of predicting rock mechanical strength from elastic parameters in this glutenite formation. Statistical analysis confirmed that the mechanical parameters of these highly compacted, low-porosity glutenites are primarily controlled by lithology and gravel content, exhibiting a very weak correlation with burial depth. This justifies the use of a unified predictive model across the entire studied depth interval. Second, a high-resolution 3D mechanical parameter model was constructed. A depth-domain structural model was built using logging data and a smoothed time-depth velocity field. Following attribute extraction, a comprehensive 3D mechanical parameter model for the target block was established. This model effectively overcomes the discreteness and non-continuity inherent in core and logging data, accurately characterizing the continuous lateral and vertical variations of mechanical properties. Third, the results are directed toward engineering application. To fully leverage the high vertical and lateral resolution of the mechanical parameter volume, the calculated seismic attributes were integrated into the 3D geological model based on engineering requirements. This outcome provides an accurate model for fracturing design, enabling precise assessment of the rock mechanical distribution along horizontal well sections, rational design of stage and cluster placement, optimization of pumping parameters, and enhancement of fracture conductivity. Consequently, it significantly increases the stimulated reservoir volume, effectively boosting single-well productivity and recovery rates. [Conclusion] The study leads to the following main conclusions: The integrated methodology of pre-stack inversion and statistical regression is a viable and effective solution for predicting 3D mechanical parameters in tight glutenite reservoirs. This method builds a bridge between petrophysical and seismological parameters, effectively resolving the challenge of poorly constrained rock mechanical properties in complex unconventional reservoirs. The constructed 3D mechanical parameter model provides a more reliable geological basis for optimizing well trajectories and fracturing designs. [Significance] The primary significance of this research lies in providing a reliable and scalable method for 3D rock mechanical parameter prediction and modeling, possessing substantial theoretical innovation and practical application value. It offers a dependable data foundation and a theoretical framework for defining mechanical boundaries and optimizing fracturing designs in heterogeneous tight reservoirs. This approach holds significant potential for improving fracturing efficiency and maximizing production in challenging tight glutenite formations.

MA Zhanrong, LI ZhenHong, LIU JianPing, HU AiPing, LinLin KOU

doi: 10.12090/j.issn.1006-6616.2025031

[Abstract](124) [PDF 3282KB](244)

Abstract:
[Objective] The dolomite of Ordos basin west margin complex tectonic belt Ordovician Kelimoli Formation as a high quality reservoir for natural gas exploration, its genesis mechanism and the relationship between sedimentary environment and tectonic superimposed transformation, there are still many disputes, which restricts the guidance of oil and gas exploration.[Methods] Based on comprehensive test and analysis including thin-section identification, cathodoluminescence, carbon-oxygen isotope, X-ray diffraction order, geochemical rare earth and trace elements, and strontium isotope, combined with the regional tectonic evolution process, this study explores the genetic mechanism of dolomite.[Results] Cathodoluminescence overall exhibits a relatively weak dark brown coloration with distinct ring bands, and authigenic quartz and saddle-shaped dolomite as hydrothermal minerals are visible, characterized by features of multi-stage recrystallization and burial origin. Carbon and oxygen isotope characteristics indicate that the dolomite has a burial origin. The overall order of the dolomite shows a relatively low degree, and the higher the temperature, the lower the order, suggesting that the dolomite formed in an environment with relatively high temperature and rapid crystallization rate. The rare earth element partitioning pattern is characterized by positive Ce and positive Eu anomalies, indicating that the formation process of dolomite is the result of internal fluid adjustment and redistribution within the diagenetic system under relatively closed, high-temperature, and high-pressure conditions. The lower the Sr content and the higher the Fe and Mn element contents, overall showing the characteristics of multi-stage superimposed modification under deep burial conditions. The strontium isotope values of medium to coarse-grained dolomite are significantly close to the average value of crustal source strontium isotopes, which may have been affected by crustal source strontium carried by synchronous tectonic activities.[Conclusion] Research indicates that dolomite formation is primarily attributed to deep burial, while also undergoing superimposed tectonic fluid modification. The evolution of Ordovician Krimolli Formation dolomite is closely linked to the deep fault system. During the co-deposition period, this fault system controlled the development of high-energy terraces. In the subsequent tectonic activity phase, the deep fault system became a fluid migration channel, facilitating the superimposed modification of dolomite bodies.[Significance] Research results can provide a fundamental support for the efficient exploration of oil and gas resources.

ZHU Shu, ZHANG Quan, WANG Yanbing, LI Jin, LI Renjie, HUANG Yong, LI Benliang, LIU Fucai, YAN Yuping

doi: 10.12090/j.issn.1006-6616.2025170

[Abstract](193) [PDF 2408KB](276)

Abstract:
The Jiali Fault on the southeastern margin of the Tibetan Plateau is a key boundary structure for the southeastward extrusion of plateau material. Its geometric distribution and activity are crucial for understanding the tectonic evolution of the plateau and assessing regional engineering risks. However, the precise spatial location and Holocene activity of its southeastern segment (Guxiang to Gongrigabu section) have long been controversial due to rugged terrain and thick vegetation cover. Targeting this key contentious segment, this study integrated multiple methods, including high-resolution remote sensing interpretation, field geological and geomorphological surveys, drilling and trenching exposure, and magnetotelluric sounding, to systematically investigate the fault's spatial distribution, structural characteristics, and activity. The results indicate that the southern branch of the Jiali Fault Zone continuously extends along a line from south of Guxiang, through Gionala, Jinzhunongba, to Langqiunongba. Tectonic geomorphic evidence such as fault troughs, sag ponds, pressure ridges, bedrock fault mirrors, and horizontal slickensides were identified via remote sensing and field investigations. Magnetotelluric data revealed clear low-resistivity fracture zones, and drilling core samples exposed significant fault-related rocks. This evidence collectively confirms the existence and distribution of the fault within this segment. Combined with regional paleoseismic studies, it is concluded that this segment has the potential for Holocene activity. The research further systematically analyzed the deep engineering effects potentially triggered by fault activity, including surrounding rock deterioration, cosismic offset, high in-situ stress, seismic motion amplification, water inrush and mud gushing, geothermal anomalies, and secondary disasters at tunnel portals. The research results not only provide key geological constraints for improving the tectonic model of the southeastern Tibetan Plateau but also offer indispensable scientific basis for the planning, seismic design, and risk prevention and control of major projects (such as the Sichuan-Tibet Railway) traversing the fault zone.

Wu Chengjie^1,2，Zeng Huaien^1,2,3，Chen Jun⁴，FengYu⁵ , Li xi^2,3，WeiPengcheng^2,3,Yan Baorui^1,2

chengjie wu, HuaiEn CENG, jun chen, Yu FENG, xi li, pengcheng wei, baorui yan

doi: 10.12090/j.issn.1006-6616.2025077

[Abstract](326) [PDF 1363KB](242)

Abstract:
Accurate prediction of landslide displacement is a crucial component of landslide early warning systems. This paper proposes a landslide displacement prediction model based on Gaussian Process Regression (GPR) combined with diverse time-series feature engineering, achieving high-precision displacement prediction and uncertainty quantification. TAKING THE BAZIMEN LANDSLIDE AS AN EXAMPLE, During the feature engineering phase, displacement lag features, rolling mean of rainfall, rolling variance of reservoir water level, and displacement change rate are constructed. Additionally, temporal decomposition features including monthly and quarterly components are extracted. SUBSEQUENTLY, EMPLOY THREE-FOLD TIME SERIES CROSS-VALIDATION, ALONG WITH A GRID SEARCH SCHEME, TO OPTIMIZE HYPERPARAMETERS IN CONJUNCTION WITH THE TIME SERIES CROSS-VALIDATION STRATEGY, THEREBY MITIGATING THE RISK OF OVERFITTING IN THE SMALL-SAMPLE SCENARIO. The results demonstrate that after incorporating multi-source temporal features, the prediction coefficients of determination (R²) for monitoring points ZG110 and ZG111 at the Bazimen Landslide significantly increase to above 0.99. Metrics such as MAE, RMSE, and MAPE are substantially reduced, indicating a significant improvement in prediction accuracy. This study integrates probabilistic modeling with feature interpretability analysis. The proposed method achieves high-precision landslide displacement prediction in small-sample environments while simultaneously quantifying prediction uncertainty. It provides effective decision support for landslide risk early warning and engineering safety assessment.

Tectonic stress field characteristics in Wushi , Xinjiang and the stress impact of the Wushi M7.1 earthquake

ZeYao SONG, YongGe WAN, PeiYuan GU, MingYue ZHOU

doi: 10.12090/j.issn.1006-6616.2025085

[Abstract](334) [PDF 2767KB](268)

Abstract:
[Objective] The Wushi region in Xinjiang is located at the intersection of multiple tectonic units, making it a key area for stress concentration and release. Although previous studies have revealed some characteristics of the tectonic stress field in this region, there is still a lack of in-depth and systematic analysis regarding the potential impact of the 23 January 2024 Wushi M 7.1 earthquake on the regional stress field. Therefore, adopt more systematic focal mechanism data to conduct a detailed analysis of the regional tectonic stress field characteristics and to explore the influence of the Wushi M 7.1 earthquake on the regional stress field. The aim is to provide more comprehensive scientific references for understanding the regional seismogenic environment and predicting future seismic activity.[Methods] Using the damped stress tensor inversion method and incorporating data from multiple institutions, we analyzed the stress field in different subregions of the study area and compared the changes in the tectonic stress field before and after the earthquake.[Results] The results of the stress field inversion show that, except for the area near the Jiashi seismic group, the R value is greater than 0.5, and the azimuth of the maximum principal compressive stress in the Wushi region gradually rotates from approximately NNW in the south to near N—S in the north, the azimuth is from 168.75° to 183.45°, and plunge angle is from 6.85° to 19.58°, it is in a compressive stress state. The Jiashi seismic area cluster shows a strike-slip feature of NNE—SSW compression and NWW—SEE extension.The northern area of the Jiashi seismic shows a thrust stress state, while the southern area presents a strike-slip stress state. By comparing and analyzing the regional stress field changes before and after the Wushi earthquake, it is found that the optimal principal compressive stress direction before the earthquake was N—S direction, and deviated by 12.53° in azimuth after the earthquake, with a spatial rotation angle of 15.06°. This indicates that this earthquake had a relatively small impact on the stress field of this area, which meaning that the stress field did not undergo significant changes after the earthquake, and still remains in the compressive stress system. [Conclusion] The tectonic stress field in the Wushi region is subject to N—S compression from the collision of the Indian plate with the Eurasian plate on the western margin of the Tibetan Plateau to form a strong near-north-south horizontal compression, and the stress from the plate collision is transmitted to the northeast to the Tian Shan orogenic belt, which leads to the shortening of the crust and retrograde thrusting between the Tarim Basin and the Tian Shan. The Wushi M 7.1 earthquake had a relatively minor impact on the regional stress field. The stress system of the entire area is still controlled by deep tectonic activities. The overall stress field is consistent, but the seismic cluster in northern Jiashi is located at the junction of the northern margin of the Tarim Plate and the Tianshan Mountains, presenting a thrust stress mechanism. This area is the plate tectonic transition boundary between the Tarim Basin and the Tianshan orogenic belt.[Significance] By analyzing the characteristics of the tectonic stress field in the Wushi region of Xinjiang and the impact of the Wushi M 7.1 earthquake on the regional stress field, the characteristics of the stress field and the effect of earthquakes on the regional stress field. This contributes to a deeper understanding of the tectonic relationship between the Tianshan orogenic belt and the Tarim Basin. In addition, the northern part of the Jiashi seismic exhibits a thrust stress mechanism, which is inferred to represent a tectonic transition boundary between the Tarim Basin and the Tianshan orogenic belt. This finding holds significant implications for regional tectonic segmentation and seismic hazard assessment.

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Supervisor： China Geological Survey

Sponsor： Institute of Geomechanics, Chinese Academy of Geological Sciences; Geological Society of China (GSC)

Editor-in-Chief： DENG Jun

ISSN 1006-6616

CN 11-3672/P

Post Issue Number 82-124

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