Myanmar's high seismic hazard is underscored by the 2025 M w 7.7 earthquake on the Sagaing Fault, yet its seismicity patterns and underlying controls remain poorly understood. Using new seismic data from the 2nd-phase array of the China-Myanmar Geophysical Survey in the Myanmar Orogen, we construct a high-resolution catalog of 1,819 local-shallow earthquakes in central and southern Myanmar by combining deep-learning algorithms and manual phase-pick refinement, with 93 robust focal mechanisms. Integrated with a previous catalog further north, our analysis reveals that the Sagaing Fault dips eastward at similar to 73 degrees in the north, transitions to a nearly-vertical geometry at similar to 20.5 degrees N, and continues further south. This newly identified fault segmentation and associated geometric variations provide essential constraints for improving fine-scale rupture modelling of the 2025 earthquake. For the whole of Myanmar, our results suggest an abrupt along-strike north-south change of shallow seismicity across similar to 20 degrees N, with contrasting earthquake distributions and focal mechanisms.

ABSTRACT The Western Slope of the Songliao Basin is a key frontier for hydrocarbon exploration, but the origin of natural gas accumulations and the depositional controls on deep Permian source rocks remain poorly constrained. This study combines gas compositional and stable carbon isotope data from 66 wells with elemental geochemical data from 35 core samples recovered from well MKD1 to characterise both the genetic types of natural gases and the paleoenvironmental conditions governing source rock development. Gas geochemical analyses show the recovered gases are dominated by CH 4 , with concentrations of 74.89% to 97.41%, and generally low CO 2 contents. Carbon isotope signatures indicate CH 4 occurs mainly as oil‐associated thermogenic gas and secondary cracking product, with primary microbial gas restricted to the Western overlap zone. CO 2 is predominantly of inorganic origin, though carbon isotope data alone cannot uniquely discriminate carbonate decomposition from other potential inorganic sources. Paleoenvironmental reconstructions from the MKD1 core section record a systematic transition through the Middle–Upper Permian succession, shifting from saline, reducing marine settings to transitional and lacustrine fresh to brackish water conditions. Organic matter enrichment is governed primarily by strongly reducing bottom‐water conditions, humid paleoclimate and elevated paleoproductivity, rather than direct salinity forcing. These depositional conditions favoured the development of Type II kerogen, and subsequent thermal cracking of this kerogen accounts for the oil‐associated thermogenic gas signatures observed in overlying Cretaceous reservoirs. These findings provide a basis for evaluating deep hydrocarbon potential across the western Songliao Basin.

High-porosity sandstones are highly susceptible to the development of deformation bands under tectonic stress.However,limited studies have been conducted on factors controlling the structures and physical properties of these bands.By combining a systematic literature review and experimental analysis,we investigate the macro-and micro-structural characteristics and deformation mechanisms of these bands in high-porosity sandstones.Furthermore,we analyze the primary and secondary factors governing the structural and physical property evolution of these deformation bands,as well as the mechanisms by which these factors operate.The results indicate that effective normal stress and shear displacement serve as the primary factors controlling the structural and permeability evolution of the deformation bands.Specifically,the effective normal stress significantly reduces the permeability by intensifying grain breakage and modifying the boundary morphologies of shear zones.In contrast,shear displacement predominantly governs the thickening and structural stratification of the deformation bands.Notably,such controlling effect exhibits a pronounced nonlinear evolutionary trend,with a critical displacement threshold observed.The secondary controlling factors include the mineral composition,initial porosity,grain size,sorting degree,clay content,and strain rate of surrounding rocks.Under certain geological conditions,these factors modulate the structural morphology and physical property parameters of the deformation bands.The evolution of the deformation bands consists of five stages:non-deformation,initial deformation,initial stratification,stratification transition,and stable formation.Each stage exhibits regular variations in the microstructural parameters of the deformation bands,including band thickness,grain-size distribution,grain roundness,and grain orientation.With increasing stress level and displacement,the deformation bands experience significantly intensified grain breakage and pronounced enrichment of fine-grained matrix.This leads to porosity reduction of up to a maximum of 70%and permeability decreases of two to three orders of magnitude.The evolutionary patterns of the structures and physical properties of the deformation bands derived from laboratory tests are highly consistent with data from field outcrops.Future research on the of deformation bands should focus on computed tomography(CT)-based three-dimensional structural modeling,thermal-hydrological-mechanical-chemical(THMC)multi-field coupling simulations,and machine learning-based modeling for predicting structures and permeability.

This study systematically investigates the genesis, migration, accumulation, and distribution patterns of natural gas and CO2 in the Changling Fault Depression of the Songliao Basin through an interdisciplinary Earth system framework, focusing on multi-sphere interactions. Integrated analyses employing gas geochemistry, numerical simulations, and core observations reveal that deep magmatic-hydrothermal processes (lithosphere) provide the primary heat and fluid sources, paleoclimate oscillations (atmosphere) modulate organic productivity and preservation efficiency, and lacustrine-level fluctuations (hydrosphere) control reservoir connectivity and gas-phase partitioning. These synergistic controls jointly determine hydrocarbon generation in source rocks, volcanic reservoir evolution, and CO2-CH4 competitive accumulation. Results indicate that natural gas within the Changling Fault Depression is predominantly thermogenic with localized abiotic contributions, as evidenced by δ13C1 values ranging from −56.8‰ to −1.7‰ and the coexistence of both normal and reversed carbon isotopic fractionation sequences. CO2 exhibits a dominant inorganic mantle-derived origin, characterized by δ13CCO2 values between −18.9‰ and −0.6‰. Thermogenic gas preferentially accumulates in volcanic reservoirs of the Quantou and Yingcheng Formations, while CO2 and CH4 display planarly complementary distributions, with high-CO2 concentrations localized in the eastern Changshen area corresponding to low-CH4 zones. Paleoenvironmental reconstructions reveal a progressive transition from deep to shallow lacustrine conditions, from humid to semi-arid climate regimes, and from freshwater to brackish depositional environments during the Early Cretaceous. Source rocks of the Shahezi Formation exhibit stronger primary productivity and higher hydrocarbon generation potential than those of the Yingcheng Formation, driven by coupled effects of tectonic subsidence, volcanic nutrient input, and redox-controlled organic preservation. Tectonic evolution governs vertical hydrocarbon migration and mantle-derived CO2 influx through volcanic activity and fault system development, whereas climate-sedimentation coupling under Ferrel circulation and global eustatic cycles regulates organic matter enrichment. This integrated analysis establishes a comprehensive framework for volcanic gas reservoir exploration and CO2 geological sequestration, contributing to the synergistic advancement of carbon neutrality and energy security strategies.

Seismological investigations of the uppermost mantle beneath Myanmar are essential for constraining the dynamic processes associated with oblique subduction in this region. We constructed a high-resolution Pn-wave velocity and azimuthal anisotropy model using a combined data set of 51,982 high-quality Pn arrivals, compiled from recordings of three newly deployed temporary seismic arrays and bulletin data from the ISC-EHB and the National Earthquake Data Center. The velocity model reveals large-scale high-velocity anomalies beneath the northeastern margin of the Indian Plate, consistent with underthrusting of cold Indian continental lithosphere. Additional high-velocity anomalies west of the Kabaw Fault spatially coincide with the geometry of the subducting Indian Plate in the Slab2 model, further supporting ongoing slab penetration. In contrast, a pronounced uppermost mantle low-velocity zone beneath northern Myanmar suggests localized upwelling of hot mantle material, likely induced by horizontal tearing of the Indian slab and potentially linked to Quaternary volcanism. Beneath the southern Indo-Burma Ranges, a low-velocity anomaly with trench-parallel anisotropy implies antigorite lattice-preferred orientation. Beneath the Central Myanmar Basin volcanic cluster, an arcuate high-velocity anomaly is interpreted as relatively cold and dry mantle-wedge exhumation associated with slab rollback.

This study investigates Archean metamorphic buried-hill reservoirs in the Bohai Bay Basin, focusing on their formation mechanisms, multi-stage fluid evolution, and geochemical characteristics. Protolith composition, chemical index of alteration (CIA), formation water chemistry, and carbon-oxygen isotopes were analyzed for three blocks: BZ19-6, BZ13-2, and BZ26-6. The protolith is dominated by sedimentary rocks including claystone, mudstone, siltstone, feldspathic sandstone, and argillaceous limestone, with minor intermediate igneous rocks and tuff. CIA values vary among blocks and stratigraphic intervals, reflecting differential weathering controlled by overlying lithology and thickness. Higher CIA corresponds to stronger meteoric leaching and better reservoir porosity. Formation water types differ systematically. BZ19-6 is dominated by Na-HCO3/SO4-type water, indicating meteoric infiltration and silicate weathering. BZ13-2 and BZ26-6 are dominated by Na-Cl-type water, suggesting residual brine or seawater influence. C-O isotopic data distinguish three calcite types: meteoric, hydrothermal, and organic-acid-modified. Their spatial distribution shows that BZ26-6 experienced the strongest hydrothermal overprint and organic acid alteration, while BZ19-6 lacks the organic acid signal. These results clarify the tectonic-fluid coupling that shaped the reservoirs. Indosinian to Yanshanian fracturing created pathways for simultaneous meteoric leaching and hydrothermal baking. Himalayan transtension enhanced differential dissolution and prolonged thermal alteration. In hydrocarbon-charged blocks, thermochemical sulfate reduction added late-stage corrosive fluids. The proposed isotopic framework provides a practical tool for identifying fluid sources in similar ancient basement reservoirs.

Abstract The Cenozoic convergence between the Indian and Asian plates has driven large‐scale mantle convection that interacts with both plates. Understanding this convergence benefits from clear imaging of the lithosphere‐asthenosphere boundary (LAB). Beneath the northeastern Indian plate margin, our Sp receiver functions (RFs) computed from dense array data reveal a regionally shallow LAB at an average depth of ∼70 km, except beneath the Indo‐Burma Ranges, where the Indian LAB dips eastward at an average of ∼20° down to ∼140 km; this dipping geometry is resolved primarily through SKS‐derived RFs. Farther east, a positive velocity gradient emerges ∼50–80 km beneath the Burma LAB, indicating an upper‐asthenospheric low‐velocity layer. Waveform modeling further indicates a sharp LAB, characterized by a Vs drop of up to ∼6%–10% over <∼20 km. These observations support melt presence below the LAB, potentially linked to the asthenospheric flow induced by the Indian plate subduction and subsequent rollback and/or tearing.

Myanmar is located on the eastern margin of the India-Eurasia collision zone, where the Indian sub-continent is subducting beneath the Burma microplate. Magmatic processes during subduction and collision in orogenic belts are significant and well-studied for oceanic subduction; however, the magmatism associated with continental subduction remains poorly understood. Seismic attenuation is highly sensitive to changes in lithospheric thermodynamics and fluid content. Understanding arc volcanism is vital for comprehending a key manifestation of subduction-related processes. However, there is still no high-resolution 3D attenuation model for this region. Here, we use the coda-normalized method to image the lithospheric-scale 3D attenuation structure in the Indo-Burma subduction zone. Our results reveal high attenuation in major sedimentary basins. The prominent high-attenuation anomalies in the mid-to-lower crust of the Indo-Burma Ranges (IBR) may represent thick, fluid-rich sediments scraped off from the subducting Indian Plate and accumulated beneath the IBR. Low-attenuation anomalies at depths of 30-50 km beneath the Monywa volcano are a clear signature of a cooled mantle wedge, which currently overlies strong attenuation anomalies deeper than 50 km, likely associated with the upwelling of hot asthenospheric material. Compared to oceanic subduction systems, the insufficient water content of the continental subduction plate, coupled with the compressional regime induced by oblique subduction, leads to weak attenuation within the mantle wedge.

Objective Deep underground spaces, far from external environmental disturbances, exhibit a lower vibration background noise environment compared to the surface, which can serve as important platforms for research such as multi-physical field observation and precision instrument testing. Therefore, investigating the characteristics of vibration background noise in deep underground spaces is of great significance for deep Earth science research. Based on this, systematic detection and analysis of vibration background noise in deep underground and shallow surface environments were carried out, and the unique advantage of the low vibration background noise background in deep underground spaces was revealed.Methods A specialized synchronous deep underground–surface vibration detection platform was constructed at the CJPL site. An ultra-broadband seismometer T360-PH1-GSN was installed in the CJPL-Ⅱ, while a very-broadband seismometer T120-PH3 was deployed at the surface observation site on Jinping Mountain. Standard seismic observation piers were constructed with firm coupling to bedrock, and additional vibration isolation trenches and waterproof-drainage systems were implemented to minimize external interference and ensure data stability. Vibration signals were synchronously recorded at a sampling rate of 100 Hz; GPS timing was adopted for the surface instrument, and NTP network timing was applied for the deep underground instrument to guarantee high-precision temporal synchronization. Time–frequency analysis was conducted using continuous waveform comparison, Fast Fourier Transform (FFT) amplitude spectra, and power spectral density (PSD) computed by Welch's method. Frequency-domain polarization analysis was performed to extract key parameters including principal eigenvalues, polarization degree, horizontal azimuth, and incident angle, so as to identify noise source types, directional distribution, and propagation characteristics. Long-term ambient temperature monitoring data were integrated to evaluate the influence of thermal fluctuations on long-period instrumental noise. Three typical natural earthquakes with epicentral distances of 240 km, 2260 km, and 5400 km were selected to conduct quantitative comparison and analysis of site effects on seismic wave responses in the deep underground and at the surface.Results and Discussions The three-component amplitudes of deep underground background noise were consistently lower than those at the surface. The horizontal amplitude in the deep underground was measured to be approximately half of the surface value, indicating an obvious reduction in vibration disturbance. The PSD of deep underground noise was lower than that at the surface in both low-frequency and high-frequency bands. Specifically, the PSD of deep underground noise was 15 dB lower than that of the surface in the frequency band above 1.0 Hz, demonstrating a much quieter high-frequency noise floor and more favorable observation conditions for high-frequency weak signals. In the ultra-low-frequency band below 0.1 Hz, the horizontal noise amplitude in the deep underground was nearly one-tenth of the surface amplitude, which provided an extremely high signal-to-noise ratio and unique advantages for detecting faint signals generated by deep geodynamic processes, crustal deformation, and internal structural activities of the Earth. Polarization analysis indicated that surface noise exhibited clear multi-source characteristics with large azimuth fluctuations, unstable energy distribution, and frequent directional variations, which were mainly induced by human activities, river dynamics, and atmospheric loading. In contrast, deep underground noise originated from a single stable source with concentrated polarization features and consistent directional distribution. Vibration energy in the deep underground was concentrated in the horizontal direction within a narrow azimuth range, but scattered in the vertical direction, reflecting a simpler and more stable noise propagation environment. Long-term environmental monitoring revealed that the deep underground maintained a nearly constant temperature with fluctuations less than 1 ℃, which effectively suppressed long-period thermal-induced instrumental noise and improved the stability and consistency of observation data. In contrast, the surface showed daily temperature variations exceeding 10 ℃, which introduced significant low-frequency noise interference, degraded signal quality, and limited the reliability of long-period observations. With increasing epicentral distance, the dominant frequency of seismic waves arriving at CJPL gradually shifted from high frequencies to ultra-low frequencies, and the surface site effect was progressively weakened. In the near-field earthquake (240 km), surface amplitudes in the 0.3–5 Hz band were approximately twice those in the deep underground, showing strong amplification effects and obvious signal distortion. In the mid-range earthquake (2 260 km), surface amplitudes in the 0.1–1 Hz band were about 40% higher than those in the deep underground. In the far-field earthquake (5 400 km), only ultra-low-frequency signals remained, and the amplitude difference between the surface and deep underground became almost negligible. These results confirmed that the surface site effect significantly amplified near-field high-frequency seismic responses and caused considerable distortion in observation data, while the deep underground was free from such amplification effects and maintained stable, undistorted, and reliable recording performance. The deep underground environment therefore provided a more accurate, stable, and trustworthy observation condition for monitoring near-field crustal activities and deep geodynamic processes, which could hardly be achieved by conventional surface observation methods.Conclusions The Jinping deep underground environment possesses a significantly lower vibration noise background compared with the surface, and demonstrates outstanding signal-to-noise ratio advantages especially in the ultra-low-frequency band below 0.1 Hz. It features a single stable noise source, weak directional variability, and a constant-temperature condition that effectively reduces thermal-induced instrument noise. The surface exhibits strong site amplification effects on near-field high-frequency seismic waves, leading to distorted measurements, whereas the deep underground avoids such distortion and provides high-fidelity, reliable observation data. This study provides systematic, original, and quantitative evidence of the differential vibration noise characteristics between the ultra-deep underground and the surface at the CJPL site. The findings strongly confirm that CJPL features an ultra-low vibration noise floor, stable environmental conditions, and weak site effects, which offer essential support for high-precision instrument testing, weak geodynamic signal detection, and advanced deep Earth science and underground physics experiments.

Deformation bands are a type of local strain concentration structure that develops in porous rocks, and they play an important role in the fluid dynamics of underground reservoirs. Although field outcrop observations can provide important information for revealing the geometry and distribution characteristics of deformation bands, capturing the dynamic processes and controlling mechanisms of deformation band formation and evolution is difficult. In recent years, laboratory-scale physical simulations have become key methods for studying the formation processes of deformation bands by precisely controlling stress, displacement, and material properties to reproduce the evolution path. In this study, the shear experiment methods, quantitative structural analysis techniques, and numerical simulation strategies that are widely used in the current research on deformation bands are systematically reviewed and evaluated. Physical simulation methods, such as ring shear, direct shear, triaxial shear, and sandbox experiments, and porosity and permeability measurement methods, which are based on computed tomography (CT) scans and image processing, are assessed in this paper. Furthermore, the ways that experimental data are used in the construction of parameters of discrete element and continuum models are discussed, as are modeling practices at the core and regional scales. Finally, the main challenges are summarized, including in situ permeability testing for consolidated rocks, the imperfection of quantitative structure analysis technologies, the difficulty in simulating the effects of cement, and the bottleneck in cross-scale modeling, and key directions for future research are proposed. The aim of this review is to establish a research framework that integrates experiments, calculations, and observations to provide theoretical and methodological support for an in-depth understanding of the formation mechanism of deformation bands and their control on underground fluid migration.

Abstract Slab tearing has been increasingly recognized as a key geodynamic process influencing the evolution of the eastern Himalayan syntaxis. However, whether, where and how the subducted Indian slab beneath the Indo‐Myanmar subduction zone has been torn remains poorly constrained. Applying seismic tomography to new wide‐aperture data in and around Myanmar, we image the detailed architecture of the Indian slab. Our results especially show two high‐velocity anomalies with opposing dips in the upper mantle: an east‐dipping anomaly representing the subducting Indian slab and a west‐dipping body preferentially interpreted as a detached slab fragment. The intersection angle between the two anomalies decreases southward, and their along‐dip lengths vary inversely, indicating southward‐shallowing slab tearing likely induced by the oblique subduction setting. Tearing‐induced mantle upwelling may be impeded by the subducting Indian slab at shallow depths and the limited gap between slab segments, likely explaining the sporadic volcanism in Myanmar since the Mid‐Miocene.

The origin and composition of the intraplate Wudalianchi volcanic field have often been linked to interaction between the heterogeneous lithosphere and underlying asthenospheric flow. An in-depth understanding of this volcano field thus requires constraints on spatial variations and nature of the lithosphere-asthenosphere boundary (LAB), which remains under-investigated. To address this, we perform wave equation-based migration using S-receiver functions derived from dense broadband data in Northeast China. The resulting images reveal a coherent negative Sp phase at ∼80–110 km depths, representing the LAB, which appears significantly shallower beneath active volcanoes. Additionally, a positive velocity discontinuity (PVD) detected at greater depths of ∼130–160 km probably marks the base of a low-velocity zone. The spatial correspondence between the LAB structure and the PVD underscores the importance of LAB imaging in revealing the presence of an asthenospheric low-velocity, melt-rich zone. Although this melt-rich layer appears regionally distributed, it provides a key geodynamic context for understanding intraplate volcanism, with the actual volcanic centers likely controlled by additional factors such as lithospheric heterogeneity, localized melt focusing, and stress-induced pathways for melt ascent.

Myanmar is located at the southeastern margin of the collision zone between the Indian and Eurasian plates, occupying a key position in the Eastern Himalayan Syntaxis. It serves as a natural laboratory for studying oblique subduction, accretionary orogeny, and crust-mantle dynamics. However, the complex crust-mantle kinematic decoupling mechanism in this region, as well as the control of deep slab geometry on magmatic thermal evolution, remain subjects of debate. Since seismic attenuation is highly sensitive to temperature, partial melting, and fluid content, conducting high-resolution attenuation tomography is crucial for revealing the deep physical state of materials and geodynamic processes in this area. In this study, we performed high-resolution 3-D P-wave attenuation tomography of the Myanmar Orogen using seismic data recorded by 70 stations from the China-Myanmar Geophysical Survey in the Myanmar Orogen (CMGSMO I) between June 2016 and February 2018. We utilized 2,313 seismic events obtained from a deep-learning-based catalog and extracted 14,273 high-quality P-wave t* measurements. By employing the trans-dimensional Bayesian Markov Chain Monte Carlo (MCMC) method, we constructed a high-precision 3-D attenuation model of the study region. The inversion results reveal two significant high-attenuation anomalies: a shallow high-attenuation zone beneath the Indo-Burma Ranges (IBR) at depths of 0–40 km, and a deep high-attenuation anomaly beneath the Central Basin at depths of 80–120 km. The shallow high-attenuation zone coincides well with low-velocity structures; we attribute this to high porosity and fluid saturation within the accretionary wedge sediments, as well as fluid overpressure and rheological weakening caused by deep metamorphic dehydration. This rheologically weak layer likely acts as a lower crustal detachment, facilitating kinematic decoupling between the upper crust and the underlying lithosphere. The deep high-attenuation anomaly reflects asthenospheric upwelling triggered by a "slab window" resulting from the tearing of the Indian Plate. The injection of high-temperature material into the mantle wedge induces partial melting and significantly enhances seismic wave attenuation.

The Archean buried-hill metamorphic reservoirs in the Bohai Bay Basin are examples of metamorphic rocks having faults with diverse strikes as a consequence of multi-phase tectonic evolution. For faults in metamorphic rocks, no method that accounts for the properties of metamorphic rocks exists for evaluating fault sealing capacity. To elucidate the mechanisms controlling sealing capacity, our study pioneers a novel methodology termed the Mylonite Gouge Ratio (MGR) method. This method integrates neutron density log responses, petrophysical characteristics, and corresponding depth-specific rock thin-section analyses to assess lateral fault sealing capacity. Application of this set of rules and procedures to metamorphic faults in the basin's Archean strata reveals two critical findings: spatially, the Block X exhibits elevated MGR values indicative of superior sealing efficiency; temporally, Yanshanian NE-trending faults demonstrate enhanced sealing capacity compared to Himalayan EW-trending counterparts, with pre-Yanshanian and syn-Yanshanian tectonic activities facilitating paleo-fluid migration while current sealing conditions favor hydrocarbon preservation. The new method provides a tailored framework for evaluating fault sealing in metamorphic rocks, where conventional methods designed for sedimentary sequences are often inapplicable. This study establishes a new theoretical model for fault-sealing analysis in complex metamorphic reservoirs, with implications for deep hydrocarbon exploration and development.

Nonhydrocarbon gases are significant components of natural gas, and their concentration levels are crucial factors affecting reservoir development value. While explorations have progressively moved from shallow to deep and now ultradeep reservoirs, research on the geochemical characteristics of nonhydrocarbon gases in such extreme depths remains limited, leaving their origins and types poorly understood. This paper analyzes the geochemical characteristics and origins of ultradeep nonhydrocarbon gases (CO 2 , H 2 S, N 2 , He, and H 2 ) across major global basins to determine their origins. CO 2 concentrations reach up to ~40% but are generally below ~15%. The concentration increases with depth, primarily due to inorganic origins, with thermochemical sulfate reduction (TSR) and magmatic CO 2 being the main causes. Depths are mainly between 6000 and 7100 m. N 2 concentrations peak at ~26% but are generally below ~6%. It mainly originates from crustal sources and the high‐temperature cracking of sedimentary organic matter during postmature. Depths are mainly between 6000 and 7100 m. H 2 concentrations reach up to ~1.6% but are generally below ~0.2%. It is concentrated at depths between 7100 and 7800 m and may primarily have a biological origin. He concentrations are generally below ~0.07% and are mainly found at depths between 6000 and 7700 m. The concentrations fall well short of the commercial threshold (0.1%), indicating limited potential for He enrichment in ultradeep reservoirs. H 2 S concentrations reach up to 46% but are generally below 10%. The concentration slightly increases with depth, mainly due to TSR processes. Depths are primarily between 6000 and ~7600 m. Understanding these common and varying patterns of nonhydrocarbon gases may provide theoretical guidance for future exploration targets in ultradeep nonhydrocarbon gases like He and H 2 .

Deformation band research has long been hindered by limited understanding of structural characteristics and physical properties during actual deformation processes. To address these knowledge gaps, this study systematically reviews experimental simulation methodologies through integrated approaches. Combining field observations with our newly developed ring shear tests for consolidated rocks, we investigate: formation mechanisms of deformation bands; key controlling factors including effective normal stress, shear displacement, clay content, mineral composition, porosity, particle size distribution, sorting, and cementation; comparative evaluation of experimental techniques (ring shear vs. direct shear vs. triaxial shear vs. sandbox modeling). Our analysis reveals two critical experimental parameters: effective normal stress and shear displacement. Notably, the advancement of consolidated rock-specific ring shear apparatus enables centimeter-scale displacement simulations, significantly enhancing deformation band experimentation. Current challenges in field measurement, image analysis, and 3D modeling are discussed with proposed solutions. Future directions emphasize: in-situ permeability testing, quantitative analysis frameworks, cementation dynamics, and numerical simulation optimization. This work aims to highlight deformation bands' crucial role in fluid migration and reservoir preservation while providing methodological guidance for designing simulation experiments. The compiled experimental protocols and analytical techniques offer researchers a systematic reference for deformation band investigations.

The deep Earth, deep sea and deep space are equally important as the national "three deep" strategy. It is an inevitable trend and a significant strategic demand to explore new mysteries of deep Earth science, expand new knowledge of deep Earth engineering technology, reveal the evolution process and mechanism of deep in-situ environment, and lay a theoretical and technical foundation for important engineering practices such as deep Earth energy resource development. In this work, the latest research progress in deep earth scientific exploration was reviewed, and the academic connotation of "deep Earth science and geology in time" was proposed. In response to the fundamental scientific question of "the correlation mechanism and law of deep geology in time and shallow geological response", focusing on the two frontier directions of "the law of deep geology in time" and "the correlation mechanism of deep and shallow for geology in time", according to the "one center and multiple nodes" detection layout based on the China Jinping Underground Laboratory, the innovative research and frontier exploration of deep Earth science and geo-information detection experiment (GeoDEX) was carried out. Based on the world's deepest Jinping ultra deep chamber group, GeoDEX conducted the multi-physics field detection and pre-research experiments at a depth of kilometers, including vibration, magnetic field, and micro deformation. It was found that the Jinping deep experimental site has extremely low environmental background interference conditions (2 orders of magnitude lower than the surface), which can greatly improve the sensitivity and reliability of precision instrument detection, and achieve "clear and accurate detection" of time-varying weak information in deep rock masses. The future development trend of in-situ detection in deep Earth science was elaborated from four aspects. GeoDEX is expected to realize precise detection of deep Earth multi-field time-varying signals and shallow time-varying response information, reveal the weak multi-field signal propagation and evolution laws for geology in time, detect the steady-state/nonstationary evolution response processes of geological bodies at different time and space scales under the action of internal and external forces, promote the field of deep Earth science to achieve original, breakthrough, and disruptive discoveries, explore the frontier technology of deep underground engineering, which has great scientific significance and research value.

Fault zones play a key role in controlling subsurface fluid migration, influencing hydrocarbon accumulation, CO2 sequestration, and geo-energy storage safety. Most previous experimental studies, however, have been restricted to static outcrop or core observations, which fail to capture the progressive evolution of fault zone structures in time as a response to changing stresses. Moreover, existing analogue experiments often use unconsolidated sediments, which cannot accurately represent brittle faulting in consolidated rocks, and quantitative analyses remain limited. To address these challenges, a new method based on ring-shear experiments was developed to physically simulate fault zone formation in consolidated sandstones. The method simulates shear deformation under variable stress and displacement conditions, followed by multi-scale quantitative analyses, including computed tomography imaging, thin section analysis, and porosity-permeability testing under confining pressure. This comprehensive testing routine allows to quantify changes in fault zone thickness, particle and pore size distributions, and grain orientations during progressive deformation and depending on shear parameters. The results demonstrate systematic relationships between effective normal stress, shear displacement, and fault zone structural attributes. The fault zone thickness shows a nonlinear trend with stress, while cataclasis and compaction intensify with increasing displacement. This work provides a methodological foundation for future applications in fault seal analysis, fluid flow modeling, and numerical simulation, offering a practical reference for petroleum systems studies, hydrogeology, and underground gas storage including CO2 and hydrogen.

CO2 is one of the important non-hydrocarbon components in natural gas, and it is relatively stable in deep underground high-temperature and high-pressure environment. High contents of CO2 are found in many gas reservoirs around the world and there is more research on how this CO2 is formed and what are the typical geochemical characteristics, but they need to be further combed and summarized. Therefore, based on literature research and data statistics, this paper analyzes the variation characteristics of CO2 content and delta 13 C CO2 value in global gases. It is concluded that CO2 in natural gas reservoir mainly includes mantle-derived, thermal decomposition of carbonate rock, thermal decomposition of organic matter, microbial, hydrocarbon TSR secondary transformation and organic acid corrosion. According to the statistical results, CO2 contents associated with TSR in both shallow and deep reservoirs generally do not exceed 20%, whereas CO2 contents of mantle-derived origin are typically above 15%. Combined with the case studies in Songliao basin, China, it is proposed that inorganic CH4 is produced by Fischer-Tropsch synthesis of CO2 gas in deep fluid, which increases the contribution of inorganic CH4 to gas reservoirs. Combined with the case studies in Sichuan basin, China, the hydrocarbon is oxidized to non-hydrocarbon gases H2S and CO2 by TSR under the action of sulfate, and the precipitation of CO2 to calcite will also reduce the porosity of the reservoir. Future research could focus on analyzing the favorable conditions for the enrichment of high CO2 reservoirs, investigating the potential for CO2 storage in depleted oil and gas fields with similar geological settings, and leveraging evidence of CO2 reservoir formation to infer volcanic episodes or cycles. This could help enhance our understanding of paleoclimate changes and provide insights into the potential impact on contemporary climate patterns. Therefore, the in-depth understanding of underground natural CO2 behavior can provide a basis for the study of underground fluid processes, carbon cycling and greenhouse gas carbon sequestration.