The Eastern Northern orogenic belt, located along the eastern margin of Eurasia, is composed of a series of microcontinents or terrenes, including, from west to east, the Erguna, Xing’an, Songliao, and Jiamusi-Khanka blocks. This belt preserves a complex Phanerozoic evolutionary history of multiple paleo-oceans, such as the Paleo-Asian, Heilongjiang, and Paleo-Pacific Oceans. However, the crustal evolution of these ocontinent microcontinents and their tectonic linkages to global supercontinent cycles remain relatively constrained, representing a key research frontier in modern geology. To address this, we first systematically compile published geochronological data from the Archean to Early Paleozoic to delineate the major evolutionary stages of the microcontinent group within the belt. We then integrate this temporal framework with the geochemical signatures of coeval magmatic records to evaluate the tectonic affinity of these microcontinents with ancient continental blocks throughout the supercontinent cycle since the Archean. Based on this integrated analysis, we propose a revised supercontinent evolutionary model for the microcontinent group. Our results indicate that the microcontinent group records five major geological events from the Archean to Early Paleozoic, which collectively define three distinct tectonic cycles.This history indicates their active involvement in the staged assembly and breakup of the Columbia, Rodinia, and Gondwana supercontinents. Furthermore, the tectonic evolution of the microcontinent group exhibits a persistent continental margin affinity, maintaining a close and dynamic tectonic relationship with the Tarim craton throughout these supercontinent cycles. During the Early Paleozoic, the microcontinent group in the Eastern North orogenic belt rifted from the northeastern margin of Gondwana and subsequently drifted northward to accrete to the southern margin of the Siberia craton. This migration established the fundamental regional tectonic framework that preconditioned the subsequent superimposition and transition of multiple paleo-oceanic systems along the eastern margin of Eurasia.

Since the Paleozoic, Northeast China has experienced the superimposition of multiple paleo-ocean tectonic regimes, including the Panthalassa, Mongol-Okhotsk Ocean, Paleo-Asian Ocean, and Paleo-Pacific Ocean. However, the processes of their superimposition and transition remain poorly understood. The Jiamusi-Khanka block, located at the easternmost end of the microcontinental blocks in Northeast China, represents a key a key tectonic nexus: It marks the final closure of the eastern segment of the Central Asian orogenic belt (Paleo-Asian Ocean tectonic domain), connects to the Mongol-Okhotsk tectonic domain in the northeast, and lies at the core of the superimposed influence of the circum-Pacific (Panthalassa) tectonic domain along the eastern margin of Eurasia. Consequently, it serves as a critical bridge for understanding the superimposition and transition processes among these paleo-ocean tectonic regimes. This study comprehensively analyzes the lithology, geochronology, and geochemical characteristics of the metamorphic basement, sedimentary cover, and peripheral tectonic mélanges of the Jiamusi-Khanka block, reconstructing its tectonic evolution from the Paleozoic to the Mesozoic. The findings provide key constraints on the tectonic regime superimposition and transition processes along the eastern margin of Eurasia. The Paleozoic-Mesozoic tectonic evolution of the Jiamusi-Khanka block can be divided into four stages: (1) Prior to the Early Paleozoic, the Jiamusi-Khanka block, together with other microcontinental blocks in Northeast China, formed a large composite block that originated in the Sayan-Baikal orogenic belt within the Siberian craton and collectively underwent Pan-African metamorphism (~500 Ma). (2) During the tectonic evolution of the Central Asian orogenic belt, these blocks drifted southward to the eastern segment of the orogen around 500 Ma. (3) In the Late Paleozoic, subduction of the Mongol-Okhotsk Ocean or Panthalassa induced a back-arc extension, leading to the opening of the Heilongjiang Ocean. This rifted the Jiamusi block from the composite block and caused its eastward drift, separating it from the eastern segment of the Central Asian orogenic belt. (4) From the Late Triassic to the Early Jurassic, the closure of the Heilongjiang Ocean and the subduction of the Paleo-Pacific Ocean in the east drove the re-amalgamation of Jiamusi block with the adjacent Central Asian orogenic belt. This event marked the final formation of the Central Asian orogenic belt and the regional transition to a new stage dominated by the Paleo-Pacific tectonic regime.

In order to unravel the spatiotemporal processes and dynamic mechanisms underlying Mesozoic multi-plate convergence in East Asia, this study focuses on the Mongol-Okhotsk tectonic domain—a critical region. By elucidating its Mesozoic tectonic evolutionary history as a vital component of the eastern segment of the Central Asian orogenic belt, this research seeks to provide constraints for reconstructing the interactions between regional plates. This study investigates the northern Heihe area of Northeast China through systematically integrating published zircon U-Pb chronology and whole-rock geochemical data of Mesozoic magmatic and sedimentary rocks, combined with detailed analysis of the sedimentary sequence in the Mohe basin, reconstructing the Late Mesozoic tectonic evolution history of this area. The present results show that the Mesozoic strata and magmatic activities in this area have comprehensively recorded the tectonic evolution process of the Mongol-Okhotsk tectonic domain from subduction, collision to post-collision extension. Zircon geochronology constrains the depositional age of the Emurhe Group in the Mohe basin to the Late Jurassic-Early Cretaceous (160-140 Ma), with the peak volcanic activity phase occurring at 125-110 Ma during the Early Cretaceou. Geochemical characteristics reveal a progressive transition of the magma sources from active continental margin arc settings to post-collisional extensional regimes. Quantitative crustal thickness reconstruction reveals an oscillatory “N” evolutionary trend (thickening-thinning-re-thickening), corresponding to three distinct geodynamic processes: subduction-related compression (~40 km), collision collapse (~35 km), and subsequent superimposed modification (~40 km). The Mongol-Okhotsk Ocean has undergone a temporally diachronous “scissor-like” closure process, with the middle section terminating during the late Middle Jurassic (~165 Ma) while the eastern section persisted until the early Early Cretaceous (~145 Ma). Following this collisional event, whole area transitioned into post-orogenic extension, subsequently overprinted by far-field effects of the Paleo-Pacific plate subduction. This study provides new evidence for understanding the ocean-continent transition process in the Mongol-Okhotsk tectonic domain and its mutual influence with the Paleo-Pacific tectonic domain.

As a key region linking the West Pacific subduction system and the Central Asian orogenic belt, Northeast China witnessed a Mesozoic basins evolution closely related to multi-plate interactions. This study systematically investigates the geodynamic mechanisms of basin formation by analyzing tectonic-stratigraphic characteristics and lithospheric structures of NNE-trending Mesozoic sedimentary basins in Northeast China and adjacent areas, combined with both shallow processes and deep dynamic evolution of plate interactions. The results indicate that the Mesozoic basins in Northeast China exhibit a basin-and-range tectonic pattern, divided into western, central, and eastern basin groups, with a lithospheric structure thickening westward and thinning eastward. The basin evolution progressed through five stages: Early-Middle Triassic erosion and planation, Late Triassic-early Late Jurassic differential response to dual-sided subduction, Late Jurassic-early Early Cretaceous regional compression, middle-late Early Cretaceous extension dominance, and latest Early Cretaceous-Late Cretaceous alternating compression and extension. The superposition of two tectonic domains — the evolving subduction style of the Paleo-Pacific plate and the closure of the Mongol-Okhotsk Ocean—constitutes the core geodynamic control on basin evolution. Specifically, the regional extension triggered by the rollback of the Paleo-Pacific plate was the key driver for basin formation.

The final closure of the eastern segment of the Paleo-Asian Ocean remains a hotly debated topic in geological research. However, the eastward extension of the Solonker suture and its exact closure location are further complicated by thick Mesozoic cover on the western margin of the Songliao basin. The recent discovery of the Tuquan ophiolite, which constitutes an important component of the ophiolitic fragments within the Solonker suture, provides key constraints on the eastward extension of the suture. LA-ICP-MS zircon U-Pb dating yields ages of (265.5 ± 3.5) Ma for serpentinized peridotite and (276.5 ± 4.6) Ma for gabbro are, indicating formaion of the Tuquan ophiolite from the late Early Permian to Middle Permian. Combined with the geochemical characteristics, it suggests that the Tuquan ophiolite originated in a forearc tectonic setting during the Early to Middle Permian, coinciding with bidirectional subduction and consumption of the Paleo-Asian Ocean. These findings further reveal that the final subduction and collision of the Paleo-Asian Ocean persisted at least until the late Permian. Collectively, the Tuquan ophiolite serves as direct geological evidence for the eastward extension of the Solonker suture and provides new constraints on the Late Paleozoic tectonic evolution of the southeastern Central Asian orogenic belt.

The tectonic evolution of the Paleo-Asian Ocean exerted a decisive control on the formation and evolution of the East Asian continent, profoundly influenced magmatic activity, stratigraphic development, and tectonic frameworks within the Central Asian orogenic belt. However, the final closure timing of its eastern segment remains controversial. This study applies machine learning techniques to reconstruct Triassic crustal thickness variations along the eastern segment of the northern margin of the North China craton and adjacent regions, thereby providing new constraints on the mechanism and timing of the final closure of the Paleo-Asian Ocean. During the Early-Middle Triassic, average crustal thickness reached its maximum of approximately 66 km in the Siping area of Jilin Province, a region concurrent with adakitic magmatism. Crustal thickness generally decreased eastward, where the lithological assemblage is dominated by calc-alkaline intermediate-acidic intrusive rocks. These findings suggest that the Paleo-Asian Ocean underwent closed first in the Siping area of Jilin Province in the Early-Middle Triassic, triggering pronounced crustal thickening. In contrast, the easternmost Yanbian area remained an active tectonic seaway, evidenced by crustal thickness comparable to that of normal continental crust. During the Late Triassic, the eastern segment of the northern margin of the North China craton and adjacent regions exhibited an eastward-increasing crustal thickening trend, reaching a maximum thickness of 66 km in the Yanbian area of Jilin Province, again accompanied by synchronous adakitic rocks. Meanwhile, regions like western Liaoning Province and central Jilin Province, which had thickened earlier, now experienced significant crustal thinning accompanied by the emplacement of Late Triassic bimodal igneous rocks. These observations indicate that final closure of the Paleo-Asian Ocean occurred in the Yanbian area during the Late Triassic, while the previously closed western segments transitioned from a collisional-compressional to a post-collisional extensional environment. The systematic spatial-temporal variations in Triassic crustal thickness, integrated with contemporaneous igneous rock assemblages, further confirm a scissor-like west-to-east diachronous closure model for the eastern segment of the Paleo-Asian Ocean, culminating in the Late Triassic.

The extensive development of Permian to Jurassic magmatic rocks in the Zhangguangcai Terrane, Northeast China, provides important information for understanding the regional tectonic evolution. This study systematically summarizes the geochronological and whole-rock geochemical characteristics of 266-163 Ma magmatic rocks from this terrane, identifying four distinct episodes of magmatic activity: The 266-240 Ma magmatic activity is mainly composed of adakitic and I-type magmatic rocks, while the 229-210,209-185 and 184-163 Ma magmatic activities are mainly composed of adakitic, I-type and A-type magmatic rocks. Based on analysis of magma sources and tectonic settings, combined with regional geological constraints, we propose that the tectono-magmatic history of the Zhangguangcai Terrane was primarily controlled by the evolution of the Heilongjiang Ocean. Specifically, westward subduction of the ocean beneath the terrane occurred during 266-210 Ma, followed by ocean closure during 210-180 Ma, which culminated in the final collision between the Jiamusi-Khanka block and the Songliao block. The obduction of residual oceanic crust during 180-163 Ma triggered tectonic exhumation and final emplacement of the Heilongjiang accretionary complex. The occurrence of a magmatic lull (240-230 Ma) is attributed to low-angle subduction of the Heilongjiang Ocean. Our findings indicate that the Zhangguangcai Terrane represents a combination of Late Paleozoic to Early Mesozoic accretionary complexes and continental arcs, rather than an ancient block with Neoproterozoic basement.

To reveal the subduction-accretion process of the Paleo-Pacific plate beneath the eastern margin of the Jiamusi block and to clarify the history of tectonic domain transition in Northeast China, this study focuses on reconstructing the subduction-accretion history of ancient oceanic plates. A comprehensive analysis was conducted on the material composition, accretion process, emplacement age, and tectonic setting of the Nadanhada terrane (Nadanhada accretionary complex belt) in Northeast China. The Nadanhada accretionary complex belt is divided into the Yuejinshan and Raohe accretionary complexes. The Yuejinshan accretionary complex is primarily composed of mafic-ultramafic rocks, siliceous rocks, marble, and metaclastic rocks. The mafic-ultramafic rocks formed between the Late Carboniferous and Late Triassic, wherein the protoliths of the metabasalt exhibit geochemical affinities of mid-ocean ridge basalt (MORB) and ocean island basalt (OIB), while the metagabbro originated in an active continental margin setting. The Yuejinshan accretionary complex records two major events: The subduction-accretion of the Panthalassa plate from the Late Carboniferous to Late Triassic, and the initiation of Paleo-Pacific plate subduction from the Late Triassic to Early Jurassic. Its emplacement age (Late Triassic to Early Jurassic) is broadly contemporaneous with the that of the Jilin-Heilongjiang high-pressure belt along the western margin of the Jiamusi block, collectively marking the initiation of the Paleo-Pacific domain in Northeast China. The Raohe accretionary complex constitutes an oceanic island assemblage, whose blocks include Carboniferous-Permian limestone, Middle Triassic-Middle Jurassic siliceous rocks and siliceous shale, Late Triassic-Middle Jurassic mafic-ultramafic rocks. The clastic matrix, which formed from the Middle Jurassic to Early Cretaceous, constrains the timing of accretion for the Raohe accretionary complex. The Raohe accretionary complex was emplaced along the eastern margin of the Yuejinshan accretionary complex in the Early Cretaceous. In summary, the formation of the Nadanhada accretionary complex belt completely records the continuous subduction-accretion history of the Panthalassa and Paleo-Pacific plates beneath the eastern margin of the Jiamusi block from the Late Carboniferous to the Early Cretaceous.

The Fanjiatun Formation in central Jilin, situated on the northern margin of the North China craton, represents a key geological unit for constraining the closure of the eastern Paleo-Asian Ocean. Systematic petrography, detrital zircon U-Pb geochronology, Lu-Hf isotopes, and whole-rock geochemical analyses were performed on its metasedimentary rocks. The youngest detrital zircon population yields a weighted mean age of （233.6±5.0) Ma (N = 11), constraining the maximum depositional age to not earlier than the Late Triassic. Whole-rock geochemistry (Al2O3/TiO2=24.65-63.69, avg. 37.84) and elemental ratios (La/Sc, Th/Sc, Cr/Th, Eu/Eu*) indicate felsic to intermediate upper-crustal sources. Detrital zircon age spectra and predominantly positive  εHf(t) values indicate provenance mainly from the Northeastern block and the northern margin of the North China craton. Tectonic discrimination parameters together with time-series variations in zircon trace elements reveal a transition from compressional orogenesis to extensional stabilization in the study area, and suggest that Paleozoic to Early Mesozoic crustal evolution was characterized by three episodes of thinning and two of thickening, closely coupled with the late subduction-closure regime of the eastern Paleo-Asian Ocean.

The Yiwulüshan area in western Liaoning constitutes a key Late Mesozoic deformational tectonic unit in the northeastern segment of the North China craton (NCC). Its multi-stage deformation events preserve critical information regarding the transition of the regional tectonic regime. Through systematic analysis of the macro- and microstructural characteristics of strongly deformed rocks in Yiwulüshan metamorphic core complex, combined with quartz EBSD fabric analysis, this study identifies two distinct phases of extensional ductile shearing events: i.e., Late Jurassic high-temperature (550-650 ℃) ductile shearing (under low amphibolite facies conditions) and Early Cretaceous low-temperature (400-500 ℃) ductile shearing (under greenschist facies conditions). The early-stage deformation is characterized by LS-type tectonites dominated by dextral shearing, exhibiting prominent simple shear properties. In contrast, the late-stage deformation forms L=S type tectonites with sinistral shearing behavior, where the contributions of simple shear and pure shear are comparable. Zircon U-Pb geochronological constraints indicate that these two phases of events occurred during 156.9-146.7 Ma (Late Jurassic) and 132.6-126.8 Ma (Early Cretaceous), respectively. Analysis of the recrystallized grain size of quartz reveals that the high-temperature shear zone was associated with lower differential stress (20.53-22.16 MPa) and higher strain rate (8.41×10-13-5.56×10-11 s-1), whereas the low-temperature shear zone showed the relative slower strain rate (differential stress: 20.62-24.07 MPa; strain rate: 1.34×10-15-9.69×10-13 s-1). The early high-temperature extensional deformation is linked to the transition of the tectonic regime in the northeastern NCC—from the north-southward closure of the Mongol-Okhotsk Ocean to the subduction of the Paleo-Pacific plate. The late low-temperature extensional deformation is related to the roll-back of the subducting Paleo-Pacific plate.

As the most significant geological units in Northeast China, the tectonic nature and evolutionary history of the Jilin-Heilongjiang high-pressure belt remain controversial. To reveal the crust-mantle-scale structure of this belt and constrain the subduction-accretion processes of the Heilongjiang Ocean, this paper constructs a deep geophysical model based on magnetotelluric  and deep seismic reflection data. The model reveals pronounced lateral heterogeneity in both electrical conductivity and seismic reflectivity across different tectonic units. A key finding is a west-dipping zone of high resistivity and strong seismic reflectivity, which extends from the crust into the lithospheric mantle within the tectonic convergence zone. We interpret this feature as a fossil subduction zone associated with the closure of the Heilongjiang Ocean. In the upper crust, both the Heilongjiang and the Zhangguangcai Range complexes exhibit consistent high resistivity and short, arcuate reflection packages. In contrast, the middle to lower crust of the Zhangguangcai Range is characterized by a pronounced high-conductivity anomaly and a distinctive reversed U-shaped reflection pattern. Integrating these geophysical observations with existing geological understanding, we propose that the Zhangguangcai Range complex is not an integral part of the Songliao block. Instead, our data support a model of westward subduction of the Heilongjiang Ocean, with successive accretion of the Zhangguangcai Range and the Heilongjiang complexes as major components of the accretionary wedge. The Zhangguangcai Range complex thus records the early stage of the subduction-accretion process.

The Central Asian orogenic belt (CAOB), which experienced ~800 Ma of subduction–accretion associated with the Paleo-Asian Ocean, represents one of the largest and most complex accretionary orogenic systems on Earth. It records key geological processes, including oceanic subduction, crustal accretion, and subsequent tectonic overprinting, thus provides a crucial window for investigating Phanerozoic continental evolution within the Paleo-Asian Ocean tectonic domain. The Solonker suture, located in the south-central segment of the CAOB, records the evolution and final closure of this ocean and is widely regarded as its terminal suture. However, the eastward extension of this suture and the subduction polarity of the Paleo-Asian Ocean in this region remain subjects of significant debate. In recent years, two deep seismic reflection profiles of large dynamite shots have been developed across the Solonker suture, extending the detection depth to the lithospheric mantle and successfully revealing the seismic structural characteristics of fossil subduction zones beneath the suture. This study synthesizes and contrasts the seismic structures imaged by these two profiles and integrates them with newly acquired geophysical datasets to characterize the lithosphere-scale deformation architecture of the study area. The combined geological and geophysical evidence demonstrates that the Paleo-Asian Ocean underwent divergent double subduction in the south-central CAOB, culminating in its final closure along the Solonker–Tuquan between the Hegenshan and Xar-Moron sutures, with its eastern extension reaching into the central Songliao basin.

To reveal the near-surface structural characteristics of the Jiamusi block-Nadanhada terrane, this study applies the first-arrival traveltime tomography method based on  deep seismic reflection profile data to invert and obtain the  near-surface P-wave velocity structure model of the study area, and further depicted the spatial distribution characteristics of the fault zones. The inversion results show that the thickness of the sedimentary cover generally exhibits a regional distribution pattern of being thicker in the west and thinner in the east. There is significant lateral heterogeneity in the vicinity of the main fault zones. Specifically, the thickness of the sedimentary cover within the Jiamusi block is relatively thin (0.5-0.7 km), which increases rapidly when crossing the Dunhua-Mishan fault zone and the Yuejinshan fault zone, with the maximum local thickness exceeding 2 km. In contrast, the thickness of the sedimentary cover within the Nadanhada terrane is generally less than 0.5 km. The Yuejinshan fault zone is manifested as a significant lithospheric-scale velocity gradient zone, which further reveals its nature as a boundary fault separating different tectonic units. Meanwhile, the Dunhua-Mishan fault zone is characterized by a nearly vertical low-velocity anomaly zone, indicating that the physical properties of the rocks wihtin the fault zone have been weakened due to fragmentation caused by tectonic activities.

The Qikou sag in the Bohai Bay basin, as a significant Cenozoic depression basin in the eastern North China craton, holds key implications for understanding regional tectonic-sedimentary responses and hydrocarbon accumulation mechanisms during the Paleogene. This study presents a systematic analysis of detrital zircon U-Pb geochronology and trace elements from clastic rock samples of the first (Es1) and second (Es2) members of the Shahejie Formation, obtained from three coring wells (X, Y, Z) in the southern Qikou sag. Integrated with provenance contribution inversion and tectonic setting discrimination, we investigate the controlling effects of the Paleogene tectonic background on the provenance system. Results reveal distinct detrital zircon age spectra between Es1 and Es2 samples: Es1 samples are dominated by age peaks at 120 Ma, 284 Ma, 1 866 Ma, and 2 515 Ma, whereas Es2 samples exhibit clusters at 252-246 Ma, 320-291 Ma, 1 882-1 877 Ma, and 2 542-2 532 Ma. The primary source of the Es1 sediments, according to provenance analysis, was the northern domain of the plate-margin orogenic belt bordering the North China block. Additional provenances included the Jiaodong and Liaodong Peninsulas. In contrast, Es2 sediments were primarily sourced from the Central Asian orogenic belt and the Sulu orogenic belt. Provenance contribution modeling further reveals that Es1 was mainly supplied by the Jiaobei (76.48%), Jiaodong (12.14%), and Liaodong (6.65%) regions, whereas Es2 was significantly influenced by the Central Asian orogenic belt (9.46%) and the Sulu orogenic belt (5.65%). Based on cumulative curves of the time difference between zircon crystallization and deposition ages (CADA) and the evolution of regional fault systems, this study proposes that the Qikou sag was generally under an extensional tectonic setting during the Oligocene. However, a significant provenance shift occurred from Es2 to Es1, reflecting a tectonic transition from a NE-trending to an approximately EW-trending fault system. This shift led to a change in sediment routing from NS to EW, further evidencing the deep-seated control of regional stress field transformation on tectonic-sedimentary processes in the basin under the influence of Pacific Plate subduction.

Spatiotemporal analysis of recurring slope lineae (RSL) heavily relies on the effective integration and correlation mining of multi-source heterogeneous data to provide a reliable scientific basis for understanding RSL formation mechanisms. Based on this, an RSL knowledge graph covering the Coprates and Melas Chasma within the Valles Marineris canyon system was constructed using the Neo4j graph database, with HiRISE (high resolution imaging science experiment) high-resolution remote sensing images as the primary data source. Subsequently, key topographic and seasonal factors controlling RSL distribution were identified through graph queries and spatiotemporal correlation analysis. Furthermore, a quantitative relationship model between RSL activity, slope aspect, and solar longitude was established. Based on 364 time-series images from 101 RSL sites, the spatiotemporal distribution patterns of RSL were systematically analyzed. Finally, by integrating previous observational results and climate event records, the effectiveness of the constructed knowledge graph in revealing RSL spatiotemporal characteristics was validated. The results indicate that RSL distribution exhibits a significant westward preference, and seasonal activity is closely coupled with slope aspect, forming an alternating intra-annual activation pattern. Following the MY34 global dust storm, RSL activity was observed on all slope aspects in Garni Crater, marking a stark contrast to previous years when activity was limited to specific aspects, confirming the significant impact of climatic events on RSL scale.

Northeast China located at the intersection of the northern margin of the East Asian Monsoon and the westerlies, is highly sensitive to global climate changes. The lake sediments in this region feature strong continuity and abundant information carriers, making them ideal for reconstructing the evolution of paleo-environments and paleo-ecosystems. This study systematically reviews the climate changes, ecosystem responses, and impacts of human activities recorded by lake sediments in Northeast China since the last glacial maximum (LGM). Research shows that the climate in Northeast China generally showed a pattern of being dry and cold during the LGM and warm and humid during the Holocene. However, since the last deglaciation, spatiotemporal heterogeneity may exist in hydroclimatic variations on a millennial scale, and the quantitative temperature reconstructions also exhibit significant uncertainties and regional differences. Dust in Northeast China is mainly sourced from the deserts in northern China and the arid regions of Mongolia. Its flux and intensity variations are closely related to climate changes and human activities. Vegetation gradually evolved from the frigid grassland during the LGM to the coniferous-broadleaved mixed forest during the Holocene, and the lake ecosystem underwent phased transformations following changes in hydrology and nutrient status. In modern times, human activities have become an important driving factor of environmental change, leading to the accumulation of lake pollutants, an increase in dust input, and regional ecosystem degradation . High-resolution multi-proxy integration, the identification of human-nature coupled processes, and the integration of models and records should be strengthened in future research. These are better for understanding regional environmental evolution mechanisms and improving future prediction.

To elucidate the mechanisms of reactive solute transport in heterogeneous rocks, it is essential to characterize their spatially heterogeneous structures. This study focuses on granite samples from Beishan in Gansu Province, China. Mineral composition segmentation is performed using both of the grayscale threshold segmentation and intelligent recognition method based on deep residual networks. Combined with geostatistical approaches, the semivariogram function is applied to establish the spatial correlation structures of sorption coefficients within the heterogeneous granite. The results indicate that the errors between the mineral segmentation results and the actual mineral components in the granite samples are less than 5%. Moreover, the intelligent recognition method can preserve the mineral continuity better. Among the major mineral components of the granite, the correlation lengths of the sorption coefficient for biotite are 3.75, 4.92, and 4.14 mm in the x, y, and z directions, while for feldspar they are 7.88, 6.15, and 5.94 mm, and for quartz, 5.25, 5.45, and 5.28 mm, respectively. These findings demonstrate that there is significant anisotropy in the granite's sorption properties.

Deep continental scientific drilling is essential for directly sampling Earth’s interior and unraveling the mechanisms of continental formation and evolution. The sophistication of such equipment reflects a country’s capability in deep Earth exploration. This paper systematically reviews the development status, core challenges, and future trends in key technologies for deep scientific drilling equipment, with a focus on extreme downhole conditions such as high temperature, high pressure, and high load. Through literature review and case studies(including the Kola Superdeep Borehole, the Continental Deep Drilling Program of Germany(KTB),Songke-2 Well of China, and Well Shendi Take-1 of China)this paper analyzes critical technical issues such as precise weight-on-bit control, wireline coring, efficient tripping, drilling fluid cooling and circulation, and intelligent operation and maintenance. China has domestically developed systems like the “Crust-1” 10 000-meter rig and the Well Shendi Take-1 project have reached world-class levels in core quality and automation, achieving breakthroughs in top drive systems, wireline coring winches, automated wellhead equipment, and intelligent mud control. Nevertheless, gaps remain in high-temperature/high-pressure sensing, dynamic sealing in ultra-deep holes, and intelligent decision-making models. Future drilling equipment should evolve toward automation, intelligence, environmental sustainability, modularity, and rig-free downhole self-propulsion. Promote the evolution of drilling equipment from conventional mechanical tools to “intelligent probes” with geological sensing capabilities. This will provide crucial technological and equipment support for China’s deep resource exploration and energy security.

To compare the differences in flow and heat transfer properties between tensile and shear fractures, this study used a custom-built flow and heat transfer testing device to conduct flow and heat transfer experiments on granite samples containing either a single tensile fracture or a single shear fracture. The experiments were respectively performed under constant temperatures of 50, 100, 150, and 200  ℃, while the confining pressure in each test was gradually increased from 5 MPa to 20 MPa. The results show that, in terms of flow properties, both the hydraulic aperture and permeability of the tensile and shear fractures decrease with increasing confining pressure. However, the hydraulic aperture and permeability of shear fractures are higher than those of tensile fractures, with the hydraulic aperture being approximately 20%-24% higher and the permeability about 44%-56% higher. In terms of heat transfer, both the heat extraction rate and overall heat transfer coefficient decrease with increasing confining pressure, but shear fractures exhibit higher values at all tested temperatures. Specifically, the heat extraction rate and heat transfer coefficient of shear fractures are about 140% higher at 50  ℃ and about 80%-84% higher in the range of 100-200  ℃. These results demonstrate that shear fractures show better flow and heat transfer properties than tensile fractures. These findings on the flow and heat transfer properties of tensile and shear fractures under different temperature and confining pressure conditions are of great importance for understanding fluid flow and heat transfer behavior in real enhanced geothermal reservoirs.

To address the technical challenges associated with enhanced geothermal systems, including hydraulic fracturing stimulation, induced seismicity, and uncertainties in reservoir permeability, this study explores an alternative development pathway with improved environmental compatibility and operational stability, namely the closed-loop geothermal system (CLGS). Through a comparative analysis, the technical advantages of CLGS are systematically clarified. First, the research progress on the mechanical stability and efficient heat extraction modes of CLGS under long-term operation is comprehensively reviewed. Particular emphasis is placed on analyzing the effects of different injection-production parameters on heat extraction performance, and the thermal energy extraction efficiency of various heat production modes is comparatively evaluated. Furthermore, the stability mechanisms of the wellbore under coupled thermo-fluid-solid processes are investigated. The results indicate that, for CLGS, a spiral wellbore configuration can significantly enhance long-term heat exchange capacity, with the average heat exchange per unit wellbore length increased by 23.73% over a 50 a operation period. Intermittent heat extraction markedly improves heat transfer efficiency, resulting in an average thermal output increase of 3.95 kW and a cumulative heat production enhancement of 34.6%. In addition, the injection rate is demonstrated to play a critical regulatory role in the evolution of the heat extraction cycle and the stress disturbance process of the wellbore.

Sulfide and carboxymethyl cellulose (CMC) stabilization dual-modified nano zero-valent iron (S-CMC-nZVI) exhibits high reactivity and strong mobility, demonstrating significant potential for remediating organically contaminated groundwater. However, the effects of common groundwater anions on its surface-modified layer and contaminant degradation performance remains unclear. This study investigated the mechanisms and effects of common groundwater anions (SO₂^-4, HCO^-3, NO^-3, Cl^-) on the degradation of nitrobenzene by S-CMC-nZVI, using nitrobenzene as the target pollutant. The results showed that the presence of NO^-3 and Cl^- did not affect the sulfidation degree of the S-CMC-nZVI surface modified layer or the degradation efficiency of nitrobenzene. The addition of SO₂^-4 or HCO^-3 led to a reduction in the sulfidation degree of the surface modification layer, causing peeling and increase in the content of Fe2+ and S2- in the solution. Consequently, the actual n(S)/n(Fe) molar ratios of the material decreased to 0.013 2 and 0.019 1, respectively. The FeS and Fe²⁺ produced by the peeling of the sulfide layer can promote the degradation of nitrobenzene. However, SO₂^-4 will cause the formation of iron oxides on the surface of S-CMC-nZVI, thereby inhibiting the sustained degradation of nitrobenzene. In contrast, HCO^-3 accelerated the decomposition of the oxide layer, facilitating the sustained degradation of nitrobenzene, with a maximum efficiency of 99.6%. This study provides a theoretical reference for the efficient application of S-CMC-nZVI in groundwater remediation.

Superconducting magnetic measurement technology, especially the vector magnetic measurement system based on superconducting quantum interference device (SQUID), has extremely high magnetic sensitivity, broadband response, and excellent vector detection ability. The white noise of the superconducting magnetometer can reach 10 fT/Hz, and the noise of the full tensor gradiometer can reach 0.01 nT/(m·Hz). This technology has become a frontier research direction in the field of geophysical detection. In this paper, the basic principle of SQUID magnetic measurement technology, the device type (high temperature and low temperature SQUID) and its corresponding system configurations such as magnetometer, magnetic gradiometer, and tensor gradiometer are systematically reviewed. The key progress in the development of SQUID vector magnetic measurement systems at home and abroad in recent years has been analyzed, covering core technologies such as system integration and noise suppression. On this basis, the typical application cases and effects of this technology in mineral resources exploration, military target detection, archaeological investigation and other fields are elaborated in detail. The article also discusses the current status of SQUID preparation process, and looks forward to the future technology development trend and application prospects in view of the challenges faced by superconducting materials, system integration, data processing, etc., so as to provide a reference for the further development of superconducting geophysical vector magnetic survey technology in China.

The ground-air frequency-domain electromagnetic (GAFDEM) method has broad application prospects in studying deep geological structures in complex terrains. However, current studies and applications mainly focus on ground resistivity imaging, with limited in-depth studies on the measurement of induced polarization effects. This paper aims to systematically investigate the influence of polarization effects on GAFDEM measurement results and proposes a method for simultaneous imaging of apparent resistivity and apparent polarizability. To this end,  based on Maxwell’s equations and the Cole-Cole model,a forward model of electric-source ground-air frequency-domain electromagnetic response considering polarization effect  is established.  The influence of parameters such as resistivity and polarization rate on the airborne magnetic field is analyzed, and a method for simultaneous calculation of apparent resistivity and apparent polarizability is proposed using Sobol sensitivity analysis and particle swarm optimization. Finally, simulation experiments are conducted to verify the effectiveness of this method in identifying low-resistivity, high-polarization targets. The results show that the apparent resistivity curves for all models exhibit a characteristic dip at the low-resistivity target layer, intuitively reflecting the low-resistivity properties of the target layer. Models including polarization effects display high values at the target layer, with the anomaly amplitude increasing as polarization rate rises. The zero-polarization model shows a relatively flat apparent polarization curve. Experimental results further indicate that both ground resistivity and polarizability significantly affect the amplitude of the airborne magnetic field, with low-resistivity, high-polarization anomalies generating significant magnetic field response anomalies. 

With the increasing requirements for reservoir precision in oil and gas exploration, the traditional seismic wave propagation theory based on the pure elasticity assumption can no longer effectively describe the dispersion and attenuation characteristics exhibited by seismic waves during propagation caused by rock viscoelasticity and pore structure in complex media. Seismic forward modeling in poro-viscoelastic media has become an important research tool for accurately characterizing such coupling effects, among which the generalized standard linear solid model and its memory variable approach reduce computational complexity by introducing auxiliary differential equations to replace convolution integrals, thus realizing effective simulation of frequency-dependent attenuation. However, under the conditions of complex reservoirs with strong nonlinearity and strong attenuation, traditional algorithms still face the dilemma of balancing computational accuracy and efficiency. This paper introduces the generalized recursive convolution method to convert the time convolution term in the constitutive equation into a high-order recursive formula, directly updating the wavefield state recursively in the time domain, avoiding the global storage of historical data and repeated integral operations, and significantly reducing computational complexity and memory consumption. Numerical experiments show that in the homogeneous model, the proposed method in this paper improves computational efficiency by approximately 9% compared with the traditional memory variable method while achieving higher wavefield amplitude fidelity; In the two-layer anisotropic model, it can depict interlayer reflection and wave mode conversion more clearly than the memory variable method, significantly improving the accuracy of wavefield simulation; And in the complex heterogeneous Marmousi model, this method can effectively simulate the wavefield interference and slow-wave attenuation characteristics under strongly undulating interfaces.

The common reflection surface (CRS) stack imaging technique enhances the signal-to-noise ratio of seismic data by utilizing information from adjacent common midpoint gathers, making it a key technology for processing seismic data with low signal-to-noise ratios and low fold coverage. Whether using classical stepwise search or synchronous global search methods for CRS three-parameter optimization, a local optimization algorithm is ultimately required to enhance accuracy. The traditional Nelder-Mead simplex algorithm, with its simple search approach, suffers from relatively low computational efficiency. This paper adopts a derivative-free optimization algorithm called NEWUOA (new unconstrained optimization algorithm) as the precision enhancement method for CRS stacking. This algorithm dynamically constructs a quadratic interpolation model, employs a trust region iterative strategy, and utilizes curvature information of the objective function to improve computational efficiency. The algorithm was tested using a layered undulating model and the Marmousi2 model. The results show that for the simple layered undulating model and the complex Marmousi2 model, the NEWUOA generally outperformed or equaled the Nelder-Mead simplex algorithm in improving coherence values, with a computational efficiency increase of approximately 48% and 45%, respectively, compared to the Nelder-Mead simplex algorithm. This demonstrates that the NEWUOA can significantly enhance computational efficiency while maintaining the accuracy of CRS stack optimization, making it well-suited as a computational tool for precision refinement.