The eastern Ordos Basin is situated in a transitional zone between the stable Ordos craton and an adjacent active orogenic belt. Episodic tectonic uplift and subsequent cooling of the eastern Ordos Basin since the Mesozoic have been spatially and temporally heterogeneous, with uplift and cooling commencing earlier in the central and northern segments than in the south. To constrain the differential tectono-thermal history of the eastern region, apatite fission-track analyses were carried out on Upper Palaeozoic samples from distinct tectonic units, and new data are presented. The results identify four discrete episodes of rapid exhumation at 110 Ma, 70 Ma, 50 Ma, and 30 Ma, confirming a heterogeneous uplift and exhumation history of the region since the Early Cretaceous. The Eastern Ordos has experienced three phases of uplift. North-south thermal histories differ significantly: the south shows later, rapid cooling (50 m/Ma, 110-90 Ma), while the north shows earlier, slower exhumation (25 m/Ma, 130-90 Ma). Since 30 Ma, the southern area experienced accelerated uplift, contrasting with the moderate exhumation observed in the north and centre. We infer that differential tectonic uplift, exhumation, and the cooling process are coupled to underlying mantle dynamics, which have resulted in the complex structure of the eastern basin. This research provides significant implications for reconstructing the divergent thermal evolution pathways of its various tectonic units.

Exploration of the Gaolihan (GLH) Sag in the Erlian Basin remains low due to the discontinuity of early-stage 2D seismic surveys that have failed to provide regional coverage, leaving the deep geological framework unclear and hindering hydrocarbon breakthroughs. To address this problem and to evaluate the resource potential of the pre-Cretaceous formation, this study applied an integrated geophysical workflow combining 1:50,000 high-precision gravity–magnetic surveys, gravity–magnetic well–seismic joining in the forward and inversion directions, layer stripping, and time–frequency electromagnetic method (TFEM) profiling. Using logging resistivity curves from wells GC1 and LT1 for electrical calibration, we delineated the fault system, stratigraphic framework, and deep lithology of the GLH Sag. The key results include the following: (1) identification of 12 faults defining a “three sags and three uplifts” structural pattern; (2) burial depths of the Cretaceous, Jurassic, and Carboniferous–Permian basements ranging from 3000 to 3300 m, 4400 to 4600 m, and 6500 to 6700 m, respectively; and (3) recognition of three electrical layers within the Jurassic, with high-resistivity intervals indicating basalt and low-resistivity intervals interpreted as coal-bearing formation of the Lower Jurassic Hongqi formation. Quantitative validation against wells GC1 and LT1 demonstrates that the TFEM-inverted resistivity values show an average absolute deviation of ~2.5 Ω·m from measured logs (relative error <12% for resistivities >5 Ω·m), with an overall stratigraphic boundary consistency exceeding 85%. Lithologic prediction accuracies reach 88% for sandstone/siltstone and 82% for mudstone/carbonaceous mudstone. This integrated workflow proves effective for deep structural imaging and lithology prediction in volcanic-covered, seismically poor areas, and provides a practical reference for similar low-exploration basins.

The eastern Ordos Basin is rich in coalbed methane resources, with distinct accumulation and generation characteristics observed across different structural zones. Therefore, this study focuses on the eastern margin, utilizing vitrinite reflectance, geochemical parameters, and fluid inclusion thermometry data to reconstruct the thermal evolution history and simulate hydrocarbon generation. By comparing the differential evolution of Upper Palaeozoic coal seams in the eastern margin, it was found that the northern area was at a low-maturity stage in the Late Triassic, with limited hydrocarbon generation. The Early Cretaceous was the primary hydrocarbon generation period, with accumulation time occurring between 145 and 130 Ma. The peak hydrocarbon generation occurred at 140 Ma, but with relatively weak intensity, producing less than 0.01 Mtons. In contrast, the southern area's main reservoir formation period was between 135 and 120 Ma, reaching a peak hydrocarbon generation of 0.02 Mtons at 120 Ma. Overall, the hydrocarbon accumulation in the eastern margin of the basin occurred between 145 and 120 Ma. The geochemical characteristics of the coal-bearing source rocks show little variation, and the thermal evolution and hydrocarbon generation processes are similar. The quality of the source rock primarily affects hydrocarbon generation intensity, while the formation of coalbed gas is mainly constrained by structural thermal evolution. This study contributes to a deeper understanding of the thermal evolution and hydrocarbon generation processes of deep Upper Palaeozoic coal seams in the eastern margin of the Ordos Basin. It provides valuable insights for coalbed gas accumulation and prediction.

The Qiangtang Basin in the Tibetan Plateau exhibits a paradoxically reversed source-rock maturity pattern (high margins, low center), which presents a challenge to classical basin models. Critically, the unclear genetic mechanism behind this anomaly has impeded hydrocarbon exploration. To address this, this study investigates a north-south-oriented 2D geological section across the central basin. By employing an integrated methodology, the genetic mechanism was elucidated through systematic calculations of paleo-burial depth, paleotemperature, and vitrinite reflectance (Ro) at ten control points (C1-C10). Specifically, tectonic burial history was reconstructed using the backstripping method, while mantle heat flow was corrected by integrating the McKenzie extensional and Royden compressional models. Maturity evolution was quantified using the Easy%Ro model. The results demonstrate that (1) since the Early Jurassic, the basin has undergone five tectono-thermal evolution stages, with the geothermal gradient reaching 30-36 degrees C/km during the end of the Early Cretaceous); (2) Ro values range from 1.2% to 1.68% at the northern basin margin (C1-C4), are approximately 1.15% in the Central Uplift Zone (C5-C7), and range from 1.45% to 1.6% at the southern basin margin (C8-C10); (3) importantly, the reversed distribution was jointly controlled by three factors: deep burial at the basin margins (5-6 km), early uplift in the central part (initiating from the Late Cretaceous), and local magmatic thermal disturbance. Their estimated contribution ratios are 40-50%, 30-40%, and 10-20%, respectively. Consequently, regions such as the Luxiongcuo Syncline, the Bandaohu-Qingshuihu area, and the Chibuzhangcuo area are identified as having favorable exploration potential.

Facies classification in tight gas reservoirs faces a critical challenge: supervised machine learning requires extensive labelled core data that is economically prohibitive, while unsupervised clustering ignores geological physics and produces petrophysically implausible results. This study presents a physics-guided contrastive learning (PGCL) framework that bridges this gap by integrating unsupervised representation learning with domain-knowledge constraints. Applied to 3284 wireline log samples from five wells penetrating the coal-bearing Shanxi Formation in the Eastern Ordos Basin, China, the framework employed SimCLR contrastive learning to construct 64-dimensional embeddings from nine log features. Hierarchical refinement using binary density-neutron cutoffs for coal separation and Ward's clustering on core permeability-porosity space transformed initial unsupervised clusters into seven geologically coherent facies spanning three orders of magnitude in permeability. Random Forest classifiers trained on PGCL-generated pseudo-labels achieved 87.0% test accuracy, exceeding traditional supervised methods by 5-6 percentage points and unconstrained clustering by 15-16 percentage points despite requiring only 346 core measurements for physics-guided refinement. Integration with reservoir quality metrics showed that 98% of predicted Sandstone intervals and 78% of Silty Sandstone intervals exceeded commercial production thresholds, enabling probabilistic well placement with quantified risk assessment. The results demonstrate that semi-supervised learning enhanced with geological physics can reduce core dependence and provide reliable facies prediction for exploration-stage reservoir evaluation.

The Fujin Basin (FJ Basin) is a Cenozoic sedimentary basin located in the northern Junggar Basin. In response to key scientific issues, including unclear stratigraphic distribution and an inadequately constrained structural framework, this study utilizes measured resistivity data acquired through the controlled-source sounding method. By integrating profile interpretation and numerical simulation, the geological structure and stratigraphic distribution of the basin are investigated, and the exploration potential for deep oil and gas resources as well as shallow sandstone-hosted uranium deposits is evaluated. Using known logging resistivity curves, electromagnetic frequency responses at different burial depths were simulated to verify the effectiveness of the acquisition parameters and survey design for detecting strata ranging from shallow Tertiary formations to deep Carboniferous sequences. Based on the processed data, combined with the known physical properties of the strata and comprehensive geological interpretation, the geological structure, stratigraphic distribution, and tectonic framework of the FJ Basin were clarified. Integrated with borehole geochemical data, the CSEM resistivity sections suggest that the Upper Carboniferous Haerjiawu Formation constitutes a potential hydrocarbon source rock within the JTL sag, warranting further drilling verification. In addition, resistivity attributes and dual-frequency phase attributes were employed to predict the metallogenic conditions and favorable targets for shallow Tertiary sandstone-hosted uranium mineralization. The prediction results show strong consistency with known uranium deposits, providing important guidance for uranium exploration. The methodology proposed in this study can serve as a technical reference for integrated multi-mineral exploration in similar regions.

The characterization of geothermal reservoirs and their genetic mechanisms is critical for understanding geothermal system evolution and evaluating geothermal resource potential. The eastern Gushi Sag of the Weihe Basin hosts three Neogene sandstone geothermal reservoirs, including the Gaoling Group, Lantian–Bahe Formation, and Zhangjiapo Formation; however, their reservoir characteristics and genetic mechanisms remain poorly constrained. This study integrates geological structures, geothermal well logging, core petrophysical properties, and hydrochemical data to characterize reservoir conditions and establish a genetic model. The results show that the Neogene reservoirs are mainly composed of feldspathic sandstone, with the Lantian–Bahe Formation identified as the primary geothermal reservoir due to its moderate porosity, low permeability, large sandstone thickness, and favorable continuity. The geothermal field exhibits an average geothermal gradient of 3.35 °C/100 m with a south-to-north decreasing trend. Hydrochemical evidence suggests that geothermal fluids originate mainly from meteoric water recharged from the northern Qinling Orogenic Belt and paleo-sedimentary water, with deep faults and pore networks controlling fluid migration and accumulation. The Quaternary strata and Zhangjiapo Formation provide effective sealing conditions. This study reveals the coupled controls of thermal conditions, reservoir architecture, fluid circulation, and preservation on sandstone geothermal systems, providing insights into geothermal resource assessment, exploration strategy optimization, and the formation mechanisms of similar sedimentary basin geothermal systems.

Research on geothermal fields and lithospheric thermal structure is crucial for understanding regional tectonic dynamics and assessing geothermal resource potential. The Huazhou-Huayin area of the Weihe Basin exhibits significant geothermal anomalies, yet detailed studies on its present-day geothermal field and deep lithospheric thermal structure remain limited. Utilizing the latest drilling-logging data, borehole temperature measurements, rock thermophysical property tests, and geophysical data, this study systematically analyzes the characteristics and spatial variations of the present-day geothermal field. Combined with the heat conduction equation and geothermal parameters, this paper calculates the key features of the deep thermal structure, quantitatively assess the thermal state of the lithosphere, and discuss the controlling effects of deep-shallow factors on the geothermal field. This enables the establishment of a genetic model for the Huazhou-Huayin geothermal field. The results indicate that: 1) The geothermal gradient in the Huazhou-Huayin area decreases northward, averaging 33.3 degrees C/km but exceeding 36 degrees C/km in the southern piedmont zone. The average surface heat flow is 69.01 mW/m(2), classifying the area as a medium-high temperature geothermal system. 2) The present-day Moho temperature ranges between 600 and 840 degrees C. Deep mantle heat flow (29-45 mW/m(2)) contributes 48-60% of the surface heat flow, reflecting a "cold crust-hot mantle" thermal structure. 3) The present-day thermal lithosphere thickness (TLT) varies from 70 to 120 km, thinning southward and thickening northward. The medium-high geothermal field is primarily controlled by deep mantle heat flow, crustal radiogenic heat (>32%), and fault structures, while basement relief and magmatic activity have relatively minor influence. The formation mechanism of geothermal field in the study area is attributed to the Cenozoic extensional stretching of the Weihe Basin, asthenospheric upwelling generating high mantle heat flow, continuous radiogenic heat production from the upper crust and Cenozoic, and enhanced hydrothermal convection facilitated by deep-seated major faults.

The geothermal resources in sedimentary basins have high potential for development and utilization, and have become an important research topic worldwide(Olasolo et al.,2016; Pasvanoğlu and Çelik., 2019; Duan et al.,2022). This paper focuses on the genetic mechanism and evolution process of deep geothermal water were explored through the analysis of hydrogeochemical and isotope geochemical data, which can provide technical and theoretical support for the sustainable development of geothermal fields in the Weihe basin. The study indicates that: (1)the hydrochemical type of geothermal water of Dongda geothermal field are predominantly HCO3·SO4-Na type. Meanwhile, the hydrochemical type of geothermal water of the northern Xi'an Depression are mainly SO4·HCO3-Na and SO4·HCO3·Cl-Na types. The ionic fraction is primarily influenced by the dissolution of silicate and evaporite minerals, as well as alternating cation adsorption. (2) Geothermal water is primarily recharged by atmospheric precipitation originating from the Qinling Mountains. The recharge elevation ranges from 677.94 m to 1467.65 m. (3) The Dongda geothermal field has a thermal storage temperature ranging from 50.19℃ to 80.29℃, and a depth of thermal circulation ranging from 1126.32 m to 2129.62m. Meanwhile, the northern Xi'an depression has a thermal storage temperature ranging from 73.17℃ to 109.50℃, and a depth of thermal circulation ranging from 1892.41 m to 3103.22 m. (4) The δ18O of the geothermal water in the northern Xi'an depression is more significantly shifted to the right of the atmospheric precipitation line than that of the Dongda geothermal water, indicating a significant “oxygen drift”.(5) The Dongda geothermal reservoir in the southern Xi'an Depression mainly experiences heat transfer through convection, while the geothermal reservoir in the northern Xi'an depression experiences heat transfer through conduction.References[1]Duan, R., Li, P., Wang, L., He, X., & Zhang, L. (2022). Hydrochemical characteristics, hydrochemical processes and recharge sources of the geothermal systems in Lanzhou City, northwestern China. Urban Climate, 43, 101152.[2]Olasolo, P., Juárez, M. C., Morales, M. P., & Liarte, I. A. (2016). Enhanced geothermal systems (EGS): A review. Renewable and Sustainable Energy Reviews, 56, 133-144.[3]Pasvanoğlu, S., & Çelik, M. (2019). Hydrogeochemical characteristics and conceptual model of Çamlıdere low temperature geothermal prospect, northern Central Anatolia. Geothermics, 79, 82-104.

IntroductionThe North China Craton experienced multiple episodes of Mesoproterozoic anorogenic magmatism, which provides critical insights into the breakup process of the Columbia supercontinent. While numerous previous studies have focused on the southern and eastern margins of the craton, the southwestern margin remains relatively understudied, and its tectonic setting is still poorly constrained.MethodsTo investigate the tectonic context of Mesoproterozoic magmatic events along the southwestern margin and their relationship with the breakup of Columbia, this study presents a systematic analysis of the petrology, zircon U–Pb geochronology, and geochemistry of the granite porphyry in the Qi’angou area of Longxian, southwestern North China Craton.ResultsThese data are integrated with geochemical characteristics of other Mesoproterozoic igneous rocks from the western margin to comprehensively analyze the magmatic activity in this region. Zircon U–Pb dating yielded an emplacement age of 1794 ± 10 Ma for the Qi’angou granite porphyry, indicating its formation during the Mesoproterozoic. Geochemical data show that the granite porphyry is peraluminous and belongs to the A2-type granite suite. It is enriched in large-ion lithophile elements (LILE) and depleted in high-field-strength elements (HFSE), with high Rb/Sr ratios (2.95–3.55), pronounced negative Eu anomalies, and low Mg# values, suggesting a crustal derivation.DiscussionCombined with previous studies on coeval intermediate-mafic rocks (1740–1804 Ma)—including calc-alkaline basaltic andesites and high-K calc-alkaline diabases—these findings indicate that the North China Craton underwent extension during the late Paleoproterozoic to early Mesoproterozoic. Upwelling of a mantle plume beneath the southwestern margin triggered lithospheric thinning and partial melting of the upper crust, leading to a series of magmatic events. Comprehensive geochemical features and regional tectonic analysis suggest that the western margin igneous assemblage formed in a post-orogenic intracontinental extensional setting. This represents the initial geological record of the global breakup of the Columbia supercontinent within the North China Craton and provides key chronological constraints for understanding the geodynamic mechanisms of supercontinental fragmentation.

The Yin-E Basin, located at the junction of the Siberian, Kazakhstan, and Tarim blocks and the North China Craton, has experienced complex tectonic activities and remains one of the underexplored onshore sedimentary basins in China. The Upper Palaeozoic is an important stratigraphic interval for oil and gas exploration, but its source rock thermal evolution lacks systematic research, thus hindering exploration progress. Addressing the frontier topic of very low-grade metamorphism's role in organic maturation, we studied the clay mineralogy (illite crystallinity: 0.42 degrees-0.25 degrees Delta 2 theta), illite polymorphism (predominantly 2 M1), and cell parameters (b0: 9.0024-9.0204 & Aring;) of the Upper Palaeozoic source rocks (wells YBC1, BD1 and YBN1) in the Suhongtu Depression, revealing the palaeogeothermal field of the Upper Palaeozoic. These data were combined with basin modelling to quantitatively constrain the thermal evolution history. The results indicate that the Upper Palaeozoic strata primarily underwent prehnite-pumpellyite-facies of very low-grade metamorphism under medium-low pressure, corresponding to peak temperatures of 211.94 degrees C-226.32 degrees C. The reconstructed palaeotemperature reached 210 degrees C-220 degrees C. By the end of the Permian, all source rocks had reached their maximum thermal maturity (vitrinite reflectance, Ro: 1.42%-2.42%), with the Ba'nan Sag showing significantly higher maturity (Ro: 1.57%-2.42%). This study provides key constraints on the thermal evolution and hydrocarbon generation potential of Upper Palaeozoic source rocks, supporting future exploration in the Yin-E Basin and adjacent areas.

The paleogeographic and tectonic environments of the North China Craton experienced dramatic transitions throughout the end-Carboniferous to Permian, having been depicted to record protracted subduction-collision orogenesis along the southern margin of the Paleo-Asian Ocean (present coordinates). The resultant topographic growth within the Andean-Type continental arc, which was constructed by the ocean plate subduction, has also significantly driven regional climatic shift from humid to arid, expressed by accumulation of coal-bearing tidal flat and deltaic facies of the Benxi, Taiyuan, Xiashihezi, and Shangshihezi formations to red-color seasonal lake associations of the Shiqianfeng Formation. To depict relations between topographic variation of the continental arc and depositional environment changes of the sink, we conducted a complied work incorporating petrology, geochemistry, and detrital zircon U-Pb geochronology on Carboniferous and Permian strata in the central Ordos Basin, western North China Craton. The geochemical data of 36 mudstone samples show that the depositional basin was characterized by oxygen-poor and anaerobic environment, as indicated by Ce/La>1.5 and Vi/(V+Ni) >0.54. The paleosalinity from deposition of the Benxi to Shiqianfeng Formation gradually decreased, reflecting the environmental transition from marine to continental environments. The geochemical signatures further reveal that the detrital materials are mainly derived from erosion of medium-acid volcanic rocks within a continental arc. In combination with sandstone petrologic data, we suggest that gneiss and intrusive rocks that made up of continental magmatic arc are the main provenance sources, in addition to a small portion of basic volcanic rocks. The U-Pb dating results of 563 detrital zircons from 6 Carboniferous–Permian clastic rocks yield three distinct age ranges: 260–470 Ma (29%), 1700–2100 Ma (40%), and 2200–2600 Ma (25%). The ca. 260–470 Ma are the age characteristics of Cambrian to Triassic subduction-related magmatic rocks in the Andean-type continental margin. The ca. 1700–2100 Ma and ca. 2200–2600 Ma aged detrital zircons compare well with age distributions for basement rocks of North China Craton. In summary, our provenance data converge to imply that the Carboniferous-Permian sediments in the central Ordos were related to the uplift and denudation of the Andean-type continental arc stretching across the northern margin of the North China Craton, which is directly related to the southward subduction of the Solonker Ocean in the southern branch of the Paleo-Asian Ocean. In addition, zircon U-Pb age distribution characteristics indicate that there is an obvious crustal thickening event that led to provenance uplift in continental arc at the end of the Permian, recorded by increasing amounts of Permian-age zircons in the Shiqianfeng Formation and a craton-wide sedimentary hiatus below the Shiqianfeng Formation. Also, this tectonic event was coeval with climatic transition from humid to arid since accumulation of the Shiqianfeng Formation, expressed in sedimentary assemblage by evolving depositional environment from coal-bearing tidal flat via deltaic, to red-color seasonal lake.

Huhehu Sag is a sag with high exploration degree in Hailar Basin. With large sedimentary thickness, complete stratigraphic development and excellent oil generation conditions, it is the main oil- and gas-producing sag in Hailar Basin. The primary source rocks are the Nantun Formation, with the Tongbomiao and Damoguaihe Formations as secondary sources. Hydrocarbon accumulation periods in the sag were comprehensively analyzed using methodologies including source rock hydrocarbon generation-expulsion history, authigenic illite dating of reservoirs, and fluid inclusion homogenization temperature analysis. Results reveal two major accumulation stages: Stage 1 (125–90 Ma), corresponding to the depositional period of the Yimin Formation, represented the peak paleo-geothermal regime and the primary hydrocarbon accumulation phase. Intensive hydrocarbon generation and expulsion, coupled with robust migration dynamics, facilitated large-scale oil and gas pooling. Stage 2(65 Ma-now), from the deposition of Qingyuangang Formation to the present, uplift and denudation reduce the burial depth of source rocks, the hydrocarbon generation intensity is weakened. This phase involved secondary adjustments of pre-existing reservoirs and continued charging of newly generated hydrocarbons. The Huhehu Sag is a typical half-graben structure. Fault-block and fault-lithologic reservoirs dominate, distributed zonally along gentle and steep slopes. Lithologic reservoirs primarily occur near or within the central hydrocarbon-generating sub-sags. The most favorable hydrocarbon accumulation zones are located in the sub-sag centers and adjacent areas with high-quality reservoirs.

This study analyzes the lacustrine hydrocarbon source rocks of the Lower Cretaceous in the Erdengsumu sag of the Erlian Basin, evaluating their characteristics and identifying areas with oil resource potential, while also investigating the ancient lake environment, material source input, and controlling factors, ultimately developing a sedimentary model for lacustrine hydrocarbon source rocks. The findings suggest the following: (1) The lower Tengger Member (K1bt1) and the Aershan Formation (K1ba) are the primary oil-producing strata, with an effective hydrocarbon source rock exhibiting a lower limit of total organic carbon (TOC) at 0.95%. The Ro value typically remains below 0.8%, indicating that high-maturity oil production has not yet been attained. (2) The oil generation threshold depths for the Dalestai and Sayinhutuge sub-sags are 1500 m and 1214 m, respectively. The thickness of the effective hydrocarbon source rock surpasses 200 m, covering areas of 42.48 km2 and 88.71 km2, respectively. The cumulative hydrocarbon generation intensity of wells Y1 and Y2 is 486 × 104 t/km2 and 26 × 104 t/km2, respectively, suggesting that the Dalestai sub-sag possesses considerable petroleum potential. The Aershan Formation in the Chagantala sub-sag has a maximum burial depth of merely 1800 m, insufficient to attain the oil generation threshold depth. (3) The research area’s productive hydrocarbon source rocks consist of organic matter types I and II1. The Pr/Ph range is extensive (0.33–2.07), signifying a reducing to slightly oxidizing sedimentary environment. This aligns with the attributes of small fault lake basins, characterized by shallow water and robust hydrodynamics. (4) The low ratio of ∑nC21−/∑nC22+ (0.36–0.81), high CPI values (>1.49), and high C29 sterane concentration suggest a substantial terrestrial contribution, with negligible input from aquatic algae–bacterial organic matter. Moreover, as sedimentation duration extends, the contribution from higher plants progressively increases. (5) The ratio of the width of the deep depression zone to the width of the depression in the Erdengsumu sag is less than 0.25. The boundary fault scale is small, its activity is low, and there is not much input from the ground. Most of the source rocks are in the reducing sedimentary environment of the near-lying gently sloping zone.

This study investigates the uplift and exhumation history of the southern segment of the western margin of the Ordos Basin using low-temperature thermochronology, including zircon (U-Th)/He (ZHe), apatite fission-track (AFT), and apatite (U-Th)/He (AHe) data, combined with thermal history modeling. The study area exhibits a complex structural framework shaped by multiple deformation events, leading to the formation of extensively developed fault systems. Such faulting can adversely affect hydrocarbon preservation. To better constrain the timing of fault reactivation in this area, we carried out an integrated study involving low-temperature thermochronology and burial history modeling. The results reveal a complex, multi-phase thermal-tectonic evolution since the Late Paleozoic. The ZHe ages (291–410 Ma) indicate deep burial and heating related to Late Devonian–Early Permian tectonism and basin sedimentation, reflecting early orogenic activity along the western North China Craton. During the Late Jurassic to Early Cretaceous (165–120 Ma), the study area experienced widespread and differential uplift and cooling, controlled by the Yanshanian Orogeny. Samples on the western side of the fault show earlier and more rapid cooling than those on the eastern side, suggesting a fault-controlled, basinward-propagating exhumation pattern. The cooling period indicated by AHe data and thermal models reflects the Cenozoic uplift, likely induced by far-field compression from the rising northeastern Tibetan Plateau. These findings emphasize the critical role of inherited faults not only as thermal-tectonic boundaries during the Mesozoic but also as a pathway for hydrocarbon migration. Meanwhile, thermal history models based on borehole data further reveal that the study area underwent prolonged burial and heating during the Mesozoic, reaching peak temperatures for hydrocarbon generation in the Late Jurassic. The timing of major cooling events corresponds to the main stages of hydrocarbon expulsion and migration. In particular, the differential uplift since the Mesozoic created structural traps and migration pathways that likely facilitated hydrocarbon accumulation along the western fault zones. The spatial and temporal differences among the samples underscore the structural segmentation and dynamic response of the continental interior to both regional and far-field tectonic forces, while also providing crucial constraints on the petroleum system evolution in this tectonically complex region.

Stromatolites, distinctive fossil records within Precambrian strata, are essential for investigating the depositional environments of early Earth and the geological settings conducive to hydrocarbon formation. The Luonan area is located in Shaanxi Province, China, where a large number of stromatolites have been discovered within the Mesoproterozoic Erathem, providing new perspectives on paleoenvironment and reservoir spaces. This study analyzes the morphology of stromatolites, associated microorganisms, mineralogy, and cathodoluminescence from the carbonate rocks of the Jixian System. Carbon and oxygen isotope analyses help reconstruct paleosalinity and climate, enhancing understanding of their petroleum geological significance. Combining carbon and oxygen isotope analysis with the fine observation and description of stromatolite can better reconstruct the paleoenvironmental features of the Mesoproterozoic Era. The results indicated a narrow range of carbon isotope values (δ13C: −5.81‰ to −2.43‰; mean: −4.03‰) and oxygen isotope values (δ18O: −9.06‰ to −5.64‰). The Longjiayuan Formation is characterized by high CaO and MgO content, with low SiO2 and minimal terrigenous input, in contrast with the Fengjiawan Formation, which exhibits elevated SiO2 and greater terrigenous material. The Luonan stromatolites display prominent rhythmic laminations, primarily composed of dolomite, indicating a potential for hydrocarbon source rocks. Stromatolite morphologies, including layered, columnar, and wavy forms, reflect varied depositional microfacies. The alternating bright and dark laminae, rich in CaO and CO2 but differing in Ca2+ and Mg2+ concentrations, signify seasonal growth cycles. These Mesoproterozoic stromatolites developed in a warm, humid, and stable climatic regime, within a marine anoxic-to-suboxic setting, typically in intertidal or supratidal zones with low hydrodynamic energy. In the southern margin of the North China Craton, stromatolites from the Mesoproterozoic Era are extensively developed and exhibit distinct characteristics. Due to the biogenic alteration of stromatolites, the porosity of the rock increased. These stromatolites have altered the physical properties of the host rocks to some extent, suggesting the possibility of becoming effective hydrocarbon reservoirs. This has significant implications for deep oil and gas exploration, providing valuable guidance for future prospecting efforts.

ABSTRACT The Late Jurassic to Early Cretaceous was a critical transformative period for the North China Craton (NCC), marked by a tectonic shift from compression to extension and the formation of numerous Yanshanian magmatic intrusions across Shanxi Province. This article presents zircon U–Pb geochronology and Hf isotope, whole‐rock geochemistry and Sr–Nd isotopic compositions of Late Jurassic to Early Cretaceous intrusive rocks from the Hunyuan area in northern Shanxi Province. The Chakou, Liulengshan and Zhongzhuangpu intrusions yield zircon U–Pb ages of 150.9 ± 1.7 Ma, 137.9 ± 2.0 Ma and 115.4 ± 0.6 Ma, respectively. The Chakou monzogranites exhibit typical features of high‐K calc‐alkaline I‐type granites, and they are enriched in Rb, Ba, K and U, and depleted in Nb and Ta. The Sr and Nd isotopes of these samples show ( 87 Sr/ 86 Sr) i values ranging from 0.7062 to 0.7103 and ε Nd ( t ) values between −8.8 and −8.7. Additionally, zircon rims show highly variable ε Hf ( t ) values, spanning from −12.7 to −8.1. Geochemistry and isotopes suggest that the Chakou monzogranites originated primarily from the partial melting of the lower crust. The Liulengshan quartz syenites exhibit low SiO 2 and high K 2 O contents, classifying them as shoshonitic I‐type quartz syenites. They are enriched in LREE and LILE, depleted in HFSE with a weak negative Eu anomaly, and display moderate ε Nd ( t ) values between −17.1 and −17.0. Zircon Hf isotope composition is relatively uniform, with ε Hf ( t ) values ranging from −22.6 to −20.4. We propose that the quartz syenites from Liulengshan were formed by mixed products of mantle‐derived and crust‐derived magmas, with the latter being dominant. The Zhongzhuangpu biotite monzogranites are petrologically and geochemically uniform, showing enrichment in Pb and Ta, and strong depletion in Sr, Ba and Eu. We consider that they originated from the partial melting of crustal materials. Collectively, our data indicate that continuous crustal extension, thinning and asthenospheric upwelling facilitated partial melting of both lithospheric mantle and crustal materials. These processes were the primary drivers behind the formation of intrusions in the NCC during the Late Jurassic to Early Cretaceous.

The study of low-temperature thermochronology at plate edges provides favourable constraints for regional tectonic evolution and surface processes. Based on the existing thermochronological data of multiple cooling events since the Mesozoic era, we conducted apatite fission-track and (U–Th) / He dating studies on drilling samples from the central-northern section of the western margin of the Ordos Basin, revealing the exhumation and cooling history, including differences, in the study area. The new thermal-history inverse modelling results show that the Zhuozishan Mountain region (ZM region) experienced large-scale exhumation in the Late Jurassic (160–150 Ma), with an average exhumation rate of ca. 45 m Ma−1 and an average cooling rate of ca. 2 °C Ma−1; slow exhumation in the Early Cretaceous–Oligocene (130–30 Ma), with an average exhumation rate of ca. 10 m Ma−1 and an average cooling rate of ca. 1 °C Ma−1; and severe exhumation after the Oligocene (30 Ma–present), with an average exhumation rate of ca. 30 m Ma−1 and an average cooling rate of ca. 1.2 °C Ma−1. The Taole–Hengshanbao region (TH region) started exhumation in the Late Jurassic–Early Cretaceous (155–145 Ma), with an average exhumation rate of ca. 48 m Ma−1 and an average cooling rate of ca. 2.4 °C Ma−1; underwent slow exhumation in the Early Cretaceous–Oligocene (145–30 Ma), with an average exhumation rate of ca. 7.5 m Ma−1 and an average cooling rate of ca. 0.3 °C Ma−1; and then underwent violently exhumation, with an average exhumation rate of ca. 25 m Ma−1 and an average cooling rate of ca. 1 °C Ma−1. The Majiatan–Huianbao region (MH region) experienced large-scale exhumation in the Late Jurassic–Early Cretaceous (158–137 Ma), with an average exhumation rate of ca. 45 m Ma−1 and an average cooling rate of ca. 1.8 °C Ma−1; featured a slightly slower exhumation rate at 137–110 Ma, with an average exhumation rate of ca. 13 m Ma−1 and an average cooling rate of ca. 0.52 °C Ma−1; and entered a severe exhumation stage again in the Late Cretaceous–Eocene (70–50 Ma), with an average exhumation rate of ca. 37.5 m Ma−1 and an average cooling rate of ca. 1.5 °C Ma−1. The Late Jurassic tectonic exhumation indicated by thermochronology corresponds to the formation of the western-margin fold-and-thrust belt, with the northern and southern sections starting earlier and the central section starting slightly later. At the same time, the exhumation time of different fault blocks decreased gradually from the edge of the basin towards the centre, following an E–W direction. This is related to the different tectonic evolution and stress patterns in the different locations.