25 February 2026, Volume 29 Issue 1

    

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  Additional small theropod remains from the Upper Cretaceous Nenjiang Formation in Songliao Basin, Northeast China

  HUANG Yuqi , WU Wenhao, Ivan Bolotsky and YU Kaifeng

  Global Geology. 2026, 29(1): 1-12.

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  Five new small theropod teeth and one manual ungual have recently been recovered from the Upper Cretaceous Nenjiang Formation in the Songliao Basin. The specimens were examined for their morphological characteristics, leading to the identification of four distinct taxa. The first taxon consists of three foliodont teeth characterized by a pronounced basal constriction and large hook-like distal denticles, which can be attributed to Troodontidae. The second taxon is represented by an elongated tooth featuring prominent longitudinal ridges, allowing for its assignment to Paronychodon. The third taxon is a bladelike tooth with notably small distal denticles, corresponding to Richardoestesia. The fourth taxon comprises a manual ungual characterized by a transversely wide and nearly symmetrical proximal articular surface, fully enclosed ventral foramina, a flattened ventral surface, and the absence of a flexor tubercle, resembling Alvarezsauridae. These specimens significantly enhance the known dinosaur diversity of the Nenjiang Formation and provide crucial insights for understanding the terrestrial ecosystem in Northeast Asia during the Late Cretaceous.
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  Solar activity and ENSO signals in Early Eocene lacustrine oil shale from Green River Basin

  ZHANG Dongzhuojian , CAI Henan , SUN Pingchang and WANG Feng

  Global Geology. 2026, 29(1): 13-23.

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  Previous studies have shown that the Eocene oil shale sequences in the Green River Basin contain long-period astronomical age information. The fine-scale chronological characteristics of the oil shale laminae remain largely unexplored.We selected finely laminated oil shales formed in deep-water environments characterized by stable water column stratification as the primary focus of this study, using microscopy and micro-area X-ray fluorescence (μ-XRF) techniques. By integrating high-resolution elemental data with timeseries analysis, we identified significant periodic signals associated with solar activity (Hale and Schwabe cycles) and ENSO. The results indicate that the alternations of light and dark laminae in the Green River Formation oil shale correspond to alternating dry and wet climate regimes: the light laminae are dominated by carbonate minerals, reflecting drier and milder conditions, while the dark laminae are enriched in terrigenous clastics and organic matter, indicating periods of increased precipitation and warmer temperatures. The detected periodicities (23.5 years, 13.3 years and 5.8 years) are highly consistent with modern observations, demonstrating that the lower Eocene Green River oil shale effectively records short-term solar activity and climate variability. Furthermore, our findings confirm that a persistent "permanent El Niño" state did not develop under Early Eocene greenhouse conditions, providing a refined chronological framework for highresolution paleoclimate studies during greenhouse intervals.
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  Research on facies and reservoir seismic description methods of volcanic oil and gas reservoirs in Zhongguai area 

  YAN Qi , HE Wenjun , BIAN Baoli , AN Guoqiang, LI Baobao , BAI Yu , YU Xing , PANG Lei1 and AN Zhiyuan

  Global Geology. 2026, 29(1): 25-30.

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  In recent years, significant breakthroughs have been achieved in the exploration of deep volcanic rocks in the Junggar Basin, highlighting their substantial exploration potential. The complex distribution of volcanic reservoirs is attributed to the multi-phase tectonic evolution within the basin, with their superior reservoir properties playing a crucial role in natural gas formation. However, due to the combined effects of multi-cyclic volcanic eruptions and tectonic activities, predicting volcanic facies distribution and favorable reservoirs remains highly challenging. This study focuses on the third member of the Jiamuhe Formation in the Zhongguai Uplift. By integrating drilling and petrophysical data with well-seismic analysis techniques, a seismic identification model for volcanic reservoirs has been established. The findings reveal that different facies exhibit distinct seismic response characteristics. Andesite, rhyolite, volcanic breccia, and volcanic clastic rocks show variability in amplitude, frequency, and continuity. Using structural-guided filtering, high-resolution coherence analysis, and 3D body carving techniques, the locations of volcanic craters and eruption centers were successfully identified, further clarifying the distribution patterns of volcanic facies. By combining multi-attribute clustering analysis and seismic attribute extraction, a volcanic facies zone distribution map was generated, and favorable exploration directions for volcanic reservoirs were proposed. The study provides technical guidance for the exploration of deep volcanic oil and gas reservoirs in the Junggar Basin and holds significant application value.
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  Geochronology, geochemistry and tectonic setting of Middle Permian ophiolites in Yaduwula region, Inner Mongolia

  JIANG He , HAN Jie , ZHOU Jianbo and LI Gongyu

  Global Geology. 2026, 29(1): 31-48.

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  The Solonker Suture records the termination of the Central Asian Orogenic Belt (CAOB), but its eastward extension beneath the Songliao Basin has not been clear. The Yaduwula ophiolite is one of the significant fragments within the Solonker Suture. LA–ICP–MS U–Pb dating of zircon grains from metamorphic basalts yield ages of 263±4 Ma and 274±3 Ma, constraining the Yaduwula ophiolite in the late Cisuralian and Guadalupian age. This might indicate that the subduction of Paleo-Asian Ocean continued until at least the Guadalupian (middle Permian). Geochemical analysis of the metamorphic basalts revealed enrichment in large ion lithophile elements (LILEs) and depletion in high field strength elements (HFSEs) and show the characteristics of a supra-subduction zone. The results provide the evidence for the closure time of the Paleo-Asian Ocean after the middle Permian and also suggest that the Yaduwula ophiolite may be considered the eastern extension of Solonker Suture. Our study provides further insights on the evolution of the southeastern Central Asian Orogenic Belt.
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  Geological characteristics and genesis of the Mailong gold deposit in the East Kunlun Orogen, Qinghai 

  Jia Bowen1 , Zhang Shunbin , Li Xiaoliang , Yang De , Yu Xiaoliang , Li Hua , Zhang Jian , Qian Ye and Sun Fengyue

  Global Geology. 2026, 29(1): 49-67.

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  The Mailong gold deposit is located in the eastern section of the East Kunlun orogenic belt and is one of the recently discovered important gold polymetallic deposits in the Qinhai Gouli region. The primary host rocks of the Mailong gold deposit consist of intermediate-acid intrusive rocks from the Varisian and Indosinian periods, as well as the Precambrian Jinshuikou Group, with mineralization controlled by northeast and northwest faults. The alteration of the host rocks is mainly characterized by silicification, sericitization, chloritization, and carbonatization. Based on the cross-cutting relationships of the veins, the hydrothermal mineralization of the gold deposit can be categorized into three stages: the quartz-pyrite stage, the quartzpolymetallic sulfide stage, and the quartz-carbonate stage. Microthermometry of fluid inclusions indicates that the Mailong gold deposit belongs to a low-density (0.73–0.86 g/cm3 ), medium-temperature (240–340 ℃), and medium-salinity (4.01–10.74 wt% NaCl) NaCl-CO2-H2O fluid system. The C-H-O isotopic analysis suggests that the mineralizing fluids is derived from magmatic water, with later contributions from atmospheric precipitation. In-situ S isotopic results indicate that the mineralizing materials mainly derive from igneous rocks. A comprehensive analysis concludes that the Mailong gold deposit is a mesothermal hydrothermal vein-type gold deposit controlled by structural factors.
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  Petrogenesis and tectonic significance of the Paleoproterozoic Chibaisong meta-mafic rocks in the northeastern Jiao-Liao-Ji Belt

  ZHANG Jirui, YU Hongchao , LIU Jin , ZHANG Hongxiang and ZHANG Yuanzhuhui

  Global Geology. 2026, 29(1): 68-85.

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  The Jiao-Liao-Ji Belt within the North China Craton had undergone a complex tectonic evolution, marked by extensive Paleoproterozoic magmatism that produced a diverse range of mafic to felsic magmatic rocks. These events provide valuable geological records for understanding the tectonic evolution of the Jiao-Liao-Ji Belt. This study focuses on the Paleoproterozoic Chibaisong meta-gabbro in southern Jilin, investigating the source of mafic magma, petrogenesis, and tectonic setting through systematic petrological analysis, zircon U-Pb dating, and geochemical studies. The findings contribute to constraining the dynamic mechanisms of Paleoproterozoic extensional rifting in the Jiao-Liao-Ji orogenic belt. Geochemical data indicate that the samples exhibit low SiO₂(47.99–50.66 wt.%), TiO₂(0.75–3.20 wt.%), Nb(3.22–8.09 ppm), and Ta(0.22–0.51 ppm) contents, along with high TFeO₃(11.97–15.82 wt.%) and MgO(5.67–12.66 wt.%) concentrations. They also show low Nb/La ratios and high (Th/Nb)N values, consistent with the geochemical characteristics of tholeiitic basalts. The samples display low total rare earth element concentrations, weak or absent Eu anomalies, slight enrichment in light rare earth elements, relatively flat heavy rare earth element patterns, and depletion in Nb, Ta, and Ti. The meta-gabbro from southern Jilin exhibits geochemical similarities to Paleoproterozoic metamafic rocks from other regions of the Jiao-Liao-Ji Belt, resembling enriched mid-ocean ridge basalts (E-MORB) with Nb, Ta, and Ti depletion. Integration of previous studies and geochemical data suggests that the 2.16–2.10 Ga metamafic rocks in the Jiao-Liao-Ji Belt experienced contamination by older crustal material. These results indicate that the 2.16–2.10 Ga metamafic rocks are unlikely to be associated with island arc, continental arc, or mid-ocean ridge settings. Instead, they are more likely related to intraplate magmatism associated with continental rifting
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  Evaluation of the susceptibility to landslide geological disasters based on different slope units and an information content random forest model: a case study of the Longhua District, Shenzhen

  XIONG Haoyu, RAN Xiangjin and XUE Linfu

  Global Geology. 2026, 29(1): 86-100.

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  Slope units are divided according to the real topography and have clear geological characteristics, making them ideal units for evaluating the susceptibility to geological disasters. Based on the results of automatically and manually corrected hydrological slope unit division,the Longhua District, Shenzhen City, Guangdong Province, was selected as the study area. A total of 15 influencing factors,namely Fluctuation,slope, slope aspect, curvature, topographic witness index (TWI),stream power index (SPI),topographic roughness index (TRI), annual average rainfall,distance to water system, engineering rock group,distance to fault, land use,normalized difference vegetation index (NDVI),nighttime light, and distance to road, were selected as evaluation indicators. The information volume model (IV) and random points were used to select non-geological disaster units, and then the random forest model (RF) was used to evaluate the susceptibility to geological disasters. The automatic slope unit and the hydrological slope unit were compared and analyzed in the random forest and information volume random forest models. The results show that the area under the curve (AUC) values of the automatic slope unit evaluation results are 0.931 for the IV-RF model and 0.716 for the RF model, which are 0.6% (IV-RF model) and 1.9% (RF model) higher than those for the hydrological slope unit. Based on a comparison of the evaluation methods based on the two types of slope units, the hydrological slope unit evaluation method based on manual correction is highly subjective, is complicated to operate,and has a low evaluation accuracy, whereas the evaluation method based on automatic slope unit division is efficient and accurate, is suitable for large-scale efficient geological disaster evaluation, and can better deal with the problem of geological disaster susceptibility evaluation.