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Global Geology

	2025 Vol.28 Issue.1 Published 2025-02-25

	1	Revision of the Strophomenida (Brachiopoda) in the Lower Devonian of central Jilin Province, China
		LI Ning and YU Lili
		A genus within the family Douvillinidae of the order Strophomenida from the Erdaogou Member of the Xibiehe Formation in the Early Devonian of central Jilin has been re-examined, with consideration given to the 56 specimens collected and described by Liu and Huang (1977). Based on its distinct external ornamentation and internal characteristics, it has been classified as Cymostrophia (Protocymostrophia). It is concluded that the three specices described by Liu and Huang (1977), Idioglyptus alatus, I. semicircularis, I. subquadratus, as well as the Mesodouvillina jilinensis Su, 1980 should be considered synonyms and be named Cymostrophia (Protocymostrophia) alatus (Liu) Li.
		Guide:
		2025 Vol. 28 (1): 1-10 [Abstract] ( 20 ) [HTML 1KB] [ PDF 434KB] ( 63 )

	11	Tectonic transition from the Paleo-Asian Ocean to the Paleo Pacific Ocean: insights from volcano-sedimentary rocks in NE China
		MENG Weihao, WANG Hongyan and ZHOU Jianbo
		Since the Paleozoic, the tectonic evolution of northeastern Eurasia has been primarily influenced by the Paleo-Asian Ocean and the Paleo-Pacific tectonic domains. However, the spatial and temporal frameworks, as well as the timing of the tectonic transition between these two oceanic domains, remain unclear. For addressing these issues, we present petrological, geochronological, and geochemical data for andesite and sandstone samples from the Seluohe Group along the Jilin-Yanji Suture between the Jiamusi Khanka Block and the North China Craton. The geochemical results indicate that the andesite sample is high-Mg andesite. Its magma source was generated by the metasomatized mantle wedge influenced by f luids derived from the subducted slab in a continental island arc setting. The high-Mg andesite gives the crystallization ages of Early Triassic (249±3 Ma). The sandstone is immature greywacke with a maximum depositional age of Early Triassic (247±1 Ma), and its sediments primarily originate from concurrent magmatic rocks within a juvenile continental arc. Based on our new findings, we propose that the Seluohe Group represents an Early Triassic volcanic-sedimentary association with continental island arc characteristics associated with the southwestward subduction of the Heilongjiang Ocean. We identified a sedimentary basin intimately associated with one or more continental arcs along the northeastern edge of the North China Craton. We suggest that the southwestward subduction of the Jilin-Heilongjiang Ocean in the Early Mesozoic accounts for this continental arc setting. There is a distinct temporal gap between the closure of the Paleo-Asian Ocean (ca. 260 Ma) and the onset of Paleo-Pacific plate subduction (234–220 Ma), which is essentially coeval with the southwestward subduction of the Jilin-Heilongjiang Ocean between 255 Ma and 239 Ma. ?
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		2025 Vol. 28 (1): 11-34 [Abstract] ( 29 ) [HTML 1KB] [ PDF 1431KB] ( 104 )

	35	Enrichment model of continental shale oil in Zhanhua Sag of Jiyang Depression
		SU Siyuan, CHENG Cheng, JIANG Zhenxue, SHAN Xuanlong and YOUSIF M. Makeen1
		The quest for enrichment model of continental shale oil in the Zhanhua Sag of the Jiyang Depression in the Bohai Bay Basin to provide reference for exploration and development requires a comprehensive approach. Therefore, this study employs rock pyrolysis, Scanning Electron Microscopy (SEM), X-Ray diffraction analysis (XRD), Nuclear Magnetic Resonance (NMR), and other experiments to analyze the conditions for shale oil enrichment and establish its patterns. The results show that favorable hydrocarbon generation potential and appropriate thermal maturation degree control “in situ enrichment”; while the storage capacity and the mobility of shale oil determine “migration enrichment.” In the process, the TOC governs the oil-generating capacity of shale with medium to large pores and microfractures serving as the main enrichment spaces and migration pathways for shale oil. Based on the deposition model, the study area can be divided into five lithofacies stages (I-algal limestone, II-laminated marl, III-laminated recrystallized limestone, IV-laminated mudstones, and IV-blocky calcareous mudstones). Integrating the geochemical parameters into the sedimentary patterns makes it clear that the study area underwent two phases of hydrocarbon expulsion during the thermal evolution of source rocks (Stage II: 3 060–3 120 m and Stage IV: 3 020–3 040 m). However, judging by the observed TOC (2% to 5.6%), thermal maturity (Ro>0.8%), S1 (>2 mg/g) and OSI (>100 mg/g) as well as moderate basin size, climate, and quantity of terrestrial input, the blocky calcareous mudstones (Stage IV) have better oil-prone characteristics and potential to generate a substantial quantity of hydrocarbons at this stage. More so, with a brittleness index exceeding 60%, it exhibits favorable fracturability accounting for the main controlling factors and enrichment patterns of shale oil in the area. Hence, this study further enriches and develops the theoretical understanding of shale oil enrichment in the area, provides valuable insights for future exploration of continental shale oil in eastern China and other similar basin around the world.
		Guide:
		2025 Vol. 28 (1): 35-47 [Abstract] ( 18 ) [HTML 1KB] [ PDF 622KB] ( 70 )

	48	Multi-source and multi-temporal remote sensing image classification for flood disaster monitoring
		LI Zhu1, JIA Zhenyang1*, DONG Jing2 and LIU Zhenghong1
		Flood disasters can have a serious impact on people's production and lives, and can cause huge losses in lives and property security. Based on multi-source remote sensing data, this study established decision tree classification rules through multi-source and multi-temporal feature fusion, classified ground objects before the disaster and extracted flood information in the disaster area based on optical images during the disaster, so as to achieve rapid acquisition of the disaster situation of each disaster bearing object. In the case of Qianliang Lake, which suffered from flooding in 2020, the results show that decision tree classification algorithms based on multi-temporal features can effectively integrate multi-temporal and multi spectral information to overcome the shortcomings of single-temporal image classification and achieve ground-truth object classification.
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		2025 Vol. 28 (1): 48-57 [Abstract] ( 18 ) [HTML 1KB] [ PDF 587KB] ( 96 )

	58	Zircon U-Pb geochronology, geochemistry and geological implications of the high-silica rhyolite from Ningyuancun Formation in the Xunke Area, Lesser Hinggan Range
		YUE Hongju, ZHAI Yanchao, CAO Yuanxing, LI Hongke, WU Mingqian, YU Haocheng and QIU Kunfeng
		To determine the geological age, petrogenesis, and tectonic setting of Mesozoic volcanic rocks in the Ningyuancun Formation in Xunke area, Lesser Hinggan Range, the zircon U-Pb geochronology, petrographic observations, and geochemical analyses of major and trace elements were conducted in this study. Zircon U-Pb dating showed that the volcanic rocks of the Ningyuancun Formation were formed in the Early Cretaceous (112.97±0.90 Ma). Major element analyses revealed that the content of SiO? weighted from 74.14% to 76.54%, indicating the volcanic rocks to be high-silica and felsic. The content of AlO varies from 12.48% to 13.65%. A total alkali content of the volcanic rocks range between 8.46% and 9.56%, with Na?O/K?O ratios from 0.69 to 0.89. This indicated that the volcanic rocks belonged to a highly differentiated calc-alkaline series. Additionally, A/CNK values range from 0.950 to 1.015, and A/NK values vary between 0.999 and 1.127, suggesting a peraluminous characteristic. Trace element analysis showed a right-sloping “V-shaped” REE pattern, with the enrichment in light REEs and a prominent negative anomaly of Eu. The volcanic rocks are enriched in Rb, Th, U, La, and Ce, while Ba, Sr, and Ti are depleted. Rb/Sr ratio ranges from 10.01 to 12.46, Ti/Y ratio is from 51.14 to 95.72, and Ti/Zr ratio is from 5.78 to 6.41. It is suggested that the magma was derived from the partial melting of crustal rocks. This evidenced that the Early Cretaceous high-silica rhyolites were formed in an intra continental extension in eastern Northeast China during the northwestward subduction of the Pacific Plate. The crustal extension, asthenospheric mantle upwelling and underplating of mantle-derived magmas resulted in the residual crystalline mush in Early Cretaceous mafic magma chambers to erupt.
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		2025 Vol. 28 (1): 58-69 [Abstract] ( 17 ) [HTML 1KB] [ PDF 677KB] ( 53 )

	70	Evaluation of paddy soil quality in Wanchang area of Jilin City

		In order to identify the nutrient level and environmental quality of paddy fields in Wanchang area, and to provide scientific basis and technical support for planting rice in Wanchang area, the soil geochemical survey was carried out, 30 samples were collected from paddy soil in Wanchang area, and 20 elements (indicators) were analyzed. The characterization of the elemental content of soils in the study area was carried out, and the geochemical level for soil nutrients, the geochemical level for the soil environment, and the comprehensive geochemical level of soil quality were evaluated. The results showed that the average values of K content and pH of the soil in the study area were smaller than the background values of Jilin Province, and the average values of 18 elements including N, P, Ca, S, Pb, Zn etc. were bigger than the background values of Jilin Province. The results of the evaluation of soil single element nutrient in the study area showed that the available state nutrient levels of Mn, Zn, Cu, and K increased compared with the total amounts of nutrients level, with Cu increasing the most; the available state nutrient level of N, P, B, and Mo decreased compared with the total amounts of nutrients level, with Mo decreasing the most. The comprehensive level of soil nutrients geochemistry in paddy fields was mainly Level III (medium), accounting for 53.33%, and the low abundance level was caused by the lack of P element; the comprehensive level of soil environmental geochemistry was mainly Level I (clean), accounting for 96.67%, with only slight pollution caused by Cd. The comprehensive geochemical level of soil quality was mainly Level II, accounting for 66.67%. Suggestions were put forward for the rational utilization of soil resources in paddy fields in the study area.
		Guide:?
		2025 Vol. 28 (1): 70-78 [Abstract] ( 15 ) [HTML 1KB] [ PDF 310KB] ( 70 )

　

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