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XIAN Zumin,PAN Zhaohui,WANG Jianhua,JIA Liantao,ZHAO Yingtian,LUO Yanchao,ZHU Min
2025,99(1):1-14, DOI: 10.1111/1755-6724.15269
Abstract:
A new species of Bothriolepis (Placodermi, Antiarcha), B. zhujiangyuanensis sp. nov., is described from the Eifelian (Middle Devonian) Shangshuanghe Formation at the Pearl River Source Scenic Area, Qujing, Yunnan Province, southwestern China and is characterized by a broad postpineal plate bearing a straight anterior margin, a premedian plate wider than long, and a weakly developed dorsal median ridge of the trunk shield. As the eighth Bothriolepis taxon in China, B. zhujiangyuanensis sp. nov. provides a wealth of morphological data to clarify the intrageneric interrelationships. Maximum parsimony analysis, using a revised data set of the genus with 76 ingroup taxa and 72 characters, yields a well-resolved consensus tree for Bothriolepis. The phylogenetic result shows a sister-group relationship between B. zhujiangyuanensis and B. babichevi from Kazakhstan, corroborating the biogeographic proximity between the South China and Kazakhstania blocks during the Middle Devonian.
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Saeed FAREED,Yasser SALAMA,Abdelaziz MAHMOUD
2025,99(1):15-37, DOI: 10.1111/1755-6724.15270
Abstract:
The Upper Cretaceous successions of Wadi Umm-Khayshar, southern Galala Plateau, North Eastern Desert, Egypt, are composed of highly diversified faunas and subdivided from base to top into the Galala (Middle–Late Cenomanian), Maghra El Hadida (Latest Cenomanian–Late Turonian), Matulla (Coniacian–Santonian), and Sudr (Campanian–Maastrichtian) formations. Five ammonite biozones are recorded in the studied section: Neolobites vibrayeanus, Vascoceras cauvini (late Cenomanian), Vascoceras proprium, Choffaticeras segne, and Coilopoceras requienianum (Turonian) zones. The paleoenvironments of the Upper Cretaceous succession are interpreted based on detailed study and microfacies analysis that reflect a deposition in a homoclinal ramp platform ranging from intertidal to deep subtidal. The paleoecology of the Cenomanian–Turonian succession in the studied section is explained based on a detailed study of macrofaunal associations and sedimentary facies. Quantitative analysis (Q-mode cluster analysis, using the Raup–Crick Paired group method) of 1029 macrobenthic specimens, including 45 species of mollusks and echinoids yielded five macrofaunal associations (A–E) that are described and interpreted as remnants of communities. The nektonic elements are represented by 235 cephalopod specimens of 20 species; heatmap cluster analyses show the distribution of these specimens during the Upper Cenomanian–Turonian stages. Environmental parameters (substrate consistency, rate of sedimentation, water energy, surface-water productivity, and oxygen availability) controlled the distribution of the studied macrofauna. The five associations are divided into two major groups: low-stress associations (A, B, C, and D), and a high-stress association (E). The low stress associations are recorded from two different habitats: (1) a high-energy, firm substrate habitat, dominated by epifaunal bivalves, large epifaunal gastropods and a regular echinoid; (2) a low-energy, soft substrate habitat dominated by infaunal bivalves and echinoids. The high stress association is dominated by only two species and recorded from a high-energy shoal environment during a regression phase. A detailed study of macrobenthos and cephalopods provides a good paleoecological understanding of Cenomanian–Turonian succession in the Wadi Umm–Khayshar section.
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HUO Hailong,CHEN Zhengle,ZHANG Qing,HAN Fengbin,ZHANG Wengao,WANG Yong,WANG Wenbao
2025,99(1):38-52, DOI: 10.1111/1755-6724.15219
Abstract:
The Southwest Tianshan is the suture zone between the Central Tianshan and the Tarim Craton. To better illustrate the subduction polarity of the Southwest Tianshan Ocean, a systematic detrital zircon LA-ICP-MS U-Pb geochronology of sedimentary rocks of the Devonian Apadaerkang Formation and the Carboniferous Akeqiayi Group of the Biedieli area in the Wushi region is the focus. Detrital zircon ages indicate that the youngest grains of the targeted quartz sandstones are Late Devonian and Early Carboniferous in age, respectively. These ages also have relatively similar age spectra, indicating a similar tectonic setting and source in the Biedieli area during the Devonian to Carboniferous. The main spectrum peaks occur at 2360, 1960, 810, 640 and 440 Ma, with a principal age peak in the early Paleozoic (474–430 Ma), and the Central Tianshan Terrane is indicated as the main source. The detrital zircon geochronology and sedimentary characteristics of the Biedieli rocks indicate that the Paleozoic sedimentary rocks in the northern Wushi region were formed at an active continental margin, associated mainly with the early Paleozoic subduction of the South Tianshan Ocean.
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GUO Jing,LI Yunshuai,ZHANG Jianxin
2025,99(1):53-68, DOI: 10.1111/1755-6724.15264
Abstract:
Deciphering high-pressure granulite-facies metamorphism and anatexis within a collisional orogeny can provide crucial constraints on geodynamic evolution and melt activity during subduction and exhumation. Combining petrographic observations, mineral chemistry, REE in Grt-Cpx thermobarometry, and previous work, at least four stages are suggested for the metamorphic evolution of the mafic granulites in the South Altun, including the protolith stage, the high-pressure granulite-facies stage (909–1037°C and 17.3–30 kbar), medium-pressure granulite-facies overprint (9.1–11.9 kbar and 753–816°C), and subsequent late amphibolite-greenschist-facies metamorphism. Zircon U-Pb dating shows that the mafic granulites underwent high-pressure granulite-facies metamorphism at 497.2 ± 3.7 Ma, while the leucosome formed at 498.2 ± 2.9 Ma. Thus, the leucosomes from the host mafic granulite may have been formed at the high-pressure granulite-facies metamorphic event. The characteristics of zircon morphology, mineral inclusions, low Th/U values, HREE enrichment, and negative Eu anomalies indicate that these zircons from the leucosome were formed from the metamorphic melts. The characteristics of whole-rock major and trace elements as well as Hf isotopic features of zircons between the leucosomes and the host mafic granulite indicate that the melt may have been generated by the partial melting of the host mafic granulite.
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CHEN Ziyuan,YUAN Mingkao,ZHONG Zhenyu,LI Tianqi,WANG Guodong,XIAO Lingling
2025,99(1):69-82, DOI: 10.1111/1755-6724.15206
Abstract:
The Yishui complex, located in the western Shandong area of the North China Craton, is representative of the Archean crystalline basement of the North China Craton to explore the early tectonic-thermal evolution history of the Earth. Detailed petrography, mineral chemistry, metamorphic evolution and zircon U-Pb dating are presented for felsic granulite and two-pyroxene granulite from the Yishui complex to contribute to new insights into the Neoarchean tectonic evolution of the North China Craton. Three mineral assemblages are recognized for these granulite samples, including the prograde (M1), peak (M2) and retrograde (M3) mineral assemblages. Conventional geothermobarometry and phase equilibrium modeling yield P-T conditions of 6.5–10.9 kbar/718–839°C for the peak metamorphism, which define a medium-pressure granulite-facies metamorphism occurred at middle to lower crust. Anticlockwise P-T paths with near-isobaric cooling (IBC) retrograde segments were reconstructed. Zircon LA-ICP-MS U-Pb dating suggests that the protolith of the felsic granulite was emplaced at 2541 ± 7 Ma and the subsequent medium-pressure granulite-facies metamorphism occurred at 2518–2494 Ma. A two-stage mantle plume related crustal-scale sagduction geodynamic regime is proposed in the western Shandong terrane in the Neoarchean.
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HUANG Haibin,SHI Yuruo,Lawford J. ANDERSON,KANG Yuelan
2025,99(1):83-99, DOI: 10.1111/1755-6724.15261
Abstract:
We report new SHRIMP zircon U-Pb ages, zircon Lu-Hf isotopic and whole rock geochemical data from Permian granitoids located in the Alxa area of Inner Mongolia, China. In combination with published geochronological and geochemical data, the granitoids in the region can be divided into two age groups: ca. 285 Ma and ca. 269 Ma. The granitoids of the first group are mainly composed of calc-alkaline to high-K calc-alkaline, weakly peraluminous I-type granodiorites with εHf(t) values of ?19.6 to ?4.3, which demonstrates evidence of crustal reworking; the granitoids of the second group, however, mainly consist of A-type granites that are high-K calc-alkaline to shoshonite, metaluminous to weakly peraluminous, and have high 10,000 × Ga/Al ratios (2.59–3.12) and εHf(t) values ranging from ?11.3 to ?2.7, all of which demonstrates a mixed crust-mantle source. We interpret the granitoids of the first group to have formed during the subduction of Central Asian oceanic crust and the second group to have formed by the asthenospheric upwelling caused by the formation of slab windows during late ocean ridge subduction.
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ZHANG Meng,JIANG Yaohui,LIU Yunchao,HAN Boning
2025,99(1):100-113, DOI: 10.1111/1755-6724.15265
Abstract:
The petrogenesis and genetic link to polymetallic mineralization of the granites in the Dayishan complex, southern Hunan province remain debated. Here, we present an integrated study on the petrology, zircon U-Pb ages and whole-rock geochemistry for this complex. Our findings indicate that the southern complex consists of (amphibole-bearing) biotite granites and muscovite granites emplaced at 153–151 Ma, and the central and northern complex consists of two-mica granites and tourmaline-bearing muscovite granites, respectively with the former emplaced at 164 Ma and the latter at 150 Ma. The (amphibole-bearing) biotite granites have SiO2 contents of 68.0–73.8 wt% and are enriched in alkalis and rare earth elements and depleted in Sr and Ba. They display Zr + Y + Ce + Nb > 350 ppm and 10000 × Ga/Al > 2.6 along with high zircon saturation temperatures (821–883oC). The two-mica granites and (tourmaline-bearing) muscovite granites have high SiO2 (74.4–77.3 wt%) and low Ga/Al, Zr + Nb + Ce + Y, K/Rb, Zr/Hf, and Nb/Ta along with low zircon saturation temperatures (709–817oC). Geochemical characteristics suggest that the (amphibole-bearing) biotite granites are A-type granites generated through shallow dehydration melting of early Paleozoic granitoids, and that the two-mica granites and (tourmaline-bearing) muscovite granites are fractionated A-type granites produced through fractionation crystallization from the (amphibole-bearing) biotite granites accompanied by fluid fractionation.
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LI Jiahui,SHAN Xuanlong,YI Jian,WU Chengzhi,Ventura GUIDO,LIU Pengcheng,GUO Jiannan,WANG Wei
2025,99(1):114-125, DOI: 10.1111/1755-6724.15271
Abstract:
The 7 ka old Qixiangzhan lava flow (QXZ, Tianchi volcano) represents the last eruptive event before the 946 CE, caldera-forming ‘Millennium’ eruption (ME). Petrographic, whole rock, mineral composition, Sr-Nd isotopic data on QXZ show that: (a) the lava consists of two components, constituted by comenditic obsidian fragments immersed in a continuous, aphanitic component; (b) both components have the same geochemical and isotopic variations of the ME magma. The QXZ and ME comendites result from fractional crystallization and crustal assimilation processes. The temperature of the QXZ magma was about 790°C and the depth of the magma reservoir around 7 km, the same values as estimated for ME. QXZ had a viscosity of 105.5–109 Pa s and a velocity of 3–10 km/yr. The emplacement time was 0.5–1.6 yr and the flow rate 0.48–1.50 m3/s. These values lie within the range estimated for other rhyolitic flows worldwide. The QXZ lava originated through a mixed explosive–effusive activity with the obsidian resulting from the ascent of undercooling, degassing and the fragmentation of magma along the conduit walls, whereas the aphanitic component testifies to the less undercooled and segregated flow at the center of the conduit. The QXZ lava demonstrates the extensive history of the ME magma chamber.
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GONG Wei,LI Chaoyang,JIANG Liang,WANG Yuyan,LI Hongyu,ZHAO Lihong,ZHAO Faqiang
2025,99(1):126-143, DOI: 10.1111/1755-6724.15272
Abstract:
The temporal and spatial evolution of the Ailao Shan–Red River (ASRR) fault zone, which serves as an important accommodation zone for the extrusion and escape of the Southeastern Tibetan Plateau, is crucial for analyzing the uplift and growth of the plateau. Based on the petrology and apatite fission track analysis, the tectonic history and active pattern of the ASRR fault zone since the middle Miocene are determined in this study. The ASRR fault zone exhibits 12–8 Ma and 8–4 Ma rapid cooling phases since the middle Miocene. The 12–8 Ma and 8–4 Ma cooling may imply that the dextral movement of the ASRR fault zone presents a migration trend from northwest to southeast, accompanied by the weakening of the activity intensity, which is directly related to deformation processes, including extrusion boundary migration and active tectonic movements of the southeastern Tibetan Plateau, since the middle–late Miocene.
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2025,99(1):144-158, DOI: 10.1111/1755-6724.15274
Abstract:
The formation of Mesozoic natural gas in the Pengyang area of southwestern Ordos Basin is discussed, from the perspective of microbial community characteristics, in order to clarify the relationship between the origin of natural gas and its associated indigenous microbial community. The types and diversity of indigenous microbial communities associated with the oil reservoir were studied by means of collecting reservoir formation water samples from exploration wells. The indigenous microbial communities in the Chang 8 member of the Yanchang Formation were primarily distributed within Proteobacteria and Firmicutes, including the specific species and genera of Methylobacter, Pseudomonas, Haibacter, Toxobacillus, Acinetobacter and Adura actinomyces. The results of diversity analysis shows that the number of common genes was 5448, while the number of unique genes and information was less. This reflects the fact that the strata in the study area are relatively closed and not invaded by external water sources, which leads to the development of biological community diversity. In conjunction with the analysis of geochemical characteristics of oil and gas reservoirs in this area, this indicates that the study area possesses the necessary geological conditions for microbial degradation. It is the first time that the species and diversity of the indigenous microbial community in the Ordos Basin have been analyzed, showing that microbial degradation is the main cause of natural gas formation here, changes the characteristics of crude oil in this area and provides first-hand information on the impact of indigenous microorganisms on the reservoir.
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CHEN Sirui,XIAN Benzhong,JI Youliang,LI Jiaqi
2025,99(1):159-176, DOI: 10.1111/1755-6724.15273
Abstract:
This study focuses on tuffaceous clastic rocks of the Lower Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin. It aims to explore the influence of sedimentation and parent rock on this kind of reservoir development. The results show that the tuffaceous components formed by the denudation of ultramafic and mafic rocks can transform into chlorite coating or hematite, while those from intermediate rock denudation can be dissolved or transformed into illite. Sedimentary facies and lithofacies are essential in controlling the evolutionary result of tuffaceous components. Matrix-supported medium conglomerate and grain-supported medium-fine conglomerate that developed in the fan delta plain, with a closed original geochemical systems, have been in the oxidizing environment for a long time. The tuffaceous matrices mainly transforms into hematite or illite. These minerals occupy the primary pores and are difficult to dissolve by felsic fluids, which inhibits the development of high-quality reservoirs. The grain-supported sandy fine conglomerate developed in the fan delta front was in the underwater reductive environment with an open original geochemical system. The tuffaceous matrices not only can transform into chlorite coating to strengthen the particle’s compaction resistance, but also can be fully dissolved, which promotes the formation of high-quality reservoirs.
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SUN Shijie,ZHANG Bin,WANG Xiaomei,TIAN Hua,ZHANG Shuichang,HOU Guiting
2025,99(1):177-193, DOI: 10.1111/1755-6724.15262
Abstract:
Controlled by fluctuating paleoclimates and sedimentary environments, the organic and inorganic features of the Lucaogou Formation exhibit strong heterogeneity in the vertical profile, challenging conventional geological interpretation. To elucidate the possible influence of heterogeneity on resource evaluation, a high-resolution sampling approach was applied to an 86.2 cm long core from the Lucaogou Formation of the Jimsar sag in the Junggar Basin. 86 sets of samples were micro-drilled from the core and subjected to comparative Rock-Eval pyrolysis. Following the classical guidelines, the organic abundance, kerogen type, and maturity of source rocks were exhaustively analyzed. Experimental results revealed that organic richness and composition vary significantly under different sedimentary backgrounds, which in turn leads to differential hydrocarbon generation. The combination of hydrocarbon generation, transport, and expulsion results in peculiar patterns for hydrocarbon accumulation in the Lucaogou Formation. Laminated shales in the Lucaogou Formation serve as both hydrocarbon source rocks and reservoirs, with laminae being migration pathways. Organic-rich dolomites in the Lucaogou Formation have a considerable hydrocarbon-generating capacity and present the characteristics of self-generation and self-storage. However, massive mudstones act purely as hydrocarbon source rocks.
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HOU Haihai,LIANG Guodong,SHAO Longyi,TANG Yue,YAN Zhifeng
2025,99(1):194-211, DOI: 10.1111/1755-6724.15202
Abstract:
Coal pore parameters are closely related to macrolithotypes and coal structures, having a large influence over the gas potential and productivity of coalbed methane (CBM). The Middle Jurassic Xishanyao Formation, located in the southern Junggar Basin of northwestern China, has geological conditions with rich CBM resources. The 46 Xishanyao coal samples gathered from the drilling cores and coal mines cover 4 types of macrolithotypes (bright coal 1, semi-bright coal 2, semi-dull coal 3, and dull coal 4) and 2 types of coal structures (primary coal I and cataclastic coal II). Based on a range of pore testing experiments and analytical methods, the dual effects of different macrolithotypes and coal structures on pore structures were intensely studied. The results showed that the specific surface area (SSA) and total pore volume (TPV) of coal samples increased gradually from bright to dull coals. For the same macrolithotypes, the SSA and TPV of the primary coals were lower than those of the cataclastic coals. Generally, the pore structures of bright and semi-bright coals are simpler when compared to semi-dull and dull coals with the same coal structure, whereas cataclastic coals have more complicated pore structure systems than primary coals with the same macrolithotypes. The bright and semi-bright coals have higher vitrinite contents and more endogenous fractures, whereas well-developed structural fractures were identified in cataclastic coals. Therefore, bright and semi-bright coals have better pore connectivity than semi-dull and dull coals with the same coal structure, the pore connectivity of cataclastic coals being slightly better than that of primary coals under the same macrolithotypes. In terms of the CBM adsorption conditions, the eight type samples formed a descending order: II-4 > I-4 > II-3 > I-3 > II-2 > I-2 > II-1 > I-1, while they ranked as follows when consideration was given to the CBM seepage capacities: II-2 > II-1 > I-2 > I-1 > I-3 > I-4 > II-3 > II-4. As a result, it could be determined that the bright and semi-bright coals had stronger adsorption capacities, whereas the cataclastic coals had better pore connectivity and seepage capacities. Pore structure characteristics should be analysed under the dual control of different macrolithotypes and coal structures, so that they can provide greater value for guiding CBM exploration and exploitation, as along for preventing underground gas accidents.
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2025,99(1):212-227, DOI: 10.1111/1755-6724.15199
Abstract:
It is of great significance for deep oil and gas exploration to understand the origin and evolution behind overpressure. Overpressure occurs in the deep Shahezi Formation of Xujiaweizi fault depression. However, due to limited degree of exploration, there are some problems in the study area, such as unclear understanding of the origin of overpressure and the vague investigation of overpressure evolution. To clarify the impact of overpressure on oil and gas migration and accumulation in the study area, this study focuses on the research of the origin and evolution of overpressure in the Shahezi Formation of the study area, utilizing single well logging parameters and combining methods such as microthermometry of fluid inclusions, laser Raman spectrum, and basin simulation. The results show that the overpressure of the Shahezi Formation in Xujiaweizi fault depression is primarily generated by hydrocarbon generation pressurization, and the evolution of overpressure is closely related to hydrocarbon generation. The development of overpressure can be divided into two evolutionary stages: early hydrocarbon generation pressurization and late uplift release, with slight variations in different regions. Tight glutenite gas reservoirs in the Shahezi Formation are characterized by continuous charging. The overall charging period ranges from the late Denglouku to the early Mingshui (110–67 Ma ago). There is an obvious paleo-overpressure during the gas reservoir formation period. The gas generation period of source rocks occurred approximately 125–60 Ma ago, and the main gas generation period (112–67 Ma ago) highly coincides with the period of natural gas charging. The anomalously high pressure during the accumulation period is considered the significant driving force for natural gas charging. In addition, the sustained effect of overpressure provides better conditions for the preservation of tight gas reservoirs within the source. The results of the study are of guiding significance for the in-depth exploration and development of deep tight sandstone gas in the Shahezi Formation of Xujiaweizi fault depression.
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TAN Xiaolin,ZENG Lianbo,SHE Min,LI Hao,MAO Zhe,SONG Yichen,YAO Yingtao,WANG Junpeng,Lü Yuzhen
2025,99(1):228-242, DOI: 10.1111/1755-6724.15166
Abstract:
Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation. Artificial carbonate samples with different internal structures were prepared, and high-temperature and high-pressure dissolution kinetic simulations were conducted. The results demonstrate that the intensity of burial dissolution is controlled by temperature and pressure, while tectonic-fluid activity influences the development pattern of burial dissolution, ultimately determining the direction of its differential modification. Extensive burial dissolution is likely to occur primarily at relatively shallow depths, significantly influencing reservoir formation, preservation, modification, and adjustment. The development of faults facilitates the maintenance of the intensity of burial dissolution. The maximum intensity of burial dissolution occurs at the tips and overlap zones of faults and intersections of multiple faults. The larger the scale of the faults, the more conducive it is to the development of burial dissolution. Burial dissolution fosters the formation of fault networks characterized by enhanced reservoir capacity and permeability. Burial dissolution controlled by episodic tectonic-fluid activity is a plausible explanation for forming the Tarim Basin’s ultra-deep fault-controlled “string-bead-like” reservoirs.
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YIN Xiaoxiao,LIN Jianwang,LI Hu,LI Huanqing,DONG Lufei,YAN Jiaxian,ZHANG Sen,LI Zheng
2025,99(1):243-257, DOI: 10.1111/1755-6724.15263
Abstract:
Large basins are currently the global focus for geothermal development, with their hydrothermal system being controlled by a variety of factors, such as basement relief and fracture development. Donglihu is located at the north of the Cangxian uplift in the North China Basin, the concentrated geothermal resource development zone in North China. This study systematically collects temperature logging data and long-term dynamic monitoring of water level and water quality as well as group well tracer test data carried out in this area in recent years, on the basis of which the hydrothermal controlling role of the deep hidden faults is systematically analyzed. The results show that the Cangdong fault communicates with different geothermal reservoirs in the shallow part and plays a specific role in the water-heat channel of the local area. As a result, the high-value area of the geothermal temperature gradient in the sedimentary layer of the Donglihu area is distributed around the Cangdong fault. The geothermal reservoir temperature of the Minghuazhen Formation within the influence of the fault is also significantly higher than the regional average, the hydraulic head of different geothermal reservoirs showing a consistent and synergistic trend. However, the water quality has been stable for many years without any apparent changes. This understanding has a particular significance for further deepening understanding of the geothermal genesis mechanism in sedimentary basins and guiding future geothermal exploration and development in the Donglihu area.
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XIA Rui,YUAN Guoli,CUI Minli,HOU Hongxing,YU Guangming,GE Liangsheng,Lü Kaining,REN Bingzhang
2025,99(1):258-271, DOI: 10.1111/1755-6724.15268
Abstract:
Black soil is essential for maintaining regional food security and promoting global agricultural production. Understanding the weathering process of parent material and the accumulation of organic carbon is crucial to comprehending the developmental history and future trends of black soil, especially against the background of large-scale global cultivation and climate change. Although the importance of black soil formation and evolution cannot be ignored, the relevant research is still very scarce. In this study, a typical eight-meter-deep soil core was collected from the Keshan area of the Songnen Plain, Northeast China, where surface black soil developed on paleo-sediments. Using 14C dating, the formation age of the black soil was determined. Based on the characteristics of the geochemical composition, grain size and the magnetic susceptibility of the sediments, it was demonstrated that the black soil and its parent material originated from reworked loess. Furthermore, the mass transfer coefficient (τ) of some elements was determined, in order to explore the soil weathering process. By calculating the transported amount of alkaline and alkaline-earth elements, the weathering rate of parent material to black soil was found to be weak, at 0.16 kEq·ha?1·year?1. Combining the results of dating and carbon density in the different layers of black soil, the accumulation rate of organic carbon was determined as follows: rapidly increasing in the initial period of 13.2–2.2 ka, reaching its maximum average value of 34.0 g·cm?2·a?1 at 2.2–0.8 ka, then showing a decreasing trend with an average value of ?77.5 g·cm?2·a?1. Compared with regional climate change, Keshan black soil has developed under a colder and wetter climate during the Holocene. Predictably, ongoing global warming may lead to the degradation of black soils in the Songnen Plain, as well as in other regions. Our results will enrich geological knowledge of black soil formation and future evolutionary trends.
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LU Cunjin,CHAI Jincheng,XU Jinpeng,LI Pu,BIAN Kai
2025,99(1):272-283, DOI: 10.1111/1755-6724.15266
Abstract:
The water conductivity of karst collapsed column is affected by multiple factors such as the characteristics of its own column filling, structure and mining disturbance. As a structural water-conducting channel, fault usually plays a controlling role in hydrogeological structure. During the process of mine water hazard prevention and control, it was discovered that the lithology composition, compaction and cementation degree and water physical properties of karst collapsed column fillings were all non-conducting water, but due to the influence of combined development faults, some exploration drill holes showed concentrated water outflow. Based on this, the scientific hypothesis was proposed that fault cutting leads to water conduction in karst collapsed columns. The study comprehensively used methods like chronology, exploration data analysis, and hydrochemical testing to analyze the chronological relationship between faults and karst collapsed columns, their spatial relationship, outlet point distribution and water chemical properties, and the impact of faults on the water-conductivity of karst collapsed columns, which proved the effect of fault cutting on changing water conductivity of karst collapsed column. The research showed that later fault cutting through karst collapsed columns turned the originally non-conductive karst collapsed columns into water-conductive collapsed columns at the fault plane, creating a longitudinally connected water-conducting channel. A new model of fault cutting karst collapsed column to change the original water conductivity of karst collapsed column was proposed. The research results can provide a theoretical basis for the prediction of the water conductivity of the karst collapsed column. According to whether the karst collapsed column was cut by the fault, it was predicted theoretically, so as to determine the key areas of water conductivity detection and prevention and control, and has broad application prospects under the background of source control of mine water disaster.
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XIAO Yidong,QI Shengwen,GUO Songfeng,ZHANG Shishu,WANG Zan,GONG Fengqiang
2025,99(1):284-295, DOI: 10.1111/1755-6724.15267
Abstract:
As one of the most serious geological disasters in deep underground engineering, rockburst has caused a large number of casualties. However, because of the complex relationship between the inducing factors and rockburst intensity, the problem of rockburst intensity prediction has not been well solved until now. In this study.
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2025,99(1):296-296, DOI:
Abstract:
2025年第99卷第1期
2025年第99卷第1期
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青藏高原东北缘祁连–海原断裂带中段金强河断裂晚第四纪滑动行为
梁淑敏, 郑文俊, 陈干, 张培震, 张冬丽, 毕海芸, 杨雪, 张逸鹏, 段磊, 卢本添
Abstract:
祁连–海原断裂带控制着青藏高原东北缘地区的强震活动。在其中段的金强河断裂是天祝地震空区一条关键的活动断裂,但目前对该断裂的滑动行为认识不足。本文针对沿金强河断裂的水平位移分布,利用WorldView-2立体像对和无人机摄影测量数据,提取断裂沿线高精度的DEM数据,并进行精细的构造地貌解译和水平位错测量。通过断错地貌标志的测量,得到135个位错量和8个位错丛集。同时,利用放射性碳测年方法构建4个典型点断错河流阶地的地貌单元年龄序列,从而通过位错与年龄的关系将位错丛集和地貌单元年龄序列关联起来,并获得金强河断裂全新世的滑动速率在 ~4–12 ka期间为4.8–5.6 mm/a ,在 ~4 ka以来为2.9–4.7 mm/a。最近的三次地震事件的复发间隔约为1000年,形成了一个地震活跃期,揭示着近1500年来缺乏破裂记录的金强河断裂可能具有较高的地震危险性。
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南阿尔金早古生代构造演化:来自茫崖花岗质岩石地球化学、锆石U-Pb和Lu-Hf同位素的证据
徐楠, 吴才来, 刘和武, 宋帅兵, 张贵生, 郑坤, 高栋
Abstract:
南阿尔金造山带是中国西南典型的俯冲造山带,由南阿尔金蛇绿混杂岩带和南阿尔金陆块组成,位于柴达木板块北侧。造山带出露大量早古生代花岗质岩石,但是这些岩石的成因及构造环境尚未查明。本文对茫崖花岗质岩石进行岩石学和地球化学研究,确定岩浆活动的期次,并深入了解南阿尔金造山带的构造演化过程。茫崖花岗质岩浆活动可以划分为三期:494-458Ma,450-436Ma和416-404Ma。根据这些岩石的成岩构造环境,我们认为第一期岩浆活动与南阿尔金洋的北向俯冲有关,形成了大量高价钙碱性、I型花岗质岩石。南阿尔金洋闭合后,柴达木板块开始向南阿尔金陆块碰撞,行了了一系列高价钙碱性、I型花岗岩。第三期岩浆活动形成了大量的造山后A-型花岗岩。
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超微量(80nanomole)硫化物硫酸盐硫同位素的EA-IRMS测试
Abstract:
常规EA-IRMS进行硫同位素测试时需硫量大于2 μmol,这限制了该技术在测试含硫量低的样品时的使用。如此大的需硫量是因为He载气携带样品气体在经过元素分析仪(EA)时的流速为~100 mL/min,而气体同位素质谱仪仅允许气体以低流速进入,所以99.7%的混合气体会通过连续流接口排出,以保证混合气体以~0.3 mL/min的流速通过连续流接口。因此,大部分的样品气体会被浪费,样品的利用率仅有0.3%。在本研究中,我们将自主研发的冷冻富集、分离与纯化系统与EA-IRMS联用测试了六种标准物质的硫同位素,并检测该系统的表现。实验结果表明,使用本研究中改进的方法进行硫化物和硫酸盐标准物质的硫同位素测试,得到的硫同位素结果与常规方法一致,即需硫量仅80 nmol即可得到硫同位素测试结果精度 ±0.24‰–±0.76‰ (1σ),与使用吸附柱进行硫同位素测试的方法获得的精度相似。所以,改进后的EA-IRMS可以实现超微量硫化物、硫酸盐的硫同位素测试。此外,本方法也可应用至需样量低至100 nmol的碳、氮和氧同位素分析测试工作中。
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粤北早古生代强过铝质花岗岩及其共生岩石的岩石成因及对广西运动的指示意义:来自元素和Sr-Nd-Hf同位素的制约
Abstract:
本文系统报道了粤北地区早古生代强过铝质花岗岩及其共生岩石的锆石U-Pb年代学、主、微量元素及Sr-Nd-Hf同位素组成,探讨其源区特征、岩石成因及构造意义。青州花岗闪长岩为弱-强过铝质,A/CNK= 1.05–1.96。它们具有相对高的初始Sr同位素组成ISr= 0.7087– 0.7148和低的εNd(t)值(-11.2 – -10.1),以及变化的εHf(t)值-13.4– +4.81。与之不同,大帽山花岗闪长岩为准铝质(A/CNK= 0.79– 0.94),ISr= 0.7083– 0.7110, εNd(t)= -7.92– -5.28和εHf(t)= -8.69– -2.06。高寿石英闪长岩为准铝-强过铝质(0.87– 1.24),ISr值和εNd(t)值分别为0.7104– 0.7111和-9.64– -8.63。元素和Sr-Nd-Hf同位素组成结果显示,青州、大帽山和高寿花岗质侵入岩主要分别源自变杂砂岩、英安质岩和角闪石岩的部分熔融。结合前人的研究成果,这些强过铝质花岗岩形成于同造山环境。本文尝试提出一种关于华南早古生代花岗岩的岩石成因及区域地壳重组的新思路。而广西运动动力机制的揭示需要更加广阔的视野和更加丰富的地质证据。
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Birendra P. Singh, Kapesa Lokho, Naval Kishore, Nancy Virmani
2014,88(2):380-393, DOI:
Abstract:
A new locality bearing ichnofossils of the Cruziana Assemblage Zone-III from the Mussoorie syncline, Lesser Himalaya, is located in rocks of Member-B of the Dhaulagiri Formation, Tal Group, exposed along the Maldewta-Chhimoli fresh road cut section. The site yielded ichnofossils Bergaueria perata, Cochlichnus anguineus, ?Diplocraterion isp., Dimorphichnus obliquus, diplichnitiform Cruziana bonariensis, Diplichnites gouldi, Glockeria isp., Helminthopsis isp., Monomorphichnus lineatus, Phycodes palmatum, Palaeophycus striatus, Planolites beverleyensis, Planolites montanus, Treptichnus cf. T. pedum, scratch marks and an undetermined worm impression. An Early Cambrian age (Cambrian Series 2) is assigned to the ichnofossil-bearing strata based on the stratigraphic position between the Drepanuroides and Palaeoolenus trilobite zones. A revised Cambrian ichnofossil zonation is presented for the Tal Group of the Mussoorie syncline. Together with their occurrence on rippled surfaces, and the lateral displacement of some trackways (due to current action), a sub-aqueous shallow-marine depositional setting is proposed for the rocks of Member-B.
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ZHU Song, WU Zhenhan, ZHAO Xitao, LI Jianping, WANG Hua
2012,86(1):266-283, DOI:
Abstract:
Many moraines formed between Daduka and Chibai in the Tsangpo River valley since Middle Pleistocene. A prominent set of lacustrine and alluvial terraces on the valley margin along both the Tsangpo and Nyang Rivers formed during Quaternary glacial epoch demonstrate lakes were created by damming of the river. Research was conducted on the geological environment, contained sediments, spatial distribution, timing, and formation and destruction of these paleolakes. The lacustrine sediments 14C (10537±268 aBP at Linzhi Brick and Tile Factory, 22510±580 aBP and 13925±204 aBP at Bengga, 21096±1466 aBP at Yusong) and a series of ESR (electron spin resonance) ages at Linzhi town and previous data by other experts, paleolakes persisted for 691~505 kaBP middle Pleistocene ice age, 75–40 kaBP the early stage of last glacier, 27–8 kaBP Last Glacier Maximum (LGM), existence time of lakes gradually shorten represents glacial scale and dam moraine supply potential gradually cut down, paleolakes and dam scale also gradually diminished. This article calculated the average lacustrine sedimentary rate of Gega paleolake in LGM was 12.5 mm/a, demonstrates Mount Namjagbarwa uplifted strongly at the same time, the sedimentary rate of Gega paleolake is more larger than that of enclosed lakes of plateau inland shows the climatic variation of Mount Namjagbarwa is more larger and plateau margin uplifted more quicker than plateau inland. This article analyzed formation and decay cause about the Zelunglung glacier on the west flank of Mount Namjagbarwa got into the Tsangpo River valley and blocked it for tectonic and climatic factors. There is a site of blocking the valley from Gega to Chibai. This article according to moraines and lacustrine sediments yielded paleolakes scale: the lowest lake base altitude 2850 m, the highest lake surface altitude 3585 m, 3240 m and 3180 m, area 2885 km2, 820 km2 and 810 km2, lake maximum depth of 735 m, 390 m and 330 m. We disclose the reason that previous experts discovered there were different age moraines dividing line of altitude 3180 m at the entrance of the Tsangpo Grand Canyon is dammed lake erosive decay under altitude 3180 m moraines in the last glacier era covering moraines in the early ice age of late Pleistocene, top 3180 m in the last glacier moraine remained because ancient dammed lakes didn’t erode it under 3180 m moraines in the early ice age of late Pleistocene exposed. The reason of the top elevation 3585 m moraines in the middle Pleistocene ice age likes that of altitude 3180 m. There were three times dammed lakes by glacier blocking the Tsangpo River during Quaternary glacial period. During other glacial and interglacial period the Zelunglung glacier often extended the valley but moraine supplemental speed of the dam was smaller than that of fluvial erosion and moraine movement, dam quickly disappeared and didn’t form stable lake.
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WANG Runfu, XU Shichao, WU Xiaochun, LI Chun, WANG Suozhu
2013,87(5):1185-1197, DOI:
Abstract:
Shansisuchus shansisuchus Young, 1964 was restudied on the basis of a new specimen. Some anatomical features that were either briefly or not described at all in the original study were detailed. The new specimen not only provides further information on the skull anatomy and the vertebral column but also expands the range of the geographical distribution of the taxon. With new information, the diagnosis of S. shansisuchus was emended and its phylogenetic relationships were further analyzed. S. shansisuchus differs from other archosauriforms primarily in the presence of a large subnarial fenestra anterior to the antorbital fenestra, tongue-in-groove articulations between the ascending process of the premaxilla and nasal and between the premaxilla and maxilla, a tall and posterodorsally directed ascending process of the maxilla, a knee-shaped process of the postorbital projecting into the orbit, a broad descending process of squamosal distally well forked and a large, deeply bow-shaped intercentrum tightly anchoring/capping the sharp ventral edges of two neighboring centra together in cervical and at least first eight dorsal vertebrae. With additional information derived from the new specimen, the phylogenetic relationships of S. shansisuchus were reanalyzed; it is closely related to Erythrosuchus-Vjushkovia clade.
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CHEN Lan1, 2, 3, * , YI Haisheng4, 5, TSAI Louis Loung-Yie2, XU Guiwen1, DA Xuejuan1, LIN Andrew Tien-Shun3
2013,87(2):540-554, DOI:
Abstract:
The Biluo Co and Amdo 114 station, northern Tibet, cropping out the Early Toarcian and Middle-Late Tithonian (Jurassic) organic-rich black shales, have been a focus to petroleum geologists in discussing their oil-producing potential. This paper first reports the trace elements and rare earth elements to discuss the paleoenvironments, redox conditions and sedimentary mechanisms of those black shales. Both sections exhibit variation in trace element abundances with concentrations <0.1 ppm to 760 ppm, mostly enriched in V, Cr, Ni, Cu, Zn, Mo, Ba and U. Element ratios of Ni/Co, V/Cr, U/Th and V/(V+Ni) plus U were used to identify redox conditions. The shale-normalized rare earth element (REE) patterns are characterized by the flat-shale type with instable Ce anomalies and very weekly positive Eu anomalies. Positive Ceanom values are significant with values varying between –0.064 and 0.029 in Biluo Co, which may be interpreted as release of REE and input of riverine terrestrial matter with rich Ce (resulting in pH change) during the anoxic conditions. In the middle parts of Amdo 114 station, distinct negative Ceanom values are observed (?0.238 to ?0.111) and associated surface water warming were interpreted as being related to a major sea level rise. In contrast, the formation of the black shales in the lower and upper part of the studied succession took place during a cooler (Ceanom values >–0.10), lower surface water productivity, and lower sea-level stage. Thus, we emphasize the role of different factors that control the formation of local and regional black shales. The most important factors are sea-level fluctuations and increasing productivity.
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2014,88(1):260-275, DOI:
Abstract:
This paper reviews the current progress and problems in the study of microbialites and microbial carbonates. Microbialites and microbial carbonates, formed during growth of microbes by their calcification and binding of detrital sediment, have recently become one of the most popular geological topics. They occur throughout the entire geological history, and bear important theoretical and economic significances due to their complex structures and formative processes. Microbialites are in place benthic microbial buildups, whereas microbial carbonates can be classified into two categories: stabilized microbial carbonates (i.e., carbonate microbialites, such as stromatolites and thrombolites) and mobilized microbial carbonates (i.e., microbial carbonate grains, such as oncoids and microbial lumps). Various texture, structures, and morphologies of microbialites and microbial carbonates hamper the systematic description and classification. Moreover, complex calcification pathways and diagenetic modifications further obscure the origin of some microbialites and microbial carbonates. Recent findings of abundant sponge spicules in previously identified “microbialites” challenge the traditional views about the origins of these “microbialites” and their implications to reef evolution. Microbialites and microbial carbonates did not always flourish in the aftermath of extinction events, which, together with other evidences, suggests that they are affected not only by metazoans but also by other geological factors. Their growth, development, and demise are also closely related to sea-level changes, due to their dependence on water depth, clarity, nutrient, and sunlight. Detailed studies on microbialites and microbial carbonates throughout geological history would certainly help understand causes and effects of major geological events as well as the co-evolution of life and environment.
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SHEN Caizhi, Lü Junchang, LIU Sizhao, Martin KUNDRáT, Stephen L. BRUSATTE, GAO Hailong
2017,91(3):763-780, DOI:
Abstract:
A new troodontid dinosaur, Daliansaurus liaoningensis gen. et sp. nov., is erected based on a nearly complete specimen from the Lower Cretaceous Yixian Formation of Beipiao City, Liaoning Province, China. This well preserved skeleton provides important new details of the anatomy for Liaoning troodontids, and gives new insight into their phylogenetic relationships and evolution. Daliansaurus is distinguished from other troodontids by an enlarged ungual on pedal digit IV, which is approximately the same size as the sickle-shaped second ungual, and is differentiated from other Liaoning troodontids by a number of characters of the skull, manus, pelvis, and hindlimb. A phylogenetic analysis recovers Daliansaurus within a subclade of Liaoning troodontids that also includes Sinovenator, Sinusonasus, and Mei. We erect a name for this group—Sinovenatorinae—and argue that it reflects a localized radiation of small-bodied troodontids in the Early Cretaceous of eastern Asia, similar to previously recognized radiations of Liaoning dromaeosaurids and avialans. As more Liaoning theropods are discovered, it is becoming apparent that small, feathered paravians were particularly diverse during the Early Cretaceous, and future work is needed to clarify how this diversity arose, which species coexisted, and how these numerous species partitioned niches.
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2014,88(z2):597-598, DOI:
Abstract:
Please refer to the attachment(s) for more details
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DU Chunguo, WANG Jianjun, ZHANG Jun, WANG Ping, XUE Mei, ZHOU Huayao
2014,88(3):865-877, DOI:
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On the basis of field observations, microscopic thin-sections and laboratory data analysis of ten faults in Xuanhan County area, northeastern Sichuan Basin, central China, the internal and megascopic structures and tectonite development characteristics are mainly controlled by the geomechanical quality in brittle formation of the Changxing-Feixianguan Formation. The fluid transportation performance difference between the faults formed by different geomechanics or different structural parts of the same fault are controlled by the megascopic structure and tectonite development characteristics. For instance, the extension fault structure consists of a tectonite breccia zone and an extension fracture zone. Good fluid transportation performance zones are the extension fracture zone adjacent to the tectonite breccia zone and the breccia zone formed at the early evolutionary stage. The typical compression fault structure consists of a boulder-clay zone or zones of grinding gravel rock, compression foliation, tectonite lens, and dense fracture development. The dense fracture development zone is the best fluid transporting area at a certain scale of the compression fault, and then the lens, grinding gravel rock zone and compression foliation zones are the worst areas for hydrocarbon migration. The typical tensor-shear fault with a certain scale can be divided into boulder-clay or grinding gravel rock zones of the fault, as well as a pinnate fractures zone and a derivative fractures zone. The grinding gravel rock zone is the worst one for fluid transportation. Because of the fracture mesh connectivity and better penetration ability, the pinnate fractures zone provides the dominant pathway for hydrocarbon vertical migration along the tensor-shear fault.
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MA Shengming, ZHU Lixin, LIU Chongmin, XI Mingjie, TANG Shixin
2013,87(3):843-857, DOI:
Abstract:
This paper discusses the enrichment and depletion regularities for porphyry copper-molybdenum ore deposits in different regions and varied deposit genetic types in the same area, taking three porphyry copper-molybdenum ore deposits (i.e., the Chengmenshan in Jiangxi, Wunugetushan in Inner Mongolia, Baishantang in Gansu) and two copper deposits in Gansu Province (the Huitongshan skarn deposit and Gongpoquan composite deposit) as case studies. The results show that porphyry Cu-Mo deposits or skarn copper deposits include both enrichment of the ore-forming elements and associated elements, and depletion of some lithophile dispersed elements, rare earth elements (REE) and some major elements. And the depleted elements vary with deposits, having generality and their own features. On a deposit scale, the positive anomalies of enriched elements and negative anomalies of depleted elements follow in a sequence to comprise regular anomaly models of spatial structures. The exploration in the Tongchang deposit in Jiangxi and Huitongshan deposit in Gansu suggests that anomaly models play a key role in the identification of mineral occurrences and deposits compared to one single enriched element anomaly. And the anomaly models exert a critical effect on the optimization of prospecting targets and their potential evaluation.
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2010,84(2):241-246, DOI:
Abstract:
A new boreopterid pterosaur: Zhenyuanopterus longirostris gen. et sp. nov. from the Yixian Formation of western Liaoning is erected, based on the complete skeleton with a skull and lower jaws preserved. It is characterized by: a large boreopterid pterosaur with a high number of teeth, where the anterior teeth are much larger than posterior ones; the length of the dorsal + sacral vertebrae is nearly half the length of the skull; ratio of the length of the humerus to metacarpal IV is approximately 91% and the, humerus, femur and third wing phalanx are all equal in length and the feet are specially small. It represents the largest boroepterid pterosaur discovered from western Liaoning and its surrounding areas so far
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WANG Sufen, ZHANG Tingshan, ZHOU Jixian, HU Yu
2017,91(1):320-340, DOI:
Abstract:
The distribution characteristics of the oil-water contact are the basis for the reservoir exploration and development and reserves evaluation. The reservoir with a tilted oil-water contact has a unique formation mechanism, and the understanding of its distribution and formation mechanism will directly affect the evaluations for the reservoir type, well deployment, selection of well pattern and type, determination of test section, and reserves evaluation. Based on the analysis of reservoir characteristics, petrophysical properties and geological structure in 40 reservoirs worldwide with tilted oil-water contacts, the progress of the research on the formation mechanisms of titled oil-water contacts is summarized in terms of the hydrodynamic conditions, reservoir heterogeneity, neotectonic movement and oil-gas exploitation. According to the formation mechanism of tilted oil-water contacts and the needs of exploration research, different aspects of research methods are summarized and classified, such as the calculation of equipotential surfaces for oil and water in the formation, analysis of formation pressure and analysis of reservoir physical properties and so on. Based upon statistical analysis, it is suggested that the degree of the inclination of the oil-water contact be divided based on the dip of oil-water contact (DipTOWC). The tilted oil-water contact is divided into three categories: large dip (DipTOWC≥55 m/km), medium dip (4 m/km≤DipTOWC<55 m/km), and small dip (DipTOWC<4 m/km). The classification and evaluation method can be combined with structure amplitude and reservoir property. The formation mechanism of domestic and international reservoirs with tilted oil-water contacts are summarized in this paper, which have important significance in guiding the exploration and development of the oilfield with tilted oil-water contacts, reserves evaluation, and well deployment.
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Mahboobeh JAMSHIDI BADR, Fariborz MASOUDI, Alan S. COLLINS, Ali SORBI
2012,86(1):48-64, DOI:
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The Soursat metamorphic complex (SMC) in northwestern Iran is part of the Sanandaj–Sirjan metamorphic belt. The complex is composed of different metamorphic and plutonic rocks, but is dominated by metapelites composed of garnet, staurolite, kyanite, fibrolite, cordierite, and andalusite. Porphyroblasts in schists have the same fabric, and three stages of schistosity are present. The internal schistosity (Sn) inclusion trails are also offset by conjugate sets of extensional schistosity (Sn+1) and a second (Sn+2) that crenulates (Sn+1). Polyphase metamorphisms are present in the complex. Garnet, staurolite, kyanite, and fibrolite assemblage preserves conditions during the M1 metamorphic event. This assemblage yields a P–t estimate of 645±11°C and 6.5±0.5 kbar. Other samples of the central part of SMC contain cordierite and andalusite (M2) overgrowth that yields a P–t estimate of 532±33°C and 2.1±1.1 kbar.
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ZHENG Yadong, ZHANG Qing, HOU Quanlin
2015,89(4):1133-1152, DOI:
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The essential difference in the formation of conjugate shear zones in brittle and ductile deformation is that the intersection angle between brittle conjugate faults in the contractional quadrants is acute (usually ~60°) whereas the angle between conjugate ductile shear zones is obtuse (usually 110°). The Mohr-Coulomb failure criterion, an experimentally validated empirical relationship, is commonly applied for interpreting the stress directions based on the orientation of the brittle shear fractures. However, the Mohr-Coulomb failure criterion fails to explain the formation of the low-angle normal fault, high-angle reverse fault, and the conjugate strike-slip fault with an obtuse angle in the σ1 direction. Although it is ten years since the Maximum-Effective-Moment (MEM) criterion was first proposed, and increasingly solid evidence in support of it has been obtained from both observed examples in nature and laboratory experiments, it is not yet a commonly accepted model to use to interpret these anti-Mohr-Coulomb features that are widely observed in the natural world. The deformational behavior of rock depends on its intrinsic mechanical properties and external factors such as applied stresses, strain rates, and temperature conditions related to crustal depths. The occurrence of conjugate shear features with obtuse angles of ~110° in the contractional direction on different scales and at different crustal levels are consistent with the prediction of the MEM criterion, therefore ~110° is a reliable indicator for deformation localization that occurred at medium-low strain rates at any crustal levels. Since the strain–rate is variable through time in nature, brittle, ductile, and plastic features may appear within the same rock.
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CHI Guoxiang1, *, CHU Haixia1, Ryan SCOTT1, CHOU I-Ming2
2014,88(4):1169-1182, DOI:
Abstract:
Raman peaks of various hydrates in the H2O-NaCl-CaCl2 system have been previously identified, but a quantitative relationship between the Raman peaks and XNaCl (i.e., NaCl/(NaCl+CaCl2)) has not been established, mainly due to the difficulty to freeze the solutions. This problem was solved by adding alumina powder to the solutions to facilitate nucleation of crystals. Cryogenic (-185oC) Raman spectroscopic studies of alumina-spiced solutions indicate that XNaCl is linearly correlated with the total peak area fraction of hydrohalite. Capsules of solutions made from silica capillary were prepared to simulate fluid inclusions. Most of these artificial fluid inclusions could not be totally frozen even at temperatures as low as -185oC, and the total peak area fraction of hydrohalite is not correlated linearly with XNaCl. However, the degree of deviation (DXNaCl) from the linear correlation established earlier is related to the amount of residual solution, which is reflected by the ratio (r) of the baseline “bump” area, resulting from the interstitial unfrozen brine near 3435 cm-1, and the total hydrate peak area between 3350 and 3600 cm-1. A linear correlation between DXNaCl and r is established to estimate XNaCl from cryogenic Raman spectroscopic analysis for fluid inclusions.
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LI Jianjun, Martin G. LOCKLEY, ZHANG Yuguang, HU Songmei, MATSUKAWA Masaki, BAI Zhiqiang
2012,86(1):1-10, DOI:
Abstract:
A large track site with multiple, well-preserved trackways of an Early Jurassic quadrupedal ornithischian dinosaur is the first report of Moyenisauripus-like trackways from Asia, herein named Shenmuichnus youngteilhardorum. The tracks occur in a clastic fluvial sequence in the Fuxian Formation in Shenmu County, Shaanxi Province, which is in the same general region as the discovery site of Sinoichnites,the first dinosaur track reported from China. Based on size and morphology, it is likely that Sinoichnites, which is now lost, also represents an ornithischian. The Shenmuichnus youngteilhardorum trackways show two modes of preservation: the first representing deeper tracks, with sediment rims, results in Deltapodus-like tracks, with indistinct pes digit traces and sub-circular manus traces, the second produces Moyenosauripus-like tracks, with clear tridactyl and pentadactyl digit traces in the pes and manus respectively. Thus the Shenmu trackways play a key role in resolving globally significant ichnotaxonomic problems surrounding the nomenclature of Sinoichnites, Moyenosauripus, Deltapodus and other named (Ravatichnus) and unnamed trackways from Asia, Africa and Europe. In addition they shed important light on the paleogeographical and paleoecological distribution of quadrupedal ornithischians in the Early Mesozoic. The track site has been the focus of a major excavation to transfer the trackways from their original remote location to the new Shenmu Museum, in Shenmu City. Other tracksites in the area which reveal Anomoepus, Grallator and the Deltapodus morphotype, together with Shenmuichnus and plant fossil evidence, suggest an Early Jurassic age for the tracksite.
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DU Jianjun, LI Dunpeng, WANG Yufang, MA Yinsheng
2017,91(1):76-92, DOI:
Abstract:
The Weihe Graben is not only an important Cenozoic fault basin in China but also a significant active seismic zone. The Huashan piedmont fault is an important active fault on the southeast side of the Weihe Graben and has been highly active since the Cenozoic. The well–known Great Huaxian County Earthquake of 1556 occurred on the Huashan piedmont fault. This earthquake, which claimed the lives of approximately 830000 people, is one of the few large earthquakes known to have occurred on a high–angle normal fault. The Huashan piedmont fault is a typical active normal fault that can be used to study tectonic activity and the associated hazards. In this study, the types and characteristics of late Quaternary deformation along this fault are discussed from geological investigations, historical research and comprehensive analysis. On the basis of its characteristics and activity, the fault can be divided into three sections, namely eastern, central and western. The eastern and western sections display normal slip. Intense deformation has occurred along the two sections during the Quaternary; however, no deformation has occurred during the Holocene. The central section has experienced significant high–angle normal fault activity during the Quaternary, including the Holocene. Holocene alluvial fans and loess cut by the fault have been identified at the mouths of many stream valleys of the Huashan Mountains along the central section of the Huashan piedmont fault zone. Of the three sections of the Huashan piedmont fault, the central section is the most active and was very active during the late Quaternary. The rate of normal dip–slip was 1.67–2.71±0.11 mm/a in the Holocene and 0.61±0.15 mm/a during the Mid–Late Pleistocene. As is typical of normal faults, the late Quaternary activity of the Huashan piedmont fault has produced a set of disasters, which include frequent earthquakes, collapses, landslides, mudslides and ground fissures. Ground fissures mainly occur on the hanging–wall of the Huashan piedmont fault, with landslides, collapses and mudslides occurring on the footwall.
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2015,89(3):715-725, DOI:
Abstract:
Re-equilibration of fluid inclusions in crystals takes place by loss or gain of solvents and solutes from fluid inclusions and by changes in their volumes. Volume change of fluid inclusions are primarily dictated by elastic properties and available slip planes of host crystals. In the present study, the phase-behavior of fluids entrapped in co-precipitated calcite and barite is studied. While calcite contains only biphase fluid inclusions, barite has predominantly monophase fluid inclusions. Fluid inclusion petrography, microthermometry and leachate analysis are used to establish the nature of entrapped fluids and entrapment temperature is substantiated through independent sulfur isotope geothermometry using coexisting barite and pyrite. Phase transitions in the monophase fluid inclusions in barite are explained in terms of over-pressuring of fluids in these fluid inclusions relative to fluids entrapped in calcite owing to the low bulk modulus of barite.
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2021,95(3):1056-1056, DOI: 10.1111/1755-6724.14310
Abstract:
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ZHANG Gang, WANG Xuben, FANG Hui, GUO Ziming, ZHANG Zhaobin, LUO Wei, CAI Xuelin, LI Jun, LI Zhong, WU Xing
2015,89(2):531-541, DOI:
Abstract:
The Panxi region is located in the frontal zone of positive squeezing subduction and side squeezing shearing between the Indian plate and the Eurasian plate. The long-period magnetotelluric (LMT) and broadband magnetotelluric (MT) techniques are both used to study the deep electrical conductivity structure in this region; magnetic and gravity surveys are also performed along the profile. According to the 2-D resistivity model along the Yanyuan-Yongshan profile, a high-conductivity layer (HCL) exists widely in the crust, and a high-resistivity block (HRB) exists widely in the upper mantle in general, as seen by the fact that a large HCL exists from the western Jinpingshan tectonic zone to the eastern Mabian tectonic zone in the crust, while the HRB found in the Panxi tectonic zone is of abnormally high resistivity in that background compared to both sides of Panxi tectonic zone. In addition, the gravity and magnetic field anomalies are of high value. Combined with geological data, the results indicate that there probably exists basic or ultrabasic rock with a large thickness in the lithosphere in the Panxi axial region, which indicates that fracture activity once occurred in the lithosphere. As a result, we can infer that the high-resistivity zone in the Panxi lithosphere is the eruption channel for Permian Emeishan basalt and the accumulation channel for basic and ultrabasic rock. The seismic sources along the profile are counted according to seismic record data. The results indicate that the most violent earthquake sources are located at the binding site of the HRB and the HCL, where the tectonic activity zone is generally acknowledged to be; however, the earthquakes occurring in the HCL are not so violent, which reflects the fact that the HCL is a plastic layer, and the fracture threshold of a plastic layer is low generally, making high stress difficult to accumulate but easy to release in the layer. As a result, a higher number of smaller earthquakes occurred in the HCL at Daliangshan tectonic zone, and violent earthquakes occurred at the binding site of high- and low-resistivity blocks at the Panxi tectonic zone.