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Elemental Compositions of Clinopyroxenes from Southern Okinawa Trough Basalt:Implications for Magmatism and Structural Environment in an Initial Back-Arc Basin

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Journal of Ocean University of China 2024年第3期23卷 643-653页

作者： GUO Kun ZHAI Shikui FAN Di ZHANG Xia ZHANG Yu ZHU Zhimin Laoshan laboratory Qingdao 266237China key laboratory of submarine geosciences and Prospecting Techniques Ministry of EducationCollege of Marine GeosciencesOcean University of ChinaQingdao 266100China key laboratory of submarine geosciences&Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China

The major and trace elemental compositions of clinopyroxene from basalt were used to characterize the nature of the primitive magma and structural environment beneath the southern Okinawa Trough(SOT),which is an initial back-arc basin at a continental *** clinopyroxenes in the basalt were augite with variable Mg^(#)contents(73.37-78.22).The regular variations in major oxide contents(i.e.,CaO,FeO,TiO_(2),and Cr)with decreasing Mg#implied that the clinopyroxenes evolved from being enriched in Mg,Ca,and Cr to being enriched in Fe and *** clinopyroxenes had relatively low rare earth element concentrations(7.51×10^(-6) to 12.68×10^(-6))and negative Eu anomalies(δEu=0.67-0.95).The Kd_(cpx) values of clinopyroxenes(0.2-0.26),which were used to examine whether the clinopyroxene was equilibrated with its host basalt,demonstrate that these clinopyroxene phenocrysts were not captured crystals but were instead produced by crystallization differentiation of the *** calculated clinopyroxene crystallization temperatures showed a narrow range of 990-1061℃,and their crystallization pressures ranged from 2.0 to 3.2 *** geochemistry features of these clinopyroxenes indicated that the parent magma belonged to the subalkaline tholeiitic magma series and suggested that the magma experienced crystallization differentiation of olivine,plagioclase,and clinopyroxene,where the crystallization of plagioclase occurred earlier than that of *** with geophysical data,this research on primitive magma and its crystallization differentiation from clinopyroxene indicates that the SOT is in the stage of‘seafloor spreading’and that basaltic rocks produced from tholeiitic magma represent the generation of oceanic crust.

关键词： trace elements clinopyroxenes southern Okinawa Trough seafloor spreading back-arc basin

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Microearthquake reveals the lithospheric structure at midocean ridges and oceanic transform faults

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Journal of Oceanology and Limnology 2024年第3期42卷 697-700页

作者： Zhiteng YU Jiabiao LI Weiwei DING key laboratory of submarine geosciences&Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China

Mid-ocean ridge and oceanic transforms are among the most prominent features on the seafloor surface and are crucial for understanding seafloor spreading and plate tectonic dynamics,but the deep structure of the oceanic lithosphere remains poorly *** large number of microearthquakes occurring along ridges and transforms provide valuable information for gaining an indepth view of the underlying detailed seismic structures,contributing to understanding geodynamic processes within the oceanic *** studies have indicated that the maximum depth of microseismicity is controlled by the 600-℃***,this perspective is being challenged due to increasing observations of deep earthquakes that far exceed this suggested isotherm along mid-ocean ridges and oceanic transform *** mechanisms have been proposed to explain these deep events,and we suggest that local geodynamic processes(e.g.,magma supply,mylonite shear zone,longlived faults,hydrothermal vents,etc.)likely play a more important role than previously thought.

关键词： microearthquake mid-ocean ridge oceanic transform fault oceanic lithosphere thermal structure earthquake location

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Auto-Detection Method Using Convolution Neural Network for Bottom-Simulating Reflectors

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Journal of Ocean University of China 2024年第3期23卷 683-694页

作者： XU Haowei XING Junhui YANG Boxue LIU Chuang key laboratory of submarine geosciences and Prospecting Techniques MOE and College of Marine GeosciencesOcean University of ChinaQingdao 266100China laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266071China

In studies on gas hydrate,bottom-simulating reflectors(BSR)are used to determine the potential hydrate-bearing sedimentary ***,BSR detection is performed manually by experienced ***,a method for implementing an auto-matic BSR detection process should be *** this study,we develop a novel architecture for BSR characterization using the convolutional neural network(CNN)*** propose the use of Stokes’transform(ST)to obtain a time-frequency spectrum for the input of *** fully uses the frequency content of the seismic data,and a part of the 3D seismic data collected from the Blake Ridge is utilized to train the *** seismic records with variable signal-to-noise ratios(SNR),as well as Blake Ridge seismic data,were used to validate the detection effect of the *** show that the CNN trained by this method exhibits excellent performance in noise-resistant testing and achieves an accuracy of more than 89% in field seismic data detection.

关键词： BSR CNN Stocks’transform gas hydrate Blake Ridge

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Inversion of Seabed Geotechnical Properties in the Arctic Chukchi Deep Sea Basin Based on Time Domain Adaptive Search Matching Algorithm

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Journal of Ocean University of China 2024年第4期23卷 933-942页

作者： AN Long XU Chong XING Junhui GONG Wei JIANG Xiaodian XU Haowei LIU Chuang YANG Boxue Jiangsu Automation Research Institute Lianyungang 222061China key laboratory of submarine geosciences and Prospecting Techniques MOE and College of Marine GeosciencesOcean University of ChinaQingdao 266100China laboratory for Marine Mineral Resources Qingdao Marine Science and Technology CenterQingdao 266071China

The chirp sub-bottom profiler,for its high resolution,easy accessibility and cost-effectiveness,has been widely used in acoustic *** this paper,the acoustic impedance and grain size compositions were obtained based on the chirp sub-bottom profiler data collected in the Chukchi Plateau area during the 11th Arctic Expedition of *** time-domain adaptive search matching algorithm was used and validated on our established theoretical *** misfit between the inversion result and the theoretical model is less than 0.067%.The grain size was calculated according to the empirical relationship between the acoustic impedance and the grain size of the *** average acoustic impedance of sub-seafloor strata is 2.5026×10^(6) kg(s m^(2))^(-1)and the average grain size(θvalue)of the seafloor surface sediment is 7.1498,indicating the predominant occurrence of very fine silt sediment in the study *** of the inversion results and the laboratory measurements of nearby borehole samples shows that they are in general agreement.

关键词： time domain adaptive search matching algorithm acoustic impedance inversion sedimentary grain size Arctic Ocean Chukchi Deep Sea Basin

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Theory and classification of mass extinction causation

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National Science Review 2024年第1期11卷 16-36页

作者： Thomas J.Algeo Jun Shen State key laboratory of Biogeology and Environmental Geology China University of Geosciences—Wuhan State key laboratory of Geological Processes and Mineral Resources China University of Geosciences—Wuhan Department of geosciences University of Cincinnati

Theory regarding the causation of mass extinctions is in need of systematization, which is the focus of this contribution. Every mass extinction has both an ultimate cause, i.e. the trigger that leads to various climato-environmental changes, and one or more proximate cause(s), i.e. the specific climato-environmental changes that result in elevated biotic mortality. With regard to ultimate causes, strong cases can be made that bolide(i.e. meteor) impacts, large igneous province(LIP) eruptions and bioevolutionary events have each triggered one or more of the Phanerozoic Big Five mass extinctions, and that tectono-oceanic changes have triggered some second-order extinction events. Apart from bolide impacts, other astronomical triggers(*** flares, gamma bursts and supernova explosions) remain entirely in the realm of speculation. With regard to proximate mechanisms, most extinctions are related to either carbon-release or carbon-burial processes, the former being associated with climatic warming, ocean acidification, reduced marine productivity and lower carbonate δ13C values, and the latter with climatic cooling, increased marine productivity and higher carbonate δ13C values. Environmental parameters such as marine redox conditions and terrestrial weathering intensity do not show consistent relationships with carbon-cycle *** this context, mass extinction causation can be usefully classified using a matrix of ultimate and proximate factors. Among the Big Five mass extinctions, the end-Cretaceous biocrisis is an example of a bolide-triggered carbon-release event, the end-Permian and end-Triassic biocrises are examples of LIP-triggered carbon-release events, and the Late Ordovician and Late Devonian biocrises are examples of bioevolution-triggered carbon-burial events. Whereas the bolide-impact and LIP-eruption mechanisms appear to invariably cause carbon release, bioevolutionary triggers can result in variable carbon-cycle changes, e.g. carbon burial durin

关键词： biocrisis ultimate cause proximate cause bolide large igneous province bioevolutionary event

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Microbes in mass extinction: an accomplice or a savior?

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National Science Review 2024年第1期11卷 12-15页

作者： Genming Luo Deng Liu Hao Yang State key laboratory of Geobiology and Environmental Geology China University of geosciences (Wuhan)

Microbes include various types of organisms that are invisible to the naked eye,e.g. bacteria, archaea and microeukaryotes. Although the precise number remains largely unknown, microbes are recognized as the unseen majority of our biosphere [1]. As a group of organisms classified by body size, microbes cover a considerable spectrum of metabolisms,

关键词： AFTERMATH

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Mass extinctions, their causes and consequences: an interview with Douglas *** and Shuzhong Shen

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National Science Review 2024年第1期11卷 66-70页

作者： Shucheng Xie State key laboratory of Biogeology and Environmental Geology China University of Geosciences at Wuhan

‘Mass extinctions’ have been a hot topic for several decades. What triggers a mass extinction? How does a mass extinction impact the evolution of life? How does our ecosystem recover after a mass extinction? These questions attracted the interest of both scientists and the public *** spoke to two renowned researchers in the field of mass extinctions: Prof. Douglas H. Erwin from the National Museum of Natural History of the USA, and Prof. Shuzhong Shen from Nanjing University, China.

关键词： Stratigraphy

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Microstructure Features and the Macroscopic Acoustic Behavior of Gassy Silt in the Yellow River Delta

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Journal of Ocean University of China 2024年第2期23卷 371-382页

作者： LIU Tao GUO Zhenqi ZHANG Yan WU Chen LIU Lele DENG Shenggui laboratory for Marine Geology Pilot National Laboratory for Marine Science and TechnologyQingdao 266061China Shandong Provincial key laboratory of Marine Environment and Geological Engineering Ocean University of ChinaQingdao 266100China College of Civil Engineering Anhui Jianzhu UniversityHefei 230601China The key laboratory of Gas Hydrate Ministry of Natural ResourcesQingdao Institute of Marine GeologyQingdao 266071China College of Marine geosciences Key Laboratory of Submarine Geosciences and ProspectingOcean University of ChinaQingdao 266100China

The morphological changes in isolated bubbles in gassy silt play a critical role in the microscopic structures between soil particles and bubbles and macroscopic physical *** on X-ray CT scanning experiments under various vertical loads(four levels),self-designed acoustic macro experiments,and a series of formula revisions to the macro-air-bearing silt sound-velocity prediction model,this paper discusses the macro-and micro-scale features of gassy silts from the Yellow River *** samples consisted of different proportions of silt from the Yellow River Delta and porous media,and they were used to form two types of aerosol silts with initial gas contents of 4.23%and 7.67%.The results show that the air bubble content and external load considerably affect the microstructural parameters and acoustic behavior of gassy silt in the Yellow River *** macroscopic sound velocity showed a linear positive correlation with vertical load and relation to microstructural parameters in varying manners and *** on the traditional Biot-Stoll acoustic model,the gas-phase medium coefficient was introduced for the proper calculation and prediction of the sound velocity of air-bearing *** errors of the overall prediction varied between 5.6%and 9.6%.

关键词： gassy silt vertical load microstructure parameters bubble vibration Biot-Stoll acoustic model

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Geochronology and Geochemistry of the Xingxingxia Triassic A-type Granites in Central Tianshan,NW China:Petrogenesis and Tectonic Implications

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Acta Geologica Sinica(English Edition) 2024年第2期98卷 337-351页

作者： HUANG Zengbao LI Xiyao ZHAO Hao LU Qing Geological Survey of Gansu Province Lanzhou 735000China key laboratory of submarine geosciences and Prospecting Techniques MOE and College of Marine GeosciencesOcean University of ChinaQingdaoShandong 266100China Research Institute of Petroleum Exploration and Development Shengli OilfieldSINOPECDongyingShandong 257000China

The Triassic granitoids in Central Tianshan play a key role in determining the petrogenesis and tectonic evolution on the southern margin of the Central Asian orogenic *** this study,we present SHRIMP zircon U-Pb ages,Hf isotopic and geochemical data on the Xingxingxia biotite granite,amazonite granite and granitic pegmatite in Central Tianshan,NW *** U-Pb dating yielded formation ages of 242 Ma for the biotite granite and 240 Ma for the amazonite *** granitoid rocks have high K_(2)O with low MgO and CaO *** are enriched in Nb,Ta,Hf and Y,while being depleted in Ba and Sr,showing flat HREE patterns and negative Eu *** have typical A-type granite geochemical signatures with high Ga/A_(1)(8–13)and TFeO/(TFeO+MgO)ratios,showing an A_(2) affinity for biotite granite and an A_(1) affinity for amazonite granite and granitic *** ε_(Hf)(t)values of the granitoids are 0.45–2.66,with Hf model ages of 0.99–1.17 *** suggests that these A-type granites originated from partial melting of the lower *** propose that Xingxingxia Triassic A-type granites formed under lithospheric extension from post-orogenic to anorogenic intraplate settings and NE-trending regional strike-slip fault-controlled magma emplacement in the upper crust.

关键词： Triassic A-type granite Xingxingxia Central Tianshan Central Asian orogenic belt

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First-Arrival Picking Method for Active Source Data with Ocean Bottom Seismometers Based on Spatial Waveform Variation Characteristics

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Journal of Ocean University of China 2024年第4期23卷 970-980页

作者： LIU Hongwei XING Lei ZHU Henghua ZHANG Jin ZHANG Jing LIU Huaishan key laboratory of submarine geosciences and Prospecting Techniques Ministry of EducationCollege of Marine GeosciencesOcean University of ChinaQingdao 266100China laboratory for Marine Mineral Resources Qingdao Marine Science and Technology CenterQingdao 266071China College of Underwater Acoustic Engineering Harbin Engineering UniversityHarbin 150001China Shandong Institute of Geological Survey Jinan 250014China

The precision and reliability of first-arrival picking are crucial for determining the accuracy of geological structure inversion using active source ocean bottom seismometer(OBS)refraction *** methods for first-arrival picking based on sample points are characterized by theoretical errors,especially in low-sampling-frequency OBS data because the travel time of seismic waves is not an integer multiple of the sampling *** this paper,a first-arrival picking method that utilizes the spatial waveform variation characteristics of active source OBS data is ***,the distribution law of theoretical error is examined;adjacent traces exhibit variation characteristics in their ***,a label cross-correlation superposition method for extracting highfrequency signals is presented to enhance the first-arrival picking *** from synthetic and field data verify that the proposed approach is robust,successfully overcomes the limitations of low sampling frequency,and achieves precise outcomes that are comparable with those of high-sampling-frequency data.

关键词： first-arrival picking spatial waveform variation label cross-correlation superposition method

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