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Stratigraphic Sequence and Sedimentary Systems in the Middle-Southern Continental Slope of the East China Sea from Seismic Reflection Data: Exploration Prospects of Gas Hydrate 被引量:1
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作者 LI Deyong CHEN Hongyan +3 位作者 XU Shujuan XING Junhui CHENG Honggang WANG Jinkai 《Journal of Ocean University of China》 SCIE CAS CSCD 2019年第6期1302-1316,共15页
Many evidences for gas hydrate bearing sediments had been found in the continental slope of the East China Sea,such as bottom simulating reflections(BSRs),undersea gas springs,pyrite associated with methane leakage,mu... Many evidences for gas hydrate bearing sediments had been found in the continental slope of the East China Sea,such as bottom simulating reflections(BSRs),undersea gas springs,pyrite associated with methane leakage,mud diapirs/mud volcanos,bottom-water methane anomalies and so on.In this study,six key stratigraphic interfaces including T_0(seafloor),T_1(LGM,23 kyr B.P.),T_2(2.58 Myr),T_3(5.33 Myr),T_4(11.02 Myr)and T_5(16.12 Myr)were identified,and then five third-order sequences of SQIII1 to SQIII5 were divided.However,T5 in southern continental slope is not found,which shows that the middle-northern Okinawa Trough had begun to rift in the early Miocene,earlier than the southern segment.Four system tracts including lowstand systems tract(LST),transgressive systems tract(TST),highstand systems tract(HST)and falling stage systems tract(FSST)are further divided.The marine erosion interface of 11.02 Myr and regressive unconformity interface of 23 kyr B.P.indicate two large-scale sea level drop events in the research area.Seven typical seismic facies identified in the continental slope are continental shelf-edge deltas,littoral fluvial-delta plains,incised channels or submarine canyons,slope fans,submarine fans or coastal sandbars,littoral-neritic finegrained sediments,mud volcanos and some other geological bodies respectively.The minimum water depth for hydrate occurrence in the Okinawa Trough is 630 m,and the thickness of gas hydrate stability zone in continental slope is between 0 and 590 m.The calculated bottom boundary of hydrate stability zone is slightly deeper than BSRs on the seismic sections.The re-depositional turbidite sand bodies,such as canyon channels,slope fans and submarine fans developed in Quaternary strata,are the predominant hydrate reservoirs.According to developing process,the dynamic accumulation of hydrate systems can be divided into three evolutionary stages including canyon erosion and hydrate stability zone migration stage,sediments destabilizing and methane leakage stage,and channel filling and hydrate re-occurrence stage. 展开更多
关键词 sequence STRATIGRAPHIC architecture SYSTEMS tract seismic FACIES DEPOSITIONAL system submarine CANYON gas HYDRATE stability zone HYDRATE dynamic accumulation continental slope of the east china sea
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Types,Characteristics and Significances of Migrating Pathways of Gas-bearing Fluids in the Shenhu Area,Northern Continental Slope of the South China Sea 被引量:19
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作者 SU Ming SHA Zhibin +7 位作者 ZHANG Cuimei WANG Hongbin WU Nengyou YANG Rui LIANG Jinqiang QIAO Shaohua CONG Xiaorong LIU Jie 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2017年第1期219-231,共13页
The first marine gas hydrate expedition in China has been conducted by Guangzhou Marine Geological Survey in the Shenhu Area, northern continental slope of the South China Sea. Previous study has analyzed the P-T cond... The first marine gas hydrate expedition in China has been conducted by Guangzhou Marine Geological Survey in the Shenhu Area, northern continental slope of the South China Sea. Previous study has analyzed the P-T conditions, geophysical anomalies and saturation calculations of these gas hydrates, but has not documented in detail the migration of gas-bearing fluids in the study area. Based on the interpretations of 2D/3D seismic data, this work identified two types of migration pathways for gas-bearing fluids in the Shenhu area, i.e., vertical and lateral pathways. The vertical pathways(largescale faults, gas chimneys and mud diapirs) presented as steep seismic reflection anomalies, which could be traced downward to the Eocene source rocks and may penetrate into the Late Miocene strata. The deeper gases/fluids might be allowed migrating into the shallower strata through these vertical conduits. However, the distributions showed distinct differences between these pathways. Large-scale faults developed only in the north and northeast of the Shenhu area, while in the drilling area gas chimneys were the sole vertical migration pathways. Since the Pliocene, normal faults, detachment faults and favorable sediments have constituted the lateral pathways in the Shenhu gas hydrate drilling area. Although these lateral pathways were connected with gas chimneys, they exerted different effects on hydrate formation and accumulation. Gas-bearing fluids migrated upward along gas chimneys might further migrate laterally because of the normal faults, thereby enlarging the range of the chimneys. Linking gas chimneys with the seafloor, the detachment faults might act as conduits for escaping gases/fluids. Re-deposited sediments developed at the early stage of the Quaternary were located within the gas hydrate stability zone, so hydrates would be enriched in these favorable sediments. Compared with the migration pathways(large-scale faults and mud diapirs) in the LW3-1 deep-sea oil/gas field, the migration efficiency of the vertical pathways(composed of gas chimneys) in the gas hydrate drilling area might be relatively low. Description and qualitative discrimination of migration pathways in the Shenhu gas hydrate drilling area are helpful to further understand the relationship between good-quality deep source rocks and shallow, mainly biogenicallyproduced, hydrates. As the main source rocks of the Baiyun sag, lacustrine mudstones in the Wenchang and Enping Formations may provide thermogenic methane. Gas chimneys with relatively low migration efficiency created the vertical pathways. Caused by the Dongsha tectonic movement, the release of overpressured fluids might reduce the vertical migration rates of the thermogenic methane. The thick bathyal/abyssal fine-grained sediments since the Late Miocene provided migration media with low permeability. These preconditions may cause carbon isotopic fractionation ofthermogenic methane during long-distance vertical migrations. Therefore, although geochemical analyses indicate that the methane forming gas hydrate in the Shenhu area was mainly produced biogenically, or was mixed methane primarily of microbial origin, thermogenic methane still contribute significantly. 展开更多
关键词 migrating pathways gas-bearing fluids gas hydrates Shenhu area northern continental slope of the South china sea
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The Relationship between Tectonic Subsidence and BSR of Upper Neogene in the Deep-Water Area of the Northern Continental Slope, South China Sea 被引量:6
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作者 YU Xinghe WANG Jianzhong +5 位作者 LI Shengli FANG Jingnan JIANG Longyan CONG Xiaorong LIANG Jinqiang SHA Zhibin 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2013年第3期804-818,共15页
BSR (Bottom Simulating Reflector) occurs widely in the strata since the late Miocene in the deep-water area of the northern continental slope of South China Sea (SCS). It is an important seismic reference mark whi... BSR (Bottom Simulating Reflector) occurs widely in the strata since the late Miocene in the deep-water area of the northern continental slope of South China Sea (SCS). It is an important seismic reference mark which identifies the gas hydrate and its distribution influenced by the tectonic movements. Single-point basin modeling was conducted using 473 points in the study area. To discuss the relationships between the tectonic subsidence and BSR, the volume and rate of tectonic subsidence in each geological time have been simulated. The results show that there are three tectonic accelerate subsidence processes in the study area since the late Miocene, especially since 1.8Ma the tectonic subsidence accelerates more apparently. Since the Late Miocene to Pleistocene, the rate of tectonic subsidence in deep-water underwent a transformation from weak to strong. The ratio of tectonic subsidence to the total subsidence was relatively high (65-70%). Through the superposition of the BSR developed areas and the contours of tectonic subsidence in this area, it was discovered that more than 80% of BSR tend to be distributed at the slope break or depression-uplift structural transfer zone and the average tectonic subsidence rate ranges from 70 m/Ma to 125 m/Ma. 展开更多
关键词 BSR tectonic subsidence quantitative simulation deep-water area Northern continental slope of South china sea
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Measurement of the current and spectral analysis on the continental shelf in the East China Sea 被引量:4
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作者 LIUYonggang YUANYaochu +1 位作者 LIUCho-Teng CHENHong 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2004年第2期201-212,共12页
Direct measurements of current velocity and water temperature were undertaken at the mooring Sta. M (125°29.38' N, 31°49.70' E) on the continental shelf area in the East China Sea in June 1999 by R/V... Direct measurements of current velocity and water temperature were undertaken at the mooring Sta. M (125°29.38' N, 31°49.70' E) on the continental shelf area in the East China Sea in June 1999 by R/V Xiangyanghong 14. The relationship between various time series of oceanic fluctuations is calculated by spectral analysis. The major results are as follows: (1) an average (u,v) of (6.9,-3.0 cm/s) at the 30 m depth is obtained during the 9-day observation, and that at the 45 m depth is (3.7,-1.1 cm/s), i. e., the mean flows are southeastward at both the 30 and 45 m depths;the currents become stronger gradually during the observation period; this may be mainly attributed to the transition of the tidal currents from neap to spring; (2)semidiurnal fluctuation is the most dominant in the current fluctuations, and rotates mainly clockwise; in the next place, there is also diurnal fluctuation;the local inertial period is close to the period of diurnal fluctuation, and an inertial motion is clockwise; thus, local inertial motion combines with diurnal fluctuation, and makes the spectral peaks in clockwise components much higher than those in counterclockwise ones; except for the fluctuations of above main periods, there is also the peak at 3 d period for counterclockwise compo-nents in the upper and lower layers; (3) the calculation of cross spectra between two time series of current velocities at the 30 and 45 m depths shows that both the current fluctuations at the 30 and 45 m depths are much alike, i. e., they are synchro; this shows that the flow field here is rather vertically homogeneous; (4)power spectra of tempera-ture time series at both the 30 and 45 m depths show that the semidiurnal peak is the most predominant, and the second highest peak is the diurnal period; besides spectral peaks at above periods, there are also obvious spectral peaks at 6.8 h and 2 d; (5)plots of temperature time series at 16 , 30 , 35 , 45 and 50 m depths show that the temporal variations of temperature at these depths are synchro, which are like those in the velocity field; temperature records also show a gradual rise in temperature, which are also like those in the velocity field. 展开更多
关键词 east china sea current on the continental shelf measurements of current by the mooring system
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Submarine Landslide Identified in DLW3102 Core of the Northern Continental Slope, South China Sea 被引量:2
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作者 XU Yuanqin LIU Lejun +4 位作者 ZHOU Hang HUANG Baoqi LI Ping MA Xiudong DONG Feiyin 《Journal of Ocean University of China》 SCIE CAS CSCD 2018年第1期147-155,共9页
In this paper, we take DLW3101 core obtained at the top of the canyon(no landslide area) and DLW3102 core obtained at the bottom of the canyon(landslide area) on the northern continental slope of the South China Sea a... In this paper, we take DLW3101 core obtained at the top of the canyon(no landslide area) and DLW3102 core obtained at the bottom of the canyon(landslide area) on the northern continental slope of the South China Sea as research objects. The chronostratigraphic framework of the DLW3101 core and elemental strata of the DLW3101 core and the DLW3102 core since MIS5 are established by analyzing oxygen isotope, calcium carbonate content, and X-Ray Fluorescence(XRF) scanning elements. On the basis of the information obtained by analyzing the sedimentary structure and chemical elements in the landslide deposition, we found that the DLW3102 core shows four layers of submarine landslides, and each landslide layer is characterized by high Si, K, Ti, and Fe contents, thereby indicating terrigenous clastic sources. L1(2.15–2.44 m) occurred in MIS2, which is a slump sedimentary layer with a small sliding distance and scale. L2(15.48–16.00 m) occurred in MIS5 and is a debris flow-deposited layer with a scale and sliding distance that are greater than those of L1. L3(19.00–20.90 m) occurred in MIS5; its upper part(19.00–20.00 m) is a debris flow-deposited layer, and its lower part(20.00–20.90 m) is a sliding deposition layer. The landslide scale of L3 is large. L4(22.93–24.27 m) occurred in MIS5; its upper part(22.93–23.50 m) is a turbid sedimentary layer, and its lower part(23.50–24.27m) is a slump sedimentary layer. The landslide scale of L4 is large. 展开更多
关键词 northern continental slope of the South china sea DLW3102 CORE SUBMARINE landslide SEDIMENTARY structure XRF scanning elements
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Bottom Currents Observed in and Around a Submarine Valley on the Continental Slope of the Northern South China Sea 被引量:4
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作者 WU Lunyu XIONG Xuejun +3 位作者 LI Xiaolong SHI Maochong GUO Yongqing CHEN Liang 《Journal of Ocean University of China》 SCIE CAS 2016年第6期947-957,共11页
Bottom currents at about 1000m depth in and around a submarine valley on the continental slope of the northern South China Sea were studied by a 14-month long experiment from July 2013 to September 2014. The observati... Bottom currents at about 1000m depth in and around a submarine valley on the continental slope of the northern South China Sea were studied by a 14-month long experiment from July 2013 to September 2014. The observations reveal that bottom currents are strongly influenced by the topography, being along valley axis or isobaths. Power density spectrum analysis shows that all the currents have significant peaks at diurnal and semi-diurnal frequencies. Diurnal energy is dominant at the open slope site, which is consistent with many previous studies. However, at the site inside the valley the semi-diurnal energy dominates, although the distance between the two sites of observation is quite small (11 kin) compared to a typical horizontal first-mode internal tide wavelength (200 km). We found this phenomenon is caused by the focusing of internal waves of certain frequencies in the valley. The inertial peak is found only at the open slope site in the first deployment but missing at the inside valley site and the rest of the de- ployments. Monthly averaged residual currents reveal that the near-bottom currents on the slope flow southwestward throughout the year except in August and September, 2013, from which we speculate that this is a result of the interaction between a mesoscale eddy and the canyon/sag topography. Currents inside the valley within about 10mab basically flow along slope and in the layers above the 10mab the currents are northwestward, that is, from the deep ocean to the shelf. The monthly mean current vectors manifest an Ek- man layer-like vertical structure at both sites, which rotate counter-clockwise looking from above. 展开更多
关键词 bottom currents VALLEY continental slope South china sea
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pCO_2 distribution and CO_2 flux on the inner continental shelf of the East China Sea during summer 2011 被引量:2
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作者 曲宝晓 宋金明 +3 位作者 李学刚 袁华茂 李宁 马清霞 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2013年第5期1088-1097,共10页
Measurements ofpH, total alkalinity (TA), partial pressure of CO2 (pCO2) and air-sea CO2 flux (FCO2) were conducted for the inner continental shelf of the East China Sea (ECS) during August 2011. Variations in... Measurements ofpH, total alkalinity (TA), partial pressure of CO2 (pCO2) and air-sea CO2 flux (FCO2) were conducted for the inner continental shelf of the East China Sea (ECS) during August 2011. Variations in pCO2 distribution and FCO2 magnitude during the construction of the Three Gorges Dam (TGD) (2003-2009), and the potential effects of the TGD on the air-sea CO2 exchange were examined. Results showed that the ECS acts as an overall CO2 sink during summer, with pCO2 ranging from 107 to 585 p.atm and an average FCO2 of -6.39 mmol/(m2·d). Low pCO2 (〈350 μatm) levels were observed at the central shelf (28°-32°N, 123°-125.5°E) where most CO2-absorption occurred. HighpCO2 (〉420 μatm) levels were found in the Changjiang estuary and Hangzhou Bay which acted as the main CO2 source. A negative relationship between pCO2 and salinity (R2=0.722 0) in the estuary zone indicated the predominant effect of the Changjiang Diluted Water (CDW) on the seawater CO2 system, whereas a positive relationship (R2=0.744 8) in the offshore zone revealed the influence of the Taiwan Current Warm Water (TCWW). Together with the historical data, our results indicated that the CO2 sink has shown a shift southwest while FC02 exhibited dramatic fluctuation during the construction of the TGD, which is located in the middle reaches of the Changjiang. These variations probably reflect fluctuation in the Changjiang runoff, nutrient import, phytoplankton productivity, and sediment input, which are likely to have been caused by the operations of the TGD. Nevertheless, the potential influence of the TGD on the CO2 flux in the ECS is worthy of further study. 展开更多
关键词 carbon dioxide exchange flux continental shelf east china sea Three Gorges Dam
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Comprehensive Investigation of Submarine Slide Zones and Mass Movements at the Northern Continental Slope of South China Sea 被引量:1
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作者 CHEN Hongjun LIANG Jin GONG Yuehua 《Journal of Ocean University of China》 SCIE CAS CSCD 2018年第1期101-117,共17页
Multi-beam bathymetry and seismic sequence surveys in the northern slope of the South China Sea reveal detailed geomorphology and seismic stratigraphy characteristics of canyons, gullies, and mass movements. Modern ca... Multi-beam bathymetry and seismic sequence surveys in the northern slope of the South China Sea reveal detailed geomorphology and seismic stratigraphy characteristics of canyons, gullies, and mass movements. Modern canyons and gullies are roughly elongated NNW–SSW with U-shaped cross sections at water depths of 400–1000 m. Mass movements include slide complexes, slide scars, and debris/turbidity flows. Slide complexes and slide scars are oriented in the NE–SW direction and cover an area of about 1790 and 926 km^2, respectively. The debris/turbidity flows developed along the lower slope. A detailed facies analysis suggests that four seismic facies exist, and the late Cenozoic stratigraphy above the acoustic basement can be roughly subdivided into three sequences separated by regional unconformities in the study area. The occurrence of gas hydrates is marked by seismic velocity anomalies, bottom-simulating reflectors, gas chimneys, and pockmarks in the study area. Seismic observations suggest that modern canyons and mass movements formed around the transition between the last glacial period and the current interglacial period. The possible existence and dissociation of gas hydrates and the regional tectonic setting may trigger instability and mass movements on the seafloor. Canyons may be the final result of gas hydrate dissociation. Our study aims to contribute new information that is applicable to engineering construction required for deep-water petroleum exploration and gas hydrate surveys along any marginal sea. 展开更多
关键词 SOUTH china sea SUBMARINE SLIDE ZONES mass movements continental slope
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Characteristics and evaluation of Mesozoic source rocks in the southeastern East China Sea continental shelf 被引量:3
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作者 Ming-jian Wang Guo-lin Xiao +3 位作者 Chang-qing Yang Yan-qiu Yang Xi Chen Long Huang 《China Geology》 2019年第2期133-141,共9页
Source rocks are the material basis of oil and gas generation and determine the potential resources of exploration blocks and have important research value. This paper studies the lithology, thickness, and geochemistr... Source rocks are the material basis of oil and gas generation and determine the potential resources of exploration blocks and have important research value. This paper studies the lithology, thickness, and geochemistry of Mesozoic source rocks in the southeastern East China Sea continental shelf. The results show that the Mesozoic source rocks are mainly dark mudstone and coal-bearing strata. The total thickness of Lower–Middle Jurassic source rocks ranges from 100 m to 700 m, and that of Lower Cretaceous source rocks ranges from 50 m to 350 m. The overall thickness of Mesozoic source rocks is distributed in the NE direction and their thickness center is located in the Jilong Depression. The Lower–Middle Jurassic source rocks are mainly developed shallow marine dark mudstone and transitional coal measure strata. Those of the Lower Cretaceous are mainly mudstone of a fan delta front. Lower –Middle Jurassic and Lower Cretaceous hydrocarbon source rocks are dominated by type III kerogen, with Lower –Middle Jurassic hydrocarbon source rocks having high organic matter abundance and being medium –good hydrocarbon source rocks, while Lower Cretaceous hydrocarbon source rocks have relatively poor quality. From northwest to southeast, the vitrinite reflectance Ro of Mesozoic source rocks increases gradually. Source rocks in the study area are divided into three types. The first hydrocarbon-generating area is mainly located in the southeastern region of the study area, and the Jilong Depression is the hydrocarbongenerating center. The results of this study can provide a basis for exploration of Mesozoic oil and gas resources in the southeastern East China Sea continental shelf. 展开更多
关键词 east china sea continental SHELF Southeastern part MESOZOIC Source ROCKS EVALUATION
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Statistical characteristics of mesoscale eddies on the continental slope in the northern South China Sea 被引量:1
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作者 Zi Cheng Meng Zhou +3 位作者 Yisen Zhong Zhaoru Zhang Hailong Liu Lei Zhou 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2020年第3期36-44,共9页
The continental slope in the northern South China Sea(SCS) is rich in mesoscale eddies which play an important role in transport and retention of nutrients and biota. In this study, we investigate the statistical prop... The continental slope in the northern South China Sea(SCS) is rich in mesoscale eddies which play an important role in transport and retention of nutrients and biota. In this study, we investigate the statistical properties of eddy distributions and propagation in a period of 24 years between 1993 and 2016 by using the altimeter data. A total of 147 eddies are found in the continental slope region(CSR), including 70 cyclonic eddies(CEs) and 77 anticyclonic eddies(ACEs). For those eddies that appear in the CSR, the surrounding areas of Dongsha Islands(DS) and southwest of Taiwan(SWT) are considered as the primary sources, where eddies generated contribute more than 60% of the total. According to the spatial distribution of eddy relative vorticity, eddies are weakening as propagating westward. Although both CEs and ACEs roughly propagate along the slope isobaths, there are discrepancies between CEs and ACEs. The ACEs move slightly faster in the zonal direction, while the CEs tend to cross the isobaths with large bottom depth change. The ACEs generally move further into the basin areas after leaving the CSR while CEs remain around the CSR. The eddy propagation on the continental slope is likely to be associated with mean flow at a certain degree because the eddy trajectories have notable seasonal signals that are consistent with the seasonal cycle of geostrophic current. The results indicate that the eddy translation speed is statistically consistent with geostrophic velocity in both magnitude and direction. 展开更多
关键词 the SOUTH china sea continental slope Dongsha ISLANDS EDDY statistics EDDY propagation
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Widespread Methane Seep Activities along the Western Slope of the Okinawa Trough, East China Sea 被引量:2
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作者 LI Qing CAI Feng +7 位作者 YAN Guijing LIANG Jie SHAO Hebin WANG Meng DONG Gang WANG Feng SUN Yunbao LUO Di 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2017年第4期1505-1506,共2页
The westem slope of the Okinawa trough has been considered to experience important methane seep activities. Abundant terrigenous sediments supply and widely developed normal faults make this area an ideal place for me... The westem slope of the Okinawa trough has been considered to experience important methane seep activities. Abundant terrigenous sediments supply and widely developed normal faults make this area an ideal place for methane production, methane fluids migration and associated anaerobic oxidation of methane. 展开更多
关键词 than this Widespread Methane Seep Activities along the Western slope of the Okinawa Trough east china sea SMI show AOM
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Morphology and architecture of the typical erosion-genesis submarine canyons on the East China Sea slope 被引量:1
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作者 LIU Baohua ZHAO Yuexia +3 位作者 LI Xishuang KAN Guangming PEI Yanliang ZHENG Yanpeng 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2009年第6期42-52,共11页
The Yithi submarine canyons, composed of four canyons less than 60 km in length, are located on the narrowest part of the East China Sea (ECS) slope. They extend from the shelf break at 160 m down to water depth of ... The Yithi submarine canyons, composed of four canyons less than 60 km in length, are located on the narrowest part of the East China Sea (ECS) slope. They extend from the shelf break at 160 m down to water depth of 1 500 m with an average gradient (along the canyon axis) of 3°(〈1 000 m) and 0.7°(〈1 000 m). The sinuosity of the canyons ranges form 1.02 to 1.14 and their pathways extend radially from the shelf break to the axis of the Okinawa Trough. Structural and evolution pattern of the Yithi canyons are mainly controlled by sediment mass-movements and turbidity current and similar with that of the canyons in Ebro continental slope. The whole canyon system consists of three parts: the canyon, the channel and the fan. Slumps and slides often develop in the upper part of canyon where the water depth is less than 1 000 m, and the turbidities usually developed on the fan. The scale of turbidites becomes smaller and their inner structures become more regular towards the ends of the canyons. Canyon-fans are often associated with small angle progradational reflection. Most canyon-fans and levees were transversely cut by active normal faults with NEE- SWW trending that are coupled to the modern extension of the Okinawa Trough. According to the age of formation of canyon-fans and sediments incised by canyons, we can infer that the Yithi canyons were formed since the middle the Medio-Pleistocene. 展开更多
关键词 moroholouv ARCHITECTURE uenesis CANYON the east china sea slope
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Vertical Structure of the Tidal Currents on the Continental Shelf of the East China Sea 被引量:4
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作者 LI Lei JIANG Weiwei +1 位作者 LI Peiliang YANG Bo 《Journal of Ocean University of China》 SCIE CAS 2012年第3期347-353,共7页
The available data on tidal currents spanning periods greater than six months for the continental shelf of the East China Sea (26°30.052′N, 122°35.998′E) were analyzed using several methods. Tidal Current ... The available data on tidal currents spanning periods greater than six months for the continental shelf of the East China Sea (26°30.052′N, 122°35.998′E) were analyzed using several methods. Tidal Current Harmonic Analysis results demonstrated that semi-diurnal tides dominated the current movement. The tidal currents of the principal diurnal and semidiurnal rotated clockwise with depth, with the deflection of the major semi-axes to the right in the upper layer and to the left in the lower layer. The vertical structures of two principal semi-diurnal constituents-M2 and S2-were similar, which indicates that the tidal currents are mainly barotropic in this area. The main features of the variation of the four principal tidal constituents with depth demonstrate that the currents in this region are influenced by the upper and lower boundary layers. Therefore, the tidal constituents of the shallow water are similar. Different vertical modes were calculated based on the Empirical Orthogonal Function (EOF) analysis of the Eastern and Northern components of the tidal currents, with a variance contribution for the zero-order model of at least 90%. The variance contribution of the baroclinic model is minimal, which further reveals a strong barotropic character for the tidal currents of this region. 展开更多
关键词 continental shelf of the east china sea tidal current vertical mode barotropic tide
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Types of the Continental Slope System Since Miocene in Qiongdongnan Basin,Offshore Hainan,Northern South China Sea
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作者 Yunlong He~1,Xinong Xie~1,Ming Su~1,Tao Jiang~1,Chen Zhang~1,Shanshan Tian~1,Junliang Li~2 1.Faculty of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074,China. 2.Department of Technology,Zhanjiang Branch of CNOOC,Zhanjiang 524057,China 《地学前缘》 EI CAS CSCD 北大核心 2009年第S1期226-226,共1页
Very high resolution seismic record were used to study the sedimentary processes and morphosedimentary features of the continental slope system since Miocene in Qiongdongnan Basin(QDNB),offshore Hainan,northern South ... Very high resolution seismic record were used to study the sedimentary processes and morphosedimentary features of the continental slope system since Miocene in Qiongdongnan Basin(QDNB),offshore Hainan,northern South China Sea.It can be divided into four types based on the sedimentary processes and morphology:wide and gentle slope,sigmoid-progradational slope,slumping slope and channeled slope.Different features of 展开更多
关键词 continental slope system MIOCENE Qiongdongnan Basin SOUTH china sea
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Sediment Provenance and Climate Changes Since the Middle Pleistocene in the Yingqiong Continental Slope of the South China Sea
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作者 XIAO Xiao FENG Xiuli LIU Jie 《Journal of Ocean University of China》 SCIE CAS CSCD 2019年第6期1282-1290,共9页
The age,grain size compositions and major elemental compositions for sediments in core YQ1 from the Yingqiong continental slope in the South China Sea was determined in this paper.It is noted that the periodically cyc... The age,grain size compositions and major elemental compositions for sediments in core YQ1 from the Yingqiong continental slope in the South China Sea was determined in this paper.It is noted that the periodically cyclic change of sedimentation rates occurred in the Yingqiong continental slope in the South China Sea.During the interglacial periods,the sedimentation rates were high,while the sedimentation rates exhibited low values during the glacial periods.During Marine Isotope Stage 1(MIS1),the sedimentary rate could reach about 800 cm kyr-1 and during the MIS6 this area is characterized by the lowest sedimentary rate,which is lower than 3 cm kyr-1.According to the R-mode factor analysis of the major element data,three factors F1(Al2O3,Fe2O3,TiO2 and K2O),F2(MgO and MnO)and F3(Na2O and P2O5)were obtained,which shows that vertical change of the major elemental concentrations in the core was mainly controlled by the nearby terrestrial inputs and the early diagenesis,while the effect of volcanic and biogenous inputs was less.The obvious glacial-interglacial cyclic features are presented in the changes of the typical terrestrial element ratios contained in factor F1,which reflects the impact of glacial-interglacial climatic cycle on the evolution of the East Asian monsoon.This indicates that the major element ratios in terrestrial sediments are significant indicators of regional climate changes. 展开更多
关键词 the SOUTH china sea Yingqiong continental slope major element composition SEDIMENTATION rate climate change glacial-interglacial cycle
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The continental shelf wave of the East China Sea and its effect on the Kuroshio
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作者 Kong Xiangde, Yin Xunf u and Li Fanhua First Institute of Oceanography, State Oceanic Administration, Qingdao 266003, China 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1992年第3期367-374,共8页
The free shelf wave theory is applied to the practical case of the continental shelf in the East China Sea to analyse the effects of the shelf wave on the Kuroshio. The results indicate that the shelf wave in lower fr... The free shelf wave theory is applied to the practical case of the continental shelf in the East China Sea to analyse the effects of the shelf wave on the Kuroshio. The results indicate that the shelf wave in lower frequency travels from north to south and its phase velocity is proportional to the Kuroshio's current velocity) the maximum current velocity of the Kuroshio lies at the continental margin. The analytical solutions obtained indicate that the hydrodynamic characters of the sea region over the shelf present band structure. The horizontal motion ( x -component) caused by the shelf wave at the margin may be one of the causes for generating wavy pattern of the Kuroshio's axis . 展开更多
关键词 the continental shelf wave of the east china sea and its effect on the Kuroshio WAVE
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Transport patterns of micro nutrient elements from the continental shelf of the East China Sea to the Kuroshio area
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作者 Lu Saiying, Yao Qiao’er and Chen Zhen 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1992年第2期219-230,共12页
On the basis of the in situ data of DO2, pH, SiO2. PO4-P, NO3-N and NO2-N collected in the north of the East China Sea during 1987-1988, the following points are mainly expounded.1.The inorgonic nutrients are obviousl... On the basis of the in situ data of DO2, pH, SiO2. PO4-P, NO3-N and NO2-N collected in the north of the East China Sea during 1987-1988, the following points are mainly expounded.1.The inorgonic nutrients are obviously affected by continent runoff in the north of the East China Sea. Their distributions are characteristic of its distribution of terrigenous materials.2.There are three transport paths of nutrients from the shelf to the Kuroshio area. The first is mixing-diffusing-advec-tion and upwelling process, the process of biology and biochemistry belongs to the second, and the sinking process is the last one.3.The swing of the Kuroshio axis affectes both the range of the migration of substances through mixing-diffusing-advec-tion process and the upwelling degree of the subsurface Kuroshio water to the shelf.4.Most part of the substances sink as macroparticles to the deep layer before reaching the Kuroshio area. 展开更多
关键词 Transport patterns of micro nutrient elements from the continental shelf of the east china sea to the Kuroshio area
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Sedimentary Environment Analysis of Ancient Sand Ridges from Zk23 Hole in the East China Sea
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作者 杜文博 叶银灿 庄振业 《Marine Science Bulletin》 CAS 2009年第2期72-80,共9页
Abstract: Based on the analysis of core samples from the hole of Zk23 in the East China Sea Continental Shelf and by means of sedimentary stratigraphy, biostratigraphy and chronostratigraphy, the authors consider tha... Abstract: Based on the analysis of core samples from the hole of Zk23 in the East China Sea Continental Shelf and by means of sedimentary stratigraphy, biostratigraphy and chronostratigraphy, the authors consider that the fine-sand deposition in borehole was part of buried ancient estuary sand ridges of the Yangtze River. The deposition history of study area around the hole before and after the glacial period as well as postglacial period is made clear after our research: (1) the estuarine sublayer -undersea delta facies strata was deposited under the fast sea level rise about 15 kaB.P; (2) sand ridges mostly consisting of fine-sand, were formed when the sea level was the fluctuant range of 60 - 80 m of isoba during the deglacial period around 15 - 12 kaB.P; (3) first silty clay and clay silt strata above the sand ridges were deposited during the period when the sea level rose fast from 12 to 7 kaB.P, and then it keeps stable to the present. 展开更多
关键词 ancient sand ridges sedimentary environment east china sea continental Shelf
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GRAVITY-DRIVEN SEDIMENTATION ON THE NORTHWESTERN CONTINENTAL SLOPE IN THE SOUTH CHINA SEA:RESULTS FROM HIGH-RESOLUTION SEISMIC DATA AND PISTON CORES 被引量:18
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作者 吴时国 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 1999年第2期155-169,共15页
A distinct echo-character was assigned to sedimentation processes, which were then verified using data from surface sediment samples and piston cores. of echo types on the continental slope perfectly reflecting both s... A distinct echo-character was assigned to sedimentation processes, which were then verified using data from surface sediment samples and piston cores. of echo types on the continental slope perfectly reflecting both sediment erosion and deposition, four edimentary types have been recognized:(1) submarine clides distributed on the shelfbreak and characterized by high silt and water conten, loose struture, poor consolidation and low shearing strength; (2) slumps occurring on the shelfbreak, middle slope channel and reef margin near Dongsha Islands, but having different origins; (3) debris flow occurring either in sea areas around Dongsha Atoll, or on the continental slope’s three channels, where the transparent debris flow deposits often overlie or abruptly truncate highly stratified hemipelagic sediments;are of limited to local extent, ranging from a few square kilometers to hundreds of square kilometers in area; but on the lowr slope, usually occur as 1000 km2, about 100 km2 individual complexes; and (4) turbidites, limited on the continental slope; are occurring as migrating waves of sediments at the the of the slope, and are rhythmically-bedded, coarse-grained. Their migration is a result of overbank flow downslope through the submarine channel at the west. The slope faces are dominated by mass wasting deposition, and a few turbidite current sediments. As wasting is an important process. Some debris flow eomplexes on the west are buried by well-stratified confomable sediments, whereas others on the east appear on the present seafloor and therefore are relatively recent. 展开更多
关键词 GRAVITY flow SEDIMENTATION continental slope South china sea
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Concentration and Characterization of Colored Dissolved Organic Matter in the Surface Microlayer and Subsurface Water of the Yellow Sea and the East China Sea 被引量:5
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作者 ZHANG Jing ZHAO Junjie +1 位作者 YANG Guipeng LIU Weifeng 《Journal of Ocean University of China》 SCIE CAS CSCD 2019年第2期383-393,共11页
The distribution and chemical properties of colored dissolved organic matter(CDOM) in the Yellow Sea and the East China Sea during December 2011-January 2012 were investigated. The input of freshwater and biological a... The distribution and chemical properties of colored dissolved organic matter(CDOM) in the Yellow Sea and the East China Sea during December 2011-January 2012 were investigated. The input of freshwater and biological activities had an evident influence on the CDOM levels(characterized by the light absorption coefficient at the wavelength of 355 nm a_(355)) in the study area. The spatial distribution of CDOM levels displayed a gradually decreasing trend from the coastal waters(0.37 m^(-1)) to the open sea(0.18 m^(-1)). The spectral slope ratio(the slope ratio S_R defined as S_(275-295):S_(350-400)) during the cruise was correlated with salinity, and exhibited a large variation from inshore(average of 2.515) to offshore sites(average of 5.327) compared with the distribution of a_(355). The values of S_R were related to CDOM molecular weight(MW). The a_(355), S_R, and chlorophyll a in 37 samples collected from the surface microlayer were significantly correlated with those in the corresponding subsurface water samples, implying a strong exchange action between the microlayer and bulk water. The a_(355) and S_R of CDOM exhibited significant microlayer enrichment, with mean enrichment factors(EFs) of 1.72 and 1.62, respectively. 展开更多
关键词 COLORED dissolved organic matter(CDOM) absorption coefficient spectral slope ratio YELLOW sea east china sea
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