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Stability of submarine slopes in the northern South China Sea: a numerical approach

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Chinese Journal of Oceanology and Limnology 2013年第1期31卷 146-158页

作者：张亮栾锡武 key laboratory of marine geology and environment Institute of OceanologyChinese Academy of Sciences Graduate University of Chinese Academy of Sciences key laboratory of marine hydrocarbon resources and environmental geology Ministry of Land and Resources Qingdao Institute of marine geology

Submarine landslides occur frequently on most continental margins. They are effective mechanisms of sediment transfer but also a geological hazard to seafloor installations. In this paper, submarine slope stability is evaluated using a 2D limit equilibrium method. Considerations of slope, sediment, and triggering force on the factor of safety （FOS） were calculated in drained and undrained （4=0） cases. Results show that submarine slopes are stable when the slope is 〈16° under static conditions and without a weak interlayer. With a weak interlayer, slopes are stable at 〈18° in the drained case and at 〈9° in the undrained case. Earthquake loading can drastically reduce the shear strength of sediment with increased pore water pressure. The slope became unstable at 〉13° with earthquake peak ground acceleration （PGA） of 0.5 g; whereas with a weak layer, a PGA of 0.2 g could trigger instability at slopes 〉 10°, and 〉3 ° for PGA of 0.5 g. The northern slope of the South China Sea is geomorphologically stable under static conditions. However, because of the possibility of high PGA at the eastern margin of the South China Sea, submarine slides are likely on the Taiwan Bank slope and eastern part of the Dongsha slope. Therefore, submarine slides recognized in seismic profiles on the Taiwan Bank slope would be triggered by an earthquake, the most important factor for triggering submarine slides on the northern slope of the South China Sea. Considering the distribution of PGA, we consider the northern slope of the South China Sea to be stable, excluding the Taiwan Bank slope, which is tectonically active.

关键词： submarine landslide factor of safety earthquake South China Sea

Sedimentary architecture of the Holocene mud deposit off the southern Shandong Peninsula in the Yellow Sea

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Journal of Oceanology and Limnology 2018年第1期36卷 181-191页

作者：仇建东刘健许红周良勇 The key laboratory of marine hydrocarbon resources and environment geology Qingdao 266071 China laboratory for marine geology Qingdao National Laboratory for Marine Science and Technology Qingdao 266061 China Qingdao Institute of marine geology Ministry of Land and Resources Qingdao 266071 China

Newly acquired high-resolution seismic profiles reveal a nearshore and an of fshore mud depocenter of f the southern Shandong Peninsula in the Yellow *** nearshore depocenter is distributed in bands along the south coast of Shandong *** of fshore depocenter is part of the distal subaqueous deltaic lobe,which deposited around the southeastern tip of the Shandong *** the two depocenters is a linear *** mud deposits directly overlie the postglacial transgressive surface and can be divided into lower and upper units by the Holocene maximum flooding *** nearshore and off shore units display different seismic *** lower unit of the nearshore deposit exhibits basal onlap,whereas the upper unit is characterized by *** lower and upper units of the off shore deposit display distinct acoustic *** lower unit has low-angle aggradation with internal reflectors generally dipping seaward and truncated by the Holocene maximum flooding surface,whereas the upper unit is characterized by aggradation and progradation landward rather than *** of geochemistry analysis of QDZ03 sediments and mineral analysis of WHZK01 sediments suggest that the nearshore deposit and the lower unit of the of fshore deposit are derived from the proximal coastal sediments of the Shandong Peninsula and the Huanghe(Yellow) River *** upper unit of the of fshore deposit is mainly Huanghe *** lower unit of the mud deposit represents a post-glacial transgressive system tract according to dates of core QDZ03,and the upper unit represents a highstand system tract from middle Holocene to the *** results will be of great significance to further understanding of the transportation of the Huanghe River sediments into the Yellow Sea and the spatial distribution of the subaqueous delta.

关键词： Holocene mud deposit Yellow Sea

Characteristics and provenance implication of detrital minerals since marine Isotope Stage 3 in Core SYS-0701 in the western South Huanghai Sea

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Acta Oceanologica Sinica 2013年第4期32卷 49-58页

作者： ZHANG Junqiang LIU Jian WANG Hongxia XU Gang QIU Jiandong YUE Baojing ZHAO Guangtao Ocean University of China key laboratory of marine hydrocarbon resources and environmental geology Ministry of Land and Resources Qingdao Institute of marine geology

The previous studies of the sedimentology and chronology of sediment core SYS-0701, which was recovered from the western South Huanghai Sea （Yellow Sea）, have revealed the changes in the sea-level and sedimen- tary evolution during the late Quaternary in the region. The present study used mineralogical data from the section of the core deposited since marine Isotope Stage （MIS） 3, to decipher the provenance of sediments of the paleo-delta deposited during MIS 3 and MIS 1. Based on the lithologic features and the variations with depth of the concentrations of carbonates and both heavy and light minerals in bulk samples, the up- per part of Core SYS-0701 can be divided into three units designated DU1, DU4, and DU5, in accord with previouslyused terminology. Sub-units of units DU1 （DU1-1 and DU1-2） and DU4 （DU4-1 and DU4-2） have also been identified. DU1 was deposited during MIS 1, and DIJ4 and DU 5 were formed during MIS 3. All data pertaining to dominant heavy mineral assemblages, diagnostic minerals, ratios of diagnostic minerals, light mineral associations, textural maturities, and carbonate contents, indicate that the sediments of Core SYS-0701 are comparable with Huanghe River （Yellow River） sediments. Moreover, the mineralogy of the sediment evidenced its dependence on supply rates and hydrodynamic conditions. Weak hydrodynamics （DU5 and DU4-2） and/or low sediment supply （DU1-2） led to sediment containing less hornblende and epidote, with a large specific gravity and high content of flaky minerals, and vice versa in cases of strong hydrodynamics （DIJ4-1） and very large sediment supply （DUI-1）.

关键词： heavy mineral light mineral carbonate provenance South Huanghal Sea (Yellow Sea)

Source identification of aluminum in surface sediments of the Yellow Sea off the Shandong Peninsula

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Acta Oceanologica Sinica 2015年第12期34卷 147-153页

作者： XU Gang LIU Jian PEI Shaofeng KONG Xianghuai HU Gang GAO Maosheng Qingdao Institute of marine geology Ministry of Land and Natural laboratory for marine geology Qingdao National Laboratory for Marine Science and Technology key laboratory of Ministry of Land and Natural resources for marine hydrocarbon resources and environment geology key laboratory of China Geological Survey Bureau for Coastal Wetland Biogeosciences

Surface sediment samples in the near shore area of the north Shandong Peninsula are collected for grain size and element analyses. The results indicate that the surface sediments in the study area are primarily composed of the silt-sized components similar to the Huanghe River. The total concentration of aluminum varies from 5.57% to7.37%（average（6.33 ± 0.40）%）, and its spatial distribution is mainly controlled by the grain size. Correlations between the ratio of aluminum to titanium concentration and aluminum concentration, titanium concentration and the mean grain size indicate that aluminum in the near shore surface sediments is affected majorly by the terrigenous source, and partially by the anthropogenic source. The ratios of aluminum to titanium concentrations are larger than the background value of loess matter at some stations due to the existence of excess aluminum associated with human activities. Thus, the sources of aluminum should be identified firstly when aluminum is used as an index of terrigenous matter even in the near shore area dominated by terrigenous deposits.

关键词： aluminum source identification surface sediments Shandong Peninsula Yellow Sea

A Holocene Yalu River-derived fine-grained deposit in the southeast coastal area of the Liaodong Peninsula

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Chinese Journal of Oceanology and Limnology 2013年第3期31卷 636-647页

作者：陈晓辉李铁刚张训华李日辉 key laboratory of marine geology and environment Institute of OceanologyChinese Academy of Sciences key laboratory of marine hydrocarbon Resource and environmental geology Ministry of Land and ResourcesQingdao Institute of Marine Geology Graduate University of Chinese Academy of Sciences

High-resolution seismic profiles and surface samples were studied in detail in order to determine the structures, provenance, and dynamic mechanisms of a fine-grained deposit in the southeast coastal area of the Liaodong Peninsula, China. Results indicate that there is a prominent fine-grained deposit distributed alongshore up to 14 m thick, which thins out to less than 2 m in both seaward and landward directions, forming an fl-shaped pattern of cross-section. The deposit is 180-300 km away from the Yalu River mouth and extends along the southeast coast of the Liaodong Peninsula between the northeast of Dalian Bay and southwest of the Changshan Islands, in water depths of 20-40 m. The deposit, which is mainly derived from the Yalu River, represents a Holocene Highstand System Tract sequence formed since the highest sea level around 7.0 ka. The Yalu River-derived sediments were redeposited in the area off the southeast coast of the Liaodong Peninsula after resuspension and transportation by the Liaonan Coastal Current.

关键词： North Yellow Sea Yalu River fine-grained deposit alongshore transport

Experimental study on geochemical characteristic of methane hydrate formed in porous media

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Journal of Natural Gas Chemistry 2009年第2期18卷 217-221页

作者： Qiang Chen Changling Liu Yuguang Ye Qingdao Institute of marine geology the Ministry of Land and Resources Qingdao 266071 Shandong China The key laboratory of marine hydrocarbon resources and environment resources the Ministry of Land and Resources Qingdao 266071 Shangdong China

The natural occurrence of methane hydrates in marine sediments has been intensively studied over the past decades, and geochemical charac-teristic of hydrate is one of the most attractive research fields. In this paper, we discussed the geochemical anomaly during hydrate formation in porous media. By doing so, we also investigated the temperature influence on hydrate formation under isobaric condition. It turns out that sub-cooling is an important factor to dominate hydrate formation. Larger subcooling provides more powerful driving force for hydrate formation. During the geochemical anomaly research, six kinds of ions and the total dissolved salt （TDS） were measured before and after the experiment in different porous media. The result is that all kinds of ionic concentration increased after hydrate formation which can be defined as salting out effect mainly affected by gas consumption. But the variation ratio of different ions is not equal. Ca^2＋ seems to be the most significantly influenced one, and its variation ratio is up to 80%. Finally, we theoretically made a model to calculate the TDS variation, the result is in good accordance with measured one, especially when gas consumption is large.

关键词： hydrate formation porous media subcooling salting out effect geochemical anomaly

Characteristics of modern sedimentation in Qingdao bays

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Chinese Journal of Oceanology and Limnology 2009年第3期27卷 683-696页

作者：陈正新 Paul Huang 黄海燕董贺平李少泉李春 key laboratory of marine hydrocarbon resources and environmental geology Ministry of Land and Resources Qingdao Institute of marine geology Faculty of Science University of Alberta

With available survey data and 237surface sediment samples,the modern sedimentation in Qingdao bays is *** research result shows that the east area is shallower(16.4 m) than that in the west(45.8 m).The geography was formed by a symmetric wave in a sequence of bank-offshore depression-platform-tidal channel-platform-offshore depression-foreshore from south to *** sedimentary systems were formed from inlet of the Jiaozhou Bay in the west to the barrier bar in the *** sedimentation includes mainly tidal current ridges in two tidal *** sandy sediments formed by wave lie in midland of from seashore to wave *** functions are mainly tide and *** current moves sediment in vertical and horizontal directions,sorting sediments and providing materials for coastwise *** sources of sediment are mainly from eroded headland *** general,grain sizes in this area from the inlet of the Jiaozhou Bay in the west(120°17') to the barrier bar outside in the east(120°35') are coarse-fine-coarse,forming gravel-gravelly sand(G-S),sand(S),gravel clay silt(G-YT),clay silt(YT),gravelly silty sand(G-TS),silty sand(TS),gravelly sandy silt(G-ST),and sandy silt(ST) in turn.

关键词： Qingdao bays surface sediments tidal current ridges sedimentary dynamics

Magnetic Characteristics of Surface Sediments of Liaodong Bay, China

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Journal of Ocean University of China 2015年第3期14卷 407-416页

作者： WANG Shuang WANG Yonghong LIU Jian YU Yiyong The key laboratory of marine hydrocarbon resources and environment geology Ministry of Land and Resources Qingdao Institute of marine geology Ministry of Land and Resources College of marine Geo-Science Ocean University of China

Analysis of magnetic properties of marine surface sediments has been gradually proved to be one of the effective means for researching the source of marine sediments. In this paper, samples from 39 sites in Liaodong Bay were collected to analyze the magnetic characteristics of the surface sediments. Magnetic study indicated that the surface sediments of the Liaodong Bay are char- acterized by magnetite. In the middle and eastern part and the southwest comer of the Bay, the main magnetic grains were coarse multi- domain and pseudo-single-domain particles, while in other areas single-domain and pseudo-single-domain particles constitute the majority. Based on grain size and environmental magnetism data, the content of magnetic minerals has a positive correlation with the hydrodynamic environment when the magnetic mineral domain is finer. However, the content of magnetic minerals is in a complex relationship with the hydrodynamic environment in the coarse magnetic domain of magnetic minerals found in central Liaodong Bay and places outside the Fuzhou Bay, implying that the strong hydrodynamic environment accelerates the sedimentation of coarse magnetic minerals. Based on geographic pattern of magnetic properties, it can be inferred that the main provenance of the surface sediments of the Liaodong Bay is the surrounding rivers, and the comparative analysis indicates that Yellow River substances maybe also exist in the bay.

关键词： magnetic characteristics grain size provenance Liaodong Bay surface sediments

Sedimentary Characteristics of Relict Deposits on the Western South Yellow Sea

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Journal of Ocean University of China 2014年第2期13卷 205-214页

作者： WEN Chun LIU Jian WANG Hong XU Gang QIU Jiandong ZHANG Junqiang College of marine Geo-science Ocean University of China key laboratory of marine hydrocarbon resources and environment geology Ministry of Land and Resources Qingdao Institute of marine geology Ministry of Land and Resources

Integrated studies of vertical sedimentary sequences, grain sizes, and benthic foraminifera and ostracoda, in combination with AMS 14C dating, and 210pb and 137Cs analysis were carried out in three vibracores taken from the area of relict deposits on the western South Yellow Sea. The relict sands, which are about 0.4 m thick, overlie on the Early Holocene coastal marsh or tidal fiat deposits with an evident erosional interface in between. The middle and upper parts or sometimes the whole of the relict sands have been reworked under the modern dynamic environment. The sedimentation rate varies between 0.204）.30 cmyear-l. The relict sands show a bimodal grain-size distribution pattern in frequency curves, with a sharp peak in the coarse fraction between 3（I） and 4（I） and a secondary peak in the fine fraction of about 7（I）. Of the benthic foraminiferal and ostracod assemblages, the reworked relict sands are characterized by the mixing of the nearshore euryhaline shallow-water species and deeper water species. The erosional interface at the bottom of the relict sands is considered as a regional ravinement surface formed during the transgression in the Early Holocene due to shoreface retreating landwards. The relict sands were accumulated on the ravinement surface during the transgression in the deglaciation period as lag deposits after winnowing and reworking by marine dynamic processes. And the secondary peak of fine fraction in the frequency curve for the relict sands suggests the input of fine-grained sediments during the reworking process. As the conclusion, the relict sands in the study area are interpreted as a type of reworked relict sediments.

关键词： relict sediments sedimentary characteristics deglaciation period western South Yellow Sea