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Study on Sound-Speed Dispersion in A Sandy Sediment at Frequency Ranges of 0.5–3 kHz and 90–170 kHz

China Ocean Engineering 2017年第1期31卷 103-113页

作者： YU Sheng-qi LIU Bao-hua YU Kai-ben KAN Guang-ming YANG Zhi-guo National Deep Sea Center State Oceanic Administration Qingdao 266237 China Key Laboratory of Marine sedimentology and environmental geology First Institute of Oceanography Qingdao 266061 China Laboratory for Marine geology Qingdao National Laboratory for Marine Science and Technology Qingdao 266237 China

In order to study the properties of sound-speed dispersion in a sandy sediment, the sound speed was measured both at high frequency （90-170 kHz） and low frequency （0.5-3 kHz） in laboratory environments. At high frequency, a sampling measurement was conducted with boiled and uncooked sand samples collected from the bottom of a large water tank. The sound speed was directly obtained through transmission measurement using single source and single hydrophone. At low frequency, an in situ measurement was conducted in the water tank, where the sandy sediment had been homogeneously paved at the bottom for a long time. The sound speed was indirectly inverted according to the traveling time of signals received by three buried hydrophones in the sandy sediment and the geometry in experiment. The results show that the mean sound speed is approximate 1710-1713 m/s with a weak positive gradient in the sand sample after being boiled （as a method to eliminate bubbles as much as possible） at high frequency, which agrees well with the predictions of Biot theory, the effective density fluid model （EDFM） and Buckingham＇s theory. However, the sound speed in the uncooked sandy sediment obviously decreases （about 80%） both at high frequency and low frequency due to plenty of bubbles in existence. And the sound-speed dispersion performs a weak negative gradient at high frequency. Finally, a water-unsaturated Biot model is presented for trying to explain the decrease of sound speed in the sandy sediment with plenty of bubbles.

关键词： acoustic properties of sediment sound-speed dispersion sandy sediment bubbles

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Responses of benthic foraminifera to changes of temperature and salinity:Results from a laboratory culture experiment

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Science China Earth Sciences 2019年第2期62卷 459-472页

作者： Shuaishuai DONG Yanli LEI Tiegang LI Zhimin JIAN department of Marine Organism Taxonomy & Phylogeny Institute of Oceanology Chinese Academy of Sciences University of Chinese Academy of Sciences Center for Ocean Mega-Science Chinese Academy of Sciences Key Laboratory of Marine sedimentology and environmental geology First Institute of Oceanography SOA Laboratory for Marine geology Qingdao National Laboratory for Marine Science and Technology State Key Laboratory of Marine geology Tongji University

The effects of temperature and salinity on intertidal foraminiferal community under laboratory conditions are poorly understood. We designed a two-factor crossed experiment in which foraminiferal communities were cultured at different temperatures (6, 12, and 18℃) and salinities (15, 20, 25, and 30 psu) for 10 weeks. In total, 2616 living (stained) specimens were obtained and analyzed. Foraminiferal abundance ranged from 9 to 202 individuals/10 g wet weight of sediment. The highest abundance was obtained at 12℃, 25 psu and the lowest at 6℃, 15 psu. Statistical results demonstrated that temperature affected foraminiferal community more significantly than salinity. Most foraminiferal community parameters (abundance, species richness, Margalef index, and Shannon-Wiener diversity) were significantly positively correlated to temperature, but not to salinity, whereas Pielou's evenness was significantly negatively correlated to both temperature and salinity. The interactive effect of temperature and salinity on foraminiferal abundance was significant. In addition, with increasing temperature, the species composition shifted from hyaline Rotaliida to porcellaneous Miliolida. The abundance of dominant species (e.g., Ammonia aomoriensis, A. beccarii, and Quinqueloculina seminula) showed significant positive correlations to temperature. Our study indicated that the intertidal foraminiferal community responds sensitively and rapidly to the changes of salinity and, especially,temperature by shifting foraminiferal species composition and altering the community parameters.

关键词： Benthic foraminifera Community parameter Temperature Salinity Culture experiment Intertidal zone

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Clay minerals in Arctic Kongsfjorden surface sediments and their implications on provenance and paleoenvironmental change

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Acta Oceanologica Sinica 2018年第5期37卷 29-38页

作者： SHI Fengdeng SHI Xuefa SU Xin FANG Xisheng WU Yonghua CHENG Zhenbo YAO Zhengquan School of Ocean Sciences China University of Geosciences (Beijing) Key Laboratory of State Oceanic Administration for Marine sedimentology and environmental geology The First Institute of OceanographyState Oceanic Administration Laboratory for Marine geology Qingdao National Laboratory for Marine Science and Technology

Kongsfjorden is a typical fjord on the edge of the ice cap of the Arctic Svalbard-Barents Sea. Its inner bay is connected with a modern glacier front along the direction of the fjord axis with a significant gradient change in the parameters of hydrology, sedimentation, and biology. In summer, ice and snow melt-water and floating ice collapse continuously and thus transport the weathering products on the surrounding land into the sea. Thus Kongsfjorden is regards as a natural laboratory for the study of unique sedimentation in polar fjords under modern glacial-sea water conditions. In this study, fifty-two surface sediments were collected in Kongsfjorden for clay mineral analysis to study the sediment source and sediment-transport process. Our results indicate that clay minerals in the surface sediments from Kongsfjorden are mainly composed of illite, chlorite, and kaolinite, and no smectite is found. Rocks from different periods exposed extensively in the surrounding areas of Kongsfjorden provide an important material basis for clay minerals in the Kongsfjorden. Kaolinite may be mainly derived from the fluvial deposits, weathered from reddish sandstones and conglomerates during the Carboniferous *** is mainly derived from Proterozoic low-grade and medium-grade metamorphic phyllite, mica schist, and gneiss. While chlorite is mainly from Proterozoic low-grade metamorphic phyllite and mica schist. In the direction from the fluvio-glacial estuary to the sea of the glacier front of Kongsfjorden, illite increase gradually,and the content of kaolinite declines gradually. However, the change pattern of chlorite is insignificant, which may be related to the provenance. Kongsfjorden detritus is mainly transported by the fluvio-glacial streams and icebergs into the sea and deposited in the inner bay. Coarse sediments are rapidly deposited in the glacier front,estuary, and near-shore areas. Clay fraction begins to deposit significantly by 200–400 m after flowing into

关键词： Arctic Pole Kongsfjorden clay mineral provenance sedimentation

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Paleoenvironmental changes during the late Quaternary as inferred from foraminifera assemblages in the Laizhou Bay

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Acta Oceanologica Sinica 2014年第10期33卷 10-18页

作者： YAO Jing YU Hongjun XU Xingyong YI Liang CHEN Guangquan SU Qiao Key Laboratory of Marine geology and Environment Institute of Oceanology Chinese Academy of Sciences Key Laboratory of Marine sedimentology and environmental geology First Institute of OceanographyState Oceanic Administration University of Chinese Academy of Sciences State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences

Controlled by climate changes, there were three large-scale transgressions and regressions around the Bohai Sea during the late Quaternary, which were accepted by most geologists. However, a big controversy still exists about the time when the transgressions occurred separately. In order to find out the process of the paleoenvironmental changes around the Bohai Sea in the late Quaternary, the foraminifera assemblages from a new borehole Lz908 in the southern coast of the Laizhou Bay were studied, and then the transgressive strata were indentified. Combined with accelerator mass spectrometry radiocarbon 14C（AMS14C） and optically stimulated luminescence（OSL） ages, the occurrence time of these transgressions were re-determined. The result showed that three major large-scale transgressions occurred separately at the beginning of marine isotopic stage 7（MIS7）, the last interglacial period（MIS5） and the Holocene. In addition, a small-scale transgression occurred in the mid-MIS6, and the corresponding transgressive stratum was deposited. The transgressive deposition of MIS3 was also discovered in this study. However, the characteristics of the foraminifera indicated the environment during this period was colder than that in the MIS5. By comparison with the global sea-level changes, the paleoenvironmental changes around the Bohai Sea in the late Quaternary can be consistent with the global climate changes.

关键词： foraminifera assemblage late Quaternary environmental changes Laizhou Bay Bohai Sea

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Kr and Xe isotopic compositions of Fe-Mn crusts from the western and central Pacific Ocean and implications for their genesis

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Acta Oceanologica Sinica 2014年第8期33卷 26-33页

作者： BU Wenrui SHI Xuefa LI Li ZHANG Mingjie G.P.Glasby LIU Jihua Key Laboratory of Marine sedimentology & environmental geology First Institute of OceanographyState Oceanic Administration School of Resources and Environment Lanzhou University department of Geochemistry Geowissenschafliches Zentrum der Universitat G?ttingen (GZG)G?ttingen 37077Germany

Kr and Xe nuclide abundance and isotopic ratios of the uppermost layer of Fe-Mn Crusts from the western and central Pacific Ocean have been determined. The results indicate that the Kr and Xe isotopic composi-tions, like that of He, Ne and Ar, can be classified into two types： low3He/4He type and high3He/4He type. The low3He/4He type crusts have low84Kr and132Xe abundance, while the high3He/4He type crusts have high84Kr and132Xe abundance. The82Kr/84Kr ratios of the low3He/4He type crusts are lower than that of the air, while the83Kr/84Kr and86Kr/84Kr ratios are higher than those of the air. The Kr isotopic ratios of the high-er3He/4He type crusts are quite similar to those of the air. The128Xe/132Xe,130Xe/132Xe and131Xe/132Xe ratios of the low3He/4He type sample are distinctly lower than those of the air, whereas the129Xe/132Xe,134Xe/132Xe and136Xe/132Xe ratios are higher than those of the air. The low3He/4He type samples have the diagnostic characteristics of the MORB, with excess129, 131, 132, 134, 136Xe relative to130Xe compared with the solar wind. The128Xe/132Xe,130Xe/132Xe and131Xe/132Xe ratios of the high3He/4He type samples are slightly higher than those of the air, and the129Xe/132Xe,134Xe/132Xe and136Xe/132Xe ratios are qiute similar to those of the air. The noble gases in the Fe-Mn crusts are derived from the lower mantle, and they are a mixture of lower mantle primitive component, radiogenic component and subduction recycled component. The helium isotopic ra-tios of the low mantle reservoir are predominantly controlled by primitive He （3He） and U and Th radiogenic decayed He （4He）, but the isotopic ratios of the heavier noble gases, such as Ar, Kr and Xe, are controlled to different extent by recycling of subduction components. The difference of the noble isotopic compositions of the two type crusts is the result of the difference of the noble isotopic composition of the mantle source reservoir underneath the seamounts the crusts occurred, the noble gas

关键词： Fe-Mn crusts Kr and Xe isotopes mantle reservoir Pacific Ocean subduction recycling

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Magnetic Characterization of Amphibolites from the Fomopéa Pluton(West Cameroon):Their Implication in the Pan-African Deformation of the Central African Fold Belt

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Acta Geologica Sinica(English Edition) 2012年第1期86卷 73-84页

作者： NJANKO Théophile FOZING Eric Martial KWéKAM Maurice YAKEU SANDJO Angéline Flore NJONFANG Emmanuel Laboratory of environmental geology Department of Earth SciencesDschang University Laboratory of geology ENS Yaounde I University

The Fomopea granitic pluton is emplaced in gnessic and amphibolitic basement. These gneissic and amphibolitic basement rocks are represented in the pluton＇s body as sub-rounded, elongated or stretched xenoliths. Amphibolitic xenoliths display testimonies of two main tectonic events namely：（i） El flattening deformation event characterized by a NW-SE to E-W foliation with a best pole at 246/57 and a mineral stretched lineation with a best line at 293/47; and （ii） E2 compressive event typified by （1） N-S to NNE-SSW steeply dipping foliation; （2） S-type flexion-fold indicating a sinistral shear movement. These amphibolite rocks indicate a magnetic susceptibility magnitude （Km） range from 418 ~SI to 90092 IISI for 87% of the stations showing a ferromagnetic behavior. K-T curves reveal the presence of Ti-poor magnetite as susceptibility mineral carrier. Magnetic foliation and lineation suggest that the N-S strike direction observed in the Bamendou amphibolite is, as pointed out elsewhere in the Central African Fold Belt, of paramount importance in the tectonic evaluation of the Fomopea area, since it has most likely acted as major deformation phase in the second tectonic event in the belt.

关键词： amphibolite anisotropy of magnetic susceptibility (AMS) Pan-African fold belt Cameroon

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Sedimentary facies of the subaqueous Changjiang River delta since the late Pleistocene

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Chinese Journal of Oceanology and Limnology 2013年第5期31卷 1107-1119页

作者：徐涛玉石学法王国庆乔淑卿杨刚刘升发王旭晨赵泉鸿 Institute of Oceanology Chinese Academy of Sciences First Institute of Oceanography State Oceanic Administration and Key Laboratory of State Oceanic Administration for Marine Sedimentology and Environmental Geology China University of Geosciences (Wuhan) University of Massachusetts Massachusetts Laboratory of Marine geology Tongji University

The sedimentary facies of the subaqueous Changjiang （Yangtze） River delta since the late Pleistocene was studied based on lithology and foraminifera analysis for two boreholes, CJK07 and CJK11, along with 14C dating. Four sedimentary facies were identified, namely fluvial, tidal flat, offshore, and prodelta facies. The fluvial sedimentary facies is comprised of fluvial channel lag deposits, fluvial point bar deposits, and floodplain deposits, showing a fining-upward sequence in general with no benthic foraminifera. A layer of stiff clay overlies the fluvial deposits in core CJK07, indicating a long-term exposure environment during the Last Glacial Maximum （LGM）. During the postglacial sea-level rise around 13-7.5 cal ka BP, the tidal flat facies was deposited in core CJK11, characterized by abundant silt-clay couplets. Euryhaline species dominate the subtidal fiat foraminiferal assemblages, while almost no foraminifera was found in the intertidal fiat. The offshore environment was the major sedimentary environment when the sea level reached its highest level around 7.5 cal ka BP, with a maximum accumulation rate of 10 mm/a found in core CJK11. Prodelta sediments have been deposited in core CJK11 since -3 cal ka BP, after the formation of the Changjiang River delta. The difference in sedimentary facies between core CJK07 and CJK11 is due to their location： core CJK07 was in an interfluve while core CJK11 was in an incised valley during the LGM. Furthermore, AMS 14C dating of core CJK07 shows poor chronological order, indicating that the sediments were reworked by strong tidal currents and that sediment deposited since -7.7 cal ka BP in core CJK07 was eroded away by modem hydrodynamic forces caused by the southward shift of the Changjiang River delta depocenter.

关键词： the subaqueous Changjiang (Yangtze) River delta sedimentary facies Last Glacial Maximum

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The sedimentary facies and dynamic environment of the Diaokou lobe in the modern Huanghe River Delta of China

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Acta Oceanologica Sinica 2018年第11期37卷 40-52页

作者： GAO Wei LIU Shihao LIU Jie XU Yuanqin LI Ping Key Laboratory of Marine sedimentology and environmental geology The First Institute of Oceanography State Oceanic Administration Laboratory for Marine geology Pilot National Laboratory for Marine Science and Technology (Qingdao) Research Center for Islands and Coastal Zone The First Institute of Oceanography State Oceanic Administration

The Huanghe River captures the Diaokou River in 1964 and forms a deltaic lobe in the subsequent 12 a. The progradational process of the Diaokou lobe is in associated with complicated evolution of riverine sheet flooding, merging, and swinging. On the basis of 11 borehole cores and 210 km high resolution seismic reflection data set, the sedimentary sequence and dynamic environment of the Diaokou lobe Cone subdelta lobe of the modern Huanghe River Delta） are studied. The stratigraphy of the lobe is characterized by an upward-coarsening ternary structure and forms a progradational deltaic clinoform. Totally six seismic surfaces are identifiable in seismic profiles, bounded six seismic units （SUs）. These SUs correspond to six depositional units （DUs） in the borehole cores, and among them, SUs 4-6 （DUs D to F） consist of the modern Diaokou lobe. Lithological and seismic evidences indicate that the delta plain part of the Diaokou lobe is comprised primarily by fluvial lag sediments together with sediments from sidebanks, overbanks, fluvial flood plains and levees, while the delta front part is a combination of river mouth bar sands （majority） and distal bar and deltaic margin sediments （minority）. As a result of the high sedimentation rate and weak hydrodynamic regime in the Huanghe River Delta, the sediments in the delta front are dominated by fine-grained materials. The grain size analysis indicates the Huanghe River hyperpycnal-concentrated flow shows the suspension, transportation and sedimentation characteristics of gravity flow, and the sediment transportation is primarily dominated by graded suspension, while uniform suspension and hydrostatic suspension are also observed in places. The strength of the hydrodynamic regime weakens gradually offshore from riverbed, river mouth bar, sidebank, distal bar subfacies to delta lateral margin and flooding plain subfacies.

关键词： modern Huanghe River Delta sedimentary facies sediment dynamics grain size

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A Method for Calculating Bottom Backscattering Strength Using Omnidirectional Projector and Omnidirectional Hydrophone

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Journal of Ocean University of China 2019年第2期18卷 358-364页

作者： YU Kaiben YU Shengqi LIU Baohua LIU Zhongchen YANG Zhiguo KAN Guangming ZONG Le College of Marine Geo-Sciences Ocean University of China National Deep Sea Center State Oceanic Administration Laboratory for Marine geology and Environment Pilot National Laboratory for Marine Science and Technology (Qingdao) Key Laboratory of Marine sedimentology and environmental geology First Institute of Oceanography

A method of obtaining bottom backscattering strength by employing an omnidirectional projector and omnidirectional hydrophone is proposed. The backscattering strength is extracted from monostatic backscattering data. The method was adopted in an experiment conducted in the South Yellow Sea of China. The seafloor surface was relatively smooth and covered by a small quantity of shell fragments, as observed through a digital camera system. Sampling data showed that the main component of the sediment at this experimental site was fine sand. In this paper, we detail the calculation method. Preliminary results of backscattering strength as a function of grazing angle(20?–70?) in the frequency range of 6–24 kHz are presented. The measured backscattering strength increased with the grazing angle and changed more rapidly at large grazing angles(60?–70?). A comparison of the data at different frequencies reveals that the measured backscattering strength substantially rises with the increase of acoustic frequency. A fitting curve of Lambert's law against the measured data shows that the backscattering strength deviates from Lambert's law at large grazing angles.

关键词： acoustic scattering bottom backscattering strength fine sand Lambert’s law

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Correspondence between the ENSO-like state and glacial- interglacial condition during the past 360 kyr

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Chinese Journal of Oceanology and Limnology 2017年第5期35卷 1018-1031页

作者：张帅李铁刚常凤鸣俞宙菲熊志方王海霞 Key Laboratory of Marine geology and Environment Institute of Oceanology Chinese Academy of Sciences University of Chinese Academy of Sciences Key Laboratory of Marine sedimentology and environmental geology First Institute of Oceanography State Oceanic Administration (SOA) Ningbo City Land Resources Bureau Yinzhou Branch

In the warming world, tropical Pacific sea surface temperature （SST） variation has received considerable attention because of its enormous influence on global climate change, particularly the El Nino-Southern Oscillation process. Here, we provide new high-resolution proxy records of the magnesium/ calcium ratio and the oxygen isotope in foraminifera from a core on the Ontong-Java Plateau to reconstruct the SST and hydrological variation in the center of the Western Pacific Warm Pool （WPWP） over the last 360 000 years. In comparison with other Mg/Ca-derived SST and δ18O records, the results suggested that in a relatively stable condition, e.g., the last glacial maximum （LGM） and other glacial periods, the tropical Pacific would adopt a La Nifia-like state, and the Walker and Hadley cycles would be synchronously enhanced. Conversely, El Nino-like conditions could have occurred in the tropical Pacific during fast- changing periods, e.g., the termination and rapidly cooling stages of interglacial periods. In the light of the sensitivity of the Eastern Pacific Cold Tongue （EPCT） and the inertia of the WPWP, we hypothesize an inter-restricted relationship between the WPWP and EPCT, which could control the zonal gradient variation of SST and affect climate change.

关键词： Westem Pacific Warm Pool (WPWP) sea surface temperature (SST) E1 Nifio-Southem Oscillation (ENSO)

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