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CORRELATION OF DOLOMITE OCCURRENCE WITH Sedimentation rate CHANGE

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CORRELATION OF DOLOMITE OCCURRENCE WITH SEDIMENTATION RATE C...

Effects of Different Cations on the Flocculation and sedimentation of Static Fine-Grained

理论与应用地球物理研讨会

作者： Yue-Feng Sun Lamont-Doherty Earth Observatory Columbia University, Palisades, NY 10964, USA

＜正＞ During the expedition on board the R/V JOIDES Resolution, Ocean Drilling Program （ODP） Leg 186, it is discovered that there exists several thin layers of dolomitic rocks imbedded in otherwise uniform diatomaceous silty sediments and claystone. The thickness of the dolomite layers ranges from 0.5 m to 2 m as estimated from the in-situ log data. In this paper we demonstrate that these thin dolomite layers can have profound influence to alter seismic appearance, even on conventional low-frequency seismic data. Using advanced amplitude-preserving high resolution enhancement techniques, a high-resolution dolomite imaging profile is obtained crossing one of the drill site. We provide the first geophysical evidence of large-scale dolomite occurrence in the dynamic forearc basin developed in the deep-sea terrace on the landside of the Japan Trench.The occurrence of thin dolomitic layers embedded in diatomaceous sediments is on the basin scale rather than an isolated phenomenon. The genesis of dolomite in the natural environment has been one of the outstanding problems in geology over the last two centuries. However, we find that these thin dolomite layers mostly occur at depths where abrupt Sedimentation rate change occurs. Two dolomite layers also coincide with the Miocene/Pliocene and Pliocene/Pleistocene age boundaries. It seems to suggest that the correlation between the dolomite layer occurrence and abrupt Sedimentation rate change be intrinsically related to and a signature of dramatic changes in depositional environments. Considering the fact that the Sedimentation rate at the ODP Leg 186 sites may be as fast as 250 m/m.y., high-resolution seismic stratigraphic model could help obtain a regional biostratigraphic or age model. The methodology can well be applied to other similar environments.

关键词： seismic resolution modeling synthetic seismogram thin-bed dolomite formation Sedimentation rate age model

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Journal of Environmental & Earth Sciences 2023年第2期5卷 1-14页

作者： Xiaomin Liu Yaotian Yang Rui Wang Wenjuan Wang Qiang Luo College of Water Conservancy and Civil Engineering Inner Mongolia Agricultural UniversityHohhotInner Mongolia010018China Collaborative Innovation Center for Integrated Management of Water Resources and Water Environment in the Inner Mongolia Reaches of the Yellow River HohhotInner Mongolia010018China Inner Mongolia JinHua Yuan Environmental Resource Engineering Consulting Co. ItdHohhotInner Mongolia010020China Wuhai Wuda District Agriculture of Animal Husbandry and Water Affairs Bureau WuhaiInner Mongolia016000China Yellow River Hai Bo-Wan Water Conservancy Project Development Center WuhaiInner Mongolia016000China

Natural water bodies mostly contain cations,and the type and content of these cations are the main factors affecting the flocculation of fine-grained cohesive sediments and the floc Sedimentation rate at the interface between clear and turbid water.From the microscopic aspect,this study examined the changing patterns of porosity and the fractal dimension of the flocs of fine-grained cohesive sediments.sedimentation experiments under different sediment contents and electrolyte conditions were conducted,and microscopic images of the flocs were analysed using Image-Pro Plus(IPP)and MATLAB based on the fractal theory.From the macroscopic aspect,this study experimentally investigated the flocculation and sedimentation of fine-grained cohesive sediments and proposed a Sedimentation rate equation by introducing an ion concentration-related parameter into an existing Sedimentation rate equation(stagnation zone)based on the adsorption isotherm equation.The equation proposed in this study was validated with measured data.The calculated values were in good agreement with the measured values,with a relative error of 16%.The findings of this study provide a reference for further research on the flocculation and sedimentation of fine-grained cohesive sediments in different water bodies.

关键词： Flocs Electrolyte Fractal dimension Porosity Sedimentation rate

On the sediment age estimated by ^(210)Pb dating: probably misleading “prolonging” and multiple-factor-caused “loss”

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Acta Oceanologica Sinica 2018年第6期37卷 30-39页

作者： JIA Jianjun YANG Yang CAI Tinglu GAO Jianhua XIA Xiaoming LI Yan GAO Shu State Key Laboratory of Estuarine and Coastal Research East China Normal University Key Laboratory of Coast and Island Development of MOE Nanjing University State Research Centre for Island Exploitation and Management Second Institute of Oceanography State Oceanic Administration College of the Environment and Ecology Xiamen University

The radionuclide ^（210） Pb is suitable for century-scale dating and has been used to calculate the Sedimentation rate in a variety of environments. However, two common ways to apply 210 Pb dating techniques may give misleading results. One is ＂prolonging of age＂, i.e., using the calculated Sedimentation rate to date back to 200 or 300 years.This practice must be treated with caution because the 210 Pb dating techniques do not guarantee direct dating for ages much older than 100 years. Another is ＂loss of age＂, i.e., the calculated time span between the topmost layer and the 210 Pb background layer in cores is less than 100 years when an apparent Sedimentation rate is used in the calculation. Here, we propose that based on the principle of 210 Pb dating, the upper limit of age suitable for direct210 Pb dating is between 110 and 155 years. The ＂prolonging＂ application is acceptable only if the sedimentary environment in the past several hundred years was stable and the Sedimentation rate was generally constant, and verification with independent evidence（such as historical records or biomarker methodology） is needed.Furthermore, after analyzing many published and collected data, we found four possible reasons for the ＂loss of age＂. First, the compaction effect of sediment should be corrected in laboratory analysis or else the calculated age will be underestimated. Second, the accuracy and uncertainty of 210 Pb activity measurement affect the judgment of the background. To be cautious, researchers are apt to choose a background activity with a younger age. Third,use of a slightly smaller value of supported 210 Pb activity in a calculation will lead to considerable underestimation of the time span. Finally, later-stage erosion and migration are common for sedimentation, which lead to loss of sedimentary records and are often reflected as a ＂loss of age＂ in cores. We believe that proper use of 210 Pb dating data may provide helpful information on our understanding of sediment records and recent environmental changes.

关键词： ^210Pb dating Sedimentation rate sediment flux

Characteristics of Milankovitch cycles recorded in Eocene strata in the eastern depression of North Yellow Sea Basin, North China

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China Geology 2021年第2期4卷 274-287页

作者： Shu-yu Wu Jun Liu Jian-wen Chen Hao-ran Wu School of Engineering China University of GeoscienceWuhan 430074China Yantai Coastal Zone Geological Survey Center China Geological SurveyYantai 264001China Chinese Academy of Geological Sciences Beijing 100037China The Key Laboratory of Gas Hydrate Ministry of Natural ResourcesQingdao Institute of Marine GeologyQingdao 266071China Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266061China

As cyclical orbital movements of Earth,Milankovitch cycles can be recorded in sedimentary strata.The time they reflect can be used to accurately divide and compare strata.Milankovitch cycles recorded in strata enrich the stratigraphic theory,especially the theories of cycle stratigraphy,and thus they are widely used in geological survey engineering nowadays.This study explored the characteristics of the Milankovitch cycles recorded in the eastern depression of the North Yellow Sea Basin,highlighting their control over high-frequency stratigraphic sequences.The Eocene Milankovitch cycles in the depression were calculated based on the method proposed by J.Laskar,and their parameters primarily include eccentricity cycles of 125 ka and 99 ka,obliquity cycles of 51 ka and 39 ka,and precession cycles of 23 ka and 19 ka.Spectral analysis of gamma-ray(GR)and spontaneous potential(SP)log curves of the Eocene strata was carried out to divide and compare stratigraphic sequences,revealing that the spectral peaks correspond well to astronomical cycles.This indicates that the strata in the depression fully record Milankovitch cycles.Furthermore,there are long-,medium-,and short-term stratigraphic cycles in the eastern depression,with a thickness of 13.03-15.89 m,3.70-5.21 m,and 2.17-2.94 m,respectively.The Sedimentation rates of the Eocene strata were calculated to be 121.2-127.12 m/Ma accordingly.From the uplift to the center of the lacustrine basin along the slope in the eastern depression,both the sedimentation duration and the sediment thickness increase,while the Sedimentation rate remains relatively stable.The Eocene strata can be divided into six stages of high-frequency sequences by continuous wavelet transformation,namely E_(6)-E_(1) from bottom to top.The sedimentation duration and Sedimentation rates of the sequences were calculated using spectral analysis with each of the sequences as a separate window.Moreover,the impacts of climate change on the sedimentary environment in the eastern depression were analyzed.It c

关键词： Milankovitch cycle Sedimentation rate sedimentation duration Geophysics Eocene Geological survey engineering Eastern depression North Yellow Sea Basin(NYSB)

Does Glacial-Interglacial Transition Affect Sediment Accumulation in Monsoon-Dominated Regions?

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Acta Geologica Sinica(English Edition) 2017年第3期91卷 1079-1094页

作者： Dharmendra Pratap SINGH Rajeev SARASWAT Dinesh K.NAIK Micropaleontology Laboratory Geological Oceanography DivisionNational Institute of Oceanography

The spatio-temporal changes in Sedimentation rate along the continental margin of the monsoon-dominated eastern Arabian Sea during the last 24 kyr have been estimated from a compilation of 58 radiocarbon dated cores, in order to understand the effect of glacial-interglacial variation on sedimentation. The Sedimentation rate has been computed for four-time slices, viz. the last glacial maximum, glacial-interglacial transition, early Holocene and late Holocene. We report that the average Sedimentation rate in the slope to the abyssal region of the entire eastern Arabian Sea, although higher during the Holocene as compared with that during the last glacial maximum and glacial-interglacial transition, does not significantly vary during all four-time intervals. The Sedimentation rate during any particular time interval, however, varies from core to core, thus indicating zonal changes. We report four zones of relatively high Sedimentation rate, viz. the northeastern Arabian Sea, the region off the Gulf of Khambhat, the region off Goa and Mangalore, and off the southern tip of India. We suggest that a complex interaction of land-ocean-atmospheric processes controlled Sedimentation rate in the eastern Arabian Sea during the last 24 kyr in such a way that the average Sedimentation rate does not vary significantly, even during highly contrasting climatic conditions.

关键词： Sedimentation rate monsoon glacial Holocene Arabian Sea

sedimentation and morphological changes at Yuantuojiao Point, estuary of the North Branch, Changjiang River

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Acta Oceanologica Sinica 2013年第2期32卷 24-34页

作者： XIE Li ZHANG Zhenke ZHANG Yunfeng WANG Yaping HUANG Xianjin School of Geographic and Oceanographic Sciences Key Laboratory of Coast and Island Development of MOENanjing University School of Resources and Environment of Guangdong University of Business Studies

The North Branch, separated by the Chongming Island, was once the main channel in the estuary of the Changjiang River. Reclamation and a decrease in runoffto the North Branch had led to the narrowing and shallowing of the channel. The Yuantuojiao Point is located at the intersecting point connecting the North Branch of the Changjiang River and the Jiangsu coastline. Erosion cliffs are developed between the typical silty-muddy tidal flat and the salt marsh occupied by Spartina alterniflorea, and this has changed rapidly over the past few years. The sediment grain size analysis results of the surficial and two core samples indi- cate that the Yuantuoiiao Point tidal fiat experienced continuous accretional processes. Based upon 137Cs analysis results of the YT and YY Cores sampled from the tidal flat at the Yuantuojiao Point, the average sed- imentation rate of the YT Core was 2.30 cm/a from 1963 to 2007, and 2.38 cm/a from 1954 to 2007 for the YY Core. The Sedimentation rates of both core locations have declined since the 1960s corresponding to the seaward reclamation at the Yuantuojiao Point. The average Sedimentation rates at the Yuantnojiao Point were similar to that of the silty-muddy tidal flat at the northern ]iangsu coast, but lower than that of the south of the Changjiang River Estuary. According to field morphological investigations from 2006 to 2008 on the salt marsh at the Yuantuojiao Point, cliffs retreated markedly by storm surges and disappeared gradu- ally because of the rapid sedimentation on the silty-muddy tidal flat. The maximum annual retreat reached 10 m. The recent sedimentation and morphological changes of the Yuantuojiao Point tidal flat not only displayed the retreat of the salt marsh and the disappearance of cliffs, but also was accompanied by rapid sedimentation of the silty-muddy tidal flat and the salt marsh, indicating the responses to the tidal currents, storm surges, Spartina alterniflorea trapping sediments and large-scale reclamation. The sediment grain size and their trends, south

关键词： Sedimentation rate morphological changes the tidal fiat salt marsh cliff seaward reclamation Yuantuojiao Point the North Branch of the Changjiang River

Implications of excess ^(210)Pb and ^(137)Cs in sediment cores from Mikawa Bay, Japan

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Journal of Environmental Sciences 2009年第5期21卷 707-712页

作者： LU Xueqiang MATSUMOTO Eiji Tianjin Academy of Environmental Sciences Tianjin 300191 China Graduate School of Environmental Studies Nagoya University Nagoya 464-8601 Japan

Four sediment cores were collected from Mikawa Bay, Japan, and excess ^210pb and ^137Cs were measured by gamma spectrometry. Sedimentation rates for the four cores were determined by ^210Pb method. The Sedimentation rate range is 0.10-0.70 g/（cm^2.year）. The bio-mixing depth for each core is less than 7.0 cm, and was determined by the excess 210^pb profiles as well. Therefore, the bioturbation is slight. The 210^pb-derived dates coincided with the results from ^137Cs geochronology. Acceleration in Sedimentation rate due to environmental alteration has been found in cores A2.5 and 05AS8, representing two depocenters due to their topography. Evidence of the Tokal Flood in 2000 was found in core 05AS8 according to the profiles of both radioisotopes and trace metals.

关键词： ^210pb ^137Cs Sedimentation rate Mikawa Bay

Astronomical Cycles of the Late Permian Lopingian in South China and Their Implications for Third-Order Sea-Level Change

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Journal of Ocean University of China 2020年第6期19卷 1331-1344页

作者： WANG Xiuqi ZHANG Xunhua GAO Fei ZHANG Minghua College of Marine Geosciences Ocean University of ChinaQingdao 266100China Qingdao Institute of Marine Geology China Geological SurveyQingdao 266071China Qingdao Jimo Municipal Transport Bureau Qingdao 266200China The Brigade of Geological Survey of Ganxi Bureau of Geologic Exploration and Mineral Development of Jiangxi ProvinceNanchang 330002China

The late Permian(Lopingian)was a crucial climate transition period from the late Paleozoic Ice Age to the early Triassic of exceptionally high temperatures.However,the origins of the third-order sea-level changes during the Lopingian Epoch remain unclear.Here,we presented astronomically calibrated gamma-ray(GR)log and non-U GR(computed gamma ray or CGR)curves from the clastic and carbonate successions of well GFD-1 in the Pingle Depression of South China for studying the sea-level oscillations during the Lopingian.Spectral analyses of the 405 kyr-calibrated GR and CGR time data revealed periodicities close to about 405,about 100,about 44.2,about 35.1,about 21,and about 17.5 kyr,supporting the existence of Milankovitch forcing in the sedimentary records.A high-resolution astronomical time scale and high-resolution Sedimentation rate curve of the Lopingian from well GFD-1 were constructed by cyclostratigraphic analysis.The eccentricity and obliquity amplitude modulation cycles suggested long periodicities of about 2.4 and about 1.2 myr,respectively.In the Wuchiapingian greenhouse of the Lopingian,the about 2.4 myr eccentricity oscillation controlled‘weak’glacio-eustasy and/or aquifer eustatic changes related to the global third-order sea-level changes and that a lowstand(W2)was initiated by an eccentricity oscillation minimum.In contrast,during the Changhsingian,which exhibited a cooling event,an about 1.2 myr obliquity cycle was probably strong,with the sea-level records highlighting the link between the‘icehouse’sea-level lowering(C2 and C1)and the obliquity nodes.Moreover,dynamic sedimentary noise model as an indicator of sea-level showed local third-order sea-level variations,the coevolution trends in the orbital power,global and local sea-level changes,and Sedimentation rate had significant implications for establishing the global nature and synchronicity of these million-year-scale eustatic records and reconstructing the temporal depositional history at a regional scale.In addition,the volcanism and tectonism

关键词： Lopingian Milankovitch cycle third-order eustasy long-period astronomical cycle Sedimentation rate

Grain-Size Distribution of Surface Sediments in the Bohai Sea and the Northern Yellow Sea: Sediment Supply and Hydrodynamics

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Journal of Ocean University of China 2020年第3期19卷 589-600页

作者： YUAN Ping WANG Houjie WU Xiao BI Naishuang College of Marine Geosciences/Key Laboratory of Submarine Geosciences and Prospecting Techniques MOEOcean University of ChinaQingdao 266100China Laboratory of Marine Geology Qingdao National Laboratory of Marine Science and TechnologyQingdao 266237China

The grain-size distribution of surface sediments in the Bohai Sea(BS) and the northern Yellow Sea(NYS), and its relationship with sediment supply and hydrodynamic environment were investigated based on grain-size compositions of surface sediments and modern Sedimentation rates. The results showed that the surface sediments in the BS and the NYS were primarily composed of silty sand and clayey silt with a dominant size of silt. In addition, the Yellow River delivered high amount of water and sediments to the BS, and they are dominated in surface sediments(mainly silt) in the Bohai Bay, the Yellow River mouth, the center of the BS, and the north coast of Shandong Peninsula. The coarse-grained sediments were mainly deposited at the river mouth due to the estuarine filtration and physical sorting. Meanwhile, there was a significant relationship among the modern Sedimentation rate, the surface sediment grain size distribution and sediment transport pattern. The areas with coarser surface sediments generally corresponded low Sedimentation rates because of strong erosion;whereas the Sedimentation rate was relatively high at the place that the surface sediments were fine-grained. Furthermore, the grain-size trend analysis showed that the areas with fine-grained surface sediments such as the mud area in the central BS and the upper Liaodong Bay were the convergent centers of surface sediments, except for the Bohai Bay and the subaqueous Yellow River Delta where offshore sediment transport was evident.

关键词： Bohai Sea and North Yellow Sea surface sediment grain size Sedimentation rate sediment supply sedimentary dynamic environment