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Offshore high-grade limemud resources of west coast of India:Economic potential and industrial applications

Deep Underground Science and Engineering 2024年第2期3卷 163-170页

作者： Anil Kumar Adukadukkam Rachna Pillai Mamatha Puthiyathara Kanakamma marine&coastal survey division Geological Survey of IndiaSalt LakeKolkataWest BengalIndia

Limestone is one of the essential raw materials in the cement,paint,steel,ceramic,glass,chemical,pharmaceutical,paper,and fertilizer *** India,only 8%of the limestone resources are placed under the reserve category,of which 97%is of cement ***,India depends on imports to bridge the demand‐supply gap of steel,blast furnace,and chemical‐grade *** of Geological survey of India(GSI)to locate alternate sources for limestone led to the discovery of enormous quantities of carbonate minerals called limemud from the continental shelf margin of the west coast of *** carried out systematic studies to explore the nature of the disposition,quality,quantity,and suitability of the offshore limemud for various industrial applications.A preliminary estimate of resources using high‐resolution subbottom profiling and sediment core sample studies established the occurrence of more than 172 billion tonnes of high‐grade(The content of CaCO3 is greater than 80 wt%)limemud in 0.4–28.0m thick stratified sediment layers spread over an area of 18000 ***,physical,mineralogical,beneficiation,and agglomeration studies found the offshore limemud as a potential replacement for limestone in the cement,filler,blast furnace,steel melting shop,lime production,paint,and Grade‐I steel *** assessment of mining and transportation costs indicates that the offshore limemud(USD 5–6/ton)is more cost‐effective than that imported from other countries(USD16‐18/ton).With several advantageous factors like low impurity,mode of occurrence in overburden‐free stratified form,fine‐grained slurry nature,and shallow water depth,sustainable mining of offshore limemud could be a future reality with controllable technological,economic,and environmental challenges.

关键词： beneficiation industrial grade offshore limemud west coast of India

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Micro-textures in plagioclase from 1994-1995 eruption, Barren Island Volcano: Evidence of dynamic magma plumbing system in the Andaman subduction zone

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Geoscience Frontiers 2014年第1期5卷 113-126页

作者： M.L.Renjith marine and coastal survey division Geological Survey of India 4th Floor C-Block Kendriya Bhavan Kakkanadu CochinKerala 682037 India

A systematic account of micro-textures and a few compositional profiles of plagioclase from high-alumina basaltic aa lava erupted during the year 1994-1995, from Barren Island Volcano, NE India ocean, are presented for the first time. The identified micro-textures can be grouped into two categories：（i） Growth related textures in the form of coarse/fine-sieve morphology, fine-scale oscillatory zoning and resorption surfaces resulted when the equilibrium at the crystal-melt interface was fluctuated due to change in temperature or H20 or pressure or composition of the crystallizing melt; and （ii） morphological texture, like glomerocryst, synneusis, swallow-tailed crystal, microlite and broken crystals, formed by the influence of dynamic behavior of the crystallizing magma （convection, turbulence, degassing, etc.）. Each micro-texture has developed in a specific magmatic environment, accordingly, a first order magma plumbing model and crystallization dynamics are envisaged for the studied lava unit. Magma generated has undergone extensive fractional crystallization of An-rich plagioclase in stable magmatic environment at a deeper depth. Subsequently they ascend to a shallow chamber where the newly brought crystals and pre-existing crystals have undergone dynamic crystallization via dissolution-regrowth processes in a convective self- mixing environment. Such repeated recharge-recycling processes have produced various populations of plagioclase with different micro-textural stratigraphy in the studied lava unit. Intermittent degassing and eruption related decompression have also played a major role in the final stage of crystallization dynamics.

关键词： Micro-texture Plagioclase Magma chamber process Barren Island Volcano Andaman subduction zone

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Grain to outcrop-scale frozen moments of dynamic magma mixing in the syenite magma chamber,Yelagiri Alkaline Complex,South India

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Geoscience Frontiers 2014年第6期5卷 801-820页

作者： M.L.Renjith S.N.Charan D.V.Subbarao E.V.S.S.K.Babu V.B.Rajashekhar marine and coastal survey division Geological Survey of IndiaCochin 682037India Geochemistry division CSIR-National Geophysical Research InstituteHyderabad 500007India New Zealand Petroleum and Minerals Wellington 6037New Zealand

Magma mixing process is unusual in the petrogenesis of felsic rocks associated with alkaline complex worldwide. Here we present a rare example of magma mixing in syenite from the Yelagiri Alkaline Complex, South India. Yelagiri syenite is a reversely zoned massif with shoshonitic (Na2O t K2O?5e 10 wt.%, Na2O/K2O ? 0.5e2, TiO2<0.7 wt.%) and metaluminous character. Systematic modal variation of plagioclase (An11e16 Ab82e88), K-feldspar (Or27e95 Ab5e61), diopside (En34e40Fs11e18Wo46e49), biotite, and Ca-amphibole (edenite) build up three syenite facies within it and imply the role of in-situ fractional crystallization (FC). Evidences such as (1) disequilibrium micro-textures in feldspars, (2) microgranular mafic enclaves (MME) and (3) synplutonic dykes signify mixing of shoshonitic mafic magma (MgO ? 4e 5 wt.%, SiO2 ? 54e59 wt.%, K2O/Na2O ? 0.4e0.9) with syenite. Molecular-scale mixing of mafic magma resulted disequilibrium growth of feldspars in syenite. Physical entity of mafic magma preserved as MME due to high thermal-rheological contrast with syenite magma show various hybridization through chemical exchange, mechanical dilution enhanced by chaotic advection and phenocryst migration. In synplutonic dykes, disaggregation and mixing of mafic magma was confined within the conduit of injec-tion. Major-oxides mass balance test quantified that approximately 0.6 portions of mafic magma had interacted with most evolved syenite magma and generated most hybridized MME and dyke samples. It is unique that all the rock types (syenite, MME and synplutonic dykes) share similar shoshonitic and met-aluminous character;mineral chemistry, REE content, coherent geochemical variation in Harker diagram suggest that mixing of magma between similar composition. Outcrop-scale features of crystal accumu-lation and flow fabrics also significant along with MME and synplutonic dykes in syenite suggesting that Yelagiri syenite magma chamber had evolved through multiple physical processes like

关键词： Magma mixing Disequilibrium textures Petrology Synplutonic dykes Geodynamics

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Global parameter estimation of the Cochlodinium polykrikoides model using bioassay data

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Acta Oceanologica Sinica 2016年第2期35卷 39-45页

作者： CHO Hong-Yeon PARK Kwang-Soon KIM Sung coastal and Environmental Engineering division Korea Institute of Ocean Science and Technology coastal Disaster Research Center Korea Institute of Ocean Science and Technology Biological Oceanography and marine Biology division Korea Institute of Ocean Science and Technology

Cochlodinium polykrikoides is a notoriously harmful algal species that inflicts severe damage on the aquacultures of the coastal seas of Korea and Japan. Information on their expected movement tracks and boundaries of influence is very useful and important for the effective establishment of a reduction plan. In general, the information is supported by a red-tide（a.k.a algal bloom） model. The performance of the model is highly dependent on the accuracy of parameters, which are the coefficients of functions approximating the biological growth and loss patterns of the C. polykrikoides. These parameters have been estimated using the bioassay data composed of growth-limiting factor and net growth rate value pairs. In the case of the C. polykrikoides, the parameters are different from each other in accordance with the used data because the bioassay data are sufficient compared to the other algal species. The parameters estimated by one specific dataset can be viewed as locally-optimized because they are adjusted only by that dataset. In cases where the other one data set is used, the estimation error might be considerable. In this study, the parameters are estimated by all available data sets without the use of only one specific data set and thus can be considered globally optimized. The cost function for the optimization is defined as the integrated mean squared estimation error, i.e., the difference between the values of the experimental and estimated rates. Based on quantitative error analysis, the root-mean squared errors of the global parameters show smaller values, approximately 25%–50%, than the values of the local parameters. In addition, bias is removed completely in the case of the globally estimated parameters. The parameter sets can be used as the reference default values of a red-tide model because they are optimal and representative. However, additional tuning of the parameters using the in-situ monitoring data is highly *** opposed to the bioassay d

关键词： global and local estimation gain and loss parameters Cochlodinium polykrikoides bioassay data model performance

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Deposition processes of gas hydrate-bearing sediments in the inter-canyon area of Shenhu Area in the northern South China Sea

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Journal of Oceanology and Limnology 2023年第2期41卷 740-756页

作者： Zhixuan LIN Ming SU Haiteng ZHUO Pibo SU Jinqiang LIANG Feifei WANG Chengzhi YANG Kunwen LUO School of marine Sciences Sun Yat-sen UniversityZhuhai 519082China Guangdong Provincial Key Laboratory of marine Resources and coastal Engineering Guangzhou 510006China Southern marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519000China Guangzhou marine Geological survey China Geological SurveyMinistry of Natural ResourcesGuangzhou 511458China

The Shenhu Submarine Canyon Group on the northern slope of the South China Sea consists of 17 slope-confined canyons,providing a good example for investigating their hosting *** drilling sites,including W07,W18,and W19,have proven the occurrence of gas hydrate reservoirs in the inter-canyon area between canyons C11 and ***,variations of the geomorphology and seismic facies analyzed by high-resolution 3D seismic data indicate that the gas hydrate-bearing sediments may form in different sedimentary *** the upper segment,a set of small-scale channels with obvious topographic lows can be identified,revealing fine-grained turbidites supplied from the shelf region during a very short-term sea-level *** the middle part,gas hydrate units at Site W07 showing mounded or undulation external configuration are interpreted as sliding sedimentary features,and those features caused by gravity destabilization were the main formative mechanism of gas hydrate-bearing sediments that were sourced from the upper *** contrast,for the canyon transition zone of lower segments between C11-C12 inter-canyon and C12 intra-canyon areas,where W18 and W19 sites are located,the gas hydratebearing sediments are deposited in the channelized feature in the middle to lower segment and slide erosive *** hydrate-bearing sediments of the lower segment were migrated through channelized features interconnecting with the middle to lower slope by gravity-driven *** majority of deposits tended to be furtherly moved by lateral migration via erosive surface created by sediment failed to intra-canyon *** conclusion of this study may help better understand the interaction between the formation mechanism of gas hydrate-bearing sediments and the geomorphologic effects of inter-canyon areas.

关键词： submarine canyons gas hydrate-bearing sediments seismic geomorphology inter-canyon transport process

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Late Quaternary Strata and Carbon Burial Records in the Yellow River Delta, China

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Journal of Ocean University of China 2015年第3期14卷 446-456页

作者： ZHAO Guangming YE Siyuan LI Guangxue DING Xigui YUAN Hongming College of marine Geo-science Ocean University of China The Key Laboratory of coastal Wetlands Biogeosciences China Geologic Survey The Key Laboratory of marine Hydrocarbon Resource and Geology Ministry of Land and Resources

Sediment carbon sequestration plays an essential role in mitigating atmospheric CO2 increases and the subsequently global greenhouse effect. To clarify the late Quaternary strata and carbon burial records in YeUow River delta （YRD）, detailed analysis of benthic foraminifera, total carbon （TC）, organic carbon （Corg）, sedimentary characteristics and moisture contents of sediments, was performed on core ZK3, 30.3 m in length and obtained from YRD in 2007. Eight depositional units （designated U1-U8 in ascending order） were identified. A comprehensive analysis method of historical geography and sedimentary geology was used to de- termine the precise depositional ages of the modem Yellow River delta （MYRD）, from which pre-MYRD ages were deduced. The results indicates that the maximum burial rates of TC, inorganic carbon （IC） and Corg occurred in the delta front （U5）, and the mini- mum in the shallow sea （U3）. Remarkable high sedimentation rates in the MYRD are responsible for burial efficiency of carbon, with an average rate of Corg burial reaching 2087±251 g（m2yr）-1, and that of IC reaching 13741±808g（m2yr）-1, which are much higher than those of other regions with high contents of Corg. Therefore, YRD has a significant burial efficiency for carbon sequestration.

关键词： Yellow River delta late Quaternary strata carbon burial rate organic carbon inorganic carbon

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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

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Assessing the benthic quality status of the Bohai Bay(China)with proposed modifications of M-AMBI

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Acta Oceanologica Sinica 2015年第10期34卷 111-121页

作者： CAI Wenqian BORJA Angel LIN Kuixuan ZHU Yanzhong ZHOU Juan LIU Lusan State Environmental Protection Key Laboratory of Estuary and coastal Environment Chinese Research Academy of Environmental Sciences marine Research division AZTI-Tecnalia

Multivariate AZTI＇s marine Biotic Index （M-AMBI） was designed to indicate the ecological status of European coastal areas. Based upon samples collected from 2009 to 2012 in the Bohai Bay, we have tested the response of variations of M-AMBI, using biomass （M-BAMBI） in the calculations, with different transformations of the raw data. The results showed that the ecological quality of most areas in the study indicated by M-AMBI was from moderate to bad status with the worse status in the coastal areas, especially around the estuaries, harbors and ouffalls, and better status in the offshore areas except the area close to oil platforms or disposal sites. Despite large variations in nature of the input data, all variations of M-AMBI gave similar spatial and temporal distribution patterns of the ecological status within the bay, and showed high correlation between them. The agreement of new ecological status obtained from all M-AMBI variations, which were calculated according to linear regression, was almost perfect. The benthic quality, assessed using different input data, could be related to human pressures in the bay, such as water discharges, land reclamation, dredged sediment and drilling cuts disposal sites. It seems that M-BAMBI were more effective than M-NABMI （M-AMBI calculated using abundance data） in indicating human pressures of the Bay. Finally, indices calculated with more severe transformations, such as presence/absence data, could not indicate the higher density of human pressures in the coastal areas of the north part of our study area, but those calculated using mild transformation （i.e., square root） did.

关键词： macrozoobenthos M-AMBI abundance biomass data transformation ecological status

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Geochemical characteristics of cold-seep carbonates in Shenhu area,South China Sea

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Journal of Oceanology and Limnology 2022年第3期40卷 969-985页

作者： Chongmin CHEN Lifeng ZHONG Zhifeng WAN Chiyu CHENG Wei ZHOU Xing XU School of marine Sciences Guangdong Provincial Key Laboratory of Marine Resources and Coastal EngineeringSun Yat-sen UniversityZhuhai 519000China Southern marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519000China MLR Key Laboratory of marine Mineral Resources Guangzhou Marine Geological SurveyMinistry of Natural ResourcesGuangzhou 510075China

Cold seeps spread worldwide along the continental margins,which are closely related to the exploration of gas ***-seep carbonates have been reported to record the nature of seepage,including fluid source,sedimentary environment,and variation of seepage *** investigated the morphology,mineralogy,element compositions,and carbon and oxygen isotopes of 15 cold-seep carbonates collected from the Shenhu area,and compared them with 2 carbonates from the Haima cold seep,the South China Sea(SCS),to promote our knowledge of cold-seep system in *** of the Shenhu carbonates exhibit crust morphology,and some are in the form of chimneys and *** absolute(20%–65%)and relative carbonate mineral contents(mainly aragonite and calcite,with minor samples containing dolomite)vary significantly,indicating the multi-stage methane leakage in our study *** samples show a slight negative Ce anomaly,suggesting either the mixing of seawater or variation of the redox condition during the precipitation;the cooccurrence of strongly enriched U and Mo demonstrates anoxic condition during *** mixed genetic methane source was interpreted by δ^(13)C of the Shenhu carbonates to range from-22.34‰to-59.30‰Vienna PeeDee Belemnite(VPDB),and the slight ^(18)O-enrichment imprinted on the carbonates suggests the possible influence from hydrate *** Haima carbonates,with biogenic methane as the main gas source,were presumably formed in a stronger fluid flux by compared with our Shenhu samples.

关键词： cold-seep carbonates geochemistry sedimentary environment fluid source Haima cold seep Shenhu area South China Sea

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Towards automated validation of charted soundings:Existing tests and limitations

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Geo-Spatial Information Science 2019年第4期22卷 290-303,I0006页

作者： Christos Kastrisios Brian Calder Giuseppe Masetti Peter Holmberg Center for coastal and Ocean Mapping/UNH-NOAA Joint Hydrographic Center University of New HampshireDurhamNHUSA U.S.Department of Commerce National Oceanic and Atmospheric AdministrationNational Ocean ServiceOffice of Coast SurveyHydrographic Survey DivisionSeattleWAUSA

The nautical chart is one of the fundamental tools in navigation used by mariners to plan and safely execute *** compilation follows strict cartographic constraints with the most prominent being that of the ***,the cartographer is called to make the selection of the bathymetric information for portrayal on charts in a way that,at any location,the expected water depth is not deeper than the source *** validate the shoal-biased pattern of selection two standard tests are used,*** triangle and edge *** date,some efforts have been made towards the automation of the triangle test,but the edge test has been largely *** the context of research on a fully automated solution for the compilation of charts at different scales from the source information,this paper presents an algorithmic implementation of the two tests for the validation of selected *** a case study with real-world data,it presents the improved performance of the implementation near and within depth curves and coastlines and points out the importance of the edge test in the validation *** also presents the,by definition,intrinsic limitation of the two tests as part of a fully automated solution and discusses the need for a new test that will complement or supersede the existing ones.

关键词： Automated nautical cartography nautical chart generalization chart safety constraint sounding generalization nautical surface test sounding selection category zone of confidence

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