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1.
本文对采自南大西洋受不同程度热液活动影响的表层沉积物样品进行了元素和矿物组成分析,并对热液沉积物的碳酸盐相、Fe-Mn氧化物相和残渣态进行了一系列顺序提取实验。选用不同浓度的盐酸羟胺(HH)和醋酸(HAc)混合溶液对样品的Fe-Mn氧化物相进行提取,通过分析不同实验条件下Fe-Mn氧化物相Ti/Nd、Ti/Pb比值和Fe-Mn氧化物相、残渣态的稀土元素(REE)标准化配分模式及Ce和Eu异常值,确定了不同类型热液沉积物样品Fe-Mn氧化物相提取的理想试剂条件均为0.5 mol/L HH和25% HAc混合溶液。研究结果表明,受热液活动影响程度越高,沉积物中Fe、Cu、Zn等元素含量越高,Ca、Sr、Ba含量呈相反趋势,Mn、Pb和REE未受到热液活动明显影响;随着受热液活动影响增强,Ca、Sr、Nd在Fe-Mn氧化物相中所占比例增加,在残渣态中降低,Mn、Co、Ni和Zn呈相反趋势,Cu在碳酸盐相所占比例增加,在残渣态中降低,Pb赋存状态不受热液活动影响,主要赋存于Fe-Mn氧化物相;REE主要赋存于残渣态,沉积物受热液活动影响越明显,残留相对REE富集能力越强,残渣态REE球粒陨石标准化配分模式表现为LREE相对富集越来越不明显的特征。本文研究为进一步了解南大西洋热液沉积物特征和热液活动对沉积物元素赋存状态影响提供了方法和地球化学数据支持。  相似文献   

2.
渤海湾沉积物中若干重金属的存在形式   总被引:1,自引:1,他引:0  
重金属在沉积物中以不同形式存在[1-5].人为因素引起的重金属在沉积物中的积累主要以有效态的形式存在,而那些呈残渣态的重金属基本是自然界中地质过程的产物. 近年来,有些人对渤海湾重金属进行了研究.但对其在沉积物中的存在形式尚未见报道.本文采用分步提取方法,探讨重金属在渤海湾沉积物中的5种赋存形式,即可交换态、碳酸盐态、Fe-Mn氧化物态、有机态和残渣态,并与邻近岸段和渤海中部进行对比.  相似文献   

3.
冲绳海槽有孔虫壳体的微量元素Sr,Nd同位素地球化学   总被引:7,自引:1,他引:6  
钙质生物壳的微量元素组合和Sr,Nd同位素组成是识别海底混合源沉积物中生物源物质相对贡献的重要参数.冲绳海槽有孔虫壳体强烈富集Sr,P,Mn和Ba,富集Li,U,Th,Sc,Co,Pb,Zn,Cr,Rb,Y,Sb和轻稀土元素,弱富集V,Ga,Zr,Nb,Cd和中稀土元素,相对贫Ge,Mo,In,Sn,Cs,Hf,Ta,W,Tl,Bi和重稀土元素,海水中微量元素的背景含量和生物活动对微量元素的选择性吸收是有孔虫壳体中微量元素发生富集和贫化的主要机制,冲绳海槽有孔虫壳体的稀土元素配分模式与海水和太平洋有孔虫的有明显差异,表现出中稀土元素相对富集,并具有微弱的负Ce异常.有孔虫壳体的Sr,Nd同位素比值也与大洋海水不同,分别为0.709769和0.512162,前者略高于大洋海水,后者略低于大洋海水,表明冲绳海槽海水明显受大陆河水影响.  相似文献   

4.
地质样品Sr和Nd同位素的化学分离方法改进   总被引:2,自引:0,他引:2       下载免费PDF全文
多接收器等离子体质谱仪(MC-ICP-MS)高精度同位素组成的准确测定,依赖于对样品中待测元素的分离纯化。改进了Rb-Sr和Sm-Nd化学分离方法,检测AG50W-X12树脂及P507萃淋树脂对Rb-Sr和Sm-Nd的分离效果,并通过测定标准物质中Sr和Nd的同位素组成进行验证。结果表明,AG50W-X12树脂经2次分离能有效去除Rb,满足MC-ICP-MS高精度测定Sr同位素比值的要求;P507萃淋树脂能很好实现Sm-Nd分离,同时去除大部分Ce,满足仪器高精度测定Nd同位素比值的需要。  相似文献   

5.
南海东部海域表层沉积物锶同位素物源示踪研究   总被引:12,自引:3,他引:9       下载免费PDF全文
锶同位素作为物源示踪剂和计时器在海洋地球化学研究中得到了广泛应用,南海东部海域沉积物中非碳酸盐相物质由慢源型火山物质和陆源硅铝物质组成,两者呈互为消长关系,由北向南陆源物质逐渐减少而慢源物质逐渐增多,海盆内发育的火山喷发是慢源型物质的主要来源,陆源物质主要是中国大陆碎屑物质经台湾海峡进入南海,南海东部海域非碳酸盐相沉积物87Sr/86Sr比值分布特点是:(1)陆架和陆坡边缘沉积物中87Sr/86Sr比值高(0.718 994),向东至深海盆东部边缘逐渐降低(0.713 545);(2)东沙群岛、中沙群岛周围海区87Sr/86Sr比值小(0.709 232);(3)台湾海峡南部87Sr/86Sr比值(0.717 940)接近地壳平均值,黄岩岛附近87Sr/86Sr比值(0.704 241),与幔源物质的锶同位素组成一致,这种分布规律说明中国大陆物质对南海东部海域沉积物的贡献由西向东、由北向南逐渐减小,对幔源基性岩组分和陆源硅铝质组分计算得出,东沙群岛以东、黄岩岛以北海区沉积物中陆源硅铝质组分平均含量为87%,台湾省南部基性岩组分含量不到10%,黄岩岛周围基性岩组分含量接近50%,来自台湾海峡的陆源物流向南一直延伸到17°N左右。幔源基性岩组分和陆源硅铝质组分理论计算值与区内沉积物中火山碎屑、陆源碎屑实际分布相一致。  相似文献   

6.
东菲律宾海表层沉积物中元素的赋存状态   总被引:2,自引:0,他引:2  
为了解东菲律宾海不同类型表层沉积物中元素的赋存状态,采用化学提取方法对有无新型铁锰结壳发育站位表层沉积物样品进行了分级提取及测试,不同类型表层沉积物中成矿和稀土元素的赋存状态总体一致,表明研究区表层沉积物形成于相似的地质和海洋环境中。成矿元素中Fe绝大部分赋存在残渣态中,Mn、Cu、Co和Ni则主要赋存在铁锰氧化物结合态中,稀土元素也主要赋存在这两个相态中,碳酸盐结合态、铁锰氧化物结合态和有机结合态对重稀土元素优先吸附或具络合作用,引起重稀土元素的相对富集和铈的负异常,残渣态优先吸附轻稀土元素,导致轻稀土元素的富集和铈的正异常,火山物质则使表层沉积物残渣态表现出铕的正异常特征。同时,不同表层沉积物样品间也存在一定的差异,这与其局部形成条件——铁锰结壳发育与否有关。  相似文献   

7.
对东太平洋1枚水成结核和2枚成岩-水成混成结核共25个微层样品进行了同位素质谱分析和等离子光谱分析,取得了结核壳层的^87Sr/^86Sr、^143Nd/^144Nd比值以及Mn,Fe,Ti,Al、稀土元素等含量,以此为基础探讨了不同类型结核中Sr-Nd同位素特征及地质意义。在水成结核A99中^87Sr/^86Sr比值与εNd值呈弱正相关,在成岩-水成混成结核5737G和5739G中^87Sr/^86Sr比值与εNd值呈负相关。^87Sr/^86Sr比值与εNd值在A99结核剖面中的分布反应了东太平洋10Ma(晚中新世)以来海水受到了强→弱→强的火山作用影响;^87Sr/^86Sr比值与εNd在5739G结核剖面中的变化表明成岩作用结核的生长起了重要的作用;而5737G结核剖面中的变化则反应了火山作用对结核的成长起了较大作用 。同时所有类型结核的初始壳层都具有较高的εNd值,表明火山作用突然加强可能是结核生长的一个重要驱动机制。  相似文献   

8.
为了解海底热液活动对沉积物元素赋存状态的影响,对东太平洋海隆(EPR)13°N和赤道附近表层沉积物样品17A-EPR-TVG1、17A-EPR-TVG5做了全样及顺序提取分析,探讨了Al、Ca、Fe、Mn、Ti、Ba、Zn、Cu、Sr、V、Mo、U及稀土元素赋存状态。XRD结果显示,17A-EPR-TVG1沉积物的主要矿物形态为黄铁矿,17A-EPR-TVG5沉积物样品主要矿物为方解石。受热液影响明显的17A-EPR-TVG1沉积物中,除Ca、Sr外,其余元素主要赋存于铁锰氧化物与残留相中。正常深海沉积物17A-EPR-TVG5中,除Al、Ba、Ti外,其余元素主要赋存于碳酸盐相及铁锰氧化物相中。稀土元素的顺序提取结果显示,17A-EPR-TVG1沉积物4个相态稀土元素北美页岩配分曲线中均有Eu正异常,17A-EPR-TVG5沉积物4个相态稀土元素北美页岩配分曲线中均出现Ce负异常,分别指示了二者形成过程中热液与海水的加入。  相似文献   

9.
系统采集了浙闽三条中小河流的代表性表层沉积物和悬浮物样品,用1N盐酸淋滤样品,研究稀土元素(REE)在酸溶及酸不溶相态中的组成特征。浙闽河流沉积物酸溶组分中的REE在总REE中的占比可达32%~82%,其中Fe-Mn氧化物和黏土矿物吸附态是细粒沉积物酸溶组分REE的主要赋存形式。浙闽河流沉积物酸溶组分的REE组成反映其遭受化学风化的信息;酸不溶组分主要由硅酸盐造岩矿物和稳定副矿物组成,尤其是锆石对REE组成有重要贡献。酸不溶相REE组成揭示,当地流域风化物质与潮流作用带入的长江源细颗粒是浙闽河口沉积物的主要来源。REE在风化及水动力分选过程中会发生分异,使得沉积物全岩组成不直接继承其源岩的REE组成特征,运用于物源判别时候需要慎重。中国东南河流沉积物显示Gd异常,这不是人类活动引起的Gd输入所致,而只反映中国东部物质的组成特征。  相似文献   

10.
太平洋海山富钴结壳中铂族元素赋存状态与富集机理   总被引:2,自引:1,他引:1  
通过选择性化学提取法,对太平洋采薇海山富钴结壳样品中铂族元素进行分级提取实验,利用电感耦合等离子体质谱仪(ICP-MS)测定了铂族元素含量。赋存状态结果显示,富钴结壳中铂族元素在各个化学相态中富集比例从大到小依次为:铁氧化物相、残渣态、锰氧化物相、碳酸盐相、吸附态,未磷酸盐化新壳层和磷酸盐化老壳层中铂族元素都主要赋存于铁氧化物相中,其富集比例为59.26%~82.19%,残渣态中磷酸盐对铂族元素具有一定的富集能力,其富集比例为17.23%~35.37%。不同类型地质体中铂族元素的赋存状态结果,也证实了富钴结壳和海山结核中铂族元素富集主要受到铁氧化物相和残渣态的影响。太平洋海山富钴结壳中铂族元素的富集机理推测为铁氧/氢氧化物胶体粒子的吸附作用,使海水中PtC l24-离子被吸附到铁氧化物相中,从而使富钴结壳中铂族元素富集。  相似文献   

11.
梁宏锋 《海洋科学》1996,20(3):19-24
DSDP与ODP的深入研究,发展了微量元素和稳定同位素地球化学。全球变化、大规模构造隆起和海底扩张等在微量元素和稳定同位素演化上的反映,使微量元素及稳定同位素地球化学成为地层划分对比的重要手段。  相似文献   

12.
利用1994年85-904航次获取的冲绳海槽中段表层沉积物样品,测定其硅酸盐相的^87Sr/^86Cr和^143Nd/^144Nd比值,以定量研究冲绳海槽中段表层沉积物硅酸盐物质的来源,结果表明,冲绳海槽中段陆坡区表层沉积物硅酸盐相的^87Sr/^86Sr/^143Nd/^144Nd与东海陆架沉物硅酸盐相的^87Sr/^86Sr和^143Nd/^143Nd相当,槽底和东坡沉积物硅酸盐相的^87Sr/^86Cr和^143Nd/^144Nd值介于中国大陆硅酸盐物质和海槽水山碎屑的^87Sr/^86Sr,^143Nd/^144Nd比值之间,并大致具有两端员混合特征,利用以Sr同位素为参数的二端员混合方程进行物源定量分析的结果表明,冲绳海槽中段的西坡和槽底表层沉积物硅酸盐相以陆源物质为主,最大值为91.07%,由西向东,陆源物逐渐减少,在海槽东坡含量最小,最小值为9.93%,火山源物质在东坡含量最高,量大值为64.92%,由东向西,由北向东,火山源物质逐渐减少为零。  相似文献   

13.
One hundred and ten carbon and nineteen strontium isotopic values of outcropping Cambrian Series 2 and Series 3 carbonate rocks in the Penglaiba section of the Keping area were analyzed. Effective isotopic data with little influence of diagenesis were used to address the global correlation. The δ13C values exhibit two major positive excursions (peaking at 3.1‰ and 3.3‰) and three major negative excursions (peaking at −3.0‰, −4.2‰ and −3.2‰). The carbon isotope excursions (peaking at −3.0‰ and −4.2‰) across the Cambrian Series 2-Series 3 boundary show good correlations with similar variations reported in Siberia, Laurentia, North China and South China. In contrast, the other three carbon isotope excursions (peaking at 3.1‰, 3.3‰ and −3.2‰) do not have a fairly good global correlation because of the lack of biostratigraphic data. With respect to the 87Sr/86Sr ratios, they show good correlation with those reported for Laurentia, and further support the global δ13C comparison. On the basis of these new data, it is showed that the combination of δ13C curves and 87Sr/86Sr variations serves as a powerful tool for correlation and subdivision of Cambrian strata in the Tarim Basin of northwest China, and provides new data for global correlation.  相似文献   

14.
新测得 TAG热液区中 6件海底表层热液沉积物样品的铅同位素组成 ,其变化范围不大 ,具有均一性的特征。在 Pb- Pb图解上 ,热液沉积物的铅同位素数据大多落在 MARB的铅同位素组成范围内 ,与大西洋沉积物和 Fe- Mn结核相比明显具较少的放射成因铅 ,反映其上部洋壳岩石为该区热液沉积物的形成提供了铅。对比研究表明 ,因不同地质 -构造环境中的海底热液区为热液沉积物形成提供物源的情况不同 ,是导致有沉积物覆盖洋中脊中热液沉积物的铅同位素组成与无沉积物覆盖洋中脊不同的主要原因。海底扩张中心的扩张速率与热液沉积物的铅同位素组成有一定的对应关系 ,但其并不是热液沉积物铅同位素组成的唯一控制因素  相似文献   

15.
不同沉积环境和沉积机制下进入海洋沉积物中的元素分别与不同介质结合,因此,将沉积物中不同结合形态元素相分离的顺序萃取方法是研究沉积物源和沉积环境的重要手段。以Tessier等建立的萃取流程为基础,针对深海沉积物标准物质GBW07315中Fe、Mn、Co、Cu、V元素,分析了方法的准确性和重复性。结果表明:各元素回收率基本介于94%~126%之间,平均值为106%。在重复性方面,除V元素在铁锰氧化物结合态中的相对标准偏差较高外,其余元素在铁锰氧化物结合态、有机结合态以及残渣态中的相对标准偏差均低于15%,而碳酸盐结合态和可交换态中元素的相对标准偏差较大,这与其样品中这些结合态的元素含量相对较低有关。因此,对于深海沉积物来讲,顺序萃取法具有较好的稳定性和可靠性,尤其是对其中铁锰氧化物结合态、有机结合态和残渣态的萃取效果令人满意。将该方法应用于冲绳海槽热液影响沉积物中,实现了热液源铁锰氧化沉积的有效萃取和分离。  相似文献   

16.
A cross-system analysis of bulk sediment composition, total organic carbon (TOC), atomic C/N ratio, and carbon isotope composition (δ13C) in 82 surface sediment samples from natural and planted mangrove forests, bank and bottom of tidal creeks, tidal flat, and the subtidal habitat was conducted to examine the roles of mangroves in sedimentation and organic carbon (OC) accumulation processes, and to characterize sources of sedimentary OC of the mangrove ecosystem of Xuan Thuy National Park, Vietnam. Sediment grain sizes varied widely from 5.4 to 170.2 μm (mean 71.5 μm), with the fine sediment grain size fraction (< 63 μm) ranging from 11 to 99.3% (mean 72.5%). Bulk sediment composition suggested that mangroves play an important role in trapping fine sediments from river outflows and tidal water by the mechanisms of tidal current attenuation by vegetation and the ability of fine roots to bind sediments. The TOC content ranged from 0.08 to 2.18% (mean 0.78%), and was higher within mangrove forests compared to those of banks and bottoms of tidal creeks, tidal flat, and subtidal sediments. The sedimentary δ13C ranged from − 27.7 to − 20.4‰ (mean − 24.1‰), and mirrored the trend observed in TOC variation. The TOC and δ13C relationship showed that the factors of microbial remineralization and OC sources controlled the TOC pool of mangrove sediments. The comparison of δ13C and C/N ratio of sedimentary OC with those of mangrove and marine phytoplankton sources indicated that the sedimentary OC within mangrove forests and the subtidal habitat was mainly composed of mangrove and marine phytoplankton sources, respectively. The application of a simple mixing model showed that the mangrove contribution to sedimentary OC decreased as follows: natural mangrove forest > planted mangrove forest > tidal flat > creek bank > creek bottom > subtidal habitat.  相似文献   

17.
The oxygen (δ18O) and carbon (δ13C) isotope ratios of 10 species of living Bryozoa collected from the Otago Shelf, New Zealand were analysed to assess the extent to which isotopic equilibrium (relative to inorganic equilibrium isotope fractionation) is attained during the precipitation of skeletal calcium carbonate. The data reveal that whereas eight species of Bryozoa synthesise skeletal carbonate in apparent oxygen isotope equilibrium with respect to environmental conditions, two species (Celleporina grandis and Hippomonavella flexuosa) yield δ18Ocalcite values which indicate significant disequilibrium oxygen isotope fractionation during calcification. Sufficient data are available from one species (C. grandis) to demonstrate that disequilibrium is probably related to kinetic factors associated with diffusion‐controlled transport of HCO3‐ to the site of calcite precipitation. Carbon isotope signatures indicate significant departures from inorganic isotope equilibrium in all but one bryozoan species (Hippomenella vellicata). Although greater uncertainties are associated with estimates of the isotopic composition of total dissolved inorganic carbon (δ13CSDIC), the data suggest that two factors—kinetic fractionation and incorporation of respiratory CO2—are important in controlling carbon isotope disequilibrium. Where bryozoan species exhibit evidence for disequilibrium in both oxygen and carbon isotope systems (C. grandis, H. flexuosa), it is likely that kinetic factors are primarily responsible for observed departures from carbon isotope equilibrium. In contrast, the probable explanation for those species which display evidence for carbon isotope disequilibrium only, is that skeletal carbonate is precipitated from a DIC pool modified by the incorporation of respiratory CO2. Differences between the carbon isotope composition of skeletal elements from the same species and co‐existing species living in the same community suggests that significant variations may occur in the extent to which marine DIC and respiratory CO2 are utilised during calcification. Additional studies of carbon pathways associated with calcification are required to assess the relative effects of kinetic, metabolic, and environmental factors on the carbon isotopic composition of bryozoan skeletal carbonate.  相似文献   

18.
The southern coasts of Africa are influenced by two major oceanic currents, leading to biogeographic patterns in inshore and offshore species assemblages, and in the stable isotope signatures of suspended particulate matter and filter-feeding mussels. We used the stable isotope ratios of carbon (13C/12C) and nitrogen (15N/14N) from the blood and feathers of adult and chick Cape gannets (Morus capensis) to investigate whether the geographic differences observed at the lower levels in the marine communities are deep penetrating effects that reach top predators. Additionally, we evaluated whether trophic segregation occurs between adult and reared chick gannets, and whether a shift to wintering habitat occurs in adults. The study was conducted during the 2006 breeding season on Bird Island in the Agulhas system, and on Malgas and Ichaboe Islands, in the south and north Benguela respectively. Our results showed significant differences in the isotope ratios of members of different colonies, but no intra-colony differences between tissues or age groups. These results indicate that there is neither age-related nor temporal segregation in the diet of members of the same colony. Feather isotopic values suggest that adults remain all year round in the same habitats, and do not undertake long migration after reproduction. Since all gannets tend to target similar prey, we attributed among-colony differences in isotope signatures mostly to the oceanic conditions experienced by the main prey of birds rather than substantial differences in diet composition. Overall, isotopic signatures segregate the two current systems, with depleted carbon values in the Agulhas and enriched nitrogen values in the upwelled waters of the Benguela. Within the Benguela birds from Ichaboe in the north had higher δ15N values than those from Malgas in the south, which we attributed to differences in the functioning of the upwelling cells in the vicinity of the two colonies. Finally, slight variation in the proportion of main prey and discards from fisheries may contribute to the variation in the stable-isotope signatures between colonies in the Benguela.  相似文献   

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