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1.
东营凹陷南斜坡沙四段沉积环境的地球化学特征 总被引：23，自引：0，他引：23
东营凹陷是一个北断南超的不对称箕状断陷湖盆,湖盆中的常量元素和微量元素含量及有关元素比值呈现出明显的旋回变化特征。而其中元素的分配及比值的变化、组合都在一定程度上指示着古沉积环境的演化历程。通过分析Fe,Mn,Ca,Sr等元素含量和Fe／Mn,Sr／Ba,Sr／Ca,Mg／Ca等元素比值以及碳氧同位素的变化特征。对东营凹陷南斜坡沙四段沉积时期的沉积环境进行了系统的研究。结果反映了沙四段沉积时期的古气候、古盐度、古湖水面和古生产力基本上都显示出了旋回变化的特征。 相似文献
2.
准噶尔盆地晚二叠世沉积的芦草沟组湖相页岩是一套重要的烃源岩或油页岩资源。本文通过XRF和ICP-MS技术测试了该盆地东南缘博格达山地区芦草沟组油页岩的元素含量,分析了其分布与组成特征,阐述该区芦草沟组沉积时期的古环境特征。研究表明,芦草沟组油页岩样品大多数主元素含量偏低,但磷(P)含量较高, P/Ti比值为0.23～1.94;微量元素Sr/Ba比值多小于1, Sr/Cu比值处于4.88～12.36之间, V/Cr比值为2.40～3.91, V/(V+Ni)比值为0.70～0.83,古气候指数为0.48～0.61;轻重稀土元素比值为5.92～7.10,轻稀土元素明显富集。综合各参数特征及变化趋势表明,研究区芦草沟组沉积时期主要是半干旱-半湿润的古气候特征,总体上为半咸水的湖盆环境,沉积水体较深,沉积速率较慢,具有中-高的初始古生产力。从沉积初期至晚期,古气候逐渐变干旱,沉积水体盐度逐渐升高和还原性逐渐增大。研究区芦草沟组有机质富集属于生产力模式,主要受古气候和古生产力控制,但沉积后期沉积水体水化学条件的变化也为有机质保存提供了有利的条件。 相似文献
3.
新疆干旱区柴窝堡湖沉积记录的150年来气候环境特征 总被引：6，自引：5，他引：1
通过乌鲁木齐附近柴窝堡湖钻孔岩芯的粒度、有机质含量、化学元素以及同位素等多项分析,开展了研究区近150年来的气候环境演化研究.通过沉积记录与器测气象资料比较,认为沉积物的有机质含量反映了流域降水的变化,而有机质碳同位素的变化则与温度相关.在运用有序样品最优聚类分析对沉积物地球化学元素序列进行阶段划分的基础上,综合粒度、有机质含量以及同位素等多环境代用指标的分析,恢复了不同阶段的气候环境信息.结果表明,1860～1910A.D.,各环境指标显示当时湖泊水位较高,湖水较深,显示偏冷、偏湿的气候环境特征.1910～1950A.D.,粒度、地球化学元素、有机质、磁化率等指标波动明显,虽然有机碳同位素值有所升高,但仍然总体偏负,显示该阶段湖泊环境总体上波动强烈,气候不稳定.其中约1920A.D.左右,粒度显示突然变化,有机碳同位索、烧失量、元素含量等也均发生了显著的波动,指示明显气候环境事件的存在.1950A.D.以来,钻孔岩芯的磁化率升高,重金属元素含量以及总磷含量呈现明显富集,而有机质及其碳同位素变化却与器测温度和降水变化一致,指示了近期气候和人类活动对湖泊环境的影响. 相似文献
4.
东岛牛塘为目前在西沙群岛少见的淡水湖泊,发育保存完好的沉积物。文章通过对一根长126cm的沉积柱开展多方面的沉积学分析,包括沉积物的岩性特征,反映碳酸盐含量的白度、CaO和LOI950℃以及反映有机质含量的TOC,TN,TS和LOI550℃等地球化学指标随深度的变化特征,沉积物和环境介质的碳、氮同位素的对比分析,沉积物的稀土元素和Sr,F,P,Se等元素地球化学特征。结果认为:该湖泊沉积剖面自上而下可分成3个具有明显不同沉积学特征的沉积单元,其中25～96cm的沉积层明显地受到了海鸟粪的影响。识别出的海鸟粪土沉积层,为进一步研究历史时期岛屿鸟类生态系统和气候演化提供了良好的信息载体。 相似文献
5.
东营凹陷沙四下亚段沉积环境特征及沉积充填模式 总被引：5，自引：1，他引：4
沉积盆地中沉积环境特征控制了砂体沉积成因类型及盆地沉积充填模式。通过对东营凹陷丰深2井、官112井及梁120井沙四下亚段泥质沉积物系统取样,进行全岩X衍射分析和常量及微量地球化学元素分析,在此基础上对东营凹陷沙四下亚段古气候和古盐度指标进行分析。结果表明,古气候指标Rb/Sr比值与石英+长石含量、Cr元素含量及P元素含量呈正比,含量增加反映了气候相对潮湿,与古盐度指标碳酸盐+硫酸盐含量呈反比,其含量增加反映了气候相对干旱。东营凹陷沙四下亚段沉积时期气候干湿交替频繁,气候潮湿时期相对湖平面上升,湖水盐度降低;气候干旱时期相对湖平面下降,湖水盐度升高,使得此时期湖泊呈现为高频振荡性盐湖特征。气候潮湿时期以沉积碎屑沉积物为主,包括冲积扇、浅水型三角洲、滨湖滩坝及近岸水下扇沉积,由于湖水盐度较低,洼陷带主要沉积泥岩、灰质泥岩、含膏泥岩和少量泥质膏岩;气候干旱时期相对湖平面下降,湖泊水体盐度升高,洼陷带以沉积膏盐岩为特征,垂向上具有含膏泥岩、泥质膏岩、膏岩和盐岩的演化序列,平面上表现为由湖泊边缘向湖泊中心发育灰质泥岩、含膏泥岩、泥质膏岩、膏岩和盐岩的环带状结构特征。 相似文献
6.
渐新世时期,琼东南盆地海侵作用逐渐加强,由海陆交互相逐渐过渡到浅海相沉积.但对崖城组与陵水组样品有机质碳同位素分析显示,从崖城组到陵水组有机质碳同位素逐渐变重,与通常陆生植物碳同位素重于水生生物的现象相左.通过对样品显微组分分析发现,有机质碳同位素较重的样品腐泥组分含量偏高.考虑到渐新世沉积水体为微咸水或咸水,而咸水条件下水生藻类有机质碳同位素偏重,因此显微组分中腐泥组分含量的升高会使得有机质碳同位素变重.然而沉积相和显微组分基本类似的崖城组和陵水组样品有机质碳同位素仍然存在差异,这说明有机质碳同位素变重还存在显微组分变化之外的其他影响因素.结合全球渐新世以来的古气候与大气CO2浓度变化特征可知,该时期大气中CO2浓度发生了巨大变化,由崖城组沉积时期的1000～1500μL/L下降到陵水组沉积时期的500μL/L以下,导致陆生植物碳同位素逐渐变重.因此,陆源输入有机质的碳同位素变重也是造成从崖城组到陵水组有机质碳同位素变重的重要原因之一. 相似文献
7.
黑龙江省柳树河盆地始新统八虎力组发育多层油页岩。通过对油页岩样品元素地球化学分析测试,研究了其常量元素、微量元素和稀土元素特征,分析了油页岩沉积环境。研究结果表明,常量元素以富Al2O3、Fe和CaO,贫SiO2、MgO、Na2O和K2O为特征,微量元素总体上表现出不同程度的亏损特征,稀土元素总量平均为140.7×10-6,表现出轻稀土元素轻度富集特征。稀土元素具有较为一致的变化趋势,表明油页岩沉积时物源和沉积环境较为稳定。Mn/Ti值表明油页岩组成物质的搬运距离随着时间变化经历了远→近→远的变化,反映水体深度经历了深→浅→深的变化。Sr/Cu值和Rb/Sr值表明油页岩沉积时为相对炎热干旱的环境。Sr/Ba值反映当时为炎热干旱气候条件下的过渡相咸水湖泊沉积环境。V/(V+Ni)值、δEu和有机碳含量表明油页岩沉积时处于缺氧的还原沉积环境中。总体上,柳树河盆地油页岩发育于炎热干旱气候、咸水、缺氧条件下的湖泊沉积环境中。 相似文献
8.
巢湖沉积物有机碳分布变化特征 总被引：2，自引：0，他引：2
利用2003年7月用活塞取样器在湖泊靠近河口附近和湖泊内沉积最深区域内布点采集了柱样,对样品进行了有机碳和总氮含量等的测定,并对碳的分布变化特征及其影响因素进行了探讨。结果表明：AC4柱样样品有机碳含量变化整体上呈现出一个波动频繁且幅度较大的特点,AC3柱样整体上为缓慢渐变态势。AC4有机碳与细颗粒、总氮含量的相关性高于AC3柱样。两柱样的C／N比值垂向变化表明沉积物中的内、外源有机质在湖泊有机质中各占有一定比例,同时也反映了它们物质来源上有差异。可见由于位置差异导致的水动力条件、物源变化和降解作用等不同因素对其含量变化及C／N比值具有不同的影响。 相似文献
9.
内蒙古扎鲁特地区上二叠统林西组古盐度分析 总被引：1，自引：0，他引：1
通过对扎鲁特地区陶海营子剖面和鲁D2井泥岩样品中微量、常量元素和黏土矿物的测定,利用Adams和Couch古盐度计算公式及Walker相当硼判定法、锶钡比值法、硼镓比值法、生物标记化合物等方法,综合分析了扎鲁特地区林西组沉积时水体的古盐度特征.结果表明,鲁D2井林西组沉积时为半咸水环境,陶海营子剖面林西组则为淡水环境,扎鲁特地区林西组沉积时期水体环境有一个逐渐淡化的过程,下部为半咸水的湖泊环境,上部逐渐演化为淡水湖泊环境.半咸化的湖水环境为林西组巨厚层烃源岩的发育提供了有利条件. 相似文献
10.
江西永平地区石炭纪硅质岩成因地球化学特征及沉积环境 总被引：7，自引：1，他引：7
徐跃通 《大地构造与成矿学》1996,20(1):20-28
对永平地区石炭纪硅质岩的常量元素、微量元素、稀土元素、硅和氧同位素地球化学特征研究证明其为热水沉积硅质岩。硅质岩沉积大地构造地球化学表明硅质岩的沉积环境是大陆边缘的浅海。 相似文献
11.
Geochemical records of the sediments and their significance in Dongping Lake Area,the lower reach of Yellow River,North China 
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下载免费PDF全文 Yu Lin-song Liu Hong-bo Wan Fang Hu Zun-fang Luo Huai-dong Zhang Xiu-wen 《地下水科学与工程》2021,9(2):140-151
Dongping Lake area, located in the lower reaches of Yellow River, is an ideal place to study the changes of modern river and lake sedimentary environment. The sediment samples of Dawen River, Yellow River, and Dongping Lake were collected, and the major elements, trace elements and organic matter geochemical composition of the samples were analyzed. Cluster analysis, characteristic element ratio method and graphic method were used to explore the geochemical characteristics of sediments and their environmental implication. The results show that the contents of SiO_2, Na_2O, TiO_2 and Zr in sediments of Dawen River and Yellow River are relatively high, and the contents of iron and manganese oxides, organic matter, CaO, P_2O_5 and Sr in lake sediments are relatively high. That reveals the differences of sedimentary environments between the rivers and the lake. The contents of Sr and Zr in Dawen River are affected by the rapid migration of clastic materials in the upstream carbonate source area during the flood season; the δCe,ΣREE and REE's ratios in the sediments of the Yellow River reflect the influence of the Loess source; and the distribution of elements changes along the flow direction during the flood season. The characteristics of p H, element composition and LREE HREE fractionation of the lake sediments indicate that the sediment source is complex, and the lake environment is affected by the flood season. The study shows that the geochemical content and its variation characteristics of sediments effectively reveal the sedimentary environment, material composition and characteristics of flood season of rivers and the lake in the study area. 相似文献
12.
Evaluation of environmental status and geochemical assessment of sediments,Manasbal Lake,Kashmir, India 总被引：1，自引：1，他引：0
The present study was conducted on the Manasbal Lake (34°14′N: 74°40′E) to assess the geochemical characteristics of the lake bottom sediments, its environmental implications and its response in the local catchment area. This study tracks the spatial distribution of grain size, geochemical analysis, C/N ratio, calcium carbonate (CaCO3) and organic matter (OM) of the lake bottom sediments. It is observed that the clay fraction (49.79%) is predominant in the lake bottom sediments, followed by silt (35.88%) and sand (14.33%) and its spatial distribution is controlled by water depth. Geochemistry and normalized diagrams for the major oxides and trace elements reveal enrichment of CaO, K2O, P2O5, S, Cl, Ni, Zn and Sr. Chemical index of alteration (CIA) reflects low to moderate weathering intensity and near compositional similarity with the bedrock exposed in the catchment area around the lake. Environmental indices (EF, Igeo) suggest that the sediments are enriched in Cu, Ni, Zn, Cr, Co, Pb followed by Mn content. Pollution load index (PLI) reveal that all the sampling sites reflect low to moderately polluted category except for few stations that are towards the southern and southeastern side of the lake. OM (16.85%), CaCO3 (14.04%) and C/N ratio (15.5) of the lake bottom sediments is attributed to high organic activity within the lake, shell fragments, contributions from the lake flora and fauna adhering to the clayey silty sediments. The C/N ratio of 15.5 suggests a mixed source of organic matter both terrestrially and in situ formation within the lake. Sulphur and chlorine are high amongst the trace elements suggesting anthropogenic detritus input into the lake and this is due to the chemical fertilizers from the agricultural runoff and organic load into the lake. Thus, the present study suggests that in order to preserve the pristine lake ecology and the environment; continued monitoring and restoration efforts need to be undertaken. 相似文献
13.
Rayees Ahmad Shah Hema Achyuthan Aasif Mohmad Lone R. Ramanibai 《Journal of the Geological Society of India》2017,90(2):159-168
Lakes and wetlands are dynamic geomorphic units of a landscape that hold geochemical signatures of sediment provenance and paleo-environmental shifts and are major sinks for organic matter accumulation. The source of organic matter is diverse in lake sediments and varies widely with the type and size of the lake and hence it is important to understand the source of organic carbon (terrestrial or in situ) in lake systems in order to monitor the health of the lake. Wular lake, located in north Kashmir, is one of the largest fresh water lake in India, situated at an average elevation of 1580m ASL. The lake is fed by a number of watersheds that bring a diverse type of sediments and organic matter and thus deposit them into the Wular lake basin. In order to understand sediment distribution pattern, content and source of organic matter, sediment provenance and the persisting environment in the Wular lake, 32 lake floor sediment samples covering the entire lake were collected and analyzed for organic element analysis, CaCO3, organic matter, sediment texture and diatom analysis. The results indicated that sediments in the lake are dominated by silt and silty clay. The organic carbon in the lake ranged from 0.83%-4.52% and nitrogen varied from 0.06%-0.5%. The Carbon to Nitrogen (C/N) ratios (9.04 to 22.03) indicate a mixed source of organic carbon but dominated by in situ lake sources from the vascular and lake biota accumulation. The diatom analysis revealed the occurrence of a diverse type of species along the sampling sites present within the lake. The wide distribution of the diatom species such as Cymbella, Cyclotella and Tabularia etc. in the lake indicate high organic pollution and alkaline fresh water environment prevailing in the lake. 相似文献
14.
Normalizing XRF-scanner data: A cautionary note on the interpretation of high-resolution records from organic-rich lakes 总被引：2，自引：0，他引：2
L. Lwemark H.-F. Chen T.-N. Yang M. Kylander E.-F. Yu Y.-W. Hsu T.-Q. Lee S.-R. Song S. Jarvis 《Journal of Asian Earth Sciences》2011,40(6):429-1256
X-ray fluorescence (XRF) scanning of unlithified, untreated sediment cores is becoming an increasingly common method used to obtain paleoproxy data from lake records. XRF-scanning is fast and delivers high-resolution records of relative variations in the elemental composition of the sediment. However, lake sediments display extreme variations in their organic matter content, which can vary from just a few percent to well over 50%. As XRF scanners are largely insensitive to organic material in the sediment, increasing levels of organic material effectively dilute those components that can be measured, such as the lithogenic material (the closed-sum effect). Consequently, in sediments with large variations in organic material, the measured variations in an element will to a large extent mirror the changes in organic material. It is therefore necessary to normalize the elements in the lithogenic component of the sediment against a conservative element to allow changes in the input of the elements to be addressed. In this study we show that Al, which is the lightest element that can be measured using the Itrax XRF-scanner, can be used to effectively normalize the elements of the lithogenic fraction of the sediment against variations in organic content. We also show that care must be taken when choosing resolution and exposure time to ensure optimal output from the measurements. 相似文献
15.
湖平面升降对三角洲沉积体的发育具有重要影响,前人对此做了相关研究,但对于其形成过程缺乏定量分析.利用水动力数值模拟的方法正演模拟了湖平面变化情况下浅水三角洲的形成过程并精确分析了其演化规律.根据现代河流三角洲的水动力特征,设计了水动力及泥沙条件,采用Delft3D模拟了湖平面上升和湖平面下降两种沉积过程.通过对浅水三角洲的模拟分析得到湖平面的升降对沉积体的形成与分布、河道的演化具有重要影响,结合平面和剖面分析发现沉积体的多期叠置现象.研究结果表明湖平面控制着沉积体的进退及其沉积特征,且利用水动力数值模拟方法可较好地揭示湖平面变化下浅水三角洲的演化过程. 相似文献
16.
大陆架是大陆向海底的自然延伸部分,是大陆和海洋之间的过渡区,在这一特定环境中形成的沉积物,一方面对大陆有“继承性”,另一方面也留下了海洋的“烙印”,从而构成独特的地球化学特征。本文基于历年对中国海大陆架沉积物地球化学的研究,试图对大陆架沉积物地球化学的若干模式,进行初步的探讨。 相似文献
17.
Major and trace element geochemistry in Zeekoevlei, South Africa: A lacustrine record of present and past processes 总被引：2，自引：0，他引：2
Supriyo Kumar Das Joyanto Routh Alakendra N. Roychoudhury J. Val Klump 《Applied Geochemistry》2008,23(8):2496-2511
This study reports a multi-parameter geochemical investigation in water and sediments of a shallow hyper-eutrophic urban freshwater coastal lake, Zeekoevlei, in South Africa. Zeekoevlei receives a greater fraction of dissolved major and trace elements from natural sources (e.g., chemical weathering and sea salt). Fertilizers, agricultural wastes, raw sewage effluents and road runoff in contrast, constitute the predominant anthropogenic sources, which supply As, Cd, Cu, Pb and Zn in this lake. The overall low dissolved metal load results from negligible industrial pollution, high pH and elevated metal uptake by phytoplankton. However, the surface sediments are highly polluted with Pb, Cd and Zn. Wind-induced sediment resuspension results in increased particulate and dissolved element concentrations in bottom waters. Low C/N ratio (10) indicates primarily an algal source for the sedimentary organic matter. Variation in sedimentary organic C content with depth indicates a change in primary productivity in response to historical events (e.g., seepage from wastewater treatment plant, dredging and urbanization). Primary productivity controls the enrichment of most of the metals in sediments, and elevated productivity with higher accumulation of planktonic debris (and siltation) results in increased element concentration in surface and deeper sediments. Aluminium, Fe and/or Mn oxy-hydroxides, clay minerals and calcareous sediments also play an important role in adsorbing metals in Zeekoevlei sediments. 相似文献
18.
巢湖沉积物镉等重金属地球化学分布、赋存特征及危害性研究 总被引：2，自引：0，他引：2
对巢湖表层沉积物中8种重金属元素的分布特征和生态风险进行了研究和评价。结果表明：沉积物中Hg、Cd含量总体高于背景值,其中西部沉积物中重金属含量明显高于中东部湖区,并表现出多元素复合污染特征;Hakanson潜在生态危害指数表明巢湖沉积物重金属生态危害变化于轻微-强危害程度,以西北部湖区最为严重,Hg和Cd是主要影响因子,其它元素生态危害性较小;沉积物中As、cd、Hg、Pb元素主要以残渣态（非有效态）形式存在,但沉积物中腐殖酸态的As和Hg、铁锰氧化态的Pb、离子态的Cd占总量比例较高,其中又以Cd易利用态比例最高,生物有效性最强,具有较高的生态危害风险。 相似文献
19.
抚仙湖是我国面积、蓄水量最大的高原湖泊之一。通过对抚仙湖FXH-B2钻孔岩芯296 cm沉积物的矿物组成和碳酸盐含量分析,结合岩芯XRF扫描数据和AMS^14C年代的测定,探讨了抚仙湖湖泊沉积物中碳酸盐含量与方解石矿物及沉积物Ca元素相对含量之间的关系及其环境指示意义,在对比和参考水下地形测量、地球物理勘探、水质和地球化学监测和不同部位钻孔岩芯的分析结果的基础上,重建了抚仙湖全新世以来气候和湖泊水位的变化。结果指示,抚仙湖碳酸盐含量与方解石的XRD信号强度、沉积物Ca元素的XRF扫描数据之间存在很高的相关性,沉积物中碳酸盐类物质主要为方解石(其他碳酸盐类矿物相对含量极微甚至可以忽略不计),沉积物中Ca元素主要来自碳酸盐,因此其含量由碳酸盐、即方解石矿物含量决定。沉积物中碳酸盐含量的变化可以用沉积物中Ca元素XRF扫描结果进行表示。由于抚仙湖处于亚热带季风气候区,以10月至次年4月降水量极少而蒸发强烈为特点的干季和以5月至9月降水为主的湿季所形成的干湿变化控制了湖泊演化的主要过程,区域气候变化是湖泊演化和水位变化的主要动力。结合湖泊沉积碳酸盐稳定同位素δ^18O和δ^13C、有机质含量及其同位素δ^13C、抚仙湖北部边缘水下侵蚀地形测量、地球物理勘探和沉积地层年代的确定和讨论,明确了抚仙湖沉积碳酸盐含量指示湖泊水位的变化,并重建了抚仙湖过去约12 ka以来水位变化的历史。结果显示,在约12 cal.ka B.P.至2.2 cal.ka B.P.期间的湖泊水位变化主要经历了波动式降低的过程,其中4.37~2.2 cal.ka B.P.期间高CaCO3含量、偏正的碳酸盐δ^18O、δ^13C值指示抚仙湖一度出现低于现代湖面约30 m左右的低水位,可能记录了抚仙湖流域极端的干旱时期,在2.2~2.0 cal.ka B.P.期间抚仙湖水位经历了快速升高的变化事件,期间湖水位快速上升达到现代湖水水位,揭示了印度季风控制区区域降水的特殊性和气候变化的突发性。 相似文献
20.
利用高分辨率激光粒度仪MS2000对安固里淖、三台河以及长江等多个地点湖泊和河流沉积物样品细粒部分的粒度多组分分布特征进行了系统、深入研究。总结了其粒度分布特征及组分间差异并讨论了其成因机制。研究认为:1)湖泊沉积物粒度一般由多个组分叠加构成,表现为多组分粒度分布特征,其受控于水动力强度和搬运方式等因素。2)粒度分布最多可有6个组分（中值粒径范围分别为①<1μm,②2～10μm,③10～70μm,④70～>150μm,⑤150～700μm,⑥>700μm）,其中前4个组分属悬浮组分（③组分是流域内风成作用强弱的判别标志）,⑤为跳跃组分,⑥为滚动组分,整体分选性差。3)据粒度分布特征可分为湖滨、过渡和湖心三相,三相间粒度分布特征有明显差异,同时又存在此消彼长的良好过渡关系。湖滨相以④组分为优势组分,该组分含量越高,指示沉积物越靠近湖滨;过渡相④组分含量随距湖心距离靠近而减小,但②组分含量却在逐渐增加;湖心相以②组分占主导优势,该组分含量越高,指示沉积物越靠近湖心。4)湖相沉积物受湖滨拍岸浪和湖心波浪的影响而产生了明显的粒度分异规律。 相似文献