Patterns of rare earth and other trace elements in different size fractions of clays of Campanian–Maastrichtian deposits from the Portuguese western margin (Aveiro and Taveiro Formations)     

Rosa Marques  M. Isabel Prudêncio  M. Isabel Dias  Fernando Rocha 《Chemie der Erde / Geochemistry》2011,71(4):337-347

The Upper Cretaceous (Campanian–Maastrichtian) Taveiro and Aveiro Formations belong to the northern sector of the Lusitanian basin (Portuguese western margin). The Taveiro Formation was deposited in alluvial fans, including mud flow beds, lakes and sinuous rivers. The Aveiro Formation was deposited in a flat region with low hydrodynamics channels, with the formation of a barrier island-tidal system. The reconstruction of this sedimentary basin may be difficult due to its complex architecture. This work aims a methodology to be used in the reconstruction of Cretaceous sedimentary environments of the Lusitanian basin, through the establishment of geochemical patterns of different size fractions of those deposits. Chemical analysis was performed by instrumental neutron activation analysis (INAA), and the mineralogical composition obtained by X-ray diffractometry (XRD). The whole rock and different size fractions (? ≥ 125 μm, 63–125 μm, 20–63 μm, 2–20 μm and ? < 2 μm) of selected samples were studied aiming the rare earth elements (REE) and other trace elements distribution and its correlation with the grain size and mineralogy.The results obtained for the studied Cretaceous sediments showed that REE patterns and other trace elements distribution in the different size fractions may be used as a tool to differentiate deposits within and between sedimentary formations. Within the Taveiro Formation, REE are concentrated in the silt fractions (20–63 μm and 2–20 μm) of the Reveles deposit, and in the clay size fraction of S. Pedro deposit, which is richer in kaolinite. The 1st transition elements, particularly Zn, are correlated with the presence of smectite in the clay fraction of Reveles deposit. In the sand and silt size fractions (>2 μm) of samples from Taveiro Formation correlations were found between: Ga and 1st transition elements, and phyllosilicates; Cs and mica; and Rb and Ba, and K–feldspars.The Bustos deposit (Aveiro Formation) samples are very fine-grained and with a high proportion of the fine silt fraction where REE are concentrated, especially the heavy ones. Incorporation of MREE, Co and U in carbonates of the coarser fraction appears to occur. The abundances of the 1st transition elements, Ga and As, are correlated with phyllosilicates.Significant differences were found in the trace elements patterns of the various analysed size fractions of the Lusitanian basin of Cretaceous sediments, between and even within formations, which can be used as a methodological approach for a fine paleogeographic reconstruction.  相似文献   

微波消解-原子吸收光谱法测定岩芯中的8种金属元素   总被引：1，自引：1，他引：0  

赵雷  邱会东  原金海 《岩矿测试》2011,30(4):461-464

岩芯分析是油气田开采前期必须开展的必要研究工作。岩芯样品常见金属元素钾(12.30 mg/g)、钠(15.04 mg/g)、铝(28.83 mg/g)、铁(11.13 mg/g)含量较高,且含有大量有机物,文章首次提出以微波消解方式,用浓硝酸和过氧化氢分解有机物,盐酸和氢氟酸处理二氧化硅等无机物,分解稠油油藏岩芯样品效果明显,原子吸收光谱法测定样品中钾、钠、钙、镁、铝、铁、锰、钡8种金属元素的含量。分析结果表明,方法线性相关系数良好(相关系数为0.9949～0.9998),回收率在92.2%～101.6%。建立的微波消解技术无样品损失,操作简单,消解过程节省试剂,减少了环境污染,测定方法准确、可靠,检出限低。  相似文献   

微波消解-电感耦合等离子体质谱法测定土壤和沉积物中痕量稀土元素   总被引：11，自引：6，他引：5  

陈永欣  黎香荣  韦新红  吕泽娥  谢毓群  蔡维专 《岩矿测试》2011,30(5):560-565

建立了微波消解-电感耦合等离子体质谱法测定土壤和沉积物中15种痕量稀土元素的分析方法。研究了溶样试剂、微波消解程序、标准溶液配制、质谱干扰与内标元素对稀土元素测定的影响。加入氢氟酸能有效打开样品,以HNO3-HF-H2O2混合酸溶解样品,稀土元素的溶出率较高。采用模拟土壤、沉积物中稀土元素天然组成比值的校正溶液,对稀土元素间的干扰具有明显的抑制作用。通过测定单个La、Ce、Pr、Nd和Ba的氧化物及氢氧化物产率,计算出等效干扰浓度,进而校正多原子离子干扰。利用103Rh内标校正系统,有效地抑制了分析信号的动态漂移。方法检出限为1.2～7.1 ng/g,精密度(RSD)≤5.3%(n=6),加标回收率为86.1%～110.1%。使用土壤、沉积物标准物质进行验证,测定结果与标准值相符。建立的方法样品处理程序简单快速、线性范围宽、分析重现性好、结果准确,适用于大批量地质样品的分析。  相似文献   

碳酸盐沉积物的成岩作用   总被引：4，自引：2，他引：2  

赵彦彦  郑永飞 《岩石学报》2011,27(2):501-519

化学沉淀碳酸盐矿物在沉积后很容易受到各种作用的影响,其中最重要的是其在成岩阶段所经历的成岩作用.碳酸盐沉积物在成岩过程中主要受大气降水、海水和埋藏过程中孔隙流体的控制,经历一系列压实、溶解、矿物的多相转变、重结晶、胶结等成岩作用,逐渐转变为固结的岩石.在成岩过程中,由于孔隙流体与沉积流体之间的异同以及温度的变化,碳酸盐沉积物的原始矿物成分、地球化学特征可能会很好的保存下来,但在许多情况下,也可能会改变,从而使我们无法准确反演碳酸盐沉积物在沉积时水体的特征.因此,我们在应用碳酸盐岩重建相关古环境和古气候变化的时候,必须要通过有效的方法来对碳酸盐岩是否受到成岩作用的影响进行鉴定.  相似文献   

宁夏中奥陶统香山群徐家圈组大地构造环境分析   总被引：1，自引：0，他引：1       下载免费PDF全文

李向东  何幼斌刘 训游国庆王 丹郑昭昌 《中国地质》2011,38(2):374-383

宁夏香山群为一套遭受轻微区域变质的陆源碎屑岩,并夹有少量碳酸盐岩和硅质岩,属于深水浊流沉积,从下到上可分为徐家圈组、狼嘴子组和磨盘井组。长期以来对香山群的研究主要集中在时代探讨上,而在其他方面较薄弱。本文以徐家圈组为主要研究对象,从浊积砂岩的碎屑颗粒类型百分含量、常量元素和微量元素等方面对其沉积时的大地构造环境进行了综合研究。结果表明:碎屑颗粒类型显示出典型的被动大陆边缘;常量元素的判别则出现了不确定性;微量元素则显示出了过渡性质。因此,香山群徐家圈组沉积时大地构造环境可能不是简单的被动大陆边缘,其物源极有可能来自被动大陆边缘、活动大陆边缘和大陆岛弧之间的带有过渡性质的源区。  相似文献   

Distribution of heavy metals in soils of Port Harcourt and its environs,Niger Delta,Nigeria   总被引：1，自引：0，他引：1  

Minapuye I Odigi  Lucky O. Ukren  Hycienth O. Nwankwoala 《中国地球化学学报》2011,30(4):415-421

Geochemical evaluation of the distribution of heavy metals in soils of Port Harcourt and its environs in the Niger Delta region is presented in respect of anthropogenic factor and index of geoaccumulation. Sixteen (16) soil samples were collected from two horizons (0-10 cm and 100 cm) from the various grids and analyzed. The geo-chemical analyses showed the vertical and horizontal distributions of heavy metals. The results showed the ranges of the metals determined as follows: Pb (6.86-2.49)×10-6, with an average of 4.63×10-6; Cd (0.05-0.00)×10-6, with an average of 0.02×10-6, As (0.01-0.00)×10-6, with an average of 0.00×10-6. Cu (15.36-10.80) ×10-6, with an average of 13.36×10-6, and V (1.36-0.20)×10-6, with an average of 0.94×10-6. Quantification of the degree of pollution was carried out using anthropogenic factor (AF) and index of geoaccumulation (Igeo). The Igeo values of 0.06, 0.02 and 0.00 for Pb, Cd and As, respectively indicate low-level contamination while Zn (1.14) and V (1.40) show me-dium-level contamination. The sources of contamination are attributed to urbanized anthropogenic activities. The majority of the samples analyzed show that the AF values are less than 1 with the exception of vanadium (V) whose AF values range from 2.73 to 13.60×10-6. Vanadium is more enriched than As, Cd, Pb, and Cu. The order of degrees of anthropogenic contamination and index of geoaccumulation in the soil is V >Zn >Pb >Cu >Cd >AS. Metals were retained near the top soil and their concentrations in the deepest horizons were lower and normal for uncontaminated soils. Metal concentrations in the top soil horizons were significantly related to distance from the industrial and hu-man activities.  相似文献   

中国南方地区水系沉积物中元素丰度   总被引：6，自引：0，他引：6       下载免费PDF全文

程志中  谢学锦  潘含江  杨榕  商云涛 《地学前缘》2011,18(5):289-295

从中国南方12个省自治区230万km2面积上所采集的水系沉积物中按每1∶5万图幅一个组合样的密度组合成5 244件组合样,采用以ICP-MS、ICP-AES和XRF为主的先进的分析测试方法和严格的质量控制方法,准确测试了其中的76种元素。统计计算了中国南方地区76种元素的平均值,给出了中国南方地区水系沉积物中76种元素...  相似文献   

Geochemistry of environmentally sensitive trace elements in Permian coals from the Huainan coalfield, Anhui, China     

Jian Chen  Guijian Liu  Mengmeng JiangChen-Lin Chou  Hui LiBin Wu  Liugen ZhengDongdong Jiang 《International Journal of Coal Geology》2011,88(1):41-54

To study the geochemical characteristics of 11 environmentally sensitive trace elements in the coals of the Permian Period from the Huainan coalfield, Anhui province, China, borehole samples of 336 coals, two partings, and four roof and floor mudstones were collected from mineable coal seams. Major elements and selected trace elements were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation atomic absorption spectrometry (HAAS). The depositional environment, abundances, distribution, and modes of occurrence of trace elements were investigated. Results show that clay and carbonate minerals are the principal inorganic constituents in the coals. A lower deltaic plain, where fluvial channel systems developed successively, was the likely depositional environment of the Permian coals in the Huainan coalfield. All major elements have wider variation ranges than those of Chinese coals except for Mg and Fe. The contents of Cr, Co, Ni, and Se are higher than their averages for Chinese coals and world coals. Vertical variations of trace elements in different formations are not significant except for B and Ba. Certain roof and partings are distinctly higher in trace elements than underlying coal bench samples. The modes of occurrence of trace elements vary in different coal seams as a result of different coal-forming environments. Vanadium, Cr, and Th are associated with aluminosilicate minerals, Ba with carbonate minerals, and Cu, Zn, As, Se, and Pb mainly with sulfide minerals.  相似文献   

尾砂库重金属元素表生地球化学行为的初探     

端木合顺  康晓静  李万生 《矿物学报》2011,31(1):153-159

通过重金属含量分析,分级提取化学形态分析,结合矿物成分和化学成分分析,对黄龙铺矿区1号尾矿库重金属元素在风化过程中的地球化学行为进行了研究。研究结果表明在横向上,尾矿库中心排水口处地势低洼,铜、铁因相对活泼易于迁移而流失,铅、锌、铬、镉在尾矿库四周的地表浅部淋失,在尾矿库中心则相对富集。化学形态分析表明尾砂中各重金属元素赋存状态各有不同,一般以T6原生硫化物态和T7残渣态为主,铜、锌、铁迁移性较强;其他则较弱,表明对环境威胁不是很大。重金属的迁移明显的分为氧化带和次氧化带,研究结果显示尾矿覆盖方法也不一定能够有效地阻滞污染元素的迁移。  相似文献   

贵州纳雍水东铅锌矿矿床地球化学特征   总被引：2，自引：0，他引：2  

吴波  陈国勇  陶平  谯文浪 《贵州地质》2011,28(2):108-113

对贵州纳雍水东乡洗米沟、坟山脚一带灯影组地层中铅锌矿石采样,进行镜下观察和全岩主量、微量元素、稀土元素以及硫同位素地球化学研究。微量元素研究表明,矿床中N i、Mo、As、Sb等成矿元素富集明显,Sr、Ba、V等元素强烈亏损,认为早寒武世热水对铅锌矿源层进行了淋滤和改造;稀土元素研究表明,铅锌矿石稀土配分曲线向右倾斜,...  相似文献