车镇凹陷上古生界高分辨率层序地层研究   总被引：2，自引：0，他引：2  

吕大炜  李增学  李文涛  柳汉丰  刘海燕  吴立荣 《地层学杂志》2008,32(2):182-187

以高分辨率层序地层学原理为指导,利用测井、岩芯和录井等资料,对车镇凹陷上古生界不同级次基准面旋回进行了高分辨率层序划分。将上古生界划分为2个超长期、7个长期、16个中期和45个短期基准面旋回,精细对比研究了短期、中期和长期基准面旋回。其中,短期基准面旋回可分为2大类3种亚类,并区别出A型、B型不对称短期基准面旋回和C型对称性短期基准面旋回,总结了它们的结构特征、形成条件、岩性岩相组成;通过研究不同沉积体系下中期、长期基准面旋回特点,得出中期、长期基准面旋回的特点和发育特征,区别出不同沉积环境下层序界面特点;分析了研究区内超长期基准面旋回特征,综合分析认为车镇凹陷超长期基准面旋回以下降半旋回为主。  相似文献   

Anoxic nitrification: Evidence from Humber Estuary sediments (UK)   总被引：3，自引：0，他引：3  

Rebecca Bartlett  Robert J.G. Mortimer  Katherine Morris 《Chemical Geology》2008,250(1-4):29-39

Conventional understanding of the nitrogen cycle in marine sediments has changed in recent years with the discovery of an alternative pathway for ammonia oxidation via the reduction of manganese oxides (during anoxic nitrification). In anoxic sediments, the potential for manganese oxides to serve as oxidant for nitrification may be considerable yet previous work on manganese-rich sediments has suggested anoxic nitrification may not be significant. In this study, the potential for anoxic nitrification in a range of sediment types was investigated. Laboratory incubation of sediment from three sites on the Humber Estuary, a microbially diverse environment, showed anoxic accumulation of nitrate, nitrite and dinitrogen gas, with and without the addition of synthetic manganese oxides. Incubation experiments confirmed anoxic nitrification as microbially mediated, with heat-killed controls yielding negative results. The anoxic nitrification reaction significantly depleted ammonia concentrations, and occurred simultaneously with manganese-, iron- and sulphate reduction, and methanogenesis. Taken in conjunction with other studies, results suggest anoxic nitrification may not only be dependent on total manganese concentrations but on manganese dynamics. Anoxic nitrification may be explained as a non-steady state reaction, dependent on the recent stability of a sediment system. Physical perturbation of sediments may cause the redistribution and/or introduction of manganese oxides and promote anoxic nitrification. The significance and persistence of anoxic nitrification is likely to depend on the frequency and magnitude of sediment perturbation, which explains why the reaction varies so widely across studied sites, and why it may not occur in some manganese-rich sediment.  相似文献   

Correlations between heavy metals and organic carbon extracted by dry oxidation procedure in urban roadside soils   总被引：1，自引：0，他引：1  

Xue Song Wang 《Environmental Geology》2008,54(2):269-273

The organic fraction in soils has a significant influence on heavy metal transport. In this study, the organic carbon content was measured by dry oxidation procedure from 21 Xuzhou urban roadside soils to assess the relationships between the concentrations of heavy metals (Pb, Cu, Zn, and Cr) and the amount of organic carbon. The anthropogenic heavy metals (e.g. Pb, Cu, Zn) were strongly correlated with organic carbon (denoted by C_org−c) extracted by dry oxidation while natural heavy metal (e.g. Cr) showed no correlation to the C_org−c. The anthropogenic heavy metals were also strongly correlated with the amount of the total carbon. These results show that the anthropogenic heavy metals are mainly enriched in the organic matter in the Xuzhou urban roadside soils.  相似文献   

On the global stratotype section and point of the Triassic base     

G. N. Sadovnikov 《Stratigraphy and Geological Correlation》2008,16(1):31-46

A unique succession of volcanogenic deposits with representative paleontological remains characterizing the Permian-Triassic boundary interval in the North Siberian platform and Taimyr is described. The succession is suitable for selecting a standard for the Triassic base in nonmarine deposits. Abundant and diverse fossils occurring in the succession evidence that volcanism responsible for origin of the plateau basalt province in Siberia was not a brief epoch of paroxysmal eruptions, which eliminated everything alive. Throughout the formation history of relevant plateau basalts, the organic world of the plateau and around existed and gradually evolved.  相似文献   

北方泥炭沼泽中酚类物质释放的热敏感性研究:以英国威尔士地区雨养和矿养泥炭沼泽为例     

向武  Chris Freeman 《地球化学》2008,37(2):157-164

利用高精度多梯度热培养系统,对英国威尔士地区两类典型的北方泥炭沼泽中酚类物质和溶解有机碳释放的热敏感性进行了为期1年的调查研究.研究结果表明,雨养泥炭沼泽(Bog)酚类物质释放的热敏感性Q10(总酚)月变化为0.92～1.57,而矿养泥炭沼泽(Fen)的月变化范围为0.93～1.30.酚类释放的热敏感性与土壤温度大致呈正相关关系.此外,土壤温度与溶解有机碳释放的热敏感性Q10(DOC)也呈正相关关系.总体上,雨养泥炭沼泽的热敏感性比矿养泥炭沼泽略高.除温度外,水文条件和植被等多种环境因子对酚类物质和溶解有机碳释放的热敏感性也有较大影响.研究结果还表明酚碳热敏感性比值Q10o(总酚)/Q10(DOC)相对稳定,土壤温度的变化对其影响有限.  相似文献   

淡水双壳类壳体碳同位素研究:以河蚬(corbicula fluminea,Müller 1774)为例   总被引：2，自引：0，他引：2  

闫慧  李心清  周会 《地球化学》2008,37(3)

双壳类壳体碳酸盐(文石)稳定同位素组成已被广泛地用于古气候和古环境重建研究中,但是双壳类壳体碳同位素组成所指示的气候和环境意义一直是争议的问题.对双壳类河蚬(corbicula fluminea)进行了室内养殖,并选取两个壳体样品(壳高,A=13 mm,B=9mm),测定其生长部分壳体和生长期间水体碳同位素,研究表明,随着水体碳同位素的升高(δ13CDIC由-5.24‰升至1.41‰),两壳体碳同位素也随之升高,表明水体对壳体碳同位素的影响;δ13CA分布范围为-4.76‰～2.09‰,δ13CB为-8.49‰～2.89,壳体A和B碳同位素均比预测平衡值偏负,表明壳体在形成过程中利用了新陈代谢产生的富集12C的CO2.根据计算壳体A在实验中沉淀部分壳体利用新陈代谢碳的比例(M值)为24%～43%,平均值为33%;壳体B为33%～75%,平均值为58%.M值随生物的生长呈下降变化,这说明在实验中河蚬主要是通过增加对DIC的吸收和利用来满足壳体生长对物质量增加的需求.  相似文献   

Geostatistical estimation of chemical contamination in stream sediments: The case study of Vale das Gatas mine (northern Portugal)     

A.R. Salgueiro  P. Freire vila  H. Garcia Pereira  J.M. Santos Oliveira 《Journal of Geochemical Exploration》2008,98(1-2):15

Based on an environmental geochemistry case study carried out in the neighbourhood of a W–Sn abandoned mine, the pollution in stream sediments was modelled through a Global Contamination Index. Such an index permits one to summarize the combination of deleterious elements in a single variable, obtained by the projection of samples onto the first axis of a PCASD (Principal Components Analysis of Standardized Data) applied to the entire n × p matrix containing the available concentrations of p = 16 elements in the set of n = 220 collected samples.In order to provide a sound basis for a coherent planning of the remediation process which will be put in operation in the affected area, it is necessary to balance the costs of reclaiming with the probabilities of exceeding the upper limits accepted for concentrations of environmentally harmful elements in sediments. Given these limits, they are back-transformed in the index values, providing a practical threshold between ‘clean’ and ‘contaminated’ samples. On the other hand, the minimum dimension of the cell to be reclaimed is restrained by the selected remediation process to be applied in the affected area. Hence, to meet the constraints of such a remediation process, it is required to estimate the probabilities of exceeding the index threshold in technologically meaningful sub-areas. For this end, the Indicator Block Kriging technique was applied, producing a series of maps where sub-areas to be reclaimed can be spotted for different probability levels. These maps, on which the decision making remediation agency can rely for its cost-benefit analysis, take into account both the spatial structure of ‘clean’ vs. ‘contaminated’ samples and the constraints of the reclaiming process.  相似文献   

松南海坨子—大布苏地区泉四段— 姚家组层序地层研究   总被引：2，自引：1，他引：1  

张永旺  曾溅辉  邓宏文  王红亮  高霞  陈冬  徐志伟 《沉积学报》2008,26(5):737-743

根据工区内现有的钻井、测井和地震资料,应用以多级次基准面旋回为参照面的高分辨层序地层学理论与研究方法,对松辽盆地南部海坨子—大布苏地区的泉四段—姚家组地层进行了详细的层序地层研究,共识别出5个长期基准面旋回（相当于三级层序）,9个中期基准面旋回（相当于四级层序）,建立了研究区的层序划分方案,在连井剖面的层序地层对比基础上,建立了该区的地层格架,并对层序构成特征进行了分析,研究了储集层在层序格架内的分布规律,揭示出浊积砂体和三角洲前缘相的分流河道形成于基准面上升期,三角洲前缘相的河口坝、远砂坝和席状砂沉积形成于基准面下降期,指出浊积砂体和三角洲前缘相的远砂坝、席状砂沉积是研究区形成岩性油气藏的有利储集体。  相似文献   

浙江省长兴县煤山剖面二叠—三叠系过渡地层中的黑碳记录及其地质意义   总被引：2，自引：1，他引：1  

沈文杰  林杨挺  孙永革  徐琳  张华 《岩石学报》2008,24(10):2407-2414

首次报道了浙江煤山二叠-三叠系界线地层中黑碳的含量及其碳同住素的变化特征。黑碳含量在26层存在一个明显的峰值,含量高达0．51％。黑碳与总有机碳比值从25层底部开始持续升高,在26层达到最高,稳定在0．40以上。黑碳的碳同位素在24层和25层之间有一个陡然的降低,降低幅度达2‰,在25和26层中则存在一个幅度达3‰的缓慢降低,总降低幅度达5‰。黑碳是动植物和化石燃料燃烧的天然记录,浙江煤山二叠-三叠系界线附近黑碳特征反映了二叠纪末期陆地生态系统发生了突然的衰退,发生了强烈的天然大火。根据事件层大火燃烧的长期性或频繁的特征,以及黑碳同位素大幅度陡然降低和缓慢降低,认为燃烧源除了陆地植被外,还有其他富含轻碳的化石燃料,即大火的燃烧源除了植被外,还可能有煤和甲烷水合物等。浙江煤山剖面的黑碳记录,反映了二叠-三叠纪之交地球陆地环境的剧烈变化,有助于理解和揭示生物大灭绝的过程和原因。  相似文献   

近190ka BP以来菲律宾海黑潮源区的碳酸盐旋回及其控制因素   总被引：2，自引：0，他引：2  

赵京涛  常凤鸣  李铁刚  南青云  李青 《岩石学报》2008,24(6):1401-1410

对取自西菲律宾海黑潮源区的Ph05-5和WF3岩芯进行了CaCO3和钙质超微化石研究.在利用氧同位素曲线对比和AMS14C数据进行地层划分的基础上,结合钙质超微化石的碳酸盐溶解指数和初级生产力指标,分析了晚第四纪黑潮源区碳酸盐旋回特征及其控制因素.约190ka BP以来CaCO3含量整体上都表现为冰期高、间冰期低的"太平洋型"旋回特征,但菲律宾以东海区在末次冰期(MIS 4到MIS 2期)内部又显示出间冰段含量高、冰段含量低的"大西洋型"旋回特征.碳酸盐旋回的控制因素在黑潮源区内部也有明显的差异,菲律宾以东海区以碳酸盐溶解作用为主,初级生产力起次要作用;而台湾东南部海区的主要因素则是初级生产力变化引起的钙质生物输入量的波动.菲律宾以东海区末次冰期内部表现出的"大西洋型"旋回特征则是溶解作用和初级生产力共同影响的结果.  相似文献