Combined Trace Element and Pb-Nd-Sr-O Isotope Evidence for Recycled Oceanic Crust (Upper and Lower) in the Iceland Mantle Plume   总被引：2，自引：0，他引：2  

KOKFELT  THOMAS FIND; HOERNLE  KAJ; HAUFF  FOLKMAR; FIEBIG  JENS; WERNER  REINHARD; GARBE-SCHONBERG  DIETER 《Journal of Petrology》2006,47(9):1705-1749

We present the results of a comprehensive major element, traceelement and Sr–Nd–Pb–O isotopic study of post-glacialvolcanic rocks from the Neovolcanic zones on Iceland. The rocksstudied range in composition from picrites and tholeiites, whichdominate in the main rift systems, to transitional and alkalicbasalts confined to the off-rift and propagating rift systems.There are good correlations of rock types with geochemical enrichmentparameters, such as La/Sm and La/Yb ratios, and with long-termradiogenic tracers, such as Sr–Nd–Pb isotope ratios,indicating a long-lived enrichment/depletion history of thesource region. ⁸⁷Sr/⁸⁶Sr vs ¹⁴³Nd/¹⁴⁴Nd defines a negative array.Pb isotopes define well-correlated positive arrays on both ²⁰⁶Pb/²⁰⁴Pbvs ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb diagrams, indicating mixing ofat least two major components: an enriched component representedby the alkali basalts and a depleted component represented bythe picrites. In combined Sr–Nd–Pb isotopic spacethe individual rift systems define coherent mixing arrays withslightly different compositions. The enriched component hasradiogenic Pb (²⁰⁶Pb/²⁰⁴Pb > 19·3) and very similargeochemistry to HIMU-type ocean island basalts (OIB). We ascribethis endmember to recycling of hydrothermally altered upperbasaltic oceanic crust. The depleted component that is sampledby the picrites has unradiogenic Pb (²⁰⁶Pb/²⁰⁴Pb < 17·8),but geochemical signatures distinct from that of normal mid-oceanridge basalt (N-MORB). Highly depleted tholeiites and picriteshave positive anomalies in mantle-normalized trace element diagramsfor Ba, Sr, and Eu (and in some cases also for K, Ti and P),negative anomalies for Hf and Zr, and low ¹⁸O_olivine values(4·6–5·0) below the normal mantle range.All of these features are internally correlated, and we, therefore,interpret them to reflect source characteristics and attributethem to recycled lower gabbroic oceanic crust. Regional compositionaldifferences exist for the depleted component. In SW Icelandit has distinctly higher Nb/U (68) and more radiogenic ²⁰⁶Pb/²⁰⁴Pbratios (18·28–18·88) compared with the NErift (Nb/U 47; ²⁰⁶Pb/²⁰⁴Pb = 18·07–18·47).These geochemical differences suggest that different packagesof recycled oceanic lithosphere exist beneath each rift. A thirdand minor component with relatively high ⁸⁷Sr/⁸⁶Sr and ²⁰⁷Pb/²⁰⁴Pbis found in a single volcano in SE Iceland (Öræfajökullvolcano), indicating the involvement of recycled sediments inthe source locally. The three plume components form an integralpart of ancient recycled oceanic lithosphere. The slope in theuranogenic Pb diagram indicates a recycling age of about 1·5Ga with time-integrated Th/U ratios of 3·01. Surprisingly,there is little evidence for the involvement of North AtlanticN-MORB source mantle, as would be expected from the interactionof the Iceland plume and the surrounding asthenosphere in formof plume–ridge interaction. The preferential samplingof the enriched and depleted components in the off-rift andmain rift systems, respectively, can be explained by differencesin the geometry of the melting regions. In the off-rift areas,melting columns are truncated deeper and thus are shorter, whichleads to preferential melting of the enriched component, asthis starts melting deeper than the depleted component. In contrast,melting proceeds to shallower depths beneath the main rifts.The longer melting columns also produce significant amountsof melt from the more refractory (lower crustal/lithospheric)component. KEY WORDS: basalts; trace element and Sr, Nd, Pb, O isotope geochemistry; Iceland plume; isotope ratios; oceanic crustal recycling; partial melting; plume–ridge interaction  相似文献   

Constraining the hydrocarbon expulsion history of the coals in Qinshui Basin, North China, from the analysis of fluid inclusions   总被引：1，自引：0，他引：1  

Wei Li  Zhihuan Zhang  Yongcai Yang  Liguo Han  Minghua Shao 《Journal of Geochemical Exploration》2006,89(1-3):222

From the comprehensive study on the homogenization temperatures and the occurrence of fluid inclusions in the framework minerals of the strata between or above the Carboniferous–Permian coals in the Qinshui basin, Shanxi, three stages are predicted of hydrocarbon expulsion from the coals. Combined with the known history of basin evolution, it is deduced that the expulsion of hydrocarbons happened during the J₁ (210–180 Ma), the early K₁ (150–130 Ma) and K₂E₁ (110–60 Ma). In the early stage, the coals produced and discharged coal-generated oils. The average GOI value of four sandstone samples is relatively high, as they have been exposed to high paleo-oil saturation in the strata between or above the coals. The biomarker compositions of oil-bearing fluid inclusions are similar to those of extracts from the coals, and so it is concluded that those oils were derived from the same family of the coals.  相似文献   

Prediction of Resource Volumes at Untested Locations Using Simple Local Prediction Models   总被引：1，自引：1，他引：0  

Emil D. Attanasi  Timothy C. Coburn  Philip A. Freeman 《Natural Resources Research》2006,15(4):223-239

This paper shows how local spatial nonparametric prediction models can be applied to estimate volumes of recoverable gas resources at individual undrilled sites, at multiple sites on a regional scale, and to compute confidence bounds for regional volumes based on the distribution of those estimates. An approach that combines cross-validation, the jackknife, and bootstrap procedures is used to accomplish this task. Simulation experiments show that cross-validation can be applied beneficially to select an appropriate prediction model. The cross-validation procedure worked well for a wide range of different states of nature and levels of information. Jackknife procedures are used to compute individual prediction estimation errors at undrilled locations. The jackknife replicates also are used with a bootstrap resampling procedure to compute confidence bounds for the total volume. The method was applied to data (partitioned into a training set and target set) from the Devonian Antrim Shale continuous-type gas play in the Michigan Basin in Otsego County, Michigan. The analysis showed that the model estimate of total recoverable volumes at prediction sites is within 4 percent of the total observed volume. The model predictions also provide frequency distributions of the cell volumes at the production unit scale. Such distributions are the basis for subsequent economic analyses.

Emil D. AttanasiEmail:

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基于耦合模型的中国能源生产与消费预测及其环境响应(英文)     

李强  任志远 《地理学报(英文版)》2012,22(1):93-109

The paper presents the prediction of total energy production and consumption in all provinces and autonomous regions as well as determination of the variation of gravity center of the energy production, consumption and total discharge of industrial waste water, gas and residue of China via the energy and environmental quality data from 1978 to 2009 in China by use of GM(1,1) model and gravity center model, based on which the paper also analyzes the dynamic variation in regional difference in energy production, consumption and environmental quality and their relationship. The results are shown as follows. 1) The gravity center of energy production is gradually moving southwestward and the entire movement track approxi-mates to linear variation, indicating that the difference of energy production between the east and west, south and north is narrowing to a certain extent, with the difference between the east and the west narrowing faster than that between the south and the north. 2) The gravity center of energy consumption is moving southwestward with perceptible fluctuation, of which the gravity center position from 2000 to 2005 was relatively stable, with slight annual position variation, indicating that the growth rates of all provinces and autonomous regions are basically the same. 3) The gravity center of the total discharge of industrial waste water, gas and residue is characterized by fluctuation in longitude and latitude to a certain degree. But, it shows a southwestward trend on the whole. 4) There are common ground and discrepancy in the variation track of the gravity center of the energy production & consumption of China, and the comparative analysis of the gravity center of them and that of total discharge of industrial waste water, gas and residue shows that the environmental quality level is closely associated with the energy production and consumption (especially the energy consumption), indicating that the environment cost in economy of energy is higher in China.  相似文献   

青海永久冻土区天然气水合物开发的环境影响风险防治          下载免费PDF全文

常华进 《干旱区地理》2012,35(4):639-645

 青海省祁连山南缘多年冻土区发现天然气水合物,这是在我国冻土区的首次发现。虽然青海天然气水合物的发现与开发具有诸如能源战略等重要意义,但在多年冻土区开发天然气水合物具有巨大的环境影响风险,包括CH4释放对全球气候的影响、冻土层的退化和高寒草甸的破坏、开采过程中可能出现的塌方和地陷等。可以通过采用安全可靠的具有针对性的开发技术和工艺,将青海天然气水合物开发纳入柴达木循环经济范畴,采用CO2捕获和封存技术,以及控制工程过程等来防治天然气水合物开发过程中的环境影响。  相似文献   

干旱程度对C₃植物红砂和C₄植物珍珠光合生理参数的影响   总被引：2，自引：1，他引：1  

严巧娣  苏培玺  高松 《中国沙漠》2012,32(2):364-371

 C3和C4植物混生在草地生态系统中较多,而在荒漠生态系统少见。在中国荒漠地区,C3小灌木红砂和C4半灌木珍珠在特定生境下混生在一起,以独特方式适应高温强光和干旱的极端环境。通过在不同干旱程度下测定它们生长期叶片的光合气体交换参数,探讨它们在混生条件下对极端环境的生理响应特征。结果表明,红砂的净光合速率(Pn)、蒸腾速率(E)、气孔导度(Gs)均要高于珍珠;而珍珠的水分利用效率(WUE)则要高于红砂。这表明珍珠和红砂在水分匮乏的荒漠生境下采取了不同的生存策略。红砂通过维持较高净光合速率和较高蒸腾速率来生存;而珍珠则通过高水分利用效率生存。  相似文献   

深对流云向平流层的水汽垂直输送问题研究进展     

雷东洋  金莲姬  朱震宇  高蒙 《南京气象学院学报》2012,4(3):241-247

水汽是一种比CO₂温室效应更强的温室气体,在平流层中为光化学反应提供氢氧自由基,凝结成冰晶后还能为臭氧的消耗提供非均相化学反应界面,从而加速臭氧的消耗,因而对气候有重要影响.深对流云对水汽的垂直输送是平流层水汽的重要来源之一,因此研究深对流云向平流层的水汽输送可以为研究气候变化提供参考.回顾了近年来关于深对流云向平流层的水汽垂直输送问题的研究进展,包括水汽垂直输送到平流层的证据、穿透性深对流云的识别方法、水汽被深对流云垂直输送到平流层的机理以及穿透性深对流云对平流层湿度作用的影响因子4个方面,并进行了小结和展望.  相似文献   

3mm多普勒云雷达测量反演云内空气垂直速度的研究   总被引：7，自引：4，他引：3  

彭亮  陈洪滨  李柏 《大气科学》2012,36(1):1-10

垂直指向的W-波段大气云雷达(WACR)不仅测量云粒子的反射率因子Z, 而且测量多普勒速度谱。本文利用寿县气象站WACR在2008年11月1日一个时段的测量, 进行云内空气垂直速度反演试验。首先讨论个例中反射率、 Doppler平均速度及谱宽的分布特征及原因, 然后利用小粒子示踪法和改进的以小粒子示踪法为基础的粒子下降速度w0—反射率因子 (w0－Z) 关系法反演了云内空气垂直速度, 进而结合Doppler谱数据分析反演结果。结果显示: 小粒子示踪法在湍流较弱时能比较精确地反演空气垂直速度, 而湍流较强时, 湍流造成的误差不可忽略; 改进算法在湍流较强时能够减少湍流对反演结果的影响。  相似文献   

大气本底站反应性气体观测数据处理系统功能设计及实现     

靳军莉  张晓春  林伟立  徐晓斌  王亚强  王瑛 《气象科技》2012,40(5):738-744

基于反应性气体多年观测的较为成熟的数据处理和质量控制方法,采用模块化功能结构设计,通过应用Visual Studio开发平台并结合MAP WinGIS等空间和时间显示控件,对反应性气体观测数据处理系统进行了设计和开发.系统实现了观测数据在空间和时间上的可视化显示,实际业务应用表明,具有良好的人机交互和数据处理能力,具备一定的数据统计分析功能.实现了对大气本底站反应性气体观测数据的统一管理和综合处理,已成为大气成分观测数据质量控制业务系统的一个重要组成部分.  相似文献   

中国汽车空调行业HFC-134a需求和排放预测   总被引：1，自引：0，他引：1       下载免费PDF全文

胡建信  万丹  李春梅  张剑波  易旭 《气候变化研究进展》2009,5(1):1-06

 近年来HFC-134a作为中国汽车空调行业CFC-12制冷剂最主要的替代品,其消费量增长迅速,是中国消费量最大的HFCs（氢氟烃类物质）。以2005年为基线,通过制冷剂替代、技术进步、熟练操作和政策控制等情景假设,预测了中国汽车空调行业HFC-134a的需求量及排放量。结果表明：到2010和2015年,汽车空调HFC-134a的消费量将分别接近2.0万和3.5万t,排放量将分别接近1.6万和3.0万t,约折合排放21.0 和39.0 Mt CO₂当量。上述排放相对基线情景（即维持当前政策措施和不开展回收活动）,2010年和2015年减排温室气体分别为6.7 和13.0 Mt CO₂当量。  相似文献