内蒙古鄂尔多斯高原古冰缘遗迹科学考察研究进展     

何瑞霞  金会军  蒋观利  张泽  陈雪梅  Raul David SERBAN  Mihaela SERBAN  Jef VANDENBERGHE  Valentin V.SPEKTOR  Hugh M.FRENCH 《冰川冻土》2021,43(1):263-273

冰缘遗迹(特别是冷生楔形构造及融冻褶皱)是重建古气候及第四纪晚期多年冻土环境的重要证据.内蒙古鄂尔多斯高原是我国北方地区冰缘现象最为发育的地区之一.为准确了解鄂尔多斯高原冰缘遗迹类型及其分布特征、区域冻土演化历史等,中国科学院西北生态环境资源研究院和荷兰自由大学共同组成科研小组,于2018年5—6月组织了"鄂尔多斯高原...  相似文献   

The geochemistry of mantle chromitites from the northern part of the Oman ophiolite: inferred parental melt compositions   总被引：2，自引：0，他引：2  

Hugh Rollinson 《Contributions to Mineralogy and Petrology》2008,156(3):273-288

Chromitites from a single section through the mantle in the Oman ophiolite are of two different types. Low-cr# chromitites, of MORB affinity are found in the upper part of the section, close to the Moho. High-cr# chromitites, with arc affinities are found deeper in the mantle. Experimental data are used to recover the compositions of the melts parental to the chromitites and show that the low-cr# chromitites were derived from melts with 14.5–15.4 wt% Al₂O₃, with 0.4 to 0.9 wt% TiO₂ and with a maximum possible mg# of 0.76. In contrast the high-cr# chromitites were derived from melts with 11.8–12.9 wt% Al₂O₃, 0.2–0.35 wt% TiO₂ and a maximum melt mg# of 0.785. Comparison with the published compositions of lavas from the Oman ophiolite shows that the low-cr# chromitites may be genetically related to the upper (Lasail, and Alley) pillow lava units and the high-cr# chromitites the boninites of the upper pillow lava Alley Unit. The calculated TiO₂–Al₂O₃ compositions of the parental chromitite magmas indicate that the high-cr# chromitites were derived from high-Ca boninitic melts, produced by melting of depleted mantle peridotite. The low-cr# chromitites were derived from melts which were a mixture of two end-members—one represented by a depleted mantle melt and the other represented by MORB. This mixing probably took place as a result of melt–rock reaction. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

The ecological implications of a Yakutian mammoth's last meal   总被引：1，自引：0，他引：1  

Bas van Geel  Andr Aptroot  Claudia Baittinger  Hilary H. Birks  Ian D. Bull  Hugh B. Cross  Richard P. Evershed  Barbara Gravendeel  Erwin J.O. Kompanje  Peter Kuperus  Dick Mol  Klaas G.J. Nierop  Jan Peter Pals  Alexei N. Tikhonov  Guido van Reenen  Peter H. van Tienderen 《Quaternary Research》2008,69(3):361-376

Part of a large male woolly mammoth (Mammuthus primigenius) was preserved in permafrost in northern Yakutia. It was radiocarbon dated to ca. 18,500 ¹⁴C yr BP (ca. 22,500 cal yr BP). Dung from the lower intestine was subjected to a multiproxy array of microscopic, chemical, and molecular techniques to reconstruct the diet, the season of death, and the paleoenvironment. Pollen and plant macro-remains showed that grasses and sedges were the main food, with considerable amounts of dwarf willow twigs and a variety of herbs and mosses. Analyses of 110-bp fragments of the plastid rbcL gene amplified from DNA and of organic compounds supplemented the microscopic identifications. Fruit-bodies of dung-inhabiting Ascomycete fungi which develop after at least one week of exposure to air were found inside the intestine. Therefore the mammoth had eaten dung. It was probably mammoth dung as no bile acids were detected among the fecal biomarkers analysed. The plant assemblage and the presence of the first spring vessels of terminal tree-rings of dwarf willows indicated that the animal died in early spring. The mammoth lived in extensive cold treeless grassland vegetation interspersed with wetter, more productive meadows. The study demonstrated the paleoecological potential of several biochemical analytical techniques.  相似文献   

Thermodynamic data from redox reactions at high temperatures. V. Thermodynamic properties of NiO−MnO solid solutions from emf measurements     

Mark I. Pownceby  Hugh St. C. O'Neill 《Contributions to Mineralogy and Petrology》1995,119(4):409-421

Divariant oxide plus metal assemblages potentially make useful redox sensors for use in hydrothermal and other high pressure experiments. Here we report the calibration of the (Ni, Mn)O/Ni redox sensor in which the Ni/NiO (NNO) oxygen buffer is displaced to lower oxygen chemical potentials (O₂), by the solid solution of MnO in the oxide phase. This assemblage was chosen because: (1) it covers a useful range of O₂; (2) the system can be calibrated very accurately. Values of O₂ defined by the (Ni, Mn)O/Ni assemblage were determined electrochemically, from 900 to 1300 K, using calcia-stabilized zirconia solid electrolytes. The oxide compositions (8 in total, ranging from 0.1X _NiO0.8) were analysed afterwards by electron microprobe, and were checked for internal consistency by measuring the lattice parameters (a₀), using powder XRD. The accuracies of the measurements, both assessed theoretically and established empirically, are (1): ±80J/mol in O₂, ±0.0002 Å in a₀ and ±0.002 to 0.005 in X _NiO. Activity-composition relations were fitted to the Redlich-Kister formalism. There is a slight asymmetry (corresponding to a subregular model) across the solution with A ₀ ^G =9577(±45) J/mol, and A ₁ ^G =–477(±80) J/mol. The experimental data were also used to derive the parameters V^ex, H^ex and S^ex. There is no obvious relationship between excess volumes and enthalpies of mixing, nor between excess volumes and excess entropies. The experimental data from this study have been used to formulate the (Ni, Mn)O/Ni redox sensor expression: O₂ = ₂(NNO) + 2RTlnX _NiO + 2(1 – X _NiO)²[11483 – 1.697T] – 477(4X _NiO – 1)(900 < T(K) < 1300) where O₂(NNO)=–478967+248.514T–9.7961 T In T, from O'Neill and Pownceby(1993a).  相似文献   

Large-scale active coronal phenomena in Yohkoh SXT images     

František Fárník  Zdeněk Švestka  Hugh S. Hudson  Yutaka Uchida 《Solar physics》1996,168(2):331-343

We discuss Yohkoh SXT observations of stationary giant post-flare arches which occurred on 3–6 May, 1992 and study in detail the last arch, associated with the flare at 19:02 UT on 5 May, which extended above the west limb. The arch was similar to the first giant arch discovered on board the SMM, on 21–22 May, 1980. We demonstrate that the long lifetimes of these structures necessarily imply additional energy input from the underlying active region: otherwise, conduction would cool these arches in less than one hour and even with the unlikely assumption of conduction inhibited, pure radiative cooling would not produce the temperature decrease observed. All arch tops, although varying in brightness, stayed for several days at a fairly constant altitude of 100 000 km, and the arch studied, on 5–6 May, was just a new brightening of the pre-existing decaying structure. The brightening was apparently due to inflow of hot plasma from the flare region. Yohkoh data confirm that these stationary arches are rare phenomena when compared with the rising arches studied in Paper I and with Uchida et al.'s expanding active regions.  相似文献   

Climate policy strength compared: China,the US,the EU,India, Russia,and Japan     

Hugh Compston  Ian Bailey 《Climate Policy》2016,16(2):145-164

The few systematic international comparisons of climate policy strength made so far have serious weaknesses, particularly those that assign arbitrary weightings to different policy instrument types in order to calculate an aggregate score for policy strength. This article avoids these problems by ranking the six biggest emitters by far – China, the US, the EU, India, Russia, and Japan – on a set of six key policy instruments that are individually potent and together representative of climate policy as a whole: carbon taxes, emissions trading, feed-in tariffs, renewable energy quotas, fossil fuel power plant bans, and vehicle emissions standards. The results cast strong doubt on any idea that there is a clear hierarchy on climate policy with Europe at the top: the EU does lead on a number of policies but so does Japan. China, the US, and India each lead on one area. Russia is inactive on all fronts. At the same time climate policy everywhere remains weak compared to what it could be.

Policy relevance

This study enables climate policy strength, defined as the extent to which the statutory provisions of climate policies are likely to restrict GHG emissions if implemented as intended, to be assessed and compared more realistically across space and time. As such its availability for the six biggest emitters, which together account for over 70% of global CO₂ emissions, should facilitate international negotiations (1) by giving participants a better idea of where major emitters stand relative to each other as far as climate policy stringency is concerned, and (2) by identifying areas of weakness that need action.  相似文献   

Textures,trace elements,and Pb isotopes of sulfides from the Haopinggou vein deposit,southern North China Craton: implications for discrete Au and Ag–Pb–Zn mineralization     

Zhan-Ke Li  Jian-Wei Li  David R. Cooke  Leonid Danyushevsky  Lejun Zhang  Hugh O’Brien  Yann Lahaye  Wen Zhang  Hai-Jun Xu 《Contributions to Mineralogy and Petrology》2016,171(12):99

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A method for estimating microporosity of fine‐grained sediments and sedimentary rocks via scanning electron microscope image analysis          下载免费PDF全文

Michael Nole  Hugh Daigle  Kitty L. Milliken  Maša Prodanović 《Sedimentology》2016,63(6):1507-1521

This study presents a method of two‐dimensional scanning electron microscope image analysis that directly quantifies microporosity abundance in clay‐rich, fine‐grained sediments. The method is novel in that it is specifically designed to circumvent the challenge to porosity quantification posed by mineral surface charging and topographical artifacts created during Ar‐ion cross‐section polishing. It utilizes the finding that differences in circularity values can be used to distinguish micropores from blemishes in a thresholded image. This method is powerful because it is fast and provides a direct microporosity estimation technique to augment or replace experimental data. The pore size range to which the method is applicable is clear and can be selected depending on the application of the analysis. When used appropriately, the method can be implemented on microporous sediments and sedimentary rock in general. The method is developed using marine muds of Pliocene and Miocene ages from the Nankai margin (burial depths from approximately 200 to 1100 m). The close match between imaging‐derived microporosity and bulk N₂ microporosity measurements shows that porosity in these young and relatively shallowly buried sediments is dominated by pores of sizes that can be imaged by scanning electron microscopy. In Kumano, forearc basin sediments of the Nankai Trough, results of this method show a significant increase in microporosity with burial depth, probably due to microporosity preservation during compaction and possibly early volcanic ash diagenesis.  相似文献   

87Sr/86Sr and 18O/16O isotopic systematics and geochemistry of granitoid plutons across a steeply-dipping boundary between contrasting lithospheric blocks in western Idaho     

Cathyrn A. Manduca  Leon T. Silver  Hugh P. Taylor 《Contributions to Mineralogy and Petrology》1992,109(3):355-372

A spatially abrupt geochemical boundary is preserved within four plutonic complexes along the western margin of the Cretaceous Idaho Batholith near McCall, Idaho. These intrusives ranging in composition from tonalite to granite were emplaced across a regional boundary between accreted oceanic-arc terranes and the continental margin, and their isotopic, major-element, and trace-element geochemistry provide detailed information about this change in crustal characteristics at depth, indicating that the boundary is nearly vertical and extends deep into the lithosphere. The Hazard Creek complex, emplaced west of the transition in wall-rock lithology, has initial ⁸⁷Sr/⁸⁶Sr (R_i) less than 0.7045 and ¹⁸O greater than 7.5, indicating little or no continental crust in its source region; however, elevated ¹⁸O requires some incorporation of rocks formed or altered at the earth's surface. A large shift in R_i and ¹⁸O is observed across the 5–8 km wide Little Goose Creek complex, which was emplaced across the wall-rock boundary. This is interpreted as mixing between: (1) a basaltic or andesitic magma with low K₂O and high Na₂O, Al₂O₃, and Sr, similar to that forming the Hazard Creek complex; and (2) materials similar to Precambrian sedimentary sedimentary rocks with low Sr, high ¹⁸O (+15) and high R_i (0.83 at 100 Ma). The Payette River complex, emplaced east of the wall-rock boundary, exhibits at least one additional component with low ¹⁸O (+6), moderate R_i (0.708) and mafic composition. This component is inferred to be old basaltic material in the lower crust or upper mantle similar to that inferred to be a minor part of the Peninsular Ranges Batholith in SE California (Silver et al. 1979; Hill et al. 1986). The easternmost complex in the Idaho transect is made up of granites that may contain a component of granitic cratonal basement. The entire west-to-east geochemical transition from oceanic-arc magmas to cratonal magmas takes place over a lateral distance of less than 20 km. Although the zone of transitional protolith dominated by metasedimentary rocks is unusually narrow and may have been in part tectonically removed, the striking geochemical similarities between this traverse and several other transects across much broader areas of Nevada and California suggest that the craton itself was not rifted apart, but that juxtaposition of the accreted oceanic-arc terranes occurred along the preexisting craton margin. The data confirm that the isotopic geochemistry of granitoid plutons can be used as a probe of deep lithospheric character, and that major lateral variations in the lithosphere on the order of one to two kilometers in width can be recognized in favorable circumstances.  相似文献   

Can sodium hypochlorite reduce the risk of species introductions from diapausing invertebrate eggs in non-ballasted ships?     

Gray DK  Duggan IC  Macisaac HJ 《Marine pollution bulletin》2006,52(6):689-695

Many transoceanic vessels enter the Great Lakes carrying residual ballast water and sediment that harbours live animals and diapausing eggs. In this study, we examine the potential for sodium hypochlorite (NaOCl) to reduce the risk of species introductions from diapausing invertebrate eggs in residual ballast sediment. We collected sediment from three transoceanic vessels and from Lake Erie and exposed them to NaOCl concentrations between 0 and 10,000 mg/L for 24 h. Hatching success was reduced by >89% in all four experiments at 1,000 mg/L relative to unexposed controls. Fewer species hatched at high than at low NaOCl concentrations. Based on an average residual ballast of 46.8 tonnes, the volume of NaOCl required to treat inbound vessels is 374 L. Impacts of NaOCl use could be minimized by neutralization of treated residuals with sodium bisulfite. Further research is needed, however, to evaluate the effect of NaOCl on ballast tank corrosion.  相似文献