The mineral composition of the Napolitan yellow tuff     

Erik Norin 《International Journal of Earth Sciences》1955,43(2):526-534

Zusammenfassung Der gelbe neapolitanische Tuff scheidet sich auffallend von den übrigen Formationen der mächtigen quartären, vulkanischen Lagerfolge von Campanien durch die Art der Umwandlung, die die Glassubstanz des Tuffs erlitten hat. Diese Umwandlung ist durch folgende Merkmale charakterisiert: 1. nur das vulkanische Glas ist dabei angegriffen worden; 2. starke Anreicherung und Oxydation des Eisens und 3. starke Zeolithbildung.Die Hauptminerale der Tonfraktion sind Herschelit, Montmorillonit und ein dem Hydrobiotit nahestehendes Tonmineral. Die Bildungsweise scheint prinzipiell ähnlicher Art wie die Palagonitisierung der Sideromelane gewesen zu sein, d. h. Zersetzung von glühheißem vulkanischem Glas durch hydrochemische Reaktionen.  相似文献   

Populationsdynamik und Produktion des Zooplanktons im Greifensee und im Vierwaldstättersee   总被引：2，自引：0，他引：2  

Dr. Erik Mittelholzer 《Aquatic Sciences - Research Across Boundaries》1970,32(1):90-149

Ohne Zusammenfassung  相似文献   

Offshore petroleum and commercial fishery interactions: The case of Long Point,Port Dover,Lake Erie     

Val  Erik  Nelson  J. G. 《GeoJournal》1983,7(3):247-260

GeoJournal - From a human ecological perspective, research was undertaken on interactions between Lake Erie fisheries and offshore petroleum (gas) development from 1913 to summer, 1981. In an...  相似文献   

Cladoceran stratigraphy in two shallow brackish lakes with special reference to changes in salinity, macrophyte abundance and fish predation   总被引：4，自引：0，他引：4  

Susanne Lildal Amsinck  Erik Jeppesen  David Ryves 《Journal of Paleolimnology》2003,29(4):495-507

Sub-fossils of Cladocera and Foraminifera were used to reconstruct changes since 1870 in the trophic dynamics of two brackish lakes, Glombak and Han Vejle, located in the Vejlerne nature reserve, Denmark, a site of international conservation importance. After creation of the lakes in the mid-1870s following land reclamation, the two lakes have developed quite differently; today Glombak is turbid, while Han Vejle is clear. In both lakes, stratigraphic changes in the assemblages of foraminifers and cladocerans indicate an abrupt shift from marine to brackish conditions at the end of the 19th century, coinciding with land reclamation. However, the composition of the fossil invertebrate assemblages in the 20th century implies differences in the exposure to salinity, in fish predation and in habitat diversity. In Glombak, the cladoceran record suggests relatively saline conditions in the first quarter of the last century and high macrophyte abundance followed by lower salinities and subsequently a major decrease in macrophyte abundance and an increase in fish predation during the past ca. 40 years. By contrast, in Han Vejle low salinity, high abundance of macrophytes and only minor changes in fish predation seem to have prevailed throughout most of the 20th century. The results are consistent with recent contemporary data, the few historical records, as well as with trends in the records of diatoms and macrofossils. This study highlights the potential of using crustacean remains as indicators of long-term changes in the trophic dynamics of brackish lakes.  相似文献   

Deformation mechanism maps for feldspar rocks   总被引：6，自引：0，他引：6  

Erik Rybacki  Georg Dresen 《Tectonophysics》2004,382(3-4):173-187

Deformation mechanism maps for feldspar rocks were constructed based on recently published constitutive laws for dislocation and grain boundary diffusion creep of wet and dry plagioclase aggregates. The maps display constant temperature contours in stress-grain size space for strain rates ranging from 10⁻¹⁶ to 10⁻¹² s⁻¹.Two fields of dominance of grain boundary diffusion-controlled creep and dislocation creep are separated by a strongly grain size-sensitive transition zone. For wet rocks, diffusion-controlled creep dominates below a grain size of about 0.1–1 mm, depending on temperature, stress, strain rate and feldspar composition. Plagioclase aggregates containing up to 0.3 wt.% water as often found in natural feldspars are more than 2 orders of magnitude weaker than dry rocks. The strength of water-bearing feldspar rocks is moderately dependent on composition and water fugacity.For a grain size range of about 10–50 μm commonly observed in natural ultramylonites, the deformation maps predict that diffusion-controlled creep is dominant at greenschist to granulite facies conditions. Low viscosity estimates of 10¹⁸–10¹⁹ Pa·s from modeling postseismic stress relaxation and channel flow of the continental lower crust can only be reconciled with laboratory experiments assuming dislocation creep at high temperatures >900 °C or, at lower temperatures, diffusion creep of fine-grained rocks possibly localized in abundant high strain shear zones. For similar thermodynamic conditions and grain size, lower crustal rocks are predicted to be less than order of magnitude weaker than upper mantle rocks.  相似文献   

Rapid uplift of southern Alaska caused by recent ice loss   总被引：3，自引：0，他引：3  

Christopher F. Larsen  Roman J. Motyka  Jeffrey T. Freymueller  Keith A. Echelmeyer  Erik R. Ivins 《Geophysical Journal International》2004,158(3):1118-1133

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International Emission Trading and the Cost of Greenhouse Gas Emissions Mitigation and Sequestration   总被引：1，自引：0，他引：1  

Michael J. Scott  James A. Edmonds  Natesan Mahasenan  Joseph M. Roop  Anthony L. Brunello  Erik F. Haites 《Climatic change》2004,64(3):257-287

The deployment of carbon capture and sequestration (CC&S) technologies is greatly affected by the marginal cost of controlling carbon emissions (also the value of carbon, when emissions permits are traded). Both the severity and timing of emissions limitations and the degree to which emissions limitation obligations can be traded will affect the value of carbon and thereby the timing and magnitude of CC&S technology deployment. Emissions limits that are more stringent in the near term imply higher near-term carbon values and therefore encourage the local development and deployment of CC&S technologies.Trade in emissions obligations lowers the cost of meeting any regional or global emissions limit and so affects the rate of penetration of CC&S technologies. Trade lowers the marginal value of carbon and CC&S penetration in high cost regions and raises the marginal value of carbon and CC&S penetration in low cost regions. The net impact on the world CC&Stechnologies depends on whether their increased use in low-cost regions exceeds the reduced use in high-cost regions.In the long term, CC&S technologies must not only remove carbon but permanently sequester it. If reservoirs are not permanent, then the emissions and costs of control are merely displaced into the future. The paper presents quantitative estimates for the impacts of trade in emissions limitation obligations on the timing, magnitude, and geographic distribution of CC&S technologies and the marginal and total costs of carbon control.  相似文献   

Structure, geometry and formation of brittle discontinuities in anisotropic crystalline rocks of the Central Gotthard Massif, Switzerland     

Christian Zangerl  Simon Loew  Erik Eberhardt 《Eclogae Geologicae Helvetiae》2006,99(2):271-290

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DNAPL Transport Through Macroporous, Clayey Till Columns     

Peter R. Jørgensen  Kim Broholm  Torben O. Sonnenborg  Erik Arvin 《Ground water》1998,36(4):651-660

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Comment on Special Issue on Geostatistics with Guest Editor A. G. Journel     

Kyrre Bratvedt  Erik Bølviken  Tore Gimse  Helge Holden  Lars Holden  Ragnar Knarud 《Mathematical Geology》1998,30(2):245-246

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