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71.
Peter Müller-Wolfskeil Dipl.-Geol. Prof. Dr. Wolfgang Zacher 《International Journal of Earth Sciences》1984,73(1):321-335
Zusammenfassung Eine Neuuntersuchung der Tektonik in den Vilser Alpen und im Hochvogelgebiet, wo die Frage seit langer Zeit diskutiert wird, ob dort die Allgäu- und Lechtal-Decke getrennte Einheiten bilden, oder stratigraphisch untrennbar zusammenhängen, erbrachte eine eindeutige Entscheidung für den Deckenbau. Der Verlauf der Deckengrenze konnte zwischen Hochvogel und Hohenschwangauer Alpen präzisiert werden. Der interne Falten- und Schuppenbau der Lechtal-Decke hat nirgends zur Bildung von tektonisch tieferen Teildekken geführt, die internen Verschuppungen besitzen nur ein geringes Ausmaß.
A new investigation of the tectonics in the Vilser Alps and in the Mt. Hochvogel area where since a long time a discussion was going on if the thrust sheets of Allgäu and Lechtal-Decke are separate units or connected by stratigraphic sequences, a definite decision could be made in favour of the nappe structure in this part of the Northern Calcareous Alps. The internal structure of the Lechtal-Decke thrust sheet is characterized by local imbricate structure which originate from sheared folds.
Résumé On a dicuté depuis longtemps dans les Vilser Alpen et dans la région du Mont Hochvogel le problème, si les nappes de Allgäu et Lechtal-Decke sont des unités separées ou qu'ils forment une partie inséparable par des séquences stratigraphiques. Une nouvelle examen de la tectonique a affirmé la structure de nappes dans cette région des Alpes Calcaires du Nord. La structure intérieure de la nappe de Lechtal-Decke est caracterisée par une structure écaillée locale, qui se developpe de plis cisaillés.
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72.
The results of a research study of the carbon monoxide concentration from California to 90° S, Antarctica are presented. The data both extend and support other research studies of the latitudinal distribution of carbon monoxide in that higher concentrations are evident over the Northern Hemisphere than over the Southern Hemisphere. Carbon monoxide concentrations range between 50 to 60 ppb with a few peaks into the 60s in the latitudinal area south of the ITCZ and values of 80 ppb or higher at latitudes north of Hawaii. A comparison is also made of carbon monoxide and ozone concentrations along the flight tract between California and Antarctica, over the Ellsworth Mountains of Antarctica, and between 78° S and the South Pole. These ozone-carbon monoxide data show statistically significant negative correlations in the upper troposphere and lower stratosphere over Antarctica. It is believed that this is a good indication of mixing across the tropopause. 相似文献
73.
J.Michael Moldowan Wolfgang K. Seifert Edward Arnold Jon Clardy 《Geochimica et cosmochimica acta》1984,48(8):1651-1661
Two C28H48-pentacyclic triterpanes were isolated from Monterey shale. X-ray crystallography of a crystal containing both compounds proved their structures as 17β,18α,21α(H)-28,30-bisnorhopane and 17β,18α,21β(H)-28,30-bisnorhopane. Several differences are found between 28,30-bisnorhopanes and the regular hopanes. Unlike the regular hopane epimers, for practical purposes the three epimeric 28,30-bisnorhopanes [17α,21β(H)-, 17β,21α(H)-, and 17β,21β(H)-]cannot be distinguished by their mass spectra. Special conditions are needed to separate them by gas chromatography. The diagenetically first-formed epimer is thought to be 17α,21β(H)- because it predominates in immature shales. The order of thermodynamic stability is 17β,2lα(H) < > 17α,21β(H) > 17β,21β(H), and all three epimers are present in petroleum. 25,28,30-Trisnorhopanes can be analyzed in similar fashion and are found to have similar thermodynamic characteristics. The percent of the ring D/E cis epimer of 28,30-bisnorhopane and/or 25,28,30-trisnorhopane is a useful maturation parameter similar to the 20S/20R sterane ratio. Evidence indicates 25-demethylation of 28,30-bisnorhopane to 25,28,30-trisnorhopane during advanced stages of biodegradation. Hence, percent ring cis 25,28,30-trisnorhopane has an application to maturation assessment in heavily biodegraded oils. 相似文献
74.
Ocean Dynamics - Meeresoptische Messungen auf der Forschungsplattform “Nordsee” haben gezeigt, daß dort während schwerer Stürme, hauptsächlich durch den Einfluß... 相似文献
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77.
Wolfgang Friedrich Müller Yusof Vojdan-Shemshadi Horst Pentinghaus 《Physics and Chemistry of Minerals》1987,14(3):235-237
Transmission electron microscopic study of synthetic CaAl2Ge2O8-feldspar revealed two types of antiphase domains: type “b”-antiphase domains with the displacement vector 1/2 [110] and type “c”-antiphase domains with the displacement vector 1/2 [111]. The “b”-domains were on the order of 0.1 μm in size, while the “c”-domains displayed wall to wall distances mostly between 0.1 and 1 μm. The formation of the two types of antiphase domains is due to reductions in translational symmetry associated with the phase transitions \(C\bar 1 \to I\bar 1 \to P\bar 1\) . The antiphase domain textures of CaAl2Ge2O8-feldspar are very similar to the textures found in natural and synthetic anorthite, CaAl2Si2O8. 相似文献
78.
Karl Brunnacker Manfred Löscher Wolfgang Tillmanns Brigitte Urban 《Quaternary Research》1982,18(2):152-173
Thirteen glacial terraces are known from the western part of the northern Alpine foothills between the Lech and Iller Rivers. In the Lower Rhine region of West Germany, a similar number of terraces are capped by interglacial floodloams and soils. Whereas the environment during individual interglaciations did not differ substantially, the glaciations were progressively more severe. The Main Terrace system of the Rhine may be an exception. The duration of the Quaternary, starting at the base of Praetiglian, is estimated at approximately 2 million yr by paleomagnetic dating. The major cold-warm climatic cycles of the earliest Pleistocene lasted approximately 100,000 yr, the same as those of the Brunhes Chron. The intervening Main Terrace system has not yet been climatically subdivided. Correlation with the Netherlands is possible because of an abundance of paleobotanic and paleomagnetic evidence. In the Alpine foothills, stratigraphically useful indicators of warm climates are missing, but analogies in terrace development permit comparison with the Lower Rhine and Danube. The terrace sequence in the Alpine foothills is incomplete, as are those along most of the other rivers in Europe. Some of the older terraces may have been eroded. 相似文献
79.
Impacts of Present and Future Climate Change and Climate Variability on Agriculture in the Temperate Regions: North America 总被引:2,自引:0,他引:2
The potential impact of climate variability and climate change on agricultural production in the United States and Canada
varies generally by latitude. Largest reductions are projected in southern crop areas due to increased temperatures and reduced
water availability. A longer growing season and projected increases in CO2 may enhance crop yields in northern growing areas. Major factors in these scenarios analyzes are increased drought tendencies
and more extreme weather events, both of which are detrimental to agriculture. Increasing competition for water between agriculture
and non-agricultural users also focuses attention on water management issues. Agriculture also has impact on the greenhouse
gas balance. Forests and soils are natural sinks for CO2. Removal of forests and changes in land use, associated with the conversion from rural to urban domains, alters these natural
sinks. Agricultural livestock and rice cultivation are leading contributors to methane emission into the atmosphere. The application
of fertilizers is also a significant contributor to nitrous oxide emission into the atmosphere. Thus, efficient management
strategies in agriculture can play an important role in managing the sources and sinks of greenhouse gases. Forest and land
management can be effective tools in mitigating the greenhouse effect. 相似文献
80.
Unnaturally high hydraulic gradients below dam sites enhance dissolutional widening of fractures in limestone. A model is
presented which suggests that under unfavorable conditions, leakage rates could become unbearably high during the lifetime
of the dam. At the beginning when water is impounded, leakage rates are low and increase slowly. A positive feedback loop,
however, causes a sudden dramatic increase of leakage within a few years. Deep grouting becomes necessary to prevent such
failures. Inefficiencies in grouting may leave some open fractures in the grouting curtain. These fractures widen faster than
pathways below the grouting curtain, and reduce the effect of the grouted region located below. Therefore, open fractures
act in a similar way as reduction of the grouting depth. 相似文献