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41.
In the Gran Paradiso massif (western Alps), the boundary between the Erfaulet orthogneiss and the overlying metasediments (Money Complex) is interpreted as a Late Palaeozoic intrusive contact. Major arguments in favour of this hypothesis are: (i) the obliquity of the sedimentary layering with respect to the contact; (ii) the presence of aplitic dykes within the Money Complex; (iii) the lack of a mylonitic zone; and (iv) rare relics of an early generation of garnet in the Money metasediments, interpreted as evidence of the contact metamorphism of the Erfaulet granite. To cite this article: B. Le Bayon, M. Ballèvre, C. R. Geoscience 336 (2004). 相似文献
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Basil Tikoff Matthew R. Davis Christian Teyssier Michel de St. Blanquat Guillaume Habert Sven Morgan 《Tectonophysics》2005,400(1-4):209-226
The Cascade Lake shear zone occurs on the eastern margin of the Tuolumne Intrusive Suite, Sierra Nevada Batholith, California. Foliation in the zone is NNW trending and subvertical, and lineation is moderately south plunging. Deformation is syn-tectonic with emplacement of the Cathedral Peak granodiorite. A deformation gradient exists toward the NE margin of this pluton, with higher strains and lower temperatures of deformation found near the contact. We compare fabric data collected very densely in this shear zone using several techniques: field fabrics, 3D orientation of K-feldspar megacrysts, and AMS (anisotropy of magnetic susceptibility) analysis. In general, the results from the three different methods are in agreement. Deformation in this shear zone is part of a larger pattern of deformation within the Cathedral Peak granodiorite, as recorded by AMS analysis, and dextral shearing associated within the last stage of plutonism within the Sierra Nevada magmatic arc. 相似文献
44.
Quantum-thermodynamic treatment of intrinsic anharmonicity; Wallace’s theorem revisited 总被引:1,自引:0,他引:1
Wallace (in Thermodynamics of crystals, 1972) developed a theorem, rooted in rigid lattice dynamics, which incorporates intrinsic anharmonic effects in solids. The practical
application of this theorem in mineral physics is computationally involved and this is the main reason for the theorem not
getting the attention it deserves. Because intrinsic anharmonicity is an important issue at the extreme conditions in planetary
mantles, we derived a method which removes the computational obstacles in applying this theorem. We extended the theorem to
incorporate details of the phonon spectrum and tested our algorithm on forsterite (Mg2SiO4). Using a least squares inversion technique applied to all available experimental data, we show that it results in an accurate
representation of thermodynamic properties and sound wave velocities of Mg2SiO4 in its complete pressure–temperature stability range. We also show that the accuracy of our results is not significantly
affected by the use of a different equation of state. 相似文献
45.
This paper briefly reviews the sociological literature on the “New” Chinatown phenomenon stressing its structural location
vis-à-vis the “Old” Chinatown and the homeland. It defines the New Chinatown as a panethnopolis, that is a global neighborhood
with a majority population of Chinese immigrants and of other ethnic groups of mostly Asian descent. It analyzes more particularly
the formation, development, and integration of San Francisco’s Richmond District’s New Chinatown into both the city where
it is located and the network of transglobal sites to which it belongs. It provides an interpretation of the New Chinatown
as a cultural enclave within the context of globalization theory. 相似文献
46.
Michel Magny Matthieu Honegger et Laurent Chalumeau 《Eclogae Geologicae Helvetiae》2005,98(2):249-259
Resume. Les fouilles archéologiques réalisées de 1998 à 2002 sur le site néolithique de Marin-Les Piécettes sur la rive nord-ouest
du lac de Neuchatel ont offert l’opportunité d’observer deux séquences sédimentaires intéressantes pour la reconstitution
des variations holocènes du niveau du lac, en particulier au cours de la période correspondant au changement de cours de l’Aar
en direction du nord-est, vers 5650–5500 cal BP. La géométrie des corps sédimentaires et les changements lithologiques permettent
de reconna?tre plusieurs phases majeures de bas niveaux relatifs du plan d’eau vers 6870, 5660, 5060–3990, 3580, 2280, 1640
et 1170 cal BP. Le site néolithique de Marin-Les Piécettes s’est développé vers 5454–5433 cal BP à la faveur d’un court épisode
de bas niveau du lac qui a interrompu une importante phase de haut niveau au début du Subboréal. Les événements paléohydrologiques
identifiés à Marin-Les Piécettes apparaissent cohérents avec ceux reconstitués sur le site de Montilier au bord du lac de
Morat, ainsi qu’avec les variations paléohydrologiques reconstituées à partir des lacs du Jura, du Plateau suisse et des Préalpes
du Nord fran?aises. Ceci suggère qu’ils témoignent d’un signal climatique. La séquence sédimentaire de Marin-Les Piécettes
met enfin en évidence la formation d’un cordon littoral sur la rive nord-ouest du lac juste après 5660 cal BP.
Manuscrit re?u le 22 septembre 2004 Révision acceptée le 11 mars 2005 相似文献
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Derek G. Turner Brent C. Ward Duane G. Froese Michel Lamothe Jeffrey D. Bond Nancy H. Bigelow 《Boreas: An International Journal of Quaternary Research》2016,45(3):521-536
At least five Middle to Late Pleistocene advances of the northern Cordilleran Ice Sheet are preserved at Silver Creek, on the northeastern edge of the St Elias Mountains in southwest Yukon, Canada. Silver Creek is located 100 km up‐ice of the Marine Isotope Stage (MIS) 2 McConnell glacial limit of the St Elias lobe. This site contains ~3 km of nearly continuous lateral exposure of glacial and non‐glacial sediments, including multiple tills separated by thick gravel, loess and tilted lake beds. Infrared‐stimulated luminescence (IRSL) and AMS radiocarbon dating constrain the glacial deposits to MIS 2, 4, either MIS 6 or mid‐MIS 7, and two older Middle Pleistocene advances. This chronology and the tilt of the lake beds suggest Pleistocene uplift rates of up to 1.9 mm a?1 along the Denali Fault since MIS 7. The non‐glacial sediment consists of sand, gravel, loess and organic beds from MIS 7, MIS 3 and the early Holocene. The MIS 3 deposits date to between 30–36 14C ka BP, making Silver Creek one of the few well‐constrained MIS 3‐aged sites in Yukon. This confirms that ice receded close to modern limits in MIS 3. Pollen and macrofossil analyses show that a meadow‐tundra to steppe‐tundra mosaic with abundant herbs and forbs and few shrubs or trees, dominated the environment at this time. The stratigraphy at Silver Creek provides a palaeoclimatic record since at least MIS 8 and comprises the oldest direct record of Pleistocene glaciation in southwest Yukon. 相似文献
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