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991.
Jean H. Prevost 《国际地质力学数值与分析法杂志》1982,6(3):323-338
It is the objective of this note critically to assess the merits and shortcomings of two-surface and multi-surface plasticity theories. 相似文献
992.
993.
Peter von Ballmoos Hubert Halloin Jean Evrard Gerry Skinner Nikolai Abrosimov Jose Alvarez Pierre Bastie Bernard Hamelin Margarida Hernanz Pierre Jean Jürgen Knödlseder Bob Smither 《Experimental Astronomy》2005,20(1-3):253-267
The objective of the R&D project CLAIRE was to prove the principle of a gamma-ray lens for nuclear astrophysics. CLAIRE's Laue diffraction lens has a diameter of 45 cm and a focal length of 277 cm; 556 germanium-silicon crystals are tuned to focus 170 keV photons onto a 1.5 cm diameter focal spot. Laboratory measurements of the individual crystals and the entire lens have been used to validate a numerical model that we use to estimate the lens performance for a source at infinity. During a stratospheric balloon flight on 2001 June 14, CLAIRE was directed at the Crab nebula by a pointing system able to stabilize the lens to within a few arcseconds of the target. In 72 min of valid pointing time, 33 photons from the Crab were detected in the 3 keV bandpass of the lens: CLAIRE's first light! The performance of CLAIRE's gamma-ray lens, namely the peak reflectivity for a polychromatic source (9±1%), has been confirmed by ground data obtained on a 205 meter long test range. CLAIRE's measured performance validates the principle of a Laue lens for nuclear astrophysics, opening the way for a space-borne gamma-ray lens telescope that will achieve one to two orders of magnitude improvement in sensitivity over present technologies. 相似文献
994.
The geological structures of the eastern Calabrian Apenninic front within the Gulf of Taranto, southern Italy, are compared
to those of a convergent margin, using simple criteria such as the origin and volume of the sediment supply, and the relative
ratio between sediments carried by the sinking plate and those directly supplied by the overriding margin. Based on this criteria
we distinguish four main types of sedimentary accretion occurring at convergent continental margins: (a) Pacific type, (b)
Indonesian type, (c) Caribbean type, and (d) Apenninic type. 相似文献
995.
Gilbert Feraud Ishiro Kaneoka Claude Jean Allègre 《Earth and Planetary Science Letters》1980,46(2):275-286
We have dated by the K/Ar method the oldest volcanic formations known in the Azores archipelago. The results show a development of this oceanic island system from 5.5 m.y. to the present day.The age pattern is not compatible with a simple migration over a small fixed hot spot, but, plotting tectonic directions which control the volcanism versus age and distance to the Mid-Atlantic Ridge, a simple relationship seems to appear showing an anisotropic but fixed distribution of stress orientation at least for the last 0.7 m.y. 相似文献
996.
Clement Ganino Nicholas T.Arndt Catherine Chauvel Alexandre Jean Charlotte Athurion 《地学前缘(英文版)》2013,4(5):535-546
The Panzhihua gabbroic intrusion,part of the plumbing system of the Emeishan large igneous province, intruded late-Proterozoic dolomites and marls about~263 Ma ago.The dolomites in the contact aureole were converted to brucite marbles and a diverse suite of forsterite,diopside and garnet skarns.The variation in mineralogy is explained in part by differences in the composition of the protolith,particularly the proportion of silica minerals and clay,and in part by transfer of elements from intruding magmas.The trace element compositions of most marbles and skarns are very similar to those of unmetamorphosed dolomites and marls,but some contain high Si,Ti,and Fe contents that are interpreted to have come from a magmatic source.Three brucite marbles sampled~10 m from the contact of the intrusion and named "enriched brucite marble" have trace element compositions very different from their dolomitic protolith:their rare earth elements are strongly enriched whereas levels of Nb-Ta,Zr-Hf and Ti are very low.These characteristics resemble those of carbonate liquid in equilibrium with silicate liquid or more probably with silicate minerals in the case of Panzhihua,a similarity we take to indicate that the sample underwent partial melting.Samples taken up to 300 m from the contact contain brucite indicating that high temperatures persisted well into the country rocks.However,other samples collected only tens of metres from the contact are only slightly recrystallized indicating that conditions in the aureole were highly variable.We suggest that temperatures within the aureole were controlled by conduction of heat from the main intrusion and by supply of additional heat from abundant small dykes within the aureole.Circulation of fluids derived from deeper levels in the aureole flushed the carbon dioxide from the dolomite,lowering temperature needed to partially melt carbonate to the temperatures attained near the intrusion.Irregular but extensive heating destabilized the carbonates of the aureole and decarbonation reactions associated with carbonate breakdown and melting emitted a large volume of CO2,with potential impact on global climate. 相似文献
997.
Characterization of fracture connectivity in a siliciclastic bedrock aquifer near a public supply well (Wisconsin, USA) 总被引:4,自引:2,他引:2
Christopher A. Gellasch Kenneth R. Bradbury David J. Hart Jean M. Bahr 《Hydrogeology Journal》2013,21(2):383-399
In order to protect public supply wells from a wide range of contaminants, it is imperative to understand physical flow and transport mechanisms in the aquifer system. Although flow through fractures has typically been associated with either crystalline or carbonate rocks, there is growing evidence that it can be an important component of flow in relatively permeable sandstone formations. The objective of this work is to determine the role that fractures serve in the transport of near-surface contaminants such as wastewater from leaking sewers, to public supply wells in a deep bedrock aquifer. A part of the Cambrian aquifer system in Madison, Wisconsin (USA), was studied using a combination of geophysical, geochemical, and hydraulic testing in a borehole adjacent to a public supply well. Data suggest that bedrock fractures are important transport pathways from the surface to the deep aquifer. These fractured intervals have transmissivity values several orders of magnitude higher than non-fractured intervals. With respect to rapid transport of contaminants, high transmissivity values of individual fractures make them the most likely preferential flow pathways. Results suggest that in a siliciclastic aquifer near a public supply well, fractures may have an important role in the transport of sewer-derived wastewater contaminants. 相似文献
998.
Bruno Mastrangelo Jean Charollais Roland Wernli Jacques Metzger 《Swiss Journal of Geoscience》2013,106(2):253-263
A detailed mapping of the Salève Mountains reveals tectonically important new Molasse rouge auct. outcrops on the NW side of the Petit Salève and on the SE flank of the Grand Salève. On the SE flank the various dips indicate faults, kinks and folds that can be followed up to 5 km long and parallel to the axis of the chain and also affecting the Cretaceous substratum. This demonstrate a more complex connection of the eastern flank of the Salève Mountains with the adjacent plateau des Bornes than was previously supposed. 相似文献
999.
There is a significant relationship between ambient temperature and mortality. In healthy individuals with no underlying co-morbid conditions, there is an efficient heat regulation system which enables the body to effectively handle thermal stress. However, in vulnerable groups, especially in elderly over the age of 65 years, infants and individuals with co-morbid cardiovascular and/or respiratory conditions, there is a deficiency in thermoregulation. When temperatures exceed a certain limit, being cold winter spells or heat waves, there is an increase in the number of deaths. In particular, it has been shown that at temperatures above 27 °C, the daily mortality rate increases more rapidly per degree rise compared to when it drops below 27 °C.This is especially of relevance with the current emergency of global warming. Besides the direct effect of temperature rises on human health, global warming will have a negative impact on primary producers and livestock, leading to malnutrition, which will in turn lead to a myriad of health related issues. This is further exacerbated by environmental pollution.Public health measures that countries should follow should include not only health-related information strategies aiming to reduce the exposure to heat for vulnerable individuals and the community, but improved urban planning and reduction in energy consumption, among many others. This will reduce the carbon footprint and help avert global warming, thus reducing mortality. 相似文献
1000.
Jean Marcoux Jacques Girardeau Eric Fourcade Jean-Paul Bassoullet Jean Philip Michel Jaffrezo 《Geodinamica Acta》2013,26(4-5):313-325
Abstract— The Lhasa Block (s.l.) is bounded to the South by the Tertiary Yarlung Zangbo suture zone and to the North by the terminal Jurassic/earliest Cretaceous Bangong Nu Jiang suture zone. Several tectonostratigraphic units have been recognized in the central-northern part of the Lhasa Block. These are from bottom to top : 1) a thick turbiditic series with a few lenses of allodapic limestones which have yielded an Aalenian — Bajocian foraminiferal assemblage. This series is tectonieally overlain by the Donqiao ophiolite; 2) the continental to shallow marine late Malm to lowermost Cretaceous Zigetang Formation which disconformably overlies the Donqiao ophiolite and 3) continental red detrital rocks or marine Early/Late Aptian boundary to Early Albian foraminifera-rich bedded limestones in which some volcanic rocks are locally interbedded.We discuss the palaeogeographical distribution and biostratigraphical meaning of some foraminifera (Gutnicella cayeuxi (LUCAS), Palorbitolina fen<ícu/o?(Bl .LMKNBACIl), Praeorbitolina cormyi SCHROEDER and Palor-bilolmoides hedini CHREREHI and ScilKOKDK.lt) and their bearing on the radiometric age of the Aptian-Albian boundary. 相似文献