Levelling co-located GNSS and tide gauge stations using GNSS reflectometry     

Alvaro Santamaría-Gómez  Christopher Watson  Médéric Gravelle  Matt King  Guy Wöppelmann 《Journal of Geodesy》2015,89(3):241-258

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Nuclear field shift effect as a possible cause of Te isotopic anomalies in the early solar system—An alternative explanation of Fehr et al. (2006 and 2009)     

Frédéric Moynier  Toshiyuki Fujii  Francis Albarède 《Meteoritics & planetary science》2009,44(11):1735-1742

Abstract— We explore the possibility that Te isotopic anomalies measured in Ca‐Al‐rich inclusions (Fehr et al. 2009) and in leachates of carbonaceous chondrites (Fehr et al. 2006) may be due to mass‐independent effects controlled by nuclear field shift rather than to nucleosynthetic processes. Fehr et al.'s spectrum of mass‐independent anomalies of Te isotopes shows a smooth correlation with mass number and nuclear charge distribution. Ratios of even to odd isotopes, as the ¹²⁵Te/¹²⁶Te ratio used by these authors for normalization are particularly prone to nuclear field shift effects. We show that the alternative normalization of isotopic ratios to ¹³⁰Te/¹²⁶Te strongly reduces the trend of isotopic fractionation with mass number, leaving only ¹²⁵Te as truly anomalous. For both normalizations (¹²⁵Te/¹²⁶Te and ¹³⁰Te/¹²⁶Te), Fehr et al.'s results fit the theory of Bigeleisen (1996), which suggests that the nuclear field shift effect can potentially account for the observed Te isotope abundances, as an alternative to nucleosynthetic processes. We propose that these mass‐independent effects may be acquired during accretion of sulfides from the solar nebula.  相似文献   

Structural evolution history of the Red Sea Rift     

G. A. F. d’Almeida 《Geotectonics》2010,44(3):271-282

The Red Sea Rift has been an object of comprehensive studies by several generations of geologists and geophysicists. Many publications and open-file reports provide insights into the geological history of this rift. Paleogene and Cretaceous rocks, which are considered to be prerift, are locally exposed at the margins of the Red Sea Rift. At the same time, some evidence indicates that at least some of these rocks are related to the early stage of the evolution of the Red Sea Rift. The available geological data suggest that the Red Sea region started its active evolution in the Cretaceous. As follows from lithostratigraphic data, the Cretaceous-Paleogene trough that predated the Oligocene-Quaternary rift covered this region completely or partially. The pre-Oligocene magmatism and geological evidence show that the Cretaceous-Paleogene trough was of the rift type. The Cretaceous-Eocene and Oligocene-Quaternary phases of rifting were separated by an epoch of uplifting and denudation documented by the erosion surface and unconformity.  相似文献   

The miniaturized Möessbauer spectrometer MIMOS II for the Phobos-Grunt mission     

D. S. Rodionov  G. Klingelhoefer  E. N. Evlanov  M. Blumers  B. Bernhardt  J. Gironés  J. Maul  I. Fleischer  O. F. Prilutskii  A. F. Shlyk  V. M. Linkin  C. d’Uston 《Solar System Research》2010,44(5):362-370

Möessbauer spectroscopy is a powerful tool for the mineralogical analysis of Fe-bearing materials. The miniaturized Möessbauer spectrometer MIMOS II has already been working on the surface of Mars for 6 years as part of the NASA Mars Exploration Rovers mission. The improved version of the instrument is a component of the scientific payload of the Phobos-Grunt mission. The scientific objectives of the instrument are the following: to identify the iron-bearing phases, to determine the quantitative distribution of iron among these phases, and to determine the distribution of iron among its oxidation states.  相似文献   

Experimental and numerical behaviour of reinforced mortar plates subjected to accelerated corrosion     

Quang Thanh Nguyen  Sabine Caré  Yves Berthaud  Alain Millard  Frédéric Ragueneau 《国际地质力学数值与分析法杂志》2011,35(10):1141-1159

Most reinforced concrete structures are damaged due to corrosion of reinforcements in concrete. In normal conditions the pH near the reinforcements is around 12–13 which means that steel is in a passive state. But aggressive species, such as chloride ions or carbon dioxide, may penetrate into concrete and promote active corrosion. As a consequence (hydro)oxides are produced leading to degradation of concrete structures. For instance cracking of the concrete is generated due to the pressure induced by rust. In this paper, we study the inception and the propagation of cracking on reinforced mortar plates with rebars located either in the middle or at the corner. Additional experiments have been performed on cylindrical specimens to determine the local effect of rust pressure at the interface rust/mortar. The specimens have been subjected to imposed current density in order to enhance the corrosion and digital image intercorrelation has been used to determine displacement fields. The experiments have been compared to numerical modelling. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Ice Sheet And Satellite Altimetry     

Frédérique Rémy  Benoît Legresy  Laurent Testut 《Surveys in Geophysics》2001,22(1):1-29

Since 1991, the altimeters of the ERS European Satellites allow the observation of 80% of the Antarctica ice sheet and the whole Greenland ice sheet: They thus offer for the first time a unique vision of polar ice caps. Indeed, surface topography is an essential data thanks to its capacity to highlight the physical processes which control the surface shape, or to test models. Moreover, the altimeter is also a radar which makes it possible to estimate the snow surface or subsurface characteristics, such as surface roughness induced by the strong katabatic wind or ice grain size. The polar ice caps may not be in a stationary state, they continue to respond to the climatic warming of the beginning of the Holocene, that is 18000 years ago, and possibly start to react to present climatic warming: the altimeter offers the unique means of estimating the variations of volume and thus the contribution of polar ice caps to present sea level change.  相似文献   

Geothermal effects in the formation of electrically conducting zones and temperature distribution in the earth     

A. Ádám 《Physics of the Earth and Planetary Interiors》1978,17(2):P21-P28

Pollack and Chapman have shown that the surface heat flow in continental regions is dependent not only on the earth's crust below the observation site, but also on the upper mantle there. Therefore heat flow can be used to investigate the role of the thermal conditions in the creation of the electrically conductive zones in both the crust and mantle.Empirical exponential formulas describe the depth to the conductivity increase in the crust corresponding to granitization, the depth to the conductive zone at the top of the asthenosphere (SLVZ), as a function of heat flow. Comparing the latter with temperature estimations in the asthenosphere it is concluded that partial melting of the upper mantle occurs only where $\text{q ? 42}\text{m W m}{}^{\mathrm{?2}}\text{? 1}\text{HFU}$.The depth to the conductivity increase corresponding to the mineralogic phase transition in the upper mantle is increased with high temperatures. Such a conductive zone shows that the maximum temperature difference between stable platform areas and active zones is about 1000°C.  相似文献   

Continental Drift. the evolution of a concept: Marvin,Ursula B. (1973): 256 pp., 102 figs. Washington: Smithsonian Institution Press. $ 12.50     

L. Kádár 《Geoforum》1974,5(3):90

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Long-range Earthquake Forecasting with Every Earthquake a Precursor According to Scale     

David A.?RhoadesEmail author  Frank F.?Evison 《Pure and Applied Geophysics》2004,161(1):47-72

Scaling relations previously derived from examples of the precursory scale increase before major earthquakes show that the precursor is a long-term predictor of the time, magnitude, and location of the major earthquake. These relations are here taken as the basis of a stochastic forecasting model in which every earthquake is regarded as a precursor. The problem of identifying those earthquakes that are actually precursory is thus set aside, at the cost of limiting the strength of the resulting forecast. The contribution of an individual earthquake to the future distribution of hazard in time, magnitude and location is on a scale determined, through the scaling relations, by its magnitude. Provision is made for a contribution to be affected by other earthquakes close in time and location, e.g., an aftershock may be given low weight. Using the New Zealand catalogue, the model has been fitted to the forecasting of shallow earthquakes exceeding magnitude 5.75 over the period 1965–2000. It fits the data much better than a baseline Poisson model with a location distribution based on proximity to the epicenters of past earthquakes. Further, the model has been applied, with unchanged parameters, to the California region over the period 1975–2001. There also, it performs much better than the baseline model fitted to the same region over the period 1951–1974; the likelihood ratio is 10¹⁵ in favor of the present model. These results lend credence to the precursory scale increase phenomenon, and show that the scaling relations are pervasive in earthquake catalogues. The forecasting model provides a new baseline model against which future refinements, and other proposed models, can be tested. It may also prove to be useful in practice. Its applicability to other regions has still to be established.  相似文献   

Rift zone reorganization through flank instability in ocean island volcanoes: an example from Tenerife, Canary Islands     

T. R. Walter  V. R. Troll  B. Cailleau  A. Belousov  H.-U. Schmincke  F. Amelung  P. v.d. Bogaard 《Bulletin of Volcanology》2005,67(4):281-291

The relationship between rift zones and flank instability in ocean island volcanoes is often inferred but rarely documented. Our field data, aerial image analysis, and ⁴⁰Ar/³⁹Ar chronology from Anaga basaltic shield volcano on Tenerife, Canary Islands, support a rift zone—flank instability relationship. A single rift zone dominated the early stage of the Anaga edifice (~6–4.5 Ma). Destabilization of the northern sector led to partial seaward collapse at about ~4.5 Ma, resulting in a giant landslide. The remnant highly fractured northern flank is part of the destabilized sector. A curved rift zone developed within and around this unstable sector between 4.5 and 3.5 Ma. Induced by the dilatation of the curved rift, a further rift-arm developed to the south, generating a three-armed rift system. This evolutionary sequence is supported by elastic dislocation models that illustrate how a curved rift zone accelerates flank instability on one side of a rift, and facilitates dike intrusions on the opposite side. Our study demonstrates a feedback relationship between flank instability and intrusive development, a scenario probably common in ocean island volcanoes. We therefore propose that ocean island rift zones represent geologically unsteady structures that migrate and reorganize in response to volcano flank instability.Editorial responsibility: T. DruittThis revised version was published online in February 2005 with typographical corrections and a changed wording.  相似文献