The Hadean–Archaean transition at 4 Ga: From magma trapping in the mantle to volcanic resurfacing of the Earth          下载免费PDF全文

Anne Nédélec  Marc Monnereau  Michael J. Toplis 《地学学报》2017,29(4):218-223

The Hadean–Archaean transition is poorly known because of the dearth of Hadean rocks. A new conceptual model is presented based on variations in mantle potential temperature (T_p) with time. The critical issue is the depth of melting with respect to a negatively buoyant magma sink between 410 and 330 km (14–11 GPa). Hadean plume magmatism begins below the magma sink, leading to generation of a refractory upper mantle reservoir and the minor production of boninite‐like magmas near the surface. With cooling, the onset of melting migrates above the magma sink, a situation likely occurring since 3.9 Ga and corresponding to T_ps of ~1870°C or less. Therefore, a burst of mafic to ultramafic volcanism was produced at 3.9–3.8 Ga. This extensive volcanism may have triggered gravitational instabilities and favoured the recycling of the Hadean crust into the mantle. Results of this model are discussed in the light of existing isotopic data.  相似文献   

Rheological modelling and deformation instability of lithosphere under extension     

Gianna Bassi  Jean Bonnin 《Geophysical Journal International》1988,93(3):485-504

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Observational evidence for AGN feedback in early-type galaxies     

Kevin Schawinski  Daniel Thomas  Marc Sarzi  Claudia Maraston  Sugata Kaviraj  Seok-Joo Joo  Sukyoung K. Yi  Joseph Silk 《Monthly notices of the Royal Astronomical Society》2007,382(4):1415-1431

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The negotiating process     

RenéJean Dupuy 《Marine Policy》1981,5(3):286-287

UNCLOS III has been the forum for an unprecedented set of negotiations: the Conference has brought together all the states of the world, with the purpose of sharing out the oceans between the various categories of countries. The framework of this great meeting is seemingly that of a classic intergovernmental conference. But in fact this framework, developing certain practices that have already been tried in other assemblies, is making use of new methods of negotiation and decision making for all the questions under discussion.  相似文献   

Observations of the Mg i and ii resonance lines in an active region     

Marc S. Allen  Howard C. McAllister 《Solar physics》1978,60(2):251-264

Spectra from 2678-2931 Å were obtained of an active region during the 19 June 1974, flight of the University of Hawaii rocket-borne echelle spectrograph. We report behavior of the Mg i and ii resonance line cores in quiet Sun, plage, sunspot, and filament structures. Among the interesting variations in these lines we discern a strong suppression of the red Mg ii emission peaks and possible rapid changes in the Mg i core in the spatially partially resolved sunspot.  相似文献   

Effects On the Nutation of the Non-Zonal Harmonics of Third Degree     

Marta Folgueira  Jean Souchay  Hiroshi Kinoshita 《Celestial Mechanics and Dynamical Astronomy》1997,69(4):373-402

In this paper, we calculate the coefficients of the nutation for a rigid Earth model due to the C _3m and S _3m (m ≠ 0) harmonics of the geopotential, starting from the Hamiltonian theory as developped by Kinoshita (1977). We show that these coefficients are far from being negligible as given the level of truncation of 0.1 μas which is necessary in the reconstruction of the tables of nutation, and also that their value is very close to that given by Bretagnon et al. (1997). This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Effects of the Triaxiality on the Rotation of Celestial Bodies: Application to the Earth,Mars and Eros   总被引：1，自引：0，他引：1  

Souchay  Jean  Folgueira  Marta  Bouquillon  Sébastien 《Earth, Moon, and Planets》2003,93(2):107-144

In this paper we discuss the influence of the triaxiality of a celestialbody on its free rotation, i.e. in absence of any external gravitationalperturbation. We compare the results obtained through two different analytical formalisms, one established from Andoyer variables by usingHamiltonian theory, the other one from Euler's variables by usingLagrangian equations. We also give a very accurate formulation of thepolar motion (polhody) in the case of a small amplitude of this motion.Then, we carry out a numerical integration of the problem, with aRunge–Kutta–Felberg algorithm, and for the two kinds of methods above, that we apply to three different celestial bodies considered as rigid : the Earth, Mars, and Eros. The reason of this choice is that each of this body corresponds to a more or less triaxial shape.In the case of the Earth and Mars we show the good agreement betweenanalytical and numerical determinations of the polar motion, and theamplitude of the effect related to the triaxial shape of the body, whichis far from being negligible, with some influence on the polhody of theorder of 10 cm for the Earth, and 1 m for Mars. In the case of Eros, weuse recent output data given by the NEAR probe, to determine in detailthe nature of its free rotational motion, characterized by the presence ofimportant oscillations for the Euler angles due to the particularly largetriaxial shape of the asteroid.  相似文献   

Ellipticity and density at the inner core boundary from subcritical PKiKP and PcP data   总被引：3，自引：0，他引：3  

Annie Souriau  Marc Souriau 《Geophysical Journal International》1989,98(1):39-54

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Jean Serra 《Mathematical Geology》1987,19(4):349-355

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Linked fluid and tectonic evolution in the High Himalaya mountains (Nepal)     

Anne-Marie Boullier  Christian France-Lanord  Jean Dubessy  Jérôme Adamy  Michel Champenois 《Contributions to Mineralogy and Petrology》1991,107(3):358-372

Fluid inclusions were studied in a quartz lens from the structurally highest unit of the Himalaya mountains in Nepal from a textural, geometrical, chemical and isotopic point of view. Six types of fluid inclusions were distinguished. One of these types consists of annular inclusions; this shape is attributed to a confining pressure increase in a non-isotropic stress field. Two successive stress fields were deduced from the orientation of the inclusion planes relative to the schistosity. The bulk composition of the fluid was dominated by CO₂ (>84 mol%) and H₂O. The composition remained constant during the whole history of the sample indicating that it was buffered by the carbonaceous host rock and/or that one single fluid was reworked in situ by decrepitation. Stable isotope of fluids and minerals indicate (1) that fluids were buffered by surrounding rocks for O and C and (2) that at least two types of water (metamorphic and meteoric) were involved. Finally, a P-T-t-- path is proposed for the sample, taking into account the southward thrusting along the Main Central Thrust, the northward tectonic denudation of the Himalaya mountains inducing tectonic burying below the Annapurna Range, and lastly, rapid uplift.  相似文献