Comments on 'Thermal Effects of the Formation of Atlantic Continental Margins by Continental Break up' by N.H. Sleep     

J. P. Foucher  X. Le Pichon 《Geophysical Journal International》1972,29(1):43-46

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High resolution spectra of galaxies     

Pierre Ocvirk  Ariane Lançon  Christophe Pichon  Philippe Prugniel  Damien Le Borgne  Brigitte Rocca-Volmerange  Michel Fioc  Caroline Soubiran  Eric Thiébaut 《Astrophysics and Space Science》2003,284(2):933-936

We present inversion techniques which aim at recovering the composite nature and the kinematics of a stellar population from its high resolution absorption line spectrum. The originality of the combined inversion is its potential to recover both the stellar content and the kinematics simultaneously. These techniques use new synthetic high resolution spectra produced by PéGASE and minimization algorithms. We apply them to mock data representing the bulge and disk population of the inner region of spiral galaxies. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

STECMAP: STEllar Content from high-resolution galactic spectra via Maximum A Posteriori     

P. Ocvirk  C. Pichon  A. Lançon  E. Thiébaut 《Monthly notices of the Royal Astronomical Society》2006,365(1):46-73

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The South Marmara Fault     

Xavier Le Pichon  Caner İmren  Claude Rangin  A. M. Celâl Şengör  Muzaffer Siyako 《International Journal of Earth Sciences》2014,103(1):219-231

We use about 800 km of multichannel exploration seismic reflection profiles of the seventies as well as the results of three drill holes that penetrated the sedimentary cover down to the Upper Cretaceous basement to describe a continuous gently curvilinear, south-concave zone of deformation about 10 km wide that extended over the whole southern shelf of the Sea of Marmara from the Gulf of Gemlik to the Dardanelles Straits in Lower Pliocene time, about 4 Ma. We call this zone of deformation the South Marmara Fault (SMF) system and propose that the SMF was then a branch of the dextral North Anatolian Fault. This branch passed to the north of the Marmara Island Eocene block and thus had a south-facing concavity. This curvature resulted in a significant component of shortening in the western part of the fault. The SMF was deactivated at the end of Lower Pliocene, about 3.5 Ma, except for its easternmost branch between the Gulf of Gemlik and ?mral? Island where about 5 mm/year of dextral motion is still occurring today.  相似文献   

Deformation of the Japanese Islands and seismic coupling: an interpretation based on GSI permanent GPS observations   总被引：2，自引：0，他引：2  

Xavier Le Pichon  Stéphane Mazzotti  Pierre Henry  & Manabu Hashimoto 《Geophysical Journal International》1998,134(2):501-514

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On the kinematic deconvolution of the local neighbourhood luminosity function     

C. Pichon  A. Siebert  O. Bienaymé 《Monthly notices of the Royal Astronomical Society》2002,329(1):181-194

A method for inverting the statistical star counts equation, including proper motions, is presented; in order to break the degeneracy in that equation, it uses the supplementary constraints required by dynamical consistency. The inversion gives access to both the kinematics and the luminosity function of each population in three régimes: the singular ellipsoid, the constant ratio Schwarzschild ellipsoid plane-parallel models and the epicyclic model. This more realistic model is tailored to account for the local neighbourhood density and velocity distribution.
The first model is fully investigated, both analytically and by means of a non-parametric inversion technique, while the second model is shown to be formally its equivalent. The effect of noise and incompleteness in apparent magnitude is investigated. The third model is investigated by a     non-parametric inversion technique where positivity of the underlying luminosity function is explicitly accounted for.
It is argued that its future application to data such as the Tycho catalogue (and in the upcoming satellite GAIA ) could lead – provided that the vertical potential and or the asymmetric drift or w _⊙ are known – to a non-parametric determination of the local neighbourhood luminosity function without any reference to stellar evolution tracks. It should also yield the proportion of stars for each kinematic component and a kinematic diagnostic to split the thin disc from the thick disc or the halo.  相似文献   

On the onset of stochasticity in Λ cold dark matter cosmological simulations     

J. Thiébaut  C. Pichon  T. Sousbie  S. Prunet  D. Pogosyan 《Monthly notices of the Royal Astronomical Society》2008,387(1):397-406

The onset of stochasticity is measured in Λ cold dark matter cosmological simulations using a set of classical observables. It is quantified as the local derivative of the logarithm of the dispersion of a given observable (within a set of different simulations differing weakly through their initial realization), with respect to the cosmic growth factor. In an Eulerian framework, it is shown here that chaos appears at small scales, where dynamic is non-linear, while it vanishes at larger scales, allowing the computation of a critical transition scale corresponding to  ∼3.5 Mpc  h ⁻¹  . This picture is confirmed by Lagrangian measurements which show that the distribution of substructures within clusters is partially sensitive to initial conditions, with a critical mass upper bound scaling roughly like the perturbation's amplitude to the power 0.15. The corresponding characteristic mass,   M _crit= 2 10¹³ M_⊙  , is roughly of the order of the critical mass of non-linearities at   z = 1  and accounts for the decoupling induced by the dark energy triggered acceleration.
The sensitivity to detailed initial conditions spills to some of the overall physical properties of the host halo (spin and velocity dispersion tensor orientation) while other 'global' properties are quite robust and show no chaos (mass, spin parameter, connexity and centre-of-mass position). This apparent discrepancy may reflect the fact that quantities which are integrals over particles rapidly average out details of difference in orbits, while the other observables are more sensitive to the detailed environment of forming haloes and reflect the non-linear scale coupling characterizing the environments of haloes.  相似文献   

Seasonal variation of water-soluble inorganic components in aerosol size-segregated at the puy de D?me station (1,465?m?a.s.l.), France     

L. Bourcier  K. Sellegri  P. Chausse  J. M. Pichon  P. Laj 《Journal of Atmospheric Chemistry》2012,69(1):47-66

The size-segregated chemical composition of aerosol particles was investigated during 1?year at the puy de D?me (1,465?m?a.s.l.), France. These measurements aimed to a better understanding of the influence of the air mass origin on the size-segregated chemical composition of the aerosol at an altitude site. Mountain site measurements are important because they are representative of long range transport and useful for model validation. PM₁ mass concentration exhibits a seasonal variability with a summer maximum. The composition of PM₁ did not change significantly in terms of relative contribution of water soluble inorganic ions but is rather variable in term of total mass concentrations. For the PM_10-1, a different seasonal behaviour was found with maxima concentrations in autumn-winter. Aerosols were classified into four different categories according to their air mass origin: marine, marine modified, continental and Mediterranean. The PM₁₀ aerosol mass at 50?% relative humidity was close to 2.5???g?m^?3 in the marine, 4.3???g?m^?3 in the marine modified, 10.3???g?m^?3 in the continental and 7.7???g?m^?3 in the Mediterranean sectors. We noted that the influence of the air mass origin (on the chemical properties) could be seen especially on the PM_10-1. A significant PM_10-1 mode was found in marine, modified marine, and Mediterranean air masses, and PM₁ dominated in the continental air masses samples. As a result, the aerosol chemical composition variability at the puy de D?me is a function of both the season and air mass type and we provide a chemical composition of the aerosol as a function of each of these environmental factors.  相似文献   

Zenisu Ridge: mechanical model of formation     

Nicolas Chamot-Rooke  Xavier Le Pichon 《Tectonophysics》1989,160(1-4):175-193

Seabeam, seismic and submersible surveys took place during the Kaiko Project and revealed significant compressive deformation at the northeastern end of the Philippine Sea plate, related to the recent collision of the Izu-Ogasawara Arc against Central Japan. Intraoceanic thrusting at the base of the Zenisu Ridge, a linear topographic high running a few tens of kilometers south of the Nankai Trough, is supported by tectonic, magnetic and gravimetric data. We investigate the formation of the Zenisu Ridge in terms of compressive mechanical failure of a thin elastic-perfectly plastic plate, subducting at a trench and subject to a regional compressive axial force. The rheological envelope concept is used throughout the numerical calculations. Based on a detailed study of flexure of the present-day bending far from the deformation zone, we evaluate the bending forces involved: the bulge is 120 to 150 m high and the compressive stress all along the Nankai Trough is about −100 MPa. In the Zenisu Ridge area, an additional compressive stress is superimposed due to the nearby collision at Izu-Peninsula. We compute the vertical distribution of the deviatoric stress before failure and find that the deviatoric stress is maximum at a depth of 20–25 km in the trench area, and again at the surface 60 to 100 km seaward, in the vicinity of the bulge. The development of a thrust joining these two maxima through the entire thickness of the lithosphere is discussed. The model predicts that the formation of the Zenisu Ridge did not occur before 4 Ma and is caused by progressive tectonic uplift due to the redistribution of bending stresses as the ridge approaches the Nankai Trough.  相似文献   

Fluid venting along Japanese trenches: tectonic context and thermal modeling     

P. Henry  S. J. Lallemant  X. Le Pichon  S. E. Lallemand 《Tectonophysics》1989,160(1-4):277-291

Large benthic chemosynthetic communities have been observed at four main locations during the Kaiko submersible dives in the Japanese trenches. They appear to be associated with venting along fractures. The first site for our observation was along the Japan and Kuril trenches where the continental margin is eroded by the subducting plate and collapses into the trench. The benthic communities there seem to be related to tension gashes parallel to the subduction vector. The other communities were found on the toe of the Nankai accretionary prism, along the frontal thrust and tension gashes. The temperature anomaly associated with one of the communities is modeled to constrain the upward flow of interstitial water. As the anomaly has a small spatial extent and as the peak thermal gradient is high, the best fitting model is to be found in a vertical upward flow at a velocity of 100 m/yr in a cylindrical conduit leading out of an underlying shallow thrust.  相似文献