Tracking the isostatic and eustatic signals in an end Ordovician–early Silurian deglacial sedimentary record (Algeria – Libya border)     

Flavia Girard  Rmy Deschamps  Jean‐Franois Ghienne  Stphane Rouss  Jean‐Loup Rubino 《Sedimentology》2019,66(3):1042-1066

To elucidate the signature of isostatic and eustatic signals during a deglaciation period in pre‐Pleistocene times is made difficult because very little dating can be done, and also because glacial erosion surfaces, subaerial unconformities and subsequent regressive or transgressive marine ravinement surfaces tend to amalgamate or erode the deglacial deposits. How and in what way can the rebound be interpreted from the stratigraphic record? This study proposes to examine deglacial deposits from Late‐Ordovician to Silurian outcrops at the Algeria–Libya border, in order to define the glacio–isostatic rebound and relative sea‐level changes during a deglaciation period. The studied succession developed at the edge and over a positive palaeo‐relief inherited from a prograding proglacial delta that forms a depocentre of glaciogenic deposits. The succession is divided into five subzones, which depend on the topography of this depocentre. Six facies associations were determined: restricted marine (Facies Association 1); tidal channels (Facies Association 2); tidal sand dunes (Facies Association 3); foreshore to upper shoreface (Facies Association 4); lower shoreface (Facies Association 5); and offshore shales (Facies Association 6). Stratigraphic correlations over the subzones support the understanding of the depositional chronology and associated sea‐level changes. Deepest marine domains record a forced regression of 40 m of sea‐level fall resulting from an uplift caused by a glacio‐isostatic rebound that outpaces the early transgression. The rebound is interpreted to result in a multi‐type surface, which is interpreted as a regressive surface of marine erosion in initially marine domains and as a subaerial unconformity surface in an initially subaerial domain. The transgressive deposits have developed above this surface, during the progressive flooding of the palaeo‐relief. Sedimentology and high‐resolution sequence stratigraphy allowed the delineation of a deglacial sequence and associated sea‐level changes curve for the studied succession. Estimates suggest a relatively short (<10 kyr) duration for the glacio‐isostatic uplift and a subsequent longer duration transgression (4 to 5 Myr).  相似文献   

Synthesis of In‐House Produced Calibrated Silver Phosphate with a Large Range of Oxygen Isotope Compositions     

Christophe Lcuyer  Franois Fourel  Magali Seris  Romain Amiot  Jean Goedert  Laurent Simon 《Geostandards and Geoanalytical Research》2019,43(4):681-688

The large range of stable oxygen isotope values of phosphate‐bearing minerals and dissolved phosphate of inorganic or organic origin requires the availability of in‐house produced calibrated silver phosphate of which isotopic ratios must closely bracket those of studied samples. We propose a simple protocol to synthesise Ag₃PO₄ in a wide range of oxygen isotope compositions based on the equilibrium isotopic fractionation factor and the kinetics and temperature of isotopic exchange in the phosphate–water system. Ag₃PO₄ crystals were obtained from KH₂PO₄ that was dissolved in water of known oxygen isotope composition. Isotopic exchange between dissolved phosphate and water took place at a desired and constant temperature into PYREX? tubes that were placed in a high precision oven for defined run‐times. Samples were withdrawn at desired times, quenched in cold water and precipitated as Ag₃PO₄. We provide a calculation sheet that computes the δ¹⁸O of precipitated Ag₃PO₄ as a function of time, temperature and δ¹⁸O of both reactants KH₂PO₄ and H₂O at t = 0. Predicted oxygen isotope compositions of synthesised silver phosphate range from ?7 to +31‰ VSMOW for a temperature range comprised between 110 and 130 °C and a range of water δ¹⁸O from ?20 to +15‰ VSMOW.  相似文献   

Study of the Ammonia ice cloud layer in the equatorial region of Jupiter from the infrared interferometric experiment on voyager     

André Marten  Daniel Rouan  Jean Paul Baluteau  Daniel Gautier  Barney J. Conrath  Rudolf A. Hanel  Virgil Kunde  Robert Samuelson  Alain Chedin  Noëlle Scott 《Icarus》1981,46(2):233-248

Spectra from the Voyager 1 infrared interferometer spectrometer (IRIS) obtained near the time of closest approach to Jupiter were analyzed for the purpose of inferring ammonia cloud properties associated with the Equatorial Region. Comparisons of observed spectra with synthetic spectra computed from a radiative transfer formulation, that includes multiple scattering, yielded the following conclusions: (1) very few NH₃ ice particles with radii less than 3 μm contribute to the cloud opacity; (2) the major source of cloud opacity arises from particles with radii in excess of 30 μm; (3) column particle densities are between 1 and 2 orders of magnitude smaller than those derived from thermochemical considerations alone, implying the presence of important atmospheric motion; and (4) another cloud system is confirmed to exist deeper in the Jovian troposphere.  相似文献   

On the elimination of short-period terms in second-order general planetary theory investigated by Hori's method     

Jean Meffroy 《Astrophysics and Space Science》1973,25(2):271-354

1. The short-period terms of a second-order general planetary theory are removed through the Hori's method based on a development of the HamiltonianF in a Lie series which involves a determining functionS not depending upon mixed canonical variables as in the Von Zeipel's method but upon all the canonical variables resulting from the elimination of the short period terms ofF. Canonical variables adopted are the slow Delaunay variables. Eccentricitiese _j and sines γ_j of the semi inclinations are respectively replaced by the Jacques Henrard variablesE _j ,J _j which lead to formulas remarkably simple.F is reduced to the sumF ₀+F ₁ of its terms of degrees 0,1 in small parameter ε of the order of the masses. Only one disturbing planet is considered.F ₁ is not calculated beyond its terms of degree 3 inE _j ,E _j ,J _j , the determining functionS ₂ of degree 2 in ε not being therefore calculated beyond its terms of degree 2 inE′ _j ,E _j ,J _j and the expressions of slow Delaunay canonical variables of the disturbed planetP ₁ and the disturbing planetP ₂ in terms of the new slow Delaunay canonical variables ofP ₁ andP ₂ which result from the elimination of the short period terms ofF ₁ being therefore reduced to their terms of degree <1 in theE′ _j ,E′ _j ,J′ _j . Calculation of the principal partF _1m ofF ₁ is carried out through Laplace coefficients and operatorD=α(d/dα) applied to Laplace coefficients, α ratio of the semi major axis ofP ₁ andP ₂. Eccentricitye ₂ of the disturbed planetP ₂ is assumed to be zero, such an assumption not restricting our aim which is to investigate the mechanism of the elimination of short period terms in a second order general planetary theory carried out through the Hori's method, not to perform the elimination of those terms for a complete second order general planetary theory. Expressions of the slow Delaunay canonical variables in terms of the new ones resulting from the elimination of the short period terms ofF ₁ are written down only for the disturbed planetP ₁.
2. Small divisors in 1/E′ ₁ and 1/E′ ₁ ² appear in the longitude ?₁ of perihelia ofP ₁. No small divisors appear in the other five slow Delaunay variables ofP ₁. The only Jacques Henrard variables which appear in the longitude Ω₁ of the ascending node ofP ₁ are the J _j′ j=1, 2 and no Jacques Henrard variables appear in the slow Delaunay canonical variablesX ₁,Y ₁,Z ₁, λ₁. The solving of the ten canonical equations ofP ₁ andP ₂ in the slow Delaunay canonical variablesX′ _j ,Y′ ₁,Z′ _j ,λ′ _j ,ω′ _j ,Ω′ _j resulting from the elimination of the short period terms ofF ₁ reduces to that of four canonical equations inZ′ _j ,©′ _j and to six quadratures three of them expressing theX′ _j ,Y′ ₁ are constants and the three others expressingλ′ _j ,?′ _j as functions of timet. Solving of the four canonical equations inZ′ _j ,Ω′ _j reduces to that of a first order non linear differential equation and to two quadratures. Sinceγ′ ₁ is then constant, so is the Jacques Henrard variableE′ ₁. If the eccentricitye ₂ ofP ₂ is no more assumed to be zero, additive small divisors inE′ ₂/E′ ² ₁ appear in longitude ?′₁ of perihelia ofP ₁ and the solving of the twelve canonical equations ofP ₁ andP ₂ inX′ _j ,Y′ _j ,Z′ _j ,λ′ _j ,?′ _j ,Ω′ _j is reduced to that of eight canonical equations inY′ _j ,?′ _j ,Z′ _j ,Ω′ _j and to four quadratures expressingX′ _j are constants andλ′ _j as functions oft. Those eight canonical equations split into two systems of four canonical equations, one of them inY′ _j ,?′ _j and the other one inZ′ _j ,Ω′ _j . Each of those two systems is identical to the system inZ′ _j ,Ω′ _j corresponding toe ₂=0 and its solving reduces to that of a first order non linear differential equation and to two quadratures identical to those of the casee ₂=0.
3. Expressions ofX ₁,Y ₁,Z ₁,λ ₁,? ₁,Ω ₁ as functions ofX′ _j ,Y′ ₁,Z′ _j ,λ′ _j ,?′ ₁,Ω′ _j ;j=1, 2 are sums of sines and cosines of the multiples ofλ′ _j ,?′ ₁,Ω′ _j for the terms arising from the indirect partF _1j ofF ₁, Fourier series in those sines and cosines or products of two such Fourier series for the terms arising from the principal partF _1m ofF ₁, coefficients of those sums and Fourier series having one of the eight forms: $$A,{\text{ }}\frac{B}{{E'}},{\text{ }}\frac{C}{{E'^2 }},{\text{ }}D\frac{{j'^{2_1 } }}{{E'^{2_1 } }},{\text{ }}E\frac{{j'^{2_2 } }}{{E'^{2_1 } }},{\text{ }}F\frac{{j'^{_1 } j'^2 }}{{E'^{2_1 } }},{\text{ }}G\frac{{j'^2 }}{{j'^{_1 } }},{\text{ }}H\frac{{j'^{22} }}{{j'^{2_1 } }}{\text{.}}$$ A,..., H being constants which depend upon ratio α. Numerical calculation of the constantsA,..., H arising from the terms ofF _1j is easily carried out; that of theA,..., H arising from the terms ofF _1m require more manipulations, Fourier series in sines and cosines of the multiples ofλ′ _j ,?′ _j ,Ω _ij and products of two such Fourier series having then to be reduced to sums of a finite number of terms and treated through the methods of harmonic analysis. Divisors inp+qα^3/2;p, q relative integers, or products of such divisors appear inA,..., H.
4. the method extends to the case whenF ₁ is calculated beyond its terms of degree 3 in the Jacques Henrard variables.F ₁ being calculated up to its terms of degree 8 in the Jacques Henrard variables which is the precision required to eliminate the short period terms of a complete second order general planetary theory,S ₂ has to be calculated up to its terms of degree 7 and the expression of the slow Delaunay canonical variables ofP ₁ andP ₂ in terms of the slow Delaunay canonical variables ofP ₁ andP ₂ resulting from the elimination of the short period terms ofF ₁ have, therefore, to be calculated up to their terms of degree 5 in the Jacques Henrard variables.

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Study of the deep cloud structure in the equatorial region of Jupiter from voyager infrared and visible data     

Bruno Bézard  Jean Paul Baluteau  André Marten 《Icarus》1983,54(3):434-455

High spatial resolution infrared and visible data obtained by the Voyager 1 spacecraft have been analyzed simultaneously to infer properties of the deep cloud structure of the Jovian troposphere in the 1- to 4-bar pressure range. Influence of the ammonia upper cloud layer, in the 5μm Jovian window, has been investigated through a cloud model derived from far ir Voyager IRIS measurements. The attenuation, computed with an anisotropic scattering formulation, is too weak to explain 5-μm measurements and provides evidence for existence of a cloud structure at deeper levels. The main conclusions derived from the present analysis are summarized below: (1) the deep cloud structure appears to be vertically associated with the NH₃ upper layer; (2) the ammonia cloud is mainly responsible for the visible appearance of the Jovian equatorial region; (3) the deep cloud structure exhibits a grey opacity in the 5-μm window; (4) coldest 5-μm spectra can be interpreted by the existence of a thick cloud layer located at levels in the 180–195°K temperature range. Implications of these results are discussed in conjunction with predictions of dynamical and thermochemical models. NH₄SH is shown to be a likely candidate for the main deep cloud constituent. An even deeper thick H₂O cloud may be present too, but should not be responsible for the observed spread in 5-μm brightness temperatures.  相似文献   

Economic convergence or divergence? Modeling the interregional dynamics of EU regions, 1985–1999     

Giuseppe?ArbiaEmail author  Jean H. P.?Paelinck 《Journal of Geographical Systems》2003,5(3):291-314

In this paper we start from a continuous time framework derived from the classical predator-prey model in order to analyze the recent dynamics of regional evolution in the EU. The model describes a system of interrelated units obeying a complex functional dynamics that at any moment may encompass divergent forces. After briefly reviewing the modeling framework presented elsewhere (Arbia and Paelinck 2002), we consider the dynamics of per-capita income in 119 NUTS-2 European regions in the years 1985–1999, and fit the model using Simultaneous Dynamic Least Squares (Paelinck 1996b). The model is shown to fit the empirical data well. The – potential divergence – leads up to a formidable coordination task for public authorities responsible for regional policies, as they are supposed – if their aim is absolute convergence in an economic sense, meaning equalizing incomes per head – to produce at any time a consistent set of regional policies for all the regions concerned, and not only for the less developed ones.  相似文献   

Kinetic partitioning of Co,Mn, Cs,Fe, Ag,Zn and Cd in fresh waters (Loire) mixed with brackish waters (Loire estuary): experimental and modelling approaches   总被引：2，自引：0，他引：2  

Ciffroy P  Garnier JM  Benyahya L 《Marine pollution bulletin》2003,46(5):626-641

To simulate the behavior of radionuclides along a salinity gradient, in vitro sorption and desorption kinetics of Co, Mn, Cs, Fe, Ag, Zn and Cd were studied in Loire river water and the macrotidal Loire estuarine water over two different seasons. Partitioning between the dissolved phase and suspended solids were followed up over 100 h after adding radioactive tracers to freshly collected freshwater (sorption stage); this stage was followed by desorption in fresh and estuarine waters. A kinetic model describing the interactions between trace metals and particles under a salinity gradient was developed and calibrated. Among parameters and/or processes that control the fate and behavior of contaminated particles during their transfer in estuarine systems, this study shows that the speciation of trace metals is controlled by: (i) the chemical water composition: for all the elements except for Fe, desorption increased with salinity; however, the amplitude of such an effect strongly depended on the element and/or on the composition of the particulate phase (and consequently on the season); (ii) the possibility for a given element to form (or not) stable surface particle moieties such as oxides or inner-sphere complexes; (iii) the distribution of a given element among different types of sites characterised by different binding forces that can lead (or not) to re-adsorption processes after mixing of contaminated particles with uncontaminated water.Our model enabled the quantification of the contribution and the characteristic time of reactions that took place over short and long periods on the global partitioning between particulate and dissolved phases during sorption and desorption and to determine the extent to which these reactions were modified by the salinity.  相似文献   

Toward coastal zone management that ensures coexistence between people and nature in the 21st century   总被引：1，自引：0，他引：1  

Yanagi T  Ducrotoy JP 《Marine pollution bulletin》2003,47(1-6):1-4

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Reductive dissolution of goethite and the subsequent transformation of 4-cyanonitrobenzene: Role of ascorbic acid and pH     

Jean M. Smolen  Megan A. McLaughlin  Michael J. McNevin  Angela Haberle  Shannon Swantek 《Aquatic Sciences - Research Across Boundaries》2003,65(3):308-315

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The influence of<Emphasis Type="Italic">Phragmites</Emphasis> (common reed) on the distribution,abundance, and potential prey of a resident marsh fish in the Hackensack Meadowlands,New Jersey     

Diana?L.?RaichelEmail author  Kenneth?W.?Able  Jean?Marie?Hartman 《Estuaries and Coasts》2003,26(2):511-521

This study investigates the influence ofPhragmites australis (common reed) invasion on the habitat of the resident marsh fish,Fundulus heteroclitus (mummichog) in the Hackensack Meadowlands, New Jersey. These abundant fish play an important role in the transfer of energy from the marsh surface to adjacent subtidal waters and thus estuarine food webs. The objectives of this 2-yr study (1999 and 2000) were to compare the distribution and abundance of the eggs, larvae, juveniles, and adults of mummichog and their invertebrate prey inhabitingSpartina alterniflora-dominated marshes withPhragmites-dominated marshes, and to experimentally investigate the influence of marsh surface microtoprography on larval fish abundance withinPhragmites-dominated marshes. In 2000, we verified that egg deposition does occur inPhragmites-dominated marshes. In both years, the abundance of larvae and small juveniles (4–20 mm TL) inS. alterniflora was significantly greater than inPhragmites-dominated marshes, while larger juveniles and adults (>20 mm TL) were similarly abundant in both habitat types. The overall abundance of larvae and small juveniles was significantly greater in experimentalPhragmites plots in which microtopography was manipulated to resemble that ofSpartina marshes than inPhragmites control plots. Major groups of invertebrate taxa differed between marsh types with potential prey for larval fish being significantly more abundant inS. alterniflora marshes.Phragmites-dominated marshes may not provide the most suitable habitat for the early life-history stages of the mummichog. The low abundance of larvae and small juveniles inPhragmites marshes is likely due to inadequate larval habitat and perhaps decreased prey availability for these early life history stages.  相似文献