Study and application of the resonant secular dynamics beyond Neptune     

Melaine Saillenfest  Marc Fouchard  Giacomo Tommei  Giovanni B. Valsecchi 《Celestial Mechanics and Dynamical Astronomy》2017,127(4):477-504

We use a secular representation to describe the long-term dynamics of transneptunian objects in mean-motion resonance with Neptune. The model applied is thoroughly described in Saillenfest et al. (Celest Mech Dyn Astron, doi: 10.1007/s10569-016-9700-5, 2016). The parameter space is systematically explored, showing that the secular trajectories depend little on the resonance order. High-amplitude oscillations of the perihelion distance are reported and localised in the space of the orbital parameters. In particular, we show that a large perihelion distance is not a sufficient criterion to declare that an object is detached from the planets. Such a mechanism, though, is found unable to explain the orbits of Sedna or \(2012\text {VP}_{113}\), which are insufficiently inclined (considering their high perihelion distance) to be possibly driven by such a resonant dynamics. The secular representation highlights the existence of a high-perihelion accumulation zone due to resonances of type 1:k with Neptune. That region is found to be located roughly at \(a\in [100;300]\) AU, \(q\in [50;70]\) AU and \(I\in [30;50]^{\circ }\). In addition to the flux of objects directly coming from the Scattered Disc, numerical simulations show that the Oort Cloud is also a substantial source for such objects. Naturally, as that mechanism relies on fragile captures in high-order resonances, our conclusions break down in the case of a significant external perturber. The detection of such a reservoir could thus be an observational constraint to probe the external Solar System.  相似文献   

Non-resonant secular dynamics of trans-Neptunian objects perturbed by a distant super-Earth     

Melaine Saillenfest  Marc Fouchard  Giacomo Tommei  Giovanni B. Valsecchi 《Celestial Mechanics and Dynamical Astronomy》2017,129(3):329-358

We use a secular model to describe the non-resonant dynamics of trans-Neptunian objects in the presence of an external ten-Earth-mass perturber. The secular dynamics is analogous to an “eccentric Kozai mechanism” but with both an inner component (the four giant planets) and an outer one (the eccentric distant perturber). By the means of Poincaré sections, the cases of a non-inclined or inclined outer planet are successively studied, making the connection with previous works. In the inclined case, the problem is reduced to two degrees of freedom by assuming a non-precessing argument of perihelion for the perturbing body. The size of the perturbation is typically ruled by the semi-major axis of the small body: we show that the classic integrable picture is still valid below about 70 AU, but it is progressively destroyed when we get closer to the external perturber. In particular, for \(a>150\) AU, large-amplitude orbital flips become possible, and for \(a>200\) AU, the Kozai libration islands at \(\omega =\pi /2\) and \(3\pi /2\) are totally submerged by the chaotic sea. Numerous resonance relations are highlighted. The most large and persistent ones are associated with apsidal alignments or anti-alignments with the orbit of the distant perturber.  相似文献   

The Allende multicompound chondrule (ACC)—Chondrule formation in a local super‐dense region of the early solar system          下载免费PDF全文

Addi Bischoff  Gerhard Wurm  Marc Chaussidon  Marian Horstmann  Knut Metzler  Mona Weyrauch  Julia Weinauer 《Meteoritics & planetary science》2017,52(5):906-924

In Allende, a very complex compound chondrule (Allende compound chondrule; ACC) was found consisting of at least 16 subchondrules (14 siblings and 2 independents). Its overall texture can roughly be described as a barred olivine object (BO). The BO texture is similar in all siblings, but does not exist in the two independents, which appear as relatively compact olivine‐rich units. Because of secondary alteration of pristine Allende components and the ACC in particular, only limited predictions can be made concerning the original compositions of the colliding melt droplets. Based on textural and mineralogical characteristics, the siblings must have been formed on a very short time scale in a dense, local environment. This is also supported by oxygen isotope systematics showing similar compositions for all 16 subchondrules. Furthermore, the ACC subchondrules are isotopically distinct from typical Allende chondrules, indicating formation in or reaction with a more ¹⁶O‐poor reservoir. We modeled constraints on the particle density required at the ACC formation location, using textural, mineral‐chemical, and isotopic observations on this multicompound chondrule to define melt droplet collision conditions. In this context, we discuss the possible relationship between the formation of complex chondrules and the formation of macrochondrules and cluster chondrites. While macrochondrules may have formed under similar or related conditions as complex chondrules, cluster chondrites certainly require different formation conditions. Cluster chondrites represent a mixture of viscously deformed, seemingly young chondrules of different chemical and textural types and a population of older chondrules. Concerning the formation of ACC calculations suggest the existence of very local, kilometer‐sized, and super‐dense chondrule‐forming regions with extremely high solid‐to‐gas mass ratios of 1000 or more.  相似文献   

Using archaeological data and sediment parameters to review the formation of the Gravettian layers at Krems-Wachtberg     

Marc Händel  Roswitha Thomas  Tobias Sprafke  Philipp Schulte  Michael Brandl  Ulrich Simon  Thomas Einwögerer 《第四纪科学杂志》2021,36(8):1397-1413

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Origin of magmatic sulfides in a Proterozoic island arc—an example from the Portneuf–Mauricie Domain,Grenville Province,Canada     

Anne-Aurélie Sappin  Marc Constantin  Thomas Clark 《Mineralium Deposita》2011,46(3):211-237

The Portneuf–Mauricie Domain (PMD), located in the south-central part of the Grenville province, contains Mesoproterozoic Ni–Cu ± platinum-group element (PGE) prospects hosted in a variety of plutonic intrusions (layered, with simple structures, or zoned) and emplaced in a mature island arc setting. A two-stage model is envisaged to explain the formation of magmatic sulfides. An early loss of a small amount of sulfides in the conduits of primitive, hydrous mantle-derived melts under high fO₂, resulted in depletion of the magmas in chalcophile and precious metals (Cu/Pd ratios vary from initial mantle values up to 1.6 × 10⁶). Then, nearer the mineralized zones, the magmas interacted with sulfide-bearing country rocks, resulting in felsification of the magmas, assimilation of crustal sulfur (δ ³⁴S values up to +5.5‰), and the formation of an immiscible sulfide liquid. Liquid-sulfide formation was followed by variable interactions between the silicate and sulfide magmas, which were responsible for the enrichment of sulfides in Ni, Cu, and, locally, PGE. Indeed, low R factors are found for prospects hosted in intrusions with a simple internal structure and in layered intrusions whereas high R factors are found for prospects hosted in zoned intrusions. Finally, sulfide melt may have been partly incorporated into later pulses of magma and injected into shallow magma chambers to form the PMD prospects. The PMD prospects share common characteristics with other well-known deposits (Aguablanca, Vammala, Stormyrplunen, and deposits in Alaskan/Ural-type intrusions), attesting to the Ni, Cu, and PGE potential of deposits associated with subduction-zone settings.  相似文献   

Ontogenetic Habitat Shifts of the Atlantic Tomcod (<Emphasis Type="Italic">Microgadus tomcod</Emphasis>) Across an Estuarine Transition Zone     

Marc Antoine Couillard  Gilbert Cabana  Jean François Dery  Gaétan Daigle  Julian John Dodson 《Estuaries and Coasts》2011,34(6):1234-1245

Tomcod (Microgadus tomcod) in the St. Lawrence estuarine transition zone (ETZ) undergo an ontogenetic habitat shift. Older age classes, characterised by a male-dominated sex ratio, disperse downstream over the summer months to occupy the colder more saline waters of the estuary. Significant differences in length and mass along the salinity gradient were observed in September with upstream fish of any given age class generally exhibiting greater growth. These differences were not seen in early summer. Benthic amphipod δ ³⁴S signatures were strongly correlated with salinity and served to demonstrate that tomcod δ ³⁴S signatures were not in isotopic equilibrium in the more saline waters of the ETZ. Seasonal distributional patterns, growth dynamics and isotopic disequilibrium all indicate that the observed habitat shift may occur on an annual basis, following winter aggregation in warmer, less saline waters. Tomcod located in the downstream parts of the ETZ, predominantly males, were significantly more sexually developed than upstream tomcod for a given age. On the other hand, greater growth early in life is insured by occupying warmer, upstream waters during the summer months.  相似文献   

Groundwater exploitation and recharge rate estimation of a quaternary sand aquifer in Dar-es-Salaam area,Tanzania   总被引：1，自引：1，他引：0  

Ibrahimu Chikira Mjemah  Marc Van Camp  Kristine Martens  Kristine Walraevens 《Environmental Earth Sciences》2011,63(3):559-569

Dar-es-Salaam City gets water supply from surface water and groundwater. The groundwater is used to supplement surface water supply and has increasingly become a major source of water supply in the city. The study area comprises three major parts: the central coastal plain with quaternary fluvial–deltaic sediments, the deltaic Mio-Pliocene clay-bound sands and gravels in the northwest and southeast and the Lower Miocene fluviatile sandstones of Pugu Hills in the west of the study area. The main objective of this study was to quantify the integrated water balance. The major source of renewable groundwater in the aquifer is rainfall. Hence, the average recharge of 256.2 mm/year (for the year 2006) to the aquifer was estimated using the balance method of Thornthwaite and Mather, which is equal to 99.4 hm³/year for the whole alluvial aquifer. This value was balanced with total groundwater abstraction of 8.59 hm³/year, baseflow to rivers of 75.7 hm³/year and discharge into the sea (15.11 hm³/year).  相似文献   

Overview of the subsurface structural pattern of the Paris Basin (France): Insights from the reprocessing and interpretation of regional seismic lines     

Laurent Beccaletto  Olivier Serrano Stéphane Marc 《Marine and Petroleum Geology》2011,28(4):861-879

The study presents the methodology used by the French Geological Survey (BRGM) for the building, reprocessing and interpretation of selected regional seismic lines in the Paris intracratonic basin (France): the 14 constructed E-W and N-S regional transects represent a total of 2,516 km length, and are based on the merge of 240 seismic single profiles recorded by petroleum operators between 1971 and 1995. The regional lines have been selected to cross the main oil fields of the Paris Basin, as well as high potential areas for oil exploration. A first difficulty was to recover the raw data necessary to build-up the regional transects. The signal reprocessing, harmonization and merge of the single seismic lines, constituent of the regional transects, are then described; these operations represent the cornerstone of the study. We put the emphasis on the primary static corrections, as the targeted structures are commonly spatially associated with large seismic velocity variations in the upper Cretaceous chalk and Tertiary sedimentary cover.The interpreted regional transects definitely give complementary information to the existing studies, which generally lack seismic (and therefore structural) data: we give an overview of the main structural and geometrical features of the Paris Basin: inversion structures, major unconformities, as well as Permo-Carboniferous basins. We also describe the structural pattern, and show the close relationships between the faults geometry, the faults density, and the geological evolution of the Paris Basin: we distinguish (1) few large-scale polyphase faults, with a Variscan origin, representing the first order structural frame of the Paris Basin; (2) monophase normal faults, with strike-slip features, representing the subsurface prolongation of Cenozoic grabens cropping out in the neighbourhood; (3) deep normal faults, sealed by the base Calcareous Dogger sequence, related to the Permo-Liassic extensional tectonic regime. This large-scale view of the Paris Basin has highlighted several potential exploration targets.  相似文献   

The vulnerability of Pyrenean ski resorts to climate-induced changes in the snowpack     

Marc Pons  Juan Ignacio López-Moreno  Martí Rosas-Casals  Èric Jover 《Climatic change》2015,131(4):591-605

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Oxygen isotopic constraints on the origin of Mg-rich olivines from chondritic meteorites     

Guy Libourel  Marc Chaussidon 《Earth and Planetary Science Letters》2011,301(1-2):9-21

Chondrules are the major high temperature components of chondritic meteorites which accreted a few millions years after the oldest solids of the solar system, the calcium–aluminum-rich inclusions, were condensed from the nebula gas. Chondrules formed during brief heating events by incomplete melting of solid dust precursors in the protoplanetary disk. Petrographic, compositional and isotopic arguments allowed the identification of metal-bearing Mg-rich olivine aggregates among the precursors of magnesian type I chondrules. Two very different settings can be considered for the formation of these Mg-rich olivines: either a nebular setting corresponding mostly to condensation–evaporation processes in the nebular gas or a planetary setting corresponding mostly to differentiation processes in a planetesimal. An ion microprobe survey of Mg-rich olivines of a set of type I chondrules and isolated olivines from unequilibrated ordinary chondrites and carbonaceous chondrites revealed the existence of several modes in the distribution of the ?¹⁷O values and the presence of a large range of mass fractionation (several ‰) within each mode. The chemistry and the oxygen isotopic compositions indicate that Mg-rich olivines are unlikely to be of nebular origin (i.e., solar nebula condensates) but are more likely debris of broken differentiated planetesimals (each of them being characterized by a given ?¹⁷O). Mg-rich olivines could have crystallized from magma ocean-like environments on partially molten planetesimals undergoing metal–silicate differentiation processes. Considering the very old age of chondrules, Mg-rich olivine grains or aggregates might be considered as millimeter-sized fragments from disrupted first-generation differentiated planetesimals. Finally, the finding of only a small number of discrete ?¹⁷O modes for Mg-rich olivines grains or aggregates in a given chondrite suggests that these shattered fragments have not been efficiently mixed in the disk and/or that chondrite formation occurred in the first vicinity of the breakup of these planetary bodies.  相似文献