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51.
There is now strong evidence that stratal geometries on basin margins are most likely a consequence of multiple controls, not just variations in accommodation. Consequently, correct sequence stratigraphic interpretation of stratal geometries requires an understanding of how multiple different controls may generate similar geometries. Using a simple numerical stratigraphic forward model, we explore the impact of time variable sediment supply and different sediment transport rates on stratal geometries. We demonstrate how four common types of stratal geometry can form by more than one set of controlling parameter values and are thus likely to be non‐unique, meaning that there may be several sets of controlling factors that can plausibly explain their formation. For example, a maximum transgressive surface can occur in the model due to an increase in rate of relative sea‐level rise during constant sediment supply, and due to a reduction in rate of sediment supply during a constant rate of relative sea‐level rise. Sequence boundaries, topset aggradation and shoreline trajectories are also examples of non‐unique stratal geometries. If the model simulations in this work are sufficiently realistic, then the modelled stratal geometries are important examples of non‐uniqueness, suggesting the need for a shift towards sequence stratigraphic methods based on constructing and evaluating multiple hypotheses and scenarios. 相似文献
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Rene Laprise Daniel Caya Michel Giguere Guy Bergeron Hélène Côté Jean‐Pierre Blanchet 《大气与海洋》2013,51(2):119-167
Abstract A þrst climate simulation performed with the novel Canadian Regional Climate Model (CRCM) is presented. The CRCM is based on fully elastic non‐hydrostatic þeld equations, which are solved with an efþcient semi‐implicit semi‐Lagrangian (SISL) marching algorithm, and on the parametrization package of subgrid‐scale physical effects of the second‐generation Canadian Global Climate Model (GCMII). Two 5‐year integrations of the CRCM nested with GCMII simulated data as lateral boundary conditions are made for conditions corresponding to current and doubled CO2 scenarios. For these simulations the CRCM used a grid size of 45 km on a polar‐stereographic projection, 20 scaled‐height levels and a time step of 15 min; the nesting GCMII has a spectral truncation of T32, 10 hybrid‐pressure levels and a time step of 20 min. These simulations serve to document: (1) the suitability of the SISL numerical scheme for regional climate modelling, (2) the use of GCMII physics at much higher resolution than in the nesting model, (3) the ability of the CRCM to add realistic regional‐scale climate information to global model simulations, and (4) the climate of the CRCM compared to that of GCMII under two greenhouse gases (GHG) scenarios. 相似文献
54.
Riccardo Camattari Alessandro Battelli Valerio Bellucci Vincenzo Guidi 《Experimental Astronomy》2014,37(1):1-10
The realization of a Laue lens for astronomical purposes involves the mass production of a series of crystalline tiles as optical components, allowing high-efficiency diffraction and high-resolution focusing of photons. Crystals with self-standing curved diffraction planes is a valid and promising solution. Exploiting the quasi-mosaic effect, it turns out to be possible to diffract radiation at higher resolution. In this paper we present the realization of 150 quasi-mosaic Ge samples, bent by grooving one of their largest surface. We show that grooving method is a viable technique to manufacture such crystals in a simple and very reproducible way, thus compatible with mass production. Realized samples present very homogenous curvature. Furthermore, with a specific chemical etch, it is possible to fine adjust one by one the radius of curvature of the grooved samples. Realized crystals was selected for the ASI’s Laue project, that involves the implementation of a prototype of a Laue lens for hard X- and soft γ-ray astronomy. 相似文献
55.
There is a disconcerting global trend of retiring telescopes of modest aperture, supplanting them instead with fewer expensive telescopes of quite large aperture. As a consequence, the available time and feasibility of following transient objects in astrophysics is diminishing. We show the utility of having a suite of small to moderate aperture telescopes capable of conducting imaging and spectroscopic observations in a service queue mode. The example we provide is the high-cadence early observations of the classical nova V475 Scuti (2003) carried out with the SMARTS suite of telescopes located at CTIO. 相似文献
56.
A prominent structure in the Western Escarpment of the Andes of northern Chile is the Oxaya anticline, dissected at the culmination by >1500 m deep valleys. The distribution of fault and fold structures indicates that the anticline could represent a simple buckle. Buckling thus appears to have accommodated crustal shortening in the plate overriding the subducting plate, between the trench and the Western Cordillera. Cross-cutting relationships between structures and dated strata indicated that the time interval of enhanced buckling coincides with the period when rates of valley formation were enhanced. We thus propose that the formation of this anticline was enhanced by fluvial incision, which is consistent with the results of published theoretical models. 相似文献
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Guy Masters 《Geophysical Journal International》1979,57(2):507-534
Summary. The observations of the periods of free oscillation of the Earth provide direct constraints on the density distribution in the Earth. These in turn allow constraints to be placed on the size of departures from a state of adiabaticity and chemical homogeneity. These departures are quantified in terms of a stratification parameter '8' first introduced as an index of chemical homogeneity. The resolving power theory of Backus & Gilbert is used to determine the ability of the observed free oscillations to constrain η in the lower mantle and outer core. The results suggest that the outer core is not strongly chemically stratified although a significantly thermally stable core cannot be excluded. The free oscillations also apparently require a compositional difference between the inner and outer cores. 相似文献
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Robert A. Watson Pedro Carreira Kieran Cleary Rod D. Davies Richard J. Davis Clive Dickinson Keith Grainge † Carlos M. Gutiérrez Michael P. Hobson Michael E. Jones Rüdiger Kneissl Anthony Lasenby Klaus Maisinger Guy G. Pooley Rafael Rebolo José Alberto Rubiño-Martin ‡ Ben Rusholme § Richard D. E. Saunders Richard Savage Paul F. Scott Ane Slosar Pedro J. Sosa Molina Angela C. Taylor David Titterington Elizabeth Waldram Althea Wilkinson 《Monthly notices of the Royal Astronomical Society》2003,341(4):1057-1065