Petroleum accumulation and leakage in a deeply buried carbonate reservoir,Níspero field (Mexico)

The filling history of the Níspero deeply buried Lower Cretaceous carbonate reservoir (below 4000 m) from the south part of Gulf of Mexico was studied using a combination of data from petrography, stable isotopes and fluid inclusions and compared with a one-dimensional burial model to derive timing.     

TNOs are Cool: A Survey of the Transneptunian Region

Over one thousand objects have so far been discovered orbiting beyond Neptune. These trans-Neptunian objects (TNOs) represent the primitive remnants of the planetesimal disk from which the planets formed and are perhaps analogous to the unseen dust parent-bodies in debris disks observed around other main-sequence stars. The dynamical and physical properties of these bodies provide unique and important constraints on formation and evolution models of the Solar System. While the dynamical architecture in this region (also known as the Kuiper Belt) is becoming relatively clear, the physical properties of the objects are still largely unexplored. In particular, fundamental parameters such as size, albedo, density and thermal properties are difficult to measure. Measurements of thermal emission, which peaks at far-IR wavelengths, offer the best means available to determine the physical properties. While Spitzer has provided some results, notably revealing a large albedo diversity in this population, the increased sensitivity of Herschel and its superior wavelength coverage should permit profound advances in the field. Within our accepted project we propose to perform radiometric measurements of 139 objects, including 25 known multiple systems. When combined with measurements of the dust population beyond Neptune (e.g. from the New Horizons mission to Pluto), our results will provide a benchmark for understanding the Solar debris disk, and extra-solar ones as well.     

Atlas of ocean tidal charts and maps,Part I: The semidiurnal principal lunar tide M2

Abstract

In this paper the author presents the NSWC ocean tide model of the semidiurnal principal lunar (M₂) tide in an atlas of ocean tidal charts and maps. The model is the computer result of a unique combination of mathematical and empirical techniques, which was introduced, extensively tested, and evaluated by Schwiderski (1978a, 1980a, b, 1983e). The computed M₂ amplitudes and phases are tabulated along with all specially labeled empirical input data on a 1° × 1 ° grid system in 42° × 71° overlapping charts covering the whole oceanic globe. Corresponding global and arctic corange and cotidal maps are included to provide a quick overview of the major tidal phenomena. Significant qualitative and quantitative features are explained and discussed for proper application. In particular, the charted harmonic constants may be used to compute instantaneous M₂ ocean tides with an accuracy of better than 5 cm any time and anywhere in the open oceans. Limitations of this accuracy in coastal waters and border seas are mentioned.

The following four sections of this paper deal with brief reviews, detailed evaluations, and simple improvements of general and special applications of the NSWC ocean tide model. In spite of the numerous and diverse applications with potential possibilities of erroneous interpretations, the results are gratifying without exceptions. For instance, it is concluded that the computed low‐degree spherical harmonic coefficients of the M₂ ocean tide model agree with recent empirical satellite solutions as closely as one could wish for within the elaborated nonmodel error bounds. Detailed computations of all significant tidal energy terms produced the following noteworthy results: The rate of supplied tidal energy of 3.50Z10¹² Watt matches Cartwright's (1977) estimate of 3.5Z10¹² Watt. The rate of energy loss by bottom friction and displacement over the shelves is 1.50Z10¹² Watt, which fits into Miller's (1966) estimated range of (1.4–1.7)Z10¹² Watt, with a clear bias toward his preferred lower bound. Perhaps most remarkably, the computed range (0.41–0.60)Z10¹² Watt for the rate of deep bottom friction work done by the unresolved fluctuating (internal or baroclinic) currents contains in its center Munk's (1966) estimate of 0.5Z10¹² Watt and lies safely below Wunsch's (1975) extreme upper bound of 0.7Z10¹² Watt, which both authors derived for the rate of energy needed to sustain the internal tidal circulations. As is commonly believed, the results substantiate the fact that the total rate of ocean eddy dissipation (into heat) by the averaged (surface or barotropic) currents and their fluctuating comotions is negligible within three significant figures. Finally, the total tidal energy budget of the oceans is perfectly balanced in realistic terms. Budget deficits in earlier tide models were traced to the following tacit assumptions: The ocean bottom tide is doing positive work on the oceans against the ocean tide. In fact, the bottom displacement work by the ocean tide against the bottom tide is an energy loss at the rate of 1.64Z10¹² Watt. The transfer of G. I. Taylor's quadratic bottom friction term from the Irish Sea to the global oceans without accounting for major differences in area resolution scales is directly responsible for significant budget deficits in semiempirical estimates. In contrast, the hydrodynamically more consistent and realistic linear law of bottom friction encountered no serious transplantation difficulties.     

Deformability characteristics of brazilian laterites

This paper summarizes the resilient and permanent deformation characteristics of laterite gravels, determined by cyclic loading in triaxial tests of compacted specimens. A study of laterite pavements was carried out on eight paved road sections in the state of Mato Grosso. Also reported is the influence of fine sand admixture, specimen size and soaking in two laterite samples from Roraima and Rondônia in the North of Brazil. The experimental relationships of resilient moduli against applied stresses are interpreted empirically for models what may be incorporated in a structural analysis of full depth of laterite pavement.     

Bifurcation of volcanic plumes in a crosswind

Bent-over buoyant jets distorted by a crosscurrent develop a vortex pair structure and can bifurcate to produce two distinct lobes which diverge from one another downwind. The region downwind of the source between the lobes has relatively low proportions of discharged fluid. Factors invoked by previous workers to cause or enhance bifurcation include buoyancy, release of latent heat at the plume edge by evaporating water droplets, geometry and orientation of the source, and the encounter with a density interface on the rising path of the plume. We suggest that the pressure distribution around the vortex pair of a rising plume may initially trigger bifurcation. We also report new experimental observations confirming that bifurcation becomes stronger for stronger bent-over plumes, identifying that bifurcation can also occur for straight-edged plumes but gradually disappears for stronger plumes which form a gravity current at their final level and spread for a significant distance against the current. Observations from satellites and the ground are reviewed and confirm that volcanic plumes can show bifurcation and a large range of bifurcation angles. Many of the bifurcating plumes spread out at the tropopause level and suggest the tropopause may act on the plumes as a density interface enhancing bifurcation. Even for quite moderate bifurcation angles, the two plume lobes become rapidly separated downwind by distances of tens of kilometers. Such bifurcating plumes drifting apart can only result in bilobate tephra fall deposits. The tephra fall deposit from the 16 km elevation, SE spreading, bifurcating volcanic plume erupted on 15 May 1981 from Mt Pagan was sampled by previous workers and clearly displayed bilobate characteristics. Examples of bilobate tephra fall deposits are reviewed and their origin briefly discussed. Bilobate deposits are common and may result from many causes. Plume bifurcation should be considered one of the possible mechanisms which can account for come examples of bilobate tephra fall deposits.     

From subduction to transform motion: a seabeam survey of the Hellenic trench system

Preliminary results of a multi-narrow beam survey of the Hellenic trench system, in the Eastern Mediterranean, are presented. The southwestern Ionian branch is divided in small basins, partly filled with Pleistocene sediments. The morphology suggests that the basins are deformed by a compressional stress acting roughly perpendicularly to the trench along N50°E. This direction is the direction of the regional slip vector of the shallow thrust-type earthquakes. The structure of the southeastern Pliny-Strabo branch is quite different. Narrow en-e´chelon slots, oriented N40°E, have been mapped within the main troughs oriented N60°E. The regional earthquake slip vector is also oriented along N40°E. We conclude that the Hellenic trench system is an active subduction system, dominated by thrust along the Ionian branch and by transform motion along the Pliny-Strabo branch.     

Wavelet filter analysis of splitting and coupling of seismic normal modes below 1.5 mHz with superconducting gravimeter records after the December 26, 2004 Sumatra earthquake

New generation superconducting gravimeters (SGs), which have been demonstrated to be better than the best seismometers STS-1 at frequencies below 1 mHz, can be accepted as the quietest vertical seismometers for observation of long-period earth free oscillations. Wavelet filtering with narrow band-pass frequency response as shown in this paper is very helpful in removing at- mospheric pressure effects from on gravity records in long-period seismic mode frequency bands. The processing of high quality SG records after the great Sumatra earthquake (Dec. 26, 2004) with wavelet filtering leads to clear observations of all coupled toroidal modes below 1.5 mHz except these for 0T5, 0T7 and 1T1; moreover 1T2 and 1T3 are, for the first time, unambiguously revealed in the vertical components of the free oscillations. The three well-resolved splitting singlets of overtones 2S1 are observed from a single SG record for the first time.     

A modified ISBA surface scheme for modeling the hydrology of Athabasca River Basin with GCM-scale data

A soil–vegetation–atmosphere transfer model (SVAT), interactions between the soil–biosphere–atmosphere (ISBA) of Météo France, is modified and applied to the Athabasca River Basin (ARB) to model its water and energy fluxes. Two meteorological datasets are used: the archived forecasts from the Meteorological Survey of Canada’s Global Environmental Multiscale Model (GEM) and the European Centre for Mid-range Weather Forecasts global re-analysis (ERA-40), representing spatial scales typical of a weather forecasting model and a global circulation model (GCM), respectively. The original treatment of soil moisture and rainfall in ISBA (OISBA) is modified to statistically account for sub-grid heterogeneity of soil moisture and rainfall to produce new, highly non-linear formulations for surface and sub-surface runoff (MISBA). These new formulations can be readily applied to most existing SVATs. Stand alone mode simulations using the GEM data demonstrate that MISBA significantly improves streamflow predictions despite requiring two fewer parameters than OISBA. Simulations using the ERA-40 data show that it is possible to reproduce the annual variation in monthly, mean annual, and annual minimum flows at GCM scales without using downscaling techniques. Finally, simulations using a simple downscaling scheme show that the better performance of higher resolution datasets can be primarily attributed to improved representation of local variation of land cover, topography, and climate.     

Evolution de la structure de la couche limite planetaire sur des sites oceaniques et continentaux

We have studied the evolution of the planetary boundary layer using both oceanic and continental stations. This has been possible through the analysis of twice-daily temperature radiosondes at three different oceanic stations (Point A; Point K; and Azores) and also at three continental stations (Berlin, Trappes and Madrid) all situated in the Northern Hemisphere. We have studied the annual evolution of mixing layers and of temperature inversion levels; an annual evolution presenting a minimum in winter and a maximum in summer has been observed in the continental stations; the oceanic stations present a lesser variation and in the opposite sense. As for the elevated inversion layers, their maximum frequency can be observed in summer at the oceanic stations and in winter at the continental stations. We have shown that considering the studied stations, both the level and the frequency of the elevated inversion layers are similar at 00 h and at 12 h; such a result is important because these layers regulate the intensity of the exchanges between the ground and the free atmosphere. Using the equivalent coefficient, we have determined the annual variation of the vertical exchanges between the surface and different altitudes. At the continental stations, the vertical exchanges are more important in summer than they are in winter; the opposite behaviour occurs at the oceanic stations.