The Néel transition and magnetic properties of terrestrial,synthetic, and lunar ilmenites

The magnetic susceptibility of a terrestrial, synthetic and lunar ilmenite specimen has been measured from 4 to 300 K. All specimens had a single Néel temperature transition which ranged from 56 to 57.7 K. In one case the powdered specimen was partially aligned in the magnetic field prior to the susceptibility measurements and the Néel transition was observed to shift to 60 K indicating magnetic anisotropy. A study of several magnetic parameters calculated from the experimental data showed gross impurities in the terrestrial specimen, single-domain to multi-domain metallic iron in the synthetic specimen, and a small amount of superparamagnetic metallic iron in the lunar sample. No multidomain iron was observed in the lunar ilmenite. The results of electron spin resonance measurements were also in general agreement with these findings. Because of the absence of Fe³⁺ compared to most terrestrial samples it is suggested that the anisotropic magnetic parameters be determined on lunar ilmenite when a large enough single crystal becomes available.     

Late thermal events based on zircon fission track ages in northeastern New South Wales and southeastern Queensland: Links to Sydney Basin seismicity?

Zircon, concentrated from basaltic terrains in northeastern New South Wales and southeastern Queensland, reveals some unexpectedly young fission track peaks. Between 2 to 13 Ma in age, these peaks are younger than known Tertiary basaltic ages from these regions which match older fission track peaks. Analysis of the fission track data suggests that the young dates are probably not reset ages due to recent heating events such as bush fires, but more likely mark thermal resetting by later volcanic eruptions.

The young ages decrease southwards from Queensland through northern New South Wales and trend toward seismic zones within the Sydney Basin in the Newcastle, Blue Mountains and Illawarra regions. A model based on northward motion of the Australian plate over a hot asthenospheric source (0.75° latitude/Ma over 12 Ma)) predicts the positions of most young zircon ages to within ± 70 km in latitude when projected from seismic sites at Newcastle and Bowral‐Robertson.

A minor hot spot source is proposed, some 250 km across, which triggered isolated basaltic and zircon‐bearing eruptions every few million years and now underlies the southern Sydney Basin. This would bring Sydney Basin seismicity into line with other seismic zones known at present hot spot positions across southeastern Australia and the Tasman Sea. It raises questions concerning activation of local seismicity, potential for volcanic risk and distribution of young uplift in the Sydney region. Similar studies are needed to test other puzzling seismic zones (e.g. the Dalton‐Gunning Zone).     

中国沿海地区海洋交通运输业能源消耗驱动因素的时空差异特征

海洋交通运输业是海洋经济发展的支柱型产业,也是消耗能源最多的海洋产业之一,节能减 排对推进海洋交通运输业的绿色高质量发展具有重要意义。为研究海洋交通运输业能源消耗的 驱动因素,文章构建模型计算2001—2017年中国沿海地区海洋交通运输业的运输周转量、能源消 耗量和产业增加值;建立 LMDI分解模型,分析能源强度效应、...     

Wind erosion climatic erosivity

A physically based wind-erosion climatic factor has been derived: $$CE = \rho \int {[u^2 } - (u_T^2 + \gamma ^l /\rho a^2 )]^{3/2} f(u)du$$ where ? is the air density, a is a constant made up of other constants (von Karman, height of wind speed observation, roughness parameter), u is the horizontal wind speed, u _T is threshold wind speed, f(u) u) is a wind speed probability density function, and γ is the cohesive resistance caused by water on the soil particles. Cohesive resistance is proportional to the square of water content relative to water content at ?1500 J kg^?1. Relative water content is approximated from the Budyko dryness ratio and the Thornthwaite PE index with similar results. CE is calculable from wind speed and other generally available meteorological data, and is usable in the wind erosion equation without some of the limitations of a previously used wind erosion climatic factor.     

Cross-formational hydrocarbon fluid flows in the Tertiary deltaic system of the Beaufort–Mackenzie Basin

Molecular and isotopic compositions of crude oils in the Beaufort–Mackenzie Basin confirm three genetic end-member oil groups and suggest extensive cross-formational hydrocarbon fluid flows in the Tertiary deltaic system. Inter- and intra-fractional variations in the geochemistry of the Tertiary-reservoired oils indicate that the oil source/maturity signatures were substantially masked by biomarkers that were picked up along migration pathways. Thus, many of the previously recognized “immature non-marine oils” are in fact thermally mature, probably derived from unpenetrated deeper marine source rocks. Although the effective source rock volumes have not been evaluated and their exact stratigraphic levels remain unknown, the relative timing of oil generation versus trap formation, rather than poor source quality, may be the cause of under-filled traps in the offshore area.     

渤海、黄海强温跃层数值预报模式

文中对前人关于水温垂直结构计算、模拟和预报研究成果进行了评价，并在此基础上建立了考虑海面吸收辐射和透射辐射、地形、风、海流、界面摩擦及其引起的混合作用的强温跃层三维数值预报模式。该模式运行的驱动量仅为风和气温场资料，因而具有较好的实用性；此外，从试报的结果看，效果是令人满意的。     

Generation of long barotropic waves by moving baric disturbances in a system of basins connected by a channel

We consider long barotropic waves in a system of two rectangular basins connected by a channel in the case where waves are generated by the moving region of disturbances of atmospheric pressure passing above one of the basins. By using a numerical model, we compute the characteristics of the wave process for various values of the parameters of this system. The results of numerical calculations are compared with the corresponding characteristics obtained for the case of a closed basin. We also analyze the distinctive features of long-wave processes induced in the presence of the channel. Translated by Peter V. Malyshev and Dmitry V. Malyshev     

Morphometric analysis of a subtropical Andean basin (Tucumán, Argentina)

A morphometric analysis was done to determine the drainage characteristics of Lules River basin using land-sat imageries and topographical maps. This catchment was divided into seven sub-basins for the analysis: Liquimayo, Hoyada, Ciénaga, De Las Tablas, Siambón, Potrerillo and San Javier. Yungas ecoregion covers almost all the watershed. The drainage patterns of the sub-basins are dendritic and parallel. The basin includes seventh order stream and lower streams order mostly dominate the basin. The development of stream segments is affected by slope and local relief. The mean bifurcation ratio indicates that the drainage pattern is not much influenced by geological structures. The shape parameters also reveal the elongation of the basin and sub-basins.     

Observational study of the seasonality of the submonthly and intraseasonal signal over the tropics

Summary Atmospheric variability in outgoing long-wave radiation (OLR) and tropospheric relative vorticity (VOR) over the South American region was studied from 1979 to 1996 using the complex Morlet wavelet function. The analyses focus on spatial variation in intraseasonal and submonthly scales. Scalograms were used to measure submonthly intraseasonal oscillations in convection, which were found to be predominant in the tropical regions. However, 7-day and 15-day oscillations were observed at tropical and extratropical latitudes in spring and winter, indicating that transient disturbances play a more prominent role. Regarding VOR, tropical energy intensities were highest in the spring and summer, whereas subtropical and extratropical energy intensities were highest in the autumn and winter. The dynamics of the 25-day and 45-day VOR oscillations indicates a possible correlation with Rossby waves over the eastern tropical Pacific Ocean, mainly during the summer. During winter, the 7-day and 15-day VOR oscillations are more frequent at higher latitudes and are enhanced along storm tracks. It was also observed that convection amplitudes in the regions of maximum intensity change appreciably from year to year and from season to season, showing that the behavior of the submonthly and intraseasonal oscillations is nonperiodic and correlates strongly with El Ni?o/Southern Oscillation years. These results confirm the efficiency of wavelet analysis for time-scale studies of atmospheric variability.     

Orbital elements of GSC 0114401023, a new eclipsing binary

We present Strömgrenuvby photometric observations and a series of radial velocities obtained with the Coravel scanner for the 11th magnitude star catalogued in the Guide Star Catalogue as GSC 0114401023. This star was serendipitously identified on UV frames taken with the Very-Wide-Field-Camera aboard Spacelab-1. Radial velocities show the star to be binary and we have determined accurate orbital elements. Photometric data and orbital elements are consistent with the system being a previously-unrecognized eclipsing binary, with period = 33.8766 days and eccentricity = 0.262.Based on observations collected at the Observatoire de Haute Provence (OHP), CNRS, Saint-Michel l'Observatoire, France, and at the European Southern Observatory (ESO), La Silla, Chile.