Systematic variations of sialic and volcanic detritus in piston cores from the Red Sea

The ${}^{87}\text{Sr}{}^{86}\text{Sr}$ ratios and Sr concentrations of the non-carbonate fractions of sediment from two cores taken in the median valley of the Red Sea indicate that the detrital fractions are mixtures of two components originating from old sialic and young volcanic rocks of the surrounding land areas. The mixing equations were derived from the data and were used to estimate the Sr concentrations of the two components. The volcanogenic detritus has a Sr content between 770 and 800 ppm while the component derived from old sialic rocks contains from 50 to 70 ppm. The volcanic component consists primarily of unweathered particles of alkali basalt and volcanic glass while the sialic component is represented by clay minerals and X-ray amorphous material. Systematic variations of the concentration of volcanogenic detritus were used to define layers of sediment which correlate over a distance of about 200 km separating the two cores. The concentrations of quartz, feldspar, amphibole, illite, kaolinite and chlorite were found to vary systematically with the content of volcanogenic detritus as calculated from the Sr data. The carbonate concentrations of the sediment range from 33 to 87% and appear to increase in a southerly direction. The rate of carbonate deposition increased at times of more efficient input of sediment derived from old sialic rocks. This relationship is explained by the hypothesis that both were influenced indirectly by brief warming trends during the Würm glaciation. The occurrence of sediment layers enriched in sediment derived from old sialic rocks correlates approximately with interstadials of the Würm glaciation in northern Europe. Increased input of volcanogenic detritus occurred around 37,000 and 26,000yr ago and during the past 5000 yr. A plot of ${}^{87}\text{Sr}{}^{86}\text{Sr}$ and ${}^{87}\text{Rb}{}^{86}\text{Sr}$ ratios defines a line on the Rb-Sr isochron diagram yielding a fictitious date of about 230 million yr.     

The age of ferroan anorthosite 60025: oldest crust on a young Moon?

SmNd isotopic data for mineral separates from the ferroan anorthosite 60025 define a precise isochron of 4.44 ± 0.02Ga age. This age is roughly 110 m.y. younger than the formation of the first large solid objects in the solar nebula, as recorded by the radiometric ages of the differentiated meteorites. In the magma ocean model for early lunar differentiation, ferroan anorthosites are the first crustal rocks to form on the Moon. If the Moon is as old as the oldest meteorites, the relatively young age determined for 60025 implies either that the magma ocean did not form synchronously with lunar formation, or that the magma ocean required over 100 m.y. before reaching the stage of ferroan anorthosite crystallization. Alternatively, we propose that the accumulated body of radiogenic isotope data for lunar rocks permit the Moon to be as young as 4.44–4.51 Ga. If so, isotopic evidence for chemical differentiation on the Earth at about this same time suggests that the formation of the Moon is reflected in the chemical evolution of the Earth. This, in turn, is consistent with the idea that the materials that now make up the Moon were derived from the Earth, perhaps ejected by collision between the Earth and another very large planetesimal during the final stages of accumulation of the terrestrial planets. Terrestrial origin models for the Moon lessen the requirement that the Earth and Moon each have near chondritic relative abundances of the refractory elements and could require that certain chemical and isotopic characteristics of both bodies be considered in the framework of the chemical mass-balance of the combined Earth-Moon system.     

Why do we need and how should we implement Bayesian kriging methods

The spatial prediction methodology that has become known under the heading of kriging is largely based on the assumptions that the underlying random field is Gaussian and the covariance function is exactly known. In practical applications, however, these assumptions will not hold. Beyond Gaussianity of the random field, lognormal kriging, disjunctive kriging, (generalized linear) model-based kriging and trans-Gaussian kriging have been proposed in the literature. The latter approach makes use of the Box–Cox-transform of the data. Still, all the alternatives mentioned do not take into account the uncertainty with respect to the distribution (or transformation) and the estimated covariance function of the data. The Bayesian trans-Gaussian kriging methodology proposed in the present paper is in the spirit of the “Bayesian bootstrap” idea advocated by Rubin (Ann Stat 9:130–134, 1981) and avoids the unusual specification of noninformative priors often made in the literature and is entirely based on the sample distribution of the estimators of the covariance function and of the Box–Cox parameter. After some notes on Bayesian spatial prediction, noninformative priors and developing our new methodology finally we will present an example illustrating our pragmatic approach to Bayesian prediction by means of a simulated data set.     

Modelling the water balance of a mesoscale catchment basin using remotely sensed land cover data

Hydrological modelling of mesoscale catchments is often adversely affected by a lack of adequate information about specific site conditions. In particular, digital land cover data are available from data sets which were acquired on a European or a national scale. These data sets do not only exhibit a restricted spatial resolution but also a differentiation of crops and impervious areas which is not appropriate to the needs of mesoscale hydrological models. In this paper, the impact of remote sensing data on the reliability of a water balance model is investigated and compared to model results determined on the basis of CORINE (Coordination of Information on the Environment) Land Cover as a reference. The aim is to quantify the improved model performance achieved by an enhanced land cover representation and corresponding model modifications. Making use of medium resolution satellite imagery from SPOT, LANDSAT ETM+ and ASTER, detailed information on land cover, especially agricultural crops and impervious surfaces, was extracted over a 5-year period (2000–2004). Crop-specific evapotranspiration coefficients were derived by using remote sensing data to replace grass reference evapotranspiration necessitated by the use of CORINE land cover for rural areas. For regions classified as settlement or industrial areas, degrees of imperviousness were derived. The data were incorporated into the hydrological model GROWA (large-scale water balance model), which uses an empirical approach combining distributed meteorological data with distributed site parameters to calculate the annual runoff components. Using satellite imagery in combination with runoff data from gauging stations for the years 2000–2004, the actual evapotranspiration calculation in GROWA was methodologically extended by including empirical crop coefficients for actual evapotranspiration calculations. While GROWA originally treated agricultural areas as homogeneous, now a consideration and differentiation of the main crops is possible. The accuracy was determined by runoff measurements from gauging stations. Differences in water balances resulting from the use of remote sensing data as opposed to CORINE were analysed in this study using a representative subcatchment. Resulting Nash–Sutcliff model efficiencies improved from 0.372 to 0.775 and indicate that the enhanced model can produce thematically more accurate and spatially more detailed local water balances. However, the proposed model enhancements by satellite imagery have not exhausted the full potential of water balance modelling, for which a higher temporal resolution is required.     

On the performance of a new bivariate pseudo Pareto distribution with application to drought data

A new bivariate pseudo Pareto distribution is proposed, and its distributional characteristics are investigated. The parameters of this distribution are estimated by the moment-, the maximum likelihood- and the Bayesian method. Point estimators of the parameters are presented for different sample sizes. Asymptotic confidence intervals are constructed and the parameter modeling the dependency between two variables is checked. The performance of the different estimation methods is investigated by using the bootstrap method. A Markov Chain Monte Carlo simulation is conducted to estimate the Bayesian posterior distribution for different sample sizes. For illustrative purposes, a real set of drought data is investigated.     

A meridional surface wind speed profile in MacRobertson Land,Antarctica

Summary A surface wind vector profile along the 62° East meridian in Antarctica is constructed from field observations extending from 600 kilometers inland to 16 kilometers offshore. The theory of gravity winds proposed byF. K. Ball is used successfully to explain this profile.     

Correlation of δ18O and initial87Sr/86Sr ratios in Kirkpatrick basalt on Mt. Falla,transantarctic mountains

The ¹⁸O (SMOW) values of the Kirkpatrick Basalt (Jurassic) on Mt. Falla, Queen Alexandra Range, vary between +6.3 and +8.6 The apparent enrichment of these rocks in¹⁸O excludes the possibility that they were altered by interaction with aqueous solutions of meteoric origin. The ¹⁸O values of the flows correlate significantly with the initial⁸⁷Sr/⁸⁶Sr ratios and all major elements. These correlations confirm the hypothesis that the basalt magma was contaminated by rocks of the continental crust through which it was extruded. Estimates of the chemical composition of the basalt magma and the contaminant, based on extrapolations of the new oxygen data, generally confirm earlier estimates based on extrapolations of initial⁸⁷Sr/⁸⁶Sr ratios. The⁸⁷Sr/⁸⁶Sr ratio of the uncontaminated basalt was 0.7093 which indicates that magma may have originated by melting either in old Rb-enriched lithospheric mantle under Antarctica or in the overlying crust, or both.     

Tl—Ga—S三元系的合成实验研究

作者系统地进行了Tl—Ga—S三元系的合成实验研究。在300℃等温面上,发现了四个新相,Tl_4GaS_5为三元纯相,Ⅰ、Ⅱ、Ⅲ为固溶体相区,其成分变化范围分别是:(Ⅰ)Tl_(20)GaS_(16)—Tl_(20)Ga_2S_(17),(Ⅱ)Tl_(10)Ga_6S_(17)—Tl_5Ga_3S_7,(Ⅲ)Tl_2Ga_2S_5—TlGaS_2。此外,在630—900℃还存在一个成分为TlGa_5S_8—Tl_2Ga_(10)S_(11)的固溶体相。对这些新相均进行了X-射线粉晶衍射、光性及某些物性测试。X-射线粉晶衍射数据已进行了指标化。