甘肃礼县盐关井水位短临异常与滇北强震的关系

在分析了甘肃礼县盐关井水位20多年来的异常变化与邻近地区发生中强地震的对应关系基础上,着重就18年来井水位出现两次较大幅度的负异常与相距1000 km多的云南禄劝1985年6.1级地震和云南大姚2003年6.2级地震的对应关系进行了探讨,认为该井很可能是滇北两个震区强震的“穴位”和灵敏点。     

Determination of Bromine and Iodine in Twenty-three Geochemical Reference Materials by ICP-MS

Trace amounts (from nanogram to microgram levels) of bromine and iodine were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in twenty-three geochemical reference materials issued by the GSJ, USGS, IAEA etc. The pyrohydrolysis technique was used to separate bromine and iodine from samples analysed in the form of powder. The accuracy and precision of the experimental values were assessed by the comparative analysis of well established reference materials such as USGS AGV-1, BCR-1 and IGGE GBW07312. The measured values agreed well with reported values within a 10% error range. We also report reliable new data for these elements in these geochemical reference materials.     

On the origin of oriented rutile needles in garnet from UHP eclogites

Although oriented rutile needles in garnet have been reported from several ultrahigh‐pressure (UHP) rocks and considered to be important UHP indicators, their crystallographic features including growth habit and lattice correspondences with garnet host have never been properly characterized. This paper presents a detailed analytical electron microscopic (AEM) study on evenly distributed oriented rutile needles in garnet of two eclogitic rocks from Sulu. Some garnet in one UHP diamondiferous quartzofeldspathic rock from the Saxonian Erzgebirge, and in one high‐pressure (HP) felsic granulite from Bohemia also contain a few unevenly distributed oriented rutile needles. They have also been studied for the purpose of comparison. Despite different distribution patterns, AEM revealed that all rutile needles are oriented along the 〈111〉 directions of garnet with their lateral sides surrounded by the {110} planes of garnet, and that the growth directions of most needles are close to the normal of the {101} planes of rutile. No other specific crystallographic orientation relationships between rutile and garnet host were observed, and there is no pyroxene associated with rutile, as necessitated by the precipitation reaction of rutile in garnet as previously proposed. A simple solid‐state precipitation scenario for the formation of the rutile needles in garnet in these two eclogitic rocks is not justified. Three alternative mechanisms are considered for the formation of oriented rutile needles: (i) the rutile needles may be inherited from precursor minerals; (ii) the rutile needles may be formed by a dissolution–reprecipitation mechanism; and (iii) the rutile needles may be formed by cleaving and healing of garnet with rutile deposition. None of these mechanisms can fully explain the observations, although the first one is less likely and the third one is preferred. This study presents an example where the presence of oriented/aligned inclusions in minerals does not necessarily imply a precipitation origin.     

Characteristics and implication of clay minerals in the northern and southern parts of the Chelung-pu fault, Taiwan

In this study, we report the characteristics of clay minerals present in the Chelung-pu fault in Taiwan. In the 1999 Chi-Chi earthquake, different slip motions were recorded along the Chelung-pu fault in the northern and southern parts of the fault. The characteristics of clay minerals present in the fault zones can be attributed to the differences in motion. We analyzed the shallow drill core samples obtained from the northern and southern sites penetrating the fault. The clay minerals identified in most of the samples from both the sites are smectite, illite, and chlorite. There are illite–smectite mixed layers with a high illite content and no chlorite–smectite mixed layer. In some samples, no smectite is detected. We also examined the iron content and symmetry of iron and magnesium in the silicate and hydroxide layers in chlorite. At the northern site, the total iron content in chlorite of gouge is larger than that of the host rocks. On the other hand, at the southern site, the total iron content varies widely. It is hypothesized that the smectite consumption and differences in the characteristics of chlorite may be controlled by the differences in the lithology, fluid chemistry, fluid temperature, or fault activities (heating or breakage) between the northern and southern sites.     

Trace elements in the Goze Delchev coal deposit, Bulgaria

The geochemistry of trace elements in the underground and open-pit mine of the Goze Delchev subbituminous coal deposit have been studied. The coals in both mines are highly enriched in W, Ge and Be, and at less extent in As, Mn and Y as compared with the world-wide Clarkes for subbituminous coals. Ni and Ti are also enhanced in the underground coals, and Zr, Cr and Mo in the open-pit mine coals.Characteristic for the trace element contents in the deposit is a regular variation with depth. The following patterns were distinguished for profile I: a — the element content decreases from the bottom to the top of the bed paralleling ash distribution (Fe, Co, As, Sb, V, Y, Mo, Cs, REE, Hf, Ta, Th, P and Au); b — Ge and W are enriched in the near-bottom and near-top coals; c — in the middle part of the bed the content of K and Rb is maximal, while that of U is slightly enriched; d — Ba content decreases from the top to the bottom of the bed. In profile II, W and Be contents decrease from the bottom to the top. The near-bottom, and especially the near-roof samples of profile IV are highly enriched in Ge, while for W the highest is the content of the near-bottom sample.Ge, Be, As, Mn, Cl and Br are mainly organically associated. The organic affiliation is still strong for Co, B, Sr, Ba, Sb, U, Th, Mo, La, Ce, Sm, Tb and Yb in the underground coals, and Fe, Co, Na, W, Sr, Y and Ag in the coals from the open-pit mine. K, Rb, Ti, Zr, Hf and Ta are of dominant inorganic affinity. The chalcophile and siderophile elements correlate positively with Fe and each other and may be bound partly with pyrite or other sulphides and iron containing minerals.Compared statistically by the t-criteria, the elements Na, Li, Cu, Zn, Pb, Cr, Ni, Co, Mo, Fe and Be are of higher content in the open-pit mine. Tungsten is the only element of higher concentration in the underground mine. The contents of Ge, As, Sr, V, Mn, Y, Zr and P are not statistically different in both mines.It was supposed that there were multiple sources of the trace elements in the deposit. The source of the highly enriched elements (W, Ge, Be, and As) most probably were the thermal waters in the source area. The contemporary mineral springs are of high content of these elements. Another source were the hosting Mesta volcanic rocks, which are enriched in Sb, Mo, Hf, U, Th, As, Li and Rb. Some of the volcanics were hydrothermally altered and enriched or depleted of many elements. Thus, the hydrothermal solutions were also suppliers of elements for the coals. It is obvious that the contents, distribution and paragenesis, of the trace elements in both Goze Delchev coals reflect the geochemical specialization of the source area, including rocks, paleo- and contemporary thermal waters.     

A Keystone Transform Without Interpolation for SAR Ground Moving-Target Imaging

Synthetic aperture radar (SAR) image formation for a ground moving target necessitates the compensation of the unknown target trajectory. The keystone transform has been employed to remove the linear component of the range migration for the moving target, where interpolation is required. In this letter, a realization of the keystone transform avoiding interpolation is presented. The kernel of this transform, i.e., the range-frequency-dependent azimuth time rescaling, is implemented using only complex multiplications and fast Fourier transforms based on the scaling principle, which has been successfully applied in the equalization of the space-variant range cell migration in SAR processing. In addition, the moving target is coarsely focused according to the SAR geometry and the platform velocity while exploiting the scaling principle. This preliminary focusing is helpful in the isolation of the moving target from ground clutter, so as to facilitate a more refined processing with respect to each mover. SAR raw data combined with simulated echoes of moving targets are utilized to validate the presented approach     

Detecting and Locating Dielectric Objects Buried Under a Rough Interface

We present a method to detect and locate dielectric objects buried under a rough surface. The method is based on the determination of appearing surface impedance of the half-space, where the dielectric objects are located. The equivalent surface impedance is obtained directly from the impedance boundary condition, which requires the knowledge of the electric field and its normal derivative on the surface. These field values are obtained by measuring the far-field data and using single-layer-potential representation of the scattered field. Using the equivalent surface impedance, one can detect and locate the buried objects. The efficiency and efficacy of the method are tested via numerical simulations     

Variation on PAR to global solar radiation ratio along altitude gradient in Naeba Mountain

Summary We investigated the ratio of photosynthetically active photon flux (Q _p ) to global solar radiation (R _s ) at three sites along different altitudes in Naeba Mountain, Japan at various temporal scales based on 3 years measurement data (1999–2001). The lowest values of the ratio ever reported were found for all sites on both an hourly and a daily scale. A similar slight diurnal pattern was found for all sites based on the monthly mean hourly values of the ratio. However, different sites exhibited different seasonal courses. Statistically significant altitude dependencies were found for the hourly Q _p /R _s under both clear and cloudy weather conditions (t-test, P < 0.001). For clear weather conditions, the hourly Q _p /R _s exhibited an increasing trend with altitude at an average rate of 3.6% per km. The increasing rate was more noticeable below 900 m (8.8% per km) than above (0.7% per km). The inverse trend was found for hourly Q _p /R _s with the altitude under cloudy weather conditions. The hourly Q _p /R _s decreased from 550 m to 1500 m at a rate of 1.8% per km. Again, a major decrease occurred below 900 m, which had the rate of 4.2% per km, compared with 0.2% per km over 900 m. Although the same tendencies were noted for daily Q _p /R _s , under clear sky conditions, they were not as statistically significant as the hourly counterpart (t-test, P < 0.021). The increasing rate of Q _p /R _s at this scale under clear weather conditions was near that of the hourly rate, but below the 900 m rate was reduced to near half of the hourly rate (4.7% per km). And the rate over 900 m increased to 2.7% per km. On the other hand, statistically significant altitude effect was noted for the daily under cloudy weather conditions (t-test, P < 0.002). A rapidly decreasing rate was found for it along the altitude gradient. The reason was due to the large decreasing rate below 900 m (12.4% per km). But again similar to the hourly Q _p /R _s , a very small decreasing rate of daily Q _p /R _s was found over 900 m under cloudy weather conditions. These results suggest the necessity of considering the altitude dependency of Q _p /R _s in future studies.     

Impact of different convective cloud schemes on the simulation of the tropical seasonal cycle in a coupled ocean–atmosphere model

The simulation of the mean seasonal cycle of sea surface temperature (SST) remains a challenge for coupled ocean–atmosphere general circulation models (OAGCMs). Here we investigate how the numerical representation of clouds and convection affects the simulation of the seasonal variations of tropical SST. For this purpose, we compare simulations performed with two versions of the same OAGCM differing only by their convection and cloud schemes. Most of the atmospheric temperature and precipitation differences between the two simulations reflect differences found in atmosphere-alone simulations. They affect the ocean interior down to 1,000 m. Substantial differences are found between the two coupled simulations in the seasonal march of the Intertropical Convergence Zone in the eastern part of the Pacific and Atlantic basins, where the equatorial upwelling develops. The results confirm that the distribution of atmospheric convection between ocean and land during the American and African boreal summer monsoons plays a key role in maintaining a cross equatorial flow and a strong windstress along the equator, and thereby the equatorial upwelling. Feedbacks between convection, large-scale circulation, SST and clouds are highlighted from the differences between the two simulations. In one case, these feedbacks maintain the ITCZ in a quite realistic position, whereas in the other case the ITCZ is located too far south close to the equator.     

Water vapour transport from the tropical Atlantic and summer rainfall in tropical southern Africa

An empirical orthogonal functions analysis of the onshore flow of moisture along the west coast of southern Africa using NCEP-DOE AMIP II Re-analyses suggests two dominant modes of variability that are linked to (a) variations in the circulation linked with the South Atlantic anticyclone (b) the intensity of the flow that penetrates from the tropical Atlantic. The second mode, referred as the Equatorial Westerly mode, contributes the most to moisture input from the Atlantic onto the subcontinent at tropical latitudes. Substantial correlations in austral summer between the Atlantic moisture flux in the tropics and rainfall over the upper lands surrounding the Congo basin suggest the potential role played by this zonal mode of water vapour transport. Composites for austral summer months when this Equatorial Westerly mode had a particularly strong expression, show an enhanced moisture input at tropical latitudes that feeds into the deep convection occurring over the Congo basin. Sustained meridional energy fluxes result in above normal rainfall east and south of the Congo belt. During years of reduced equatorial westerly moisture flux, a deficit of available humidity occurs in the southern tropics. A concomitant eastward shift of deep convection to the southwest Indian ocean and southeastern Africa, leads to below normal rainfall over the uplands surrounding the Congo basin.