Distribution of vertical crustal movement rates in the Tohoku district, Japan, predicted by least-squares collocation

Least-squares prediction using an empirically deduced local covariance function was performed to investigate the temporal change in the rates of vertical crustal movements in the Tohoku district, Japan. Levelling data covering an area of approximately 450 × 275 km² observed between 1966 and 1995 were used and the results shown in the form of contour maps. Firstly we derived a covariance function of the rates of vertical crustal movement with a Gaussian form function. We used this function to estimate the spatial distribution of the rates of vertical crustal movements. By the present method, a steady tilt of the Tohoku district to the east, toward the Japan Trench and an areal uplift in the southwestern part were well reproduced. Moreover, a significant temporal change in vertical movement rates is clearly seen. Received: 15 July 1996      

Temperature,composition, and f O2 effects on intersite distribution of Mg and Fe2+ in olivines

Single-crystal X-ray structure refinement of natural olivines equilibrated at high temperature under controlled oxygen fugacity (f _O2) conditions, coupled with a structure-energy model were used to establish the influence of T, f _O2 and bulk chemistry on intracrystalline disorder.The results are: 1) The k _D (k _D = [(Fe M1·Mg M2)/(Fe M2·Mg M1)]) factor describing site population on M1, M2 polyhedra increases from values lower than 1 at T below 400–600° C (depending on composition) to values higher than 1 at higher temperature. 2) The increase of k _D with T is quite regular. 3) At constant temperature and pressure, k _D increases with increasing fayalite content in the mixture; 4) Contrary to previous observations (Will and Nover 1979; Nover and Will 1981) varying f _O2, within the stability range of the substance, has a negligible influence on intracrystalline disorder. 5) As ancillary results, the model confirms the defect scheme of Nakamura and Schmalzried (1983) for the investigated solids. Moreover, it shows that cationic vacancies are always created on M 1 site at the expense of Mg ions, while trivalent iron is always stabilized on M2 site. This explains the marked anisotropies observed in Fe-Mg interdiffusion (Buening and Busek 1973; Misener 1974; Schock et al. 1989).     

山东莒南地质公园发现小型兽脚类恐龙 足迹化石Minisauripus

在山东省莒南地质公园内发现6个小型恐龙足迹化石,被归入足迹属Minisauripus。化石产于下白垩统大盛群田家楼组．时代为早白垩世巴列姆（Barremian）-阿普特期（Apdan）。5个较大,长约6cm,产于下部“主”层面上,其中4个组成2节行迹：1个较小,长约3cm,位于“主”层面30cm之上的上部层面上。山东Minisauripus的特征是：足迹个体小（长3．1～5．6cm,宽2．0～3．7cm）,三趾型,略不对称;足迹纵长,各趾近平行,趾垫较清晰;趾末端较钝,但爪迹较尖。Ⅲ趾比Ⅳ趾略长,而Ⅳ趾比Ⅱ趾略长且窄。此外,步幅较长,足长与步长之比约为10：1。与四川、韩国Minisau却淞不同之处是：足迹个体较大,长约是它们的2倍。继中国四川和韩国之后,山东是Minisau而淞在全球的第三个发现点。     

An Infra-Red model of the zodiacal emission

The Infra-Red Astronomical Satellite (IRAS) observations of the zodiacal dust emission are used to fit the dust grain composition and distribution in the ecliptical plane. We obtain a good fit to the data for a density distribution of black-body grains given by p = pr ^{0.66/log(1.7r/R)} for r < 0.87R and r < 3oR     

Polarimetry of comets: A review

Some attempts of polarimetric sounding of Comet Halley will be undertaken from the flyby probes. In order to facilitate the final planning and the future interpretation of these experiments we have done a thorough analysis of practically all available polarimetric observations. An emphasis is made on interpretation attempts and their discussion. The results of the phase dependence of polarization investigations are presented covering a wide range of phase angles . The chief peculiarities of this dependence are: maximum polarization at = 90, diminishing through zero at 20, negative values up to several per cent and a final growth to zero at zero . A division into gaseous and dusty comets on polarimetric basis is revealed. The wavelength dependence of polarization is discussed. The numerous results of detailed polarimetry are compared to the negative results of attempts to detect the elliptical polarization. New observational problems arising from the evidence given by the negative polarization at small phase angles and by the opposition effect recently discovered are discussed.     

Ground water flow analysis of a mid-Atlantic outer coastal plain watershed, Virginia, U.S.A

Models for ground water flow (MODFLOW) and particle tracking (MODPATH) were used to determine ground water flow patterns, principal ground water discharge and recharge zones, and estimates of ground water travel times in an unconfined ground water system of an outer coastal plain watershed on the Delmarva Peninsula, Virginia. By coupling recharge and discharge zones within the watershed, flowpath analysis can provide a method to locate and implement specific management strategies within a watershed to reduce ground water nitrogen loading to surface water. A monitoring well network was installed in Eyreville Creek watershed, a first-order creek, to determine hydraulic conductivities and spatial and temporal variations in hydraulic heads for use in model calibration. Ground water flow patterns indicated the convergence of flow along the four surface water features of the watershed; primary discharge areas were in the nontidal portions of the watershed. Ground water recharge zones corresponded to the surface water features with minimal development of a regional ground water system. Predicted ground water velocities varied between < 0.01 to 0.24 m/day, with elevated values associated with discharge areas and areas of convergence along surface water features. Some ground water residence times exceeded 100 years, although average residence times ranged between 16 and 21 years; approximately 95% of the ground water resource would reflect land use activities within the last 50 years.     

The substructure of the local group

The subclustering within the Local Group is studied by means of the recently developed treediagram technique, enabling one to establish substructures of different boundness. Thirty-two galaxies from 39 listed are shown to form an interacting system which includes Milky Way and M31 giant spirals; we define the Local Group as that interacting system only. Second-level boundness indicates two clear subsystems, influenced by Milky Way and that of M31. The search of systems bound stronger, specifies several pair galaxies of similar morphology.