Pressure dependence of nickel partitioning between forsterite and aluminous silicate melts

Nickel partitioning between forsterite and aluminosilicate melt of fixed bulk composition has been determined at 1300°C to 20 kbar pressure. The value of the forsterite-liquid nickel partition coefficient is lowered from >20 at pressures equal to or less than 15 kbar to <10 at pressures above 15 kbar.Published data indicate that melts on the join Na₂O-Al₂O₃-SiO₂ become depolymerized in the pressure range 10–20 kbar as a result of Al shifting from four-coordination at low pressure to higher coordination as the pressure is increased. This coordination shift results in a decreasing number of bridging oxygens in the melt. It is suggested that the activity coefficient of nickel decreases with this decrease in the number of bridging oxygens. As a result, the nickel partition coefficient for olivine and liquid is lowered.Magma genesis in the upper mantle occurs in the pressure range where the suggested change in aluminum coordination occurs in silicate melts. It is suggested, therefore, that data on nickel partitioning obtained at low pressure are not applicable to calculation of the nickel distribution between crystals and melts during partial melting in the upper mantle. Application of high-pressure experimental data determined here for Al-rich melts to the partial melting process indicates that the melts would contain about twice as much nickel as indicated by the data for the low-pressure experiments. If, as suggested here, the polymerization with pressure is related to the Al content of the melt, the difference in the crystal-liquid partition coefficient for nickel at low and high pressure is reduced with decreasing Al content of the melt. Consequently, the change ofD_Ni^{ol-andesite melt} is greater than that ofD_Ni^{ol-basalt melt}, for example.     

Central place preference by social geographic groups with reference to the tributary area of Shibuya,Southwest Tokyo

Conclusions Central place preference by social geographic groups is in the Tokyo area less determined by social status than by age and life cycles differentiated by sex.In case of the tributary area of Shibuya a simple classification into young people (male and female bachelors) and married people (husbands and housewives) indicates essential differences in central place preferences between these groups.The bachelors, particularly the young men, are most important for central place orientations in that they show distinctive spatial behavioural patterns in terms of complexity, mobility and intensity of distance-movements. The young people being employed — today joculously called dokushin kizoku (bachelors' aristocracy) because of their salary raised remarkably as well as of their extensive concumer demands and high buying power — are representative for the present-day economically independent young generation. The bachelors judge urban center attractiveness on the basis of shopping facilities and also in terms of atmosphere — meeting friends, strolling through town and amusing themselves. The young people are very much courted by commercial enterprises and are regarded as special trend setters having great influence on the image and vitality of Tokyo's inner urban centers.Most attractive for the young people are the ring centers. In the southwestern suburban areas Shibuya predominates; however generally speaking it is Shinjuku, the western and leading (ring)-center, which draws the young people most strongly. Special centers such as Harajuku, Aoyama and Roppongi are also preferred by this group, often in combination with a ring-center visit. Towards the inner city core (Ginza-Nihonbashi) central place preferences chiefly of the young male bachelors are declining gradually.Compared with young people the married people prefer the ring centers only slightly before the Ginza area, which for shopping is primarily visited by housewives, for going out mainly by husbands. Particularly in the inner city core near the main office districts a typical feature for Tokyo of central place preference is evident. For the salaryman — the most representative business type in the Tokyo area — going out is identical with not going home. This phenomenon depends on the place of work in two aspects. First, spatially in terms of a close connection between office and inner city amusement/shopping centers and additionally distance-movements towards a ring center nearest of the place of work or residence. Second, socially — social activities after working hours mainly carried out with colleagues result in a behavioural pattern, in which a clear differentiation between company and private life appears to be difficult. For not going home there are many reasons — among others the constricted living conditions of Japanese homes as Westerners believe — however, other factors play a much more important role: (i) Mainly the extremely long commuting distances, which allow the salaryman a real leaving home to go out only on Sundays or holidays. Other reasons for this typically Japanese feature closely related to inner city tavern and bar visits, may be seen in (ii) the traditionally very limited participation of Japanese housewives to their husbands' out-door social activities; (iii) a system of charging and crediting expenses to one's personal bank account or the company account; (iv) the personal atmosphere of taverns and bars providing the best chances for communication/relaxation and for overcoming stress and frustrations experienced in the office.Shopping is particularly for housewives the most important motivation for visiting urban centers, in this respect two Japanese characteristics should be mentioned: First, fashion and being well-groomed are, as far as the mass of people particularly the young women is concerned, more highly esteemed than in other urban societies. As a consequence good clothes are much in demand. Purchases of these kinds of articles are most often made in department stores and cause the longest distance-movements. Second, in rank of central goods next to fashion and quality clothes follow standard gifts such as seibo and chugen. The purchase of these articles is apart from the unique custom of giving gifts twice a year typically Japanese also in so far as it contradicts the least-effort criterion in central place theory. Though these patterns mostly bought by housewives or middle-aged and older people are substantially more of daily or periodical than episodical demand, they are related to surprisingly long distance-movements because of usually being bought for image reasons in leading department stores located in higher-ranking more distant urban centers.Typical behaviour for all groups visiting higher-order urban centers is an often used combination of shopping and taking part in out-door activities such as meeting friends/acquaintances, strolling around, going to the cinema or other show performances, eating, drinking and chatting together. This is due to the outstanding facilities available not only in retail-trade but also in the gastronomic, entertainment and amusement sectors.Taken all together, complexity and intensity of central place preferences in Tokyo reflect the higher and different attractiveness of Japanese urban centers compared with that of other urban societies. The urban centers are highly esteemed because of their excellent facilities as well as of their vitality, crowds and activity. These latter characteristics are summarized by the word nigiyaka meaning vivacity, which is most typical for Japanese urban centers. The inner city centers of Tokyo can be regarded in the true sense of this term as urban foci compensating for diverse problems such as environmental pollution or lack of inner urban green areas, making life in the most densely populated area of the world worthwhile.     

Risø 1978: Further investigations into the effects of local terrain irregularities on tower-measured wind profiles

Observations of flow over complex terrain taken at Risø during June–July 1978 and numerical studies confirm earlier findings that small variations in surface elevation have significant effects on mean wind profiles. Measured shear stresses in the nonequilibrium region of the flow are consistent with theory but quite different from those obtained assuming simple flux-profile relationships. These findings imply that flux-profile relationships can be quite complicated over other than simple homogeneous terrain.     

The PT phase relations of a primary oceanite from the Reykjanes peninsula,Iceland

The field relationships and petrographic features of the oceanites of the Reykjanes peninsula suggest that they might have originated as primary magmas. The principal phase relationships of primary liquids formed by the partial melting of lherzolites are defined. The phase relations obtained for oceanite RE78 between 0 and 30 kbar at dry conditions suggest that the oceanite originated as a primary magma at 25 kbar and 1580°C, and erupted at a temperature near 1300°C.     

Heat budget of Flakevatn,a subpolar lake

Zusammenfassung Durch Kenntnis von Sommer- und Wintertemperaturen in dem südnorwegischen Gebirgssee Flakevatn (Meeresh?he 1448 m) konnte die Thermik des subpolaren Seetypus charakterisiert werden. Im Sommer herrscht in Flakevatn wiederholte Isothermie bei relativ hohen Temperaturen, im Winter wird der See ganz ausserordentlich abgekühlt (Fig. 1, Tabelle). Die sommerliche W?rmespeicherung betr?gt +5800, die winterliche −22500 cal/cm².      

A Study of Ozone Laminae Using Diabatic Trajectories, Contour Advection and Photochemical Trajectory Model Simulations.

In this paper, we show that the rate of ozone loss in both polar and mid-latitudes, derived from ozonesonde and satellite data, has almost the same vertical distribution (although opposite sense) to that of ozone laminae abundance. Ozone laminae appear in the lower stratosphere soon after the polar vortex is established in autumn, increase in number throughout the winter and reach a maximum abundance in late winter or spring. We indicate a possible coupling between mid-winter, sudden stratospheric warmings (when the vortex is weakened or disrupted) and the abundance of ozone laminae using a 23-year record of ozonesonde data from the World Ozone Data Center in Canada combined with monthly-mean January polar temperatures at 30 hPa.Results are presented from an experiment conducted during the winter of 1994/95, in phase II of the Second European Stratospheric And Mid-latitude Experiment (SESAME), in which 93 ozone-enhanced laminae of polar origin observed by ozonesondes at different time and locations are linked by diabatic trajectories, enabling them to be probed twice or more. It is shown that, in general, ozone concentrations inside laminae fall progressively with time, mixing irreversibly with mid-latitude air on time-scales of a few weeks. A particular set of laminae which advected across Europe during mid February 1995 are examined in detail. These laminae were observed almost simultaneously at seven ozonesonde stations, providing information on their spatial scales. The development of these laminae has been modelled using the Contour Advection algorithm of Norton (1994), adding support to the concept that many laminae are extrusions of vortex air. Finally, a photochemical trajectory model is used to show that, if the air in the laminae is chemically activated, it will impact on mid-latitude ozone concentrations. An estimate is made of the potential number of ozone molecules lost each winter via this mechanism.     

Size and shape variation in the planktonic foraminiferHeterohelix striata (late cretaceous,southern Scandinavia)

The biserial planktonic foraminiferal species Heterohelix striata (Ehrenberg)has been analyzed by morphometric techniques from six sequential late Maestrichtian core samples from southern Sweden and one sample from the “Dania”quarry of Denmark. The study is based on measurements of number of chambers, size of test (length, width, and thickness),marginal angle, and chamber sizes. In addition, prolocular and apertural sizes were analyzed in the “Dania”quarry sample. The study includes analyses of the ontogenetic development of the tests, stratigraphic variation in size and shape, intrasample variability, and relationship between gross morphology of the test and prolocular and apertural dimensions.     

Temperature and pressure dependence of Fe-Mg partitioning between garnet and phengite,with particular reference to eclogites

Experimental data combined with data from natural rocks have been used to calibrate a geothermometer based on the distribution of Fe²⁺ and Mg between coexisting garnets and phengites. The pressure effect on the K _D -value appears to be considerable. The calculated thermometer is expressed as $$T(K) = \frac{{3685 + 77.1P(kb)}}{{InK_D + 3.52}}.$$ The use of this \(K_{D_{(FeO/MgO)} }^{ga + ph}\) geothermometer on eclogites with low Fe₂O₃ content, gives P-T values which are in good accordance with those obtained by other methods. The problems that arise when Fe³⁺ is present in larger amounts, are discussed.