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The regional and local variations in the composition of the wolframite series associated with the ilmeniteseries and magnetite-series granitoids in the Inner Zone of SW Japan were investigated using X-ray diffraction and microprobe analyses. It is concluded that the variation in Mn/Fe ratios in the source materials (granitic magmas in most cases) is the dominant factor controlling the regional variation in the wolframite compositions, while, as exemplified by the Kaneuchi mine, Kyoto Prefecture, the wallrock chemistry and pH of ore fluids are responsible for the local variation within a single vein system. Within a fresh euhedral crystal from the mine, only slight compositional variation of less than 3 mole% MnWO4 is found in the form of oscillatory zoning. This study, combined with the fluid inclusion research, indicates that the wolframite compositions (Mn/Fe ratios) cannot be used as a geothermometer. 相似文献
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V. I. Shvejkina Dr. 《GeoJournal》1992,27(3):309-314
Variations in climatic conditions for the East-European Plain (EEP) are analysed. The observations show that the time periods
of high-water and low-water correspond to certain circulation conditions, which points to a conceptual possibility to construct
a model correlating streamflow with atmospheric precipitation. Described is a linear model based on a regression equation
for the principal components of runoff and precipitation. The model presents the best results for a territory where a strong
reaction of the river water to a certain circulation type has been established beforehand. 相似文献
4.
Oxygen isotope ratios in streamflow of the Missouri River basin vary geographically due to differences in source precipitation and the integration of waters from upstream regions. Average '18O values in the Missouri River main stem systematically increase from less than -17 in the headwaters to about -9 in the lower basin. Seasonal variations at a given location result from fluctuations in meteoric precipitation, residence time in reservoirs and groundwater systems, evaporation, and snowmelt. Average water chemistry values are successfully predicted for the upstream stations of two reaches on the lower Missouri River based on changes in discharge along each reach and water quality measurements collected at the downstream stations. Source regions for some dissolved ions found in the lower Missouri River are also identified. Sodium and sulfate originate predominantly from the basin above Sioux City, Iowa, while nitrate is largely derived from agricultural regions below Sioux City. 相似文献
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Prof. Dr. M. Tarkian 《Mineralogy and Petrology》1987,36(3-4):169-190
Summary A detailed study of the compositional variations of 22 different platinum-group minerals, of Os-Ir-Ru- and Pt-Fe alloys, Pt-Pd- and Ru-Os-Ir sulfides, RhIr-Pt sulfarsenides and Pd-Pt tellurides from various deposits resulted in verification of extensive solid solution series and element substitution within different mineral groups. On the basis of representative new microprobe analyses and related spectral reflectance curves of the platinum-group minerals investigated significant correlations between chemical composition and reflectance are discussed.
With 17 Figures
Contribution to the Ore Mineralogy Symposium (IMA/COM) at the 14th General Meeting of the International Mineralogical Association, at Stanford, California, in July, 1986. 相似文献
Chemische Variation und Reflexion der wichtigsten Minerale der Platingruppe
Zusammenfassung Die Untersuchung der chemischen Variation bei 22 Platinmineralen aus der Gruppe der Os-Ir-Ru- und Pt-Fe-Legierungen, Pt-Pd- und Ru-Os-Ir-Sulfide, Rh-Ir-Pt-Sulfarsenide und Pd-Pt-Telluride ergibt signifikante Mischkristallbildung und Element-Substitutionen innerhalb der unterschiedlichen Mineralgruppen. Anhand neuer Mikrosondenanalysen und der zugehörigen spektralen Reflexionskurven der betreffenden Platinminerale werden die Korrelationen zwischen Chemismus und Reflexion diskutiert.
With 17 Figures
Contribution to the Ore Mineralogy Symposium (IMA/COM) at the 14th General Meeting of the International Mineralogical Association, at Stanford, California, in July, 1986. 相似文献
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Globally, rivers supply uranium to the oceans with excess 234U relative to secular equilibrium and 234U taken-up by corals can be used for dating. In addition, the 234U abundance in sea water, at the time the coral was growing, can be measured independently. The veracity of U-series ages used in determining past sea-level variations is dependent on selecting pristine corals free from diagenetic alteration. A quantitative test for alteration assumes invariant 234U abundances in the oceans for at least the past half a million years and results from samples outside of a narrow range in modern ocean 234U abundance are excluded from data sets. Here, we have used previously published data to show that 234U in the oceans appears to be variable and directly related to changes in sea-level, not only over long glacial-interglacial timescales but also at very short, centennial timescales. Most of the previously discarded data can be used to provide valuable additional sea-level information. The process permits a unique insight into the interplay between sources and sinks of uranium in the oceans mediated by sea-level changes at rates far faster than previously thought possible. Similar, rapid sea-level, forcing of other trace element abundances in the oceans is likely. 相似文献
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H. H. Lamb 《International Journal of Earth Sciences》1964,54(1):486-504
Until quite recent years meteorology was in no position to make an effective contribution to the understanding of paleoclimates. Lacking were both a theory of the general circulation of the atmosphere and the upper wind observations which have provided the essential foundation of such theoretical understanding of the circulation as we now possess. The most notable early contributions from meteorology wereSimpson's (1934) schematic construction of a presumed mean circulation at the time of the Quaternary ice age maximum andWillett's (1949) proposal of two alternative modes of the general circulation, summarized as expansions and contractions of the circumpolar vortex of upper westerly winds. Both theories lacked an observational basis, especially for their more sweeping generalizations (e.g. simultaneity of ice-ages and lowlatitude pluvials, limitation to only two main atmospheric circulation types etc.) as well as for their author's further proposals about variations of the solar radiation. Nevertheless, they marked a valuable step forward, because they stimulated workers in many fields to interpret their evidence of climatic changes as part of a world phenomenon in which the general wind circulation must be involved. A strictly empirical study of the broadest possible scope of the climatic changes observable within the last 100–1000 years was badly needed. Examination reveals that significant changes have taken place within this period. Study of them is instructive. Whatever changes (if any) of effective radiation available at the Earth's surface occur, the atmospheric and ocean circulations are the mechanism whereby the heat and moisture are distributed. As in synoptic meteorology, circulation maps have been found the most useful means of obtaining a unified view of the climatic changes of recent times. The first successful studies of this kind were byDefant (1924), who showed that the mean circulation over the North Atlantic had intensified materially from the 1880s to the present century, i.e. in part of the period of Arctic warming and increasing mildness of winters in Europe. The present paper shows how our knowledge of changes such asDefant found has been extended over more of the world and a longer period of time. This leads to some indications about the probable nature and possible origins of the phenomenon, which is revealed as rather simple and world-wide in scope. We learn some of the types of variation that actually occur.Examination of the charts indicates inter alia progressive changes of intensity and position of the mainstreams of the atmospheric circulation, and of the ocean currents and climatic zones that correspond to them, within the last 100–250 years. Consideration of the nature of the Little Ice Age epoch of 1550–1850, and comparisons with what is known of the great ice ages of the Pleistocene, appears to throw some new light on the ice age problem.
Zusammenfassung Bis vor kurzem war die Meteorologie nicht in der Lage, einen wesentlichen Beitrag zum Verständnis der Paläoklimate zu liefern. Es fehlten sowohl eine Theorie der allgemeinen Zirkulation der Atmosphäre als auch die Beobachtungen über die höheren Winde, die die wesentliche Grundlage für unser jetziges theoretisches Verständnis der Zirkulation geliefert haben. Die wichtigsten früheren Beiträge von meteorologischer Seite warenSimpson's schematische Rekonstruktion (1934) einer angenommenen mittleren Zirkulation zur Zeit des quartären Eiszeitmaximums undWillett's Annahme (1949) zweier verschiedener Arten der allgemeinen Zirkulation (Expansion und Kontraktion des zirkumpolaren Wirbels der oberen Westwinde). Beiden Theorien fehlte die Beobachtungsgrundlage, vor allem für ihre weitgehenden Verallgemeinerungen (z. B. Gleichzeitigkeit von Eiszeiten und Pluvialen der niederen Breiten, Begrenzung auf nur zwei Haupttypen der atmosphärischen Zirkulation usw.) wie auch für die weiteren Annahmen der Autoren über änderungen der Sonnenstrahlung. Trotzdem waren sie ein wertvoller Schritt vorwärts, weil sie Forscher verschiedenster Gebiete anregten, die Tatsachen von Klimaänderungen als Teil eines weltweiten Phänomens zu interpretieren, das mit der allgemeinen Windzirkulation zusammenhängt. Eine rein empirische, möglichst breit angelegte Studie über die beobachteten Klimaänderungen in den letzten 100 bis 1000 Jahren war dringend notwendig. Es zeigt sich, da\ bedeutungsvolle änderungen in dieser Zeit stattgefunden haben. Falls überhaupt irgendwelche Schwankungen der von au\en kommenden Strahlung erfolgten — immer sind die atmosphärischen und ozeanischen Strömungen der Mechanismus, der Wärme und Niederschlag verteilt. Wie in der synoptischen Meteorologie haben sich Karten der Zirkulation als wertvoll erwiesen, ein einheitliches Bild der klimatischen änderungen in jüngster Zeit zu erhalten. Die ersten erfolgreichen Versuche dieser Art stammen vonDefant (1924); er zeigte, da\ sich die mittlere Zirkulation über dem Nordatlantik seit 1880 bis zum jetzigen Jahrhundert intensiviert hatte, d. h. in der Zeit, in der die Arktis und die europäischen Winter wärmer wurden. Der nachfolgende Aufsatz zeigt, da\ wir heute ähnliche änderungen auch in weiteren Teilen der Erde und von längeren Zeiträumen kennen. Das führt zu Hinweisen über die Natur und die möglichen Ursachen des Phänomens.Das Studium der Karten zeigt für die letzten 100–250 Jahre u. a. progressive änderungen der Intensität und Lage der Hauptströme der atmosphärischen Zirkulation sowie der ozeanischen Strömungen und Klimazonen, die ihnen entsprechen. Betrachtungen über die Kleine Eiszeit 1550–1850 und Vergleiche mit den gro\en Eiszeiten des Pleistozäns werfen einiges neue Licht auf das Eiszeitproblem überhaupt.相似文献
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I. Yu. Grigor’eva A. N. Shakhovskaya M. A. Livshits I. S. Knyazeva 《Astronomy Reports》2012,56(11):887-894
Solar filtergrams obtained at the Crimean Astrophysical Observatory at the center and wings of the H?? line are used to study variations in filaments, in particular, in arch filament systems (AFSs). These are considered as an indicator of emerging new magnetic flux, providing information about the spatial locations of magnetic-field elements. Magnetic-field maps for the active region NOAA 10030 are analyzed as an example. A method developed earlier for detecting elements of emerging flux using SOHO/MDI magnetograms indicates a close link between the increase in flare activity in theNOAA 10030 group during July 14?C18, 2002 and variations in the topological disconnectedness of the magnetograms. Moreover, variations in the flare activity one day before a flare event are correlated with variations in the topological complexity of the field (the Euler characteristic) in regions with high field strengths (more than 700 G). Analysis of multi-wavelength polarization observations on the RATAN-600 radio telescope during July 13?C17, 2002 indicate dominance of the radio emission above the central spot associated with the increase in flare activity. In addition to the flare site near the large spot in the group, numerous weak flares developed along an extended local neutral line, far from the central line of the large-scale field. The statistical characteristics of the magnetic-field maps analyzed were determined, and show flare activity of both types, i.e., localized in spot penumbras and above the neutral line of the field. 相似文献
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Mira MoroviĆ 《Journal of Earth System Science》2002,111(3):215-225
Spatial and temporal variability of pigments was studied from the CZCS satellite data and fromin situ chlorophyll and transparency for the period 1979-1985. The three Adriatic sites, Northern, Middle, and Southern Adriatic
are differently influenced by meteorological, hydrological and oceanographic parameters. The differences between seasonalin situ chlorophyll and remotely sensed pigment concentrations (from CZCS satellite data) from the Adriatic are large in winter.
Through the correlation analysis, pigments were compared to meteo-oceanographic and hydrological parameters from different
Adriatic sites. The PCA (principal component analysis) was applied to the pigment data series and significant components were
compared. Different correlations are obtained for warm and cold periods of the year pointing to seasonal differences in the
underlying mechanism of pigment variability. The first PC is influenced mainly by temperature. In the warm period more parameters
seem to influence the pigment field, than in the cold period. The pigments in the Adriatic are in good correlation to a number
of hydrologic and meteo-oceanographic factors. 相似文献
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Climatic variations in China during the Quaternary have long been a question of debate. Considerable data now available support Professor Li Siguang's (J. S. Lee) suggestion that there were four glacial periods. In this later years the views of Professor Li have received support from more recent information demonstrating that a further glacial period and periglacial phenomena preceded the Boyang Period.During the Quaternary 3,500,000 years ago there were a number of climatic fluctuations in China, having an amplitude of over 10°C and a cycle of 104 to 105 years. Each fluctuation lasted from the onset of one glacial period to that of the next, encompassing a glacial period and an interglacial. Tab 1 provides a comparison between the glacial periods in China during the Quaternary and those in other regions of the world. 相似文献
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G. Springer 《Mineralium Deposita》1969,4(1):72-74
Electronprobe microanalyses were made of enargite and luzonite from various localities. It was shown that enargite can contain as much as 6 wt.% antimony. Complete solid solution was observed between the tetragonal phases luzonite and famatinite. The compositions of enargite and of luzonite-famatinite solid solution were found to be very variable even within one polished section.
Temporary address (1968/69): Department of Mineral Technology, Imperial College, London S. W. 7, England. 相似文献
Zusammenfassung Anhand quantitativer Elektronenstrahl-Mikroanalysen von Material verschiedener Lagerstätten wurde festgestellt, daß Enargit bis zu 6 Gew.% Antimon enthalten kann. Zwischen den tetragonalen Phasen Luzonit und Famatinit wurde völlige Mischbarkeit beobachtet. Es wurde gefunden, daß die Zusammensetzung von Enargit und Luzonit-Famatinit selbst im Bereich eines Anschliffes stark schwanken kann.
Temporary address (1968/69): Department of Mineral Technology, Imperial College, London S. W. 7, England. 相似文献
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Susan Ivy-Ochs Hanns Kerschner Max Maisch Marcus Christl Peter W. Kubik Christian Schlüchter 《Quaternary Science Reviews》2009,28(21-22):2137-2149
In the Alps, climatic conditions reflected in glacier and rock glacier activity in the earliest Holocene show a strong affinity to conditions in the latest Pleistocene (Younger Dryas). Glacier advances in the Alps related to Younger Dryas cooling led to the deposition of Egesen stadial moraines. Egesen stadial moraines can be divided into three or in some cases even more phases (sub-stadials). Moraines of the earliest and most extended advance, the Egesen maximum, stabilized at 12.2 ± 1.0 ka based on 10Be exposure dating at the Schönferwall (Tyrol, Austria) and the Julier Pass-outer moraine (Switzerland). Final stabilization of moraines at the end of the Egesen stadial was at 11.3 ± 0.9 ka as shown by 10Be data from four sites across the Alps. From west to east the sites are Piano del Praiet (northwestern Italy), Grosser Aletschgletscher (central Switzerland), Julier Pass-inner moraine (eastern Switzerland), and Val Viola (northeastern Italy). There is excellent agreement of the 10Be ages from the four sites. In the earliest Holocene, glaciers in the northernmost mountain ranges advanced at around 10.8 ± 1.1 ka as shown by 10Be data from the Kartell site (northern Tyrol, Austria). In more sheltered, drier regions rock glacier activity dominated as shown, for example, at Julier Pass and Larstig valley (Tyrol, Austria). New 10Be dates presented here for two rock glaciers in Larstig valley indicate final stabilization no later than 10.5 ± 0.8 ka. Based on this data, we conclude the earliest Holocene (between 11.6 and about 10.5 ka) was still strongly affected by the cold climatic conditions of the Younger Dryas and the Preboreal oscillation, with the intervening warming phase having had the effect of rapid downwasting of Egesen glaciers. At or slightly before 10.5 ka rapid shrinkage of glaciers to a size smaller than their late 20th century size reflects markedly warmer and possibly also drier climate. Between about 10.5 ka and 3.3 ka conditions in the Alps were not conducive to significant glacier expansion except possibly during rare brief intervals. Past tree-line data from Kaunertal (Tyrol, Austria) in concert with radiocarbon and dendrochronologically dated wood fragments found recently in the glacier forefields in both the Swiss and Austrian Alps points to long periods during the Holocene when glaciers were smaller than they were during the late 20th century. Equilibrium line altitudes (ELA) were about 200 m higher than they are today and about 300 m higher in comparison to Little Ice Age (LIA) ELAs. The Larstig rock glacier site we dated with 10Be is the type area for a postulated mid-Holocene cold period called the Larstig oscillation (presumed age about 7.0 ka). Our data point to final stabilization of those rock glaciers in the earliest Holocene and not in the middle Holocene. The combined data indicate there was no time window in the middle Holocene long enough for rock glaciers of the size and at the elevation of the Larstig site to have formed. During the short infrequent cold oscillations between 10.5 and 3.3 ka small glaciers (less than several km2) may have advanced to close to their LIA dimensions. Overall, the cold periods were just too short for large glaciers to advance. After 3.3 ka, climate conditions became generally colder and warm periods were brief and less frequent. Large glaciers (for example Grosser Aletschgletscher) advanced markedly at 3.0–2.6 ka, around 600 AD and during the LIA. Glaciers in the Alps attained their LIA maximum extents in the 14th, 17th, and 19th centuries, with most reaching their greatest LIA extent in the final 1850/1860 AD advance. 相似文献
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A. E. Volvach V. S. Bychkova N. S. Kardashev M. G. Larionov V. V. Vlasyuk O. I. Spiridonova 《Astronomy Reports》2009,53(5):401-409
We present coordinated synchronous observations of Active Galactic Nuclei in the radio and optical, aimed at searching for fast (intraday) flux variations and possible correlations in the flux variations in different wavebands. Our observations were performed with the 22-m radio telescope of the Crimean Astrophysical Observatory at 22.2 and 36.8 GHz and the Zeiss-1000 reflector of the Special Astrophysical Observatory in the R filter, using a CCD photometer. We performed five observing runs of 7–10 nights each in 2004–2006. We obtained radio and optical light curves for the variable extragalactic radio sources DA 55, 1633+382, 2134+004, 2145+067, and 2251+158. We detected short-duration flares of DA 55 and 2134+004 in the R band with variations of 0.2 m within about 15 minutes. The other sources did not show any considerable flux variations. The radio flux variations of DA 55 and 2134+004 reached 1.5 Jy in about 15 minutes, and those of 2145+067 reached 2 Jy in 2 hours. We observed chaotic flux variations in 2251+158, by 2–2.5 Jy in half an hour. We detected no correlation between the radiation in the optical and radio. 相似文献
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Local and regional variations in Central American arc lavas controlled by variations in subducted sediment input 总被引：9，自引：0，他引：9
Lina C. Patino Michael J. Carr Mark D. Feigenson 《Contributions to Mineralogy and Petrology》2000,138(3):265-283
The sedimentary section (at DSDP Site 495) on the subducting Cocos Plate has large stratigraphic changes in incompatible
elements and element ratios, the result of early carbonate deposition followed by late hemipelagic deposition. Lavas from
Central America define both local and regional geochemical trends that reflect the strong influence of the two Cocos Plate
sediment units. Element ratios with large stratigraphic variations on the Cocos Plate (e.g. Ba/Th, U/La) define local variations
within individual volcanic centers in Central America, indicating that marine stratigraphy controls some geochemical characteristics
of the lavas. These local trends can be explained by changing the proportions of hemipelagic sediment input into the magma
generation process. These local trends are observed in all the segments of the arc, regardless of the intensity of the slab
signature. Regional variations are most clearly seen in element ratios that are nearly constant through the Cocos Plate sediment
stratigraphy (e.g. Ba/La, U/Th), suggesting that regional variations reflect differences in the intensity of the flux from
the subducting slab. The slab signal is strongest in Nicaragua and along the volcanic front. The signal decreases to the northwest
and southeast of Nicaragua and toward the back arc. The large slab signature in the lavas from western Nicaragua occurs in
the area with the thinnest continental crust and steepest dip of the slab. The mass flux of incompatible elements into the
system is easily estimated, except for elements, like Pb, that have high and variable abundances in the basaltic oceanic crust
section. The mass flux of elements out of the system depends on eruption rates, which are variable along the arc and only
approximately known. Comparison of input and output fluxes for five different segments of the arc reveals that some elements
(K, B, Cs, and Rb) are very efficiently delivered to the volcanoes from the subducted slab. Other elements (Sr, Ba, and U)
are returned to the surface with moderate efficiency, whereas some elements (REEs) may come mostly from the mantle wedge with
minor slab contribution. The relative order of recycling efficiencies of incompatible elements implies that a hydrous fluid
dominates the transfer of material from the slab to mantle.
Received: 7 September 1998 / Accepted: 30 September 1999 相似文献
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It is shown that the centroid of the heliospheric equator undergoes quasi-periodic oscillations. During the minimum of the 11-year cycle, the centroid shifts southwards (the so-called bashful-ballerina effect). The direction of the shift reverses during the solar maximum. The solar quadrupole is responsible for this effect. The shift is compared with the tilt of the heliospheric current sheet. 相似文献