The solar differential rotation: Present status of observations   总被引：1，自引：0，他引：1  

E. H. Schröter 《Solar physics》1985,100(1-2):141-169

The present status of observations regarding the solar differential rotation is reviewed from contributions published in the last two decades. The paper does not deal with the theory; it mentions theoretical aspects only where they are needed to guide and to understand observational efforts and results.Mitteilungen aus dem Kiepenheuer-Institut Nr. 250.  相似文献   

The ELAIS deep X-ray survey – I. Chandra source catalogue and first results     

J. C. Manners †  O. Johnson  O. Almaini  C. J. Willott  E. Gonzalez-Solares  A. Lawrence  R. G. Mann  I. Perez-Fournon  J. S. Dunlop  R. G. McMahon  S. J. Oliver  M. Rowan-Robinson  S. Serjeant 《Monthly notices of the Royal Astronomical Society》2003,343(1):293-305

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Radon variations in a Hungarian village     

E. Tóth  F. Deak  C. S. Gyurkócza  Z. S. Kasztovszky  R. Kuczi  G. Marx  B. Nagy  S. Oberstedt  L. Sajó-Bohus  C. S. Sükösd  G. Toth  N. Vajda 《Environmental Geology》1997,31(1-2):123-127

 A steady radon exhalation is assumed in most publications. In a village of North-East Hungary, however, high radon concentrations have been measured, differing strongly in neighbouring houses and varying in time, due to the interplay of geochemical phenomena. Received: 20 November 1995 · Accepted: 18 June 1996  相似文献   

Origin and early evolution of the planetary system     

D. Möhlmann 《Earth, Moon, and Planets》1985,33(2):201-214

It is shown by linear stability analysis that a preplanetary (presatellite) disk of dust and gas with Keplerian velocity field can become unstable due to the collective self-gravity of the disk. The radial distribution of rings, which may result from this instability, is derived. These rings later on can be the formation sites for planets around the Sun and for satellites around the planets. The derived orbits are shown to be in good agreement with that of the planets and the satellites (of Jupiter, Saturn, and Uranus). Predictions and conclusions seem to be possible for the existence of three yet unknown Uranian satellites, the origin of the early Moon and the possible radial extension of the planetary system.  相似文献   

Multiforced statistical assessments of greenhouse-gas-induced surface air temperature change 1890–1985     

Christian-D Schönwiese  Ursula Stähler 《Climate Dynamics》1991,6(1):23-33

Based on univariate correlation and coherence analyses and considering the physical basis of the relationships, a simple multiforced (multiple) statistical concept is used which correlates observational climatic time series simultaneously with volcanic, solar, ENSO, and the anthropogenic greenhouse gases forcing. This is appropriate to remove some natural climate noise in the observed data and to evaluate the components (signals) possibly due to the anthropogenic greenhouse gas forcing (CO₂, or equivalent CO₂ implying additional gases) during industrial time. In this paper, we apply this technique to 100 global box data time series 1890–1985, of the surface air temperature, using observed data from Hansen and Lebedeff. The results are presented in terms of latitudinal-seasonal and regional trends, where the observed trend patterns are compared with the hypothetical signals (statistical assessments) possibly due to anthropogenic greenhouse forcing. These latter signals can be amplified to enable a comparison with corresponding results from general circulation model (GCM) CO₂ doubling experiments. These observed-statistical assessments lead to results which are, at least qualitatively and in respect to the zonal mean temperatures, very similar to some GCM experiments indicating the maximum CO₂ doubling signals (statistical assessment > 12 K) in the arctic winter. However, these signals are moderate in the tropics and in the Southern Hemisphere (global average 2.8–4.4 K). As far as the industrial signals are concerned (observed period) these signals are somewhat larger (maximum 7 K, global average 0.5–0.9 K) than the observed trends (maximum 5 K, global average 0.5 K). Phase shifts of cause and effect may amplify these signals but are very uncertain.This paper was presented at the International Conference on Modelling of Global Climate Change and Variability, held in Hamburg 11–15 September 1989 under the auspices of the Meteorological Institute of the University of Hamburg and the Max Planck Institute for Meteorology. Guest Editor for these papers is Dr. L. Dümenil  相似文献   

African linkage of Precambrian Sri Lanka     

Prof. Dr. A. Kröner 《International Journal of Earth Sciences》1991,80(2):429-440

New age and isotopic data show that the high-grade basement rocks of Sri Lanka were not linked to the Archaean granulite domain of southern India but experienced their main structural and metamorphic development during the Pan-African event some 950 to 550 Ma ago. This occurred when West Gondwana and East Gondwana collided to form one of the longest collisional structures in the Supercontinent — the Mozambique belt that extends from Mozambique to Ethiopia and Sudan. A major tectonic boundary, interpreted as a thrust zone, divides the Highland/Southwestern Complex in the central part of Sri Lanka from the Vijayan Complex in the E and SE. The former is interpreted to represent the remnant of a once extensive passive margin extending west, in a Gondwana reconstruction, via Madagasgar to Tanzania and Mozambique. The Vijayan Complex may have been part of a separate continental margin plutonic assemblage, and its collision with the Highland/ Southwestern Complex marks the final amalgamation of East and West Gondwana into a supercontinent some 550 Ma ago. The Sri Lankan granulites cannot be correlated with the distinctly older granulites of the Eastern Ghats belt of India, and this suggests that Sri Lanka was situated close to the SE coast of Madagascar in a Gondwana reconstruction.

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Zusammenfassung Neue Isotopen- und Altersdaten aus dem metamorphen Grundgebirge von Sri Lanka zeigen, daß dieses Gebiet nicht, wie vielfach vermutet, Teil des archaischen Granulitkomplexes von Südindien war, sondern seine strukturelle und metamorphe Entwicklung während der panafrikanischen Orogenèse zwischen ca. 950 Ma und ca. 550 Ma hatte. Diese Orogenèse ist das Resultat der Kollision zwischen West-Gondwana (Afrika und Südamerika) und Ost-Gondwana (Südindien, Australien und Antarktis) und führte zur Bildung eines der längsten Kollisionsgürtel des Superkontinentes, dem Mosambik-Gürtel, der sich von Mosambik bis nach Äthiopien und in den Sudan erstreckt. Der West- und Zentralteil Sri Lankas mit den Wanni und Highland/Southwestern Komplexen wird vom Vijayan Komplex im Osten und Südosten durch eine Überschiebungszone getrennt, die möglicherweise eine Sutur darstellt. Die Gesteine im Westen und in den Highlands werden als der Rest eines ehemals weiträumigen passiven Kontinentalrandes interpretiert, zu dem wohl auch die lithologisch ähnlichen Abfolgen der hochmetamorphen Gebiete in Mosambik, Tansania und Madagaskar gehörten. Der Vijayan Komplex war wohl Teil der separaten plutonischen Suite eines aktiven Kontinentalrandes, und seine Kollision mit dem Highland/ Southwestern Komplex markiert das endgültige Verschweißen von West- und Ost-Gondwana zu einem Superkontinent vor ca. 550 Ma. Die Granulite Sri Lankas können nicht mit den deutlich älteren Granuliten des Gürtels der Eastern Ghats in Südost Indien korreliert werden sondern ähneln eher den hochgradigen Gesteinen in Südost Madagaskar. Damit ist die Lage Sri Lankas nahe Madagaskar in einer Gondwana Rekonstruktion wahrscheinlicher als nahe der Südostküste Indiens.

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Résumé De nouvelles données isotopiques et géochronologiques montrent que les roches métamorphiques du socle du Sri Lanka ne constituent pas, comme on l'a souvent cru, une partie du complexe granulitique archéen de l'Inde méridionale, mais qu'elles ont vécu leur propre histoire tectono-métamorphique au cours de l'orogenèse panafricaine, entre 950 et 550 Ma. Cette orogenèse est le résultat de la collision entre le Gondwana occidental (Afrique et Amérique du Sud) et le Gondwana oriental (Inde du sud, Australie et Antarctique) et constitue une des plus grandes chaînes de collision du Supercontinent: la chaîne du Mozambique, qui s'étend du Mozambique jusqu'au Soudan et en Ethiopie. Un contact tectonique majeur, interprété comme un charriage, sépare le »Highland/South-western Complex« (partie centrale du Sri Lanka) du »Vijayan Complex« (partie est et sud-est). Le premier de ces complexes est interprété comme un reste d'une ancienne marge passive de grande étendue, à laquelle appartenaient aussi les séries lithologiquement analogues du domaine très métamorphique du Mozambique, de Tanzanie et de Madagascar. Le «Vijagan Complex« a pu être une partie d'un ensemble plutonique séparé de marge active; sa collision avec le »Highland/Southwestern Complex« marque la réunion finale en un super-continent il y a quelque 550 Ma, des Gondwanas oriental et occidental. Les granulites du Sri Lanka ne peuvent pas être corrélées avec celles de la chaîne des Eastern Ghats (Inde du sud-est) qui sont nettement plus anciennes; elles se rapprochent plutôt des roches très métamorphiques du sud-est de Madagascar. On en déduit que la position du Sri Lanka, dans une reconstruction du Gondwana, devait être plus proche de Madagascar que de la côte sud de l'Inde.

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Groundwater flow and contaminant transport modelling at an air weapons range     

Geneviève Bordeleau  Richard Martel  Dirk Schäfer  Guy Ampleman  Sonia Thiboutot 《Environmental Geology》2008,55(2):385-396

Numerical modelling was done at the Cold Lake Air Weapons Range, Canada, to test whether the dissolved RDX and nitrate detected in groundwater come from the same sources, and to predict whether contamination poses a threat to the surface water receptors near the site. Military live fire training activities may indeed pose a risk of contamination to groundwater resources, however field investigations on military bases are quite recent, and little information is available on the long-term behaviour of munition residues related contaminants. Very limited information was available about the contaminant source zones, which were assigned based on our knowledge of current training activities. The RDX plume was well represented with the model, but the heterogeneous distribution of nitrate concentrations was more difficult to reproduce. It was nonetheless determined that both contaminants originate from the same areas. According to the model, both contaminants should reach the nearby river, but concentrations in the river should remain very low if the source zone concentration does not change. Finally, the model allowed the recommendation of a new location for the main bombing target, which would offer added protection to the river and the lake into which it flows.  相似文献   

Geochemistry of late stage medium to high-K calc-alkaline and shoshonitic dykes in the Ulukişla Basin (Central Anatolia, Turkey): Petrogenesis and tectonic setting     

M. A. Kurt  M. Alpaslan  M. C. Göncüoǧlu  A. Temel 《Geochemistry International》2008,46(11):1145-1163

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Zircon U–Pb and Hf isotopic study of gneissic rocks from the Chinese Altai: Progressive accretionary history in the early to middle Palaeozoic     

Min Sun  Chao Yuan  Wenjiao Xiao  Xiaoping Long  Xiaoping Xia  Guochun Zhao  Shoufa Lin  Fuyuan Wu  A. Kröner 《Chemical Geology》2008,247(3-4):352-383

Gneissic rocks in the Chinese Altai Mountains have been interpreted as either Paleozoic metasedimentary rocks or Precambrian basement. This study reports geochemical and geochronological data for banded paragneisses and associated gneissic granitoids collected along a NE–SW traverse in the northwestern Chinese Altai. Petrological and geochemical data suggest that the protoliths of the banded gneisses were possibly immature sediments with significant volcanic input and that the gneissic granitoids were derived from I-type granites formed in a subduction environment. Three types of morphological features can be recognized in zircons from the banded gneisses and are interpreted to correlate with different sources. Zircons from five samples of banded paragneiss cluster predominantly between 466 and 528 Ma, some give Neoproterozoic ages, and a few yield discordant Paleoproterozoic to Archean ages. Zircon Hf isotopic compositions indicate that both juvenile/mantle and crust materials were involved in the generation of the source rocks from which these zircons were derived. In contrast, zircons occur ubiquitously as elongated euhedral prismatic crystals in the four samples of the gneissic granitoids, and define single populations for each sample with mean ages between 380 and 453 Ma. The general absence of Precambrian inheritance and positive zircon ?Hf values for these granitoids suggest insignificant crustal contribution to the generation of the precursor magmas. Our data can be interpreted in terms of a progressive accretionary history in early to middle Palaeozoic times, and the Chinese Altai may possibly represent a magmatic arc built on a continental margin dominated by Neoproterozoic rocks.  相似文献   

On the in situ aqueous alteration of soils on Mars     

Ronald Amundson  Stephanie Ewing  Brad Sutter  Oliver Chadwick  Michelle Walvoord 《Geochimica et cosmochimica acta》2008,72(15):3845-3864

Early (>3 Gy) wetter climate conditions on Mars have been proposed, and it is thus likely that pedogenic processes have occurred there at some point in the past. Soil and rock chemistry of the Martian landing sites were evaluated to test the hypothesis that in situ aqueous alteration and downward movement of solutes have been among the processes that have transformed these portions of the Mars regolith. A geochemical mass balance shows that Martian soils at three landing sites have lost significant quantities of major rock-forming elements and have gained elements that are likely present as soluble ions. The loss of elements is interpreted to have occurred during an earlier stage(s) of weathering that may have been accompanied by the downward transport of weathering products, and the salts are interpreted to be emplaced later in a drier Mars history. Chemical differences exist among the sites, indicating regional differences in soil composition. Shallow soil profile excavations at Gusev crater are consistent with late stage downward migration of salts, implying the presence of small amounts of liquid water even in relatively recent Martian history. While the mechanisms for chemical weathering and salt additions on Mars remain unclear, the soil chemistry appears to record a decline in leaching efficiency. A deep sedimentary exposure at Endurance crater contains complex depth profiles of SO₄, Cl, and Br, trends generally consistent with downward aqueous transport accompanied by drying. While no model for the origin of Martian soils can be fully constrained with the currently available data, a pedogenic origin is consistent with observed Martian geology and geochemistry, and provides a testable hypothesis that can be evaluated with present and future data from the Mars surface.  相似文献