Simulations of normal spiral galaxies     

Roelof Bottema 《Monthly notices of the Royal Astronomical Society》2003,344(2):358-384

  相似文献   

Steady-state drift-dominated modulation models for galactic cosmic rays     

R. A. Burger  M. Hattingh 《Astrophysics and Space Science》1995,230(1-2):375-382

A number of steady-state drift-dominated modulation models has been developed by the Potchefstroom modulation group. In this review a selection of these models is discussed and briefly compared. A short overview of the relevant drift theory incorporated into the models is also given.  相似文献   

Review of resource analysis and related studies: Working group,Mathematical Geology,freie Universität Berlin     

M. Shulman  H. Burger  C. Kliem  W. Skala 《Natural Resources Research》1992,1(1):97-106

The working group Mathematical Geology of the Freie Universität Berlin was formed in 1971. We review quantitative methods used by the working group since 1983 to treat mineral exploration problems. The methods applied vary from elementary statistical analysis of multivariate exploration data to optimal strategies for selecting favorable targets, and from multiobjective decision-making for additional drill hole locations to expert systems in exploration.The methods applied are directly related to the level of information at each stage of the exploration process. Special emphasis was placed on the relationship between and evaluation of subjective and objective data. Case studies illustrating the various methods are presented for different kinds of mineral deposits and exploration environments.  相似文献   

Vulkanogene Glasscherben-Relikte in Kohlentonsteinen des Saar-Lothringer Oberkarbons sowie Herkunft und Menge der Pyroklastika     

Dr. Kurt Burger 《International Journal of Earth Sciences》1990,79(3):659-691

Zusammenfassung Obwohl Kohlentonsteine aus dem Saar-Lothringer Oberkarbon seit etwa 170 Jahren bekannt sind, gelang erst in jüngster Zeit der Nachweis und die Identifikation vulkanogener Relikte im petrographischen Stoffbestand. Diese befinden sich in Kohlentonsteinen des Stefan A: KTst 0=950; Westfal D: KTst 1=700; Westfal C: KTst 3 =400, KTst 4a=330, KTst 4aß=322, KTst 4=320, KTst 5=300 und im KTst 6=270. Das entspricht einem Anteil von ca. 18 % an der Gesamtzahl der in diesem limnischen Steinkohlenrevier beobachteten Kohlentonsteine, die hier große praktische und wissenschaftliche Bedeutung besitzen. Die pseudomorphen Relikte bestehen aus kleinen Splittern, kleinen und größeren Fragmenten mit teilweise gut erhaltenem blasigen Gefüge von Vitroklasten — sie zeigen die für Aschenschmelztuffe typisch verschweißte Scherbentextur. Die Glassubstanz ist meist zu mikrokristallinem Kaolinit devitrifiziert. Der eindeutige Nachweis dieser Relikte ist für die Genese bedeutungsvoll, liefern sie doch nun den sicheren Beweis, daß der primäre Stoffbestand aus aerisch abgelagertem pyroklastischen Material bestand, das intensive chemische Verwitterungs- und diagenetische Umbildungsprozesse erfahren hat. Für die 43 Kohlentonsteine des Saar-Lothringer Oberkarbons wird eine pyroklastische Eruptionsmenge von mindestens 8,2 km³ Festvolumen bzw. 20,5 km³ Lokkervolumen angenommen. Die Eruptionen erfolgten vermutlich aus der in der Nähe befindlichen Metz-Hunsrück-Südrand-Tiefenstörung, die nach Reflexionsseismik bis unter die Moho reicht.

---

Tonsteins in the Carboniferous of the Saar-Lorraine basin are known since about 170 years. Volcanic glass remains, however, have been proven as constituents of the tonstein only recently. They occur in tonsteins of Stephanian A: KTst 0=950; Westphalian D: KTst 1=700; Westphalian C: KTst 3=400, KTst 4a=330, KTst 4aß= 322, KTst 4=320, KTst 5=300 and KTst 6=270. Tonsteins with volcanic glass fragments amount to 18% of the total tonsteins observed in the limnic Saar-Lorraine basin. They are important to applied geology, e.g. for seam identification and correlation, as well as for scientific reasons, namely for the determination of provenance and genesis of tonsteins.The volcanic remains consist of tiny glass splinters, glass fragments, and of fragments with well preserved gasbubble texture. The welded splinter texture is typical of welded pyroclastic ash deposits. Much of the glass has been devitrified to microcrystalline kaolinite. The indisputable evidence of volcanic remains is essential when considering the genesis of tonsteins, as they provide proof that tonsteins are primarily composed of eolian pyroclastic constituents which were altered by chemical weathering and diagenesis.For the 43 horizons of the coal tonsteins found in the Upper Carboniferous of the Saar-Lorraine basin, a pyroclastic eruption quantity of at least 8.2 km³ of solid volume or 20.5 km³ of bulk volume is assumed. The eruptions possibly took place along the nearby deep-seated Metz fault at the southern rim of the Hunsrück. This fault, reaches below the Moho according to reflection seismic.

---

Résumé Bien que des tonstein du Carbonifère supérieur de SarreLorraine soient connus depuis 170 ans c'est seulement il y a peu de temps que des fragments de verre volcanique y ont été identifiés. Ces fragments ont été rencontrés dans les niveaux de tonstein suivants: Stephanien A: KTst 0=950; Westphalien D: KTst 1=700; Westphalien C: KTst 3=400, KTst 4a=330, KTst 4aß=322, KTst 4=320, KTst 5=300 et KTst 6=270. Ces niveaux représentent une proportion de l'ordre de 18% dans le total des couches de tonstein carbonifère rencontrées dans ce bassin houiller limnique où elles présentent un grand intérêt tant au point de vue pratique que scientifique. Les verres se présentent en esquilles et en fragments de tailles diverses, montrant parfois une structure bulleuse bien conservée; ils présentent également les structures d'agglomération propres aux tufs soudés à chaud. Le verre est le plus souvent dévitrifié en kaolinite microcristalline. La présence de ces fragments est d'un intérêt particulier pour la genèse du dépôt puisqu'elle fournit la preuve que celui-ci était constitué de matériaux primaires pyroclastiques sédimentés dans l'air, matériaux qui ont subi ensuite des altérations chimiques et des transformations diagénétiques intenses.Pour l'ensemble des 43 horizons de tonstein du Carbonifère supérieur de la Sarre-Lorraine, on admet un volume de matières pyroclastiques d'au moins 8,2 km³ (volume à l'état monolithique) ou de 20,5 km³ (volume à l'état fragmenté). Ces éruptions ont probablement pour origine la faille de Metz, située à proximité, qui forme la limite sud du Hunsrück et que la sismique-réflexion permet de prolonger jusqu'au Moho.

---

, (²⁰⁶/²⁰⁴ > 20.0) . . , .. , , . , , 100 . . . , - 20°, , .: . , . Bouguer'a, .

---

---

Das Thema dieser Arbeit war Gegenstand des KurzvortragesBurger &Wolf (1987) auf dem XI. ICC in Peking (31. 8. bis 4. 9. 1987). Vorliegende Bearbeitung stellt die originäre Fassung dar.  相似文献   

Cloud characteristics over the rain-shadow region of North Central peninsular India during monsoon withdrawal and post-withdrawal periods     

S. B. Morwal  S. G. Narkhedkar  B. Padmakumari  R. S. Maheskumar  D. R. Kothawale  K. K. Dani  R. Burger  R. T. Bruintjes  J. R. Kulkarni 《Climate Dynamics》2016,46(1-2):495-514

  相似文献   

High precision measurements of sediment elevation in shallow coastal areas using a sedimentation-erosion table   总被引：1，自引：0，他引：1  

Roelof M. J. Boumans  John W. Day 《Estuaries and Coasts》1993,16(2):375-380

The use of a sedimentation-erosion table (SET) for the measurement of small changes in sediment surface elevation in intertidal and shallow subtidal areas is described. The SET provides a constant reference plane in space from which the distance to the sediment surface can be measured by lowering pins to the surface. The precision of the method was determined by repeated measurements in coastal marshes, mudflats, and subtidal areas in Louisiana and Georgia. The confidence interval of the SET is about ±1.5 mm. The SET is more accurate if pins are lowered manually and the sediment surface is determined visually than if pins are lowered by gravity and the sediment surface is determined by soil resistance.  相似文献   

Reply on the discussion by G.P. Glasby     

H. Burger 《Mineralium Deposita》1984,19(2):170-170

  相似文献   

Untersuchungen zum Einfluß limnischer Makrophyten auf die Absterbegeschwindigkeit von Escherichia coli im Wasser     

G. Burger  G. Weise 《洁净——土壤、空气、水》1984,12(3):301-309

In bioassays in aquaria, the dying of Escherichia coli was accelerated by Glyceria maxima, Schoenoplectus lacustris, Alisma plantago-aquatica as well as Mentha aquatia as compared with check tanks without any plants (initial concentration 15 × 10³ colony-forming units per ml). As expected, by this the antibacterial effect of the limnic macrophytes attains its maximum effectivity within the first days of the period of investigation. The decimal time of reduction is shortened by one third to half, the centimal reduction time is shortened by one fourth to one third. Mean contact times of 7… 11 h are required for the decimation of bacteria by 90 %, and mean contact times of 16… 19 h are necessary for a 99 % reduction of the population. Possibly, the antibacterial effect in mixed stands of different plant species is increased additively or superadditively.  相似文献   

Spatial structure analysis of regionalized compositions     

V. Pawlowsky  H. Burger 《Mathematical Geology》1992,24(6):675-691

Like compositions in general, regionalized compositions present the problem of spurious spatial correlation. To avoid this problem, this paper uses the additive-logratio transformation of regionalized compositions, following techniques introduced over the last few years for the statistical analysis of compositional data. It leads to an appropriate definition of a spatial covariance structure to describe spatial dependence between regionalized variables subject to constant-sum constraints in the case of weak stationarity. To illustrate stated problems, simulated data are used.  相似文献   

Stratigraphic and structural setting of the Griqualand West and the Olifantshoek Sequences at Black Rock,Beeshoek and Rooinekke Mines,Griqualand West,South Africa     

W. S. Grobbelaar  M. A. Burger  A. I. Pretorius  W. Marais  I. J. M. van Niekerk 《Mineralium Deposita》1995,30(2):152-161

The Black Rock to Rooinekke area has been influenced by the Kheis and Namaqua orogenies. Thrusting associated with the Kheis orogeny is well documented throughout the mining area. Thrusting at Rooinekke resulted in the Griqualand West Sequence rocks overlying parts of the Olifantshoek Sequence. At Black Rock lithologies of the Voëlwater Subgroup have been thrusted onto the Olifantshoek Sequence. A prominent N-S trending graben structure has been observed in the Rooinekke, Beeshoek and Black Rock mining areas. The thrusts are disrupted by these N-S faults. At Rooinekke supergene replacement and enrichment of the iron ore is associated with pre-Olifantshoek N-S faulting. The Namaqua orogeny may also have played a part in upgrading the existing ore bodies under discussion.  相似文献