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51.
Computer-assisted Image Analysis can be succesfully used to derive quantitative information about grain-size distribution, particle shape and fabric on both consolidated and unconsolidated solid aggregates. We have developed a new analytical method that provides a series of quantitative textural parameters from whatever particulate deposits by combining commercial image acquisition system with devoted C-software. After exhaustive tests of the method, we applied it to a widespread Quaternary ignimbrite formation in central Italy (the Orvieto-Bagnoregio formation). The results suggest some new aspects of emplacement mechanisms of ignimbrites: (1) elongated particles shows variable degrees of flow-related preferred orientation both on horizontal and vertical planes; (2) vertical variations of flow-related preferred particle orientations follow a “zig-zag” pattern that we interpret to result from deposition by progressive aggradation during the passage of a particulate flow. The filling up of paleovalleys by means of progressive aggradation proceeds flank to flank due to alternating flow directions, induced by the already deposited material; (3) the occurrence of vertically spaced peaks on the strength of clast orientation suggests the existence of discrete depositional units deposited by aggradation from an unsteady but persisting flow. Strong fabrics are inferred to result from the high amount of shear stress imparted to particles at the depositional boundary layer, which at the same time can be responsible for the development of the basal inversely graded layer. Image analysis can also provide useful indications of paleoflow directions, paleotopographic details and ignimbrite source areas. 相似文献
52.
Bruno Engels 《International Journal of Earth Sciences》1959,48(1):271-280
Zusammenfassung Zunächst wird die offenbar überragende Bedeutung der Diagonal-Störungen in den untersuchten Dachschiefer-Gruben dargelegt. Es ergeben sich ferner sehr spitzwinklig zum tektonischen Streichen verlaufende Drehverschiebungen, die zur gleichartigen Verformung führen, wie auch die örtlich festgestellten Auf- und Überschiebungen sowie Schieferung und Faltung (gleiche Deformationsellipse). — Die Schieferung führt in extremen Fällen zu einer fast völligen Umschichtung (tektonische Mischung).In einem Querprofil des Faltenspiegels zwischen Hunsrück und SE-Eifel kommt besonders die Moselmulde (Form und Schichtmächtigkeiten) zur Darstellung. 相似文献
53.
Bruno Huber 《International Journal of Earth Sciences》1960,49(1):120-131
Zusammenfassung Die Dendrochronologie arbeitet mit der Jahresschichtung des Holzes. Der Zuwachs gleichzeitig wachsender Hölzer ist ähnlich. Diese Forschungsrichtung braucht viel Material zur Herstellung typischer Mittelkurven. Mit Hilfe der Überbrückungsmethode kommt man örtlich sehr weit zurück. Schwierigkeiten liegen in der gesetzmäßigen Abnahme der Ähnlichkeit von Jahresringkurven mit der Entfernung voneinander. Neben einer absoluten Chronologie sind in Deutschland relative Chronologien aus Jungsteinzeit und Bronzezeit erarbeitet worden. Die Dendrochronologie kann gewisse Aussagen über Klimaschwankungen machen. 相似文献
54.
Über die Messung von Massensehwächungskoeffizienten bei der Phasenanalyse mit dem Zählrohrgoniometer
Dr. Bruno Brehler 《Contributions to Mineralogy and Petrology》1957,6(1):52-58
Zusammenfassung Es wird ein Verfahren angegeben, um bei der röntgenographischen Gemischanalyse mit dem Zählrohrgoniometer, dann wenn die Gefahr von Textureffekten nicht besteht, die Intensitäten der Analysenlinien und den Massenschäwachungskoeffizienten in demselben Präparat messen zu können; dazu wird in den Boden des Präparatträgers eine Einkristallplatte eingekittet und die Schwächung gemessen, die ein Reflex der Kristallplatte durch Einbringen der Präparatsubstanz erfährt. 相似文献
55.
We demonstrate the possibility to improve the signal-to-noise ratio of superconducting gravity time-series by correcting for
local hydrological effects. Short-term atmospheric events associated with heavy rain induce step-like gravity signals that
deteriorate the frequency spectrum estimates. Based on 4D modeling constrained by high temporal resolution rain gauge data,
rainfall admittances for the Vienna and Membach superconducting gravity stations are calculated. This allows routine correction
for Newtonian rain water effects, which reduces the standard deviation of residuals after tidal parameter adjustment by 10%.
It also improves the correction of steps of instrumental origin when they coincide with step-like water mass signals. 相似文献
56.
Doppler tracking of an interplanetary spacecraft near solar conjunction is strongly affected by the plasma in the solar corona, the main competitive contribution in measurements of the gravitational deflection of light rays. With the simultaneous availability of carriers in X band and Ka band for interplanetary communications, the plasma contribution to the corona can be accurately eliminated and measured. If, as in the Cassini mission, three different observables are available, this can be done in two ways: one deals with the total plasma content in the electric approximation, even in the ionosphere and interplanetary space; another is limited to the corona, but has access to subtler effects, like the magnetic correction to the refractive index. This technique will allow important progress in the radio investigation of the solar corona. 相似文献
57.
58.
Pier Paolo G. Bruno Giuseppe Cippitelli Antonio Rapolla 《Journal of Volcanology and Geothermal Research》1998,84(3-4)
Fifteen seismic reflection lines from AGIP surveys, in and around the Campanian Plain and Mt. Somma–Vesuvius (south Italy) have been interpreted. The attention has been focused to the horizon pertinent to the top of the Mesozoic carbonate sequence and the Quaternary faults dissecting it. As a matter of fact, both are very important elements for understanding the origin of the volcanic activity in the area, that often in the past, has been the topic of debates not supported by reliable data. In the study area, referring to the depth of the carbonate basement, comparison between the result achieved by the seismic prospecting and previous gravity studies has been made. It shows coherence in some areas but large discrepancy within others. Near the town of S. Anastasia, the gravity and seismic depth estimates differ as much as 1000 m or more. Furthermore, the seismic data show that the source of the greatest volcanic eruption in the area (the so-called ‘Campanian Ignimbrite') is probably not located in the Acerra depression, as suggested by other authors. A main NE–SW fault directed toward Vesuvius, considered as playing a primary role on volcanogenetic processes and previously recognised only offshore by marine seismic survey, has been now identified also inland using this new seismic information. The results presented here strengthen the hypothesis that Mt. Vesuvius is located at the crossing point of two regional Quaternary sets of fault heading NW–SE and NE–SW. 相似文献
59.
60.
Prof. Dr. Bruno Engels 《International Journal of Earth Sciences》1965,54(2):758-795
The basement of northern Nicaragua is still a great problem stratigraphically. Enclosed tuffits (mainly basic, partly also intermediate to acid) appear of importance for both petrology and sedimentology. Not in the least they are guide horizons for a more accurate mapping. The vast regional distribution, commonly proved yet, suggests that the composition of the basement is considerably uniform and it seems that they do not belong to different periods and formations. Structurally the region is exceedingly complicated. The folding direction as regards plication and overthrusts is mainly to the North, but partly also to the East. Probably the “Totogalpa formation” (fanglomerates, conglomerates and sandstones, mainly reddish) which follows disconformably over the basement, already indicated, belongs to the sequence of tertiary tuffites, agglomerates, lavas etc. as they conformably form a formation of uniform composition. The relation of basement to lower Cretaceous (marine Albian; “Metapan”), which follows immediately to the south, is less clear. The lower Cretacious shows intensive and complicated folding at Siuna and it appears almost unmetamorphosed (? basement in a wider sense). The marine sediments (upper Cretacious - Miocene) of South Nicaragua are orogenetically only slightly efected (folding direction to E-N). To the North follows a thick serie of Tertiary and Quarternary volcanites (initially mainly submarinal, later on continental). Together with the NW/SE lineaments (Nicaragua depression, lines of volcanoes, coast line in the SW etc.) also NS directed ones clearly appear (coastline in the East). This direction can be found e. g. in the “granite ridge of Susucayan” and the accompanying faults in the vicinity. These latter structures may have taken an active part in the development of the flexured border of the Nicaraguan depression NW of Managua. 相似文献