Lunar noise correlation, imaging and monitoring     

Christoph Sens-Schonfelder  Eric Larose 《地震学报(英文版)》2010,(5):519-530

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The chemical variability at the surface of Mars: Implication for sediment formation and rock weathering     

Christoph Kolb  Josep A. Martín-Fernández  Helmut Lammer 《Icarus》2006,183(1):10-29

Compositional data analysis was performed on chemical compositions of martian surface materials in order to unravel scenarios of past and present weathering and to evaluate the role of meteoritic accumulation. The observed chemical variability is analyzed by means of principal component analysis. Potential reservoirs that may have contributed primary material to soil formation are assessed. Chemical alteration in the course of in situ weathering is described in terms of alteration vectors that link the compositions of fresh rocks and their weathering crusts. The interplay of localized chemical alteration and global scale re-distribution and mixing of fines material is documented through the identification of different soil forming branches. These branches emanate from distinct compositional domains, which comprise basaltic and basalt-andesitic primary materials, and they converge to a global dust composition, which represents the product of chemical and physical disintegration and subsequent global mixing. Mass balance considerations applied to localized weathering phenomena are in line with findings from experimental acid-sulfate weathering on olivine-bearing basalts and the persistence of secondary silica in evaporitic rocks. In addition the composition and oxidation state of involved volcanic gases is deduced. Our findings corroborate the past activity of volcanic exhalation products in combination with liquid water. We conclude that average martian crust is dominated by basaltic materials at its topmost level and that the amount of meteoritic accumulation may contribute about 6 wt% to the martian fines. From the meteoritic contribution minimum soil formation rates of 60±20 cm/Gyr are derived. Sequestration of atmospheric oxygen during weathering of primary materials may account for the oxygen deficiency of the martian atmosphere. A 4-14-m-thick layer of oxidized martian fines may account for the estimated deficit of 1.7×¹⁰¹⁸ mol O₂ in the martian atmosphere depending on the primary oxidation state of volatile volcanic emanations.  相似文献   

Existence and stability of strong potential double layers     

Georg Knorr  Christoph K. Goertz 《Astrophysics and Space Science》1974,31(1):209-223

An elementary integral equation technique is used to construct strong and weak stationary shock solutions from the one-dimensional Vlasov equation. It is shown that the plasma is Penrose stable in all points in space under certain conditions.This work was supported in part by the Atomic Energy Commission Grant No. AT(11-1)-2059, and NSF Grant GA-31676.supported by a CSIR bursary.  相似文献   

Volcano spacing,fractures, and thickness of the lithosphere — A reply     

Peter R. Vogt 《Earth and Planetary Science Letters》1974,23(2):162-163

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Carbon,sulfur, oxygen and strontium isotope records,organic geochemistry and biostratigraphy across the Permian/Triassic boundary in Abadeh,Iran   总被引：6，自引：0，他引：6  

Christoph?KorteEmail author  Heinz?W.?Kozur  Michael?M.?Joachimski  Harald?Strauss  Ján?Veizer  Lorenz?Schwark 《International Journal of Earth Sciences》2004,93(4):565-581

Pelagic deposits at Abadeh represent a complete biostratigraphic record across the Permian/Triassic boundary (PTB). The presumed water depth during deposition of these sediments was between 60 and 90 m. Similar to other Permian/Triassic boundary sections, the succession at Abadeh is characterised by a negative carbon isotope shift of approximately 4. The values start to decrease in the lower C. changxingensis - C. deflecta s.l. Zone, reach –0.12 (V-PDB) in the uppermost Permian just below the PTB, remain low to the early I. isarcica Zone (–0.32) and increase subsequently in the upper I. isarcica Zone. For the time interval of the PTB negative carbon isotope excursion, between the C. iranica and the I. isarcica Zones, no correlation exists between the ¹³C_carb and the ¹⁸O_carb. The above observations argue against the conclusion of Heydari et al. (2001) that the carbon isotope event at the P/T transition is an alteration artefact and not a global signal. The decrease in ¹³C_carb is accompanied by a ~5 (and potentially up to 10) increase in ³⁴S_SSS. Together, these features are thought to reflect a complex global event, notably the development of widespread anoxic oceans with anoxic bottom layers rising onto the shelves. For the carbon isotope drop, other factors, such as the collapse of ocean primary productivity may also have played a role. The ⁸⁷Sr/⁸⁶Sr ratios of Dzhulfian seawater show only a minor increase from 0.70705 to 0.70710, reaching 0.70720 in the Dorashamian. The increase becomes steeper in the Early Triassic reaching 0.70754 in the N. dieneri Zone. The rise of the strontium isotope values is thought to be related to enhanced continental weathering under humid climatic conditions in the uppermost Permian (C. meishanensis - H. praeparvus Zone) and the lack of a dense land vegetation in the Early Triassic, prior to the Spathian (Upper Olenekian).  相似文献   

A search for rapid photometric variations in southern Be and Bn stars     

L. H. Barrera  R. E. Mennickent  N. Vogt 《Astrophysics and Space Science》1991,185(1):79-94

Fifteen Be, 5 Bn, and 1 B stars were monitored during 10 nights in March–April 1988 by means of photoelectricubvy photometry. At least 80% of the Be stars were found variable. Tentative periods between 0.3 and 4.3 days were derived for 13 stars of our entire sample. In all cases the stars are bluest when brightest. Variations in B0-B5e stars are, in average, of larger amplitude than in B5-B9e stars. Bn stars show, in general, variations of smaller amplitude than Be stars. We discuss these results in terms of the current models on short-term photometric variability. In addition, from the observed period distribution we deduce the existence of intrinsically slow Be rotators. We propose the rotation of slightly displaced poles of a weak global dipolar magnetic field as responsable for the rapid periodic light variations.Based on observations obtained at the European Southern Observatory, La Silla, Chile.  相似文献   

Observations of the 7 March, 1970 total solar eclipse at wavelengths of 3.2 and 8.3 mm     

John P. Hagen  Paul N. Swanson  Robert W. Haas  Fred L. Wefer  Raymond W. Vogt 《Solar physics》1971,21(2):286-296

The 7 March, 1970 total solar eclipse was observed at wavelengths of 3.2 and 8.3 mm; the object being to use the knife edge of the Moon as it passed across the Sun to improve angular resolution on the Sun. This in turn would provide a radial brightness distribution of the Sun with an angular resolution of a few seconds of arc.Excellent eclipse curves were obtained at 3 mm; however, some external interference marred the 8 mm record near totality.The 8 mm brightness distribution is subject to some uncertainty, but tends to show limb brightening. The 3 mm brightness distribution shows a well defined complex limb brightening within about 1 arc min of the optical limb. The maximum brightening is approximately 30% above the average disc temperature.  相似文献   

Landslide risk management in Switzerland   总被引：1，自引：2，他引：1  

Olivier Lateltin  Christoph Haemmig  Hugo Raetzo  Christophe Bonnard 《Landslides》2005,2(4):313-320

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The Late Paleozoic felsic lava-dominated large igneous province in northeast Germany: volcanic facies analysis based on drill cores     

Holger Paulick  Christoph Breitkreuz 《International Journal of Earth Sciences》2005,94(5-6):834-850

In the deep subsurface of the northeast German basin products of extensive volcanism are present that formed during the waning phase of the Variscan orogeny (Permian–Carboniferous boundary). Large volumes (≥48,000 km³) of dominantly felsic magma were emplaced in the northern foreland of the Variscan mountains in a terrestrial semi-arid environment. Most of these units were inferred by previous authors to represent the products of explosive volcanic eruptions such as ignimbrites. However, a detailed analysis of the volcanic texture and lithofacies association shows that most units are best interpreted as coherent lavas emplaced either as extrusive units or as shallow intrusions, with important implications for the reconstruction of the paleo-environment. This study shows that detailed textural examination of drill cores provide important observations, which can be applied as criteria for the interpretation of the mode of volcanic eruptions. Furthermore, phenocryst logging and geochemical fingerprinting based on immobile element ratios can be employed for the classification and discrimination of individual emplacement units.  相似文献   

Microthermometry, Raman and LA-ICP-MS of Fluid Inclusions Constrain on Fluids Chemistry and Evolution of Carlin-Type Gold System, Guizhou, China: Implications for Ore Genesis     

Wen-chao Su　Christoph A. Heinrich　Thomas Pettke　Xing-chun Zhang　Rui-zhong Hu　Bin Xia 《矿物岩石地球化学通报》2006,25(Z1):192

The Shuiyindong and Yata Carlin-type gold deposits, located in Southwestern Guizhou, China, are hosted by Permianbioclastic limestone in the form of stratabound mineralization and Middle Triassic calcareous clastic rocks as fault-controlled mineralization, respectively. In these deposits, quartz crystals in the veins or veinlets associated with mineralization have contained several populations of fluid inclusions with relatively quite big size and clear paragenetic relationship of entrapment. Petrography, microthermometry, Raman and LA-ICPMS of fluid inclusions analyses are used to characterize fluids chemistry and their evolution of Carlin-type system in Guizhou.  相似文献