The response of palaeomagnetic data to Earth expansion     

P. W. Schmidt  D. A. Clark 《Geophysical Journal International》1980,61(1):95-100

Summary. Attempts to estimate palaeo-radii of the Earth, using palaeomagnetic data have necessarily been based on simplistic Earth models. It has been asserted that real geological processes are too complex to enable us to approach the problem quantitatively, and such attempts yield invalid results. We examine this and argue that, to the contrary, it appears that errors introduced by allowing for more realistic behaviour of the continents, e.g. 'orange-peel effect' and crustal extension, are smaller by an order of magnitude than the response of palaeomagnetic data to simplified expansion models.
From a qualitative argument, it is shown that the observed Late Palaeozoic and Early Mesozoic palaeomagnetic data are not what should be expected from an expanded Earth. We conclude that it appears unlikely that the Earth has expanded significantly since the Early Mesozoic.  相似文献   

SMART-1 after lunar capture: First results and perspectives   总被引：1，自引：0，他引：1  

B. H. Foing  G. D. Racca  A. Marini  E. Evrard  L. Stagnaro  M. Almeida  D. Koschny  D. Frew  J. Zender  D. Heather  M. Grande  J. Huovelin  H. U. Keller  A. Nathues  J. L. Josset  A. Malkki  W. Schmidt  G. Noci  R. Birkl  L. Iess  Z. Sodnik  P. McManamon 《Journal of Earth System Science》2005,114(6):689-697

SMART-1 is a technology demonstration mission for deep space solar electrical propulsion and technologies for the future. SMART-1 is Europe’s first lunar mission and will contribute to developing an international program of lunar exploration. The spacecraft was launched on 27th September 2003, as an auxiliary passenger to GTO on Ariane 5, to reach the Moon after a 15-month cruise, with lunar capture on 15th November 2004, just a week before the International Lunar Conference in Udaipur. SMART-1 carries seven experiments, including three remote sensing instruments used during the mission’s nominal six months and one year extension in lunar science orbit. These instruments will contribute to key planetary scientific questions, related to theories of lunar origin and evolution, the global and local crustal composition, the search for cold traps at the lunar poles and the mapping of potential lunar resources  相似文献   

Thermal maturity in the Central European Basin system (Schleswig-Holstein area): results of 1D basin modelling and new maturity maps     

Sabine Rodon  Ralf Littke 《International Journal of Earth Sciences》2005,94(5-6):815-833

Thermal maturity information has been compiled for one of the deepest parts of the Central European Basin system, the Schleswig-Holstein area in northern Germany. New vitrinite reflectance data were obtained and old data were evaluated from a total of 31 wells. Furthermore, numerical 1D basin modelling was performed in order to interpolate/extrapolate vitrinite reflectance data to base Zechstein and base Keuper. For these two horizons, maturity maps were finally compiled revealing large differences in present-day thermal maturity within the basin. For example, vitrinite reflectance at base Zechstein ranges from greater than 4.5% in the Glueckstadt Graben to less than 1% in the northern part of the study area. Highest thermal maturity of base Keuper occurs in the West Holstein Trough and in the northern part of the Glueckstadt Graben. The timing of maturation is greatly affected by the complex tectonic evolution of the area. For six key wells distributed over the entire study area, burial and temperature histories as well as evolution of maturity were evaluated using 1D basin modelling. Deepest burial and maximum temperatures occurred either during Jurassic, Upper Cretaceous or Neogene times in these wells. Only some parts of the sedimentary package in Schleswig-Holstein show a significant increase in maturity during the Tertiary leading to additional hydrocarbon generation and entrapment.  相似文献   

Simulating evapotranspiration in a semi-arid environment     

H. Hübener  M. Schmidt  M. Sogalla  M. Kerschgens 《Theoretical and Applied Climatology》2005,80(2-4):153-167

Summary In this work, simulations with the mesoscale meteorological model FOOT3DK for a semi-arid research site in southern morocco are presented. The main aim of this study is to introduce two different ways to improve the soil moisture distribution towards a more realistic pattern. One of them resembles the availability of groundwater resources below the lower boundary of the soil part of the model, the other one resembles irrigation practices in the region. Additionally, we introduce a newly derived land use/land cover data set obtained from analysis of LANDSAT data and compare the simulation results to those obtained with the USGS GLCC data. To evaluate the results with the refinements in soil moisture and land use/land cover, we focus on evapotranspiration, as the quantity which is most tentative to the changes in soil moisture and is an important part of the local hydrological cycle. To evaluate the importance of sub-grid scale surface heterogeneity in soil moisture and land use/land cover, we present simulations with enhanced surface resolution. Simulation results are compared to point measurements at different sites in the research area for validation.The results show, that a deep groundwater table and irrigation of parts of the research area can be represented by the methods we used. Simulated transpiration is overestimated compared to measured values, but this is due to the maximum approach used in this work. Finer tuning of the artificial enhancement of soil moisture with the two methods presented here are expected to lead to realistic distributions of evapotranspiration and related quantities, therewith drastically enhancing simulation accuracy for this site. As uncertainties of soil moisture distribution and restricted representation of soil moisture dynamics in meteorological models is a common problem especially for arid and semi-arid sites, we expect our results to be useful for meteorological simulations in other arid or semi-arid areas as well.  相似文献   

On the estimation of a multi-resolution representation of the gravity field based on spherical harmonics and wavelets     

M. Schmidt  O. Fabert  C.K. Shum 《Journal of Geodynamics》2005,39(5):512

The gravitational potential of the Earth is usually modeled by means of a series expansion in terms of spherical harmonics. However, the computation of the series coefficients requires preferably homogeneous distributed global data sets. Since one of the most important features of wavelet functions is the ability to localize both in the spatial and in the frequency domain, regional and local structures may be modeled by means of a spherical wavelet expansion. In general, applying wavelet theory a given input data set is decomposed into a certain number of frequency-dependent detail signals, which can be interpreted as the building blocks of a multi-resolution representation. On the other hand, there is no doubt that the low-frequency part of the geopotential can be modeled appropriately by means of spherical harmonics. Hence, the main idea of this paper is to derive a combined model consisting of an expansion in spherical harmonics for the low-frequency part and an expansion in spherical wavelets for the remaining medium and high-frequency parts of the gravity field. Furthermore, an appropriate parameter estimation procedure is outlined to solve for the unknown model coefficients.  相似文献   

Mineral exploration under cover: Characterizing mineralizing fluid systems   总被引：1，自引：0，他引：1  

Andreas Schmidt Mumm  Christopher Clark  Roger Skirrow   《Journal of Geochemical Exploration》2006,89(1-3):359

Mineral exploration in areas of little bedrock exposure must increasingly rely on the predictive quality of geological, geochemical and geophysical data. In this contribution analysis of fluid inclusions is used to characterize fluid systems associated with alteration and mineralization in two locations in South Australia. In the Curnamona Province, fluids related to albitization and calc-silicate alteration with associated brecciation evolve from a saline sodic composition to a metalliferous, saline fluid also found associated with sulphide mineralization. The microthermometric distinction of inclusion types is evidence for pressure fluctuation as a cause for breccia formation. In the Central Gawler Craton gold province fluid inclusion studies have characterized the compositional and constrained the physical conditions of mineralizing fluids. Regionally identified low salinity CO₂-bearing fluids at temperatures < 350 °C and pressures < 1.5 kbar indicate a shallow-level orogenic [Groves, D.I., Goldfarb, R.J., Gebre-Mariam, M., Hagemann, S.G., Robert, F., 1998. Orogenic gold Deposits: A proposed classification in the context of their crustal distribution and relationship to other gold deposit types. Ore Geology Reviews, 13, 7–27.] or intrusion-related [Lang, J.R., Baker, T., 2001. Intrusion related gold systems: the present level of understanding. Mineralium Deposita, 36, 477–489.] setting for the mineralization.  相似文献   

The “wave turbopause”     

D. Offermann  M. Jarisch  H. Schmidt  J. Oberheide  K.U. Grossmann  O. Gusev  J.M. Russell III  M.G. Mlynczak 《Journal of Atmospheric and Solar》2007,69(17-18):2139

The “wave turbopause” is defined as the mesospheric altitude level where the temperature fluctuation field indicates a substantial increase in wave amplitudes in the vertical direction.The turbopause altitude is analyzed on the basis of four years of SABER data (2002–2005, Version 1.06). Substantial seasonal and latitudinal variations are found, with some interannual variability also present. Seasonal changes are annual at high latitudes, semi-annual at low latitudes, and a mixture of both at middle latitudes. Southern hemisphere data are similar as in the North if shifted by half a year. Latitudinal variations show a minimum in the tropics and two relative maxima at middle latitudes.The “wave turbopause” is found near to zero-wind lines or low-wind zones (zonal wind). It is compared to rocket and other measurements, and interesting similarities are obtained. The wave turbopause can also be found in the HAMMONIA GCM. A preliminary analysis shows results similar to those of the SABER measurements.  相似文献   

An assessment of metal contamination in coastal sediments of the Caspian Sea   总被引：11，自引：0，他引：11  

de Mora S  Sheikholeslami MR  Wyse E  Azemard S  Cassi R 《Marine pollution bulletin》2004,48(1-2):61-77

An assessment of marine pollution due to metals was made in the Caspian Sea based on coastal sediment collected in Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan. Despite the high carbonate content, the distribution of most metals was largely controlled by terrigenous inputs. Several metals (As, Cr, Ni) exhibited concentrations that exceed sediment quality guidelines. Such metals have a high natural background but anthropogenic activities, notably mining, may further enhance concentrations. This would explain hot spots for Cu and Zn in Azerbaijan and Iran, and Cr at the mouth of the Ural River in Kazakhstan. Contamination by Hg was observed to the south of Baku Bay, Azerbaijan. Some anomalously high concentrations of Ba in the central Caspian are probably from offshore drilling operations, but the elevated U concentrations (up to 11.1 microg g(-1)) may be natural in origin. Several metals (Ag, Cd, Pb) have relatively low levels that pose no environmental concerns.  相似文献   

Mechanical design of the solar telescope GREGOR     

R. Volkmer  P. Eisentrger  P. Emde  A. Fischer  O. von der Lühe  H. Nicklas  D. Soltau  W. Schmidt  U. Weis 《Astronomische Nachrichten》2012,333(9):816-822

The mechanical structure of the GREGOR telescope was installed at the Observatorio del Teide, Tenerife, in 2004. New concepts for mounting and cooling of the 1.5‐meter primary mirror were introduced. GREGOR is an open telescope, therefore the dome is completely open during observations to allow for air flushing through the open, but stiff telescope structure. Backside cooling system of the primary mirror keeps the mirror surface close to ambient temperature to prevent mirror seeing. The large collecting area of the primary mirror results in high energy density at the field stop at the prime focus of the primary which needs to be removed. The optical elements are supported by precision alignment systems and should provide a stable solar image at the optical lab. The coudé train can be evacuated and serves as a natural barrier between the outer environmental conditions and the air‐conditioned optical laboratory with its sensitive scientific instrumentation. The telescope was successfully commissioned and will start its nominal operation during 2013 (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

A retrospective of the GREGOR solar telescope in scientific literature     

C. Denker  O. von der Lühe  A. Feller  K. Arlt  H. Balthasar  S.‐M. Bauer  N. Bello Gonzlez  Th. Berkefeld  P. Caligari  M. Collados  A. Fischer  T. Granzer  T. Hahn  C. Halbgewachs  F. Heidecke  A. Hofmann  T. Kentischer  M. Klva&#x;a  F. Kneer  A. Lagg  H. Nicklas  E. Popow  K.G. Puschmann  J. Rendtel  D. Schmidt  W. Schmidt  M. Sobotka  S.K. Solanki  D. Soltau  J. Staude  K.G. Strassmeier  R. Volkmer  T. Waldmann  E. Wiehr  A.D. Wittmann  M. Woche 《Astronomische Nachrichten》2012,333(9):810-815

In this review, we look back upon the literature, which had the GREGOR solar telescope project as its subject including science cases, telescope subsystems, and post‐focus instruments. The articles date back to the year 2000, when the initial concepts for a new solar telescope on Tenerife were first presented at scientific meetings. This comprehensive bibliography contains literature until the year 2012, i.e., the final stages of commissioning and science verification. Taking stock of the various publications in peer‐reviewed journals and conference proceedings also provides the “historical” context for the reference articles in this special issue of Astronomische Nachrichten/Astronomical Notes (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献