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121.
122.
Dr. C. Voûte 《International Journal of Earth Sciences》1963,52(2):665-675
In connection with the UNESCO-activity to save the Nubian Monuments several geological and geotechnical problems arising are discussed. Geomorphology, regional geology, capillarity-questions and salt-action are considered and ways of saving the Philae-Monuments are sketched.
Zusammenfassung Im Zusammenhang mit der UNESCO-Aktion zur Rettung der Nubischen Denkmäler werden verschiedene geologische und geotechnische Probleme dieses Unternehmens beschrieben. Regional-geologische und geomorphologische Fragen, Kapillaritäts- und Salzverwitterungs-Probleme werden angeschnitten und diskutiert. Zum Schluß werden Maßnahmen zur Rettung der Philae-Tempel skizziert.
Résumé En regard de l'action de l'UNESCO pour le sauvetage des monuments de la Nubie, l'auteur décrit les différents problèmes géologiques et géotechniques relatifs à cette entreprise. Des questions à caractère géologique régional et géomorphologique, des problèmes d'altération par capillarité et à l'intervention de sels sont examinés et discutés. Finalement l'auteur esquisse les mesures à prendre pour la sauvegarde du temple de Philae.
UNESCO .相似文献
123.
124.
Southwest China and Southeast Asia: towards sustainability through cooperative development and management of international rivers * 总被引:1,自引:0,他引:1
HE Daming Yunnan Institute of Geography Yunnan Kunming CHINA Dept. of Geography the University of Memphis Memphis TN USA Hsiange te Kung Dept. of Geography the University of Memphis Memphis TN USA 《地理学报(英文版)》1998,(3)
I.InternationalRiversandtheLancangMekongRiverInternationalriversaredefinedastheriverswhichflowacrostwoortwomorecountries.Upt... 相似文献
125.
Philippe Cte Pierre Degauque Richard Lagabrielle Nathalie Levent 《Geophysical Prospecting》1995,43(8):1083-1107
In order to detect underground cavities, we have designed a geophysical method based on the interaction of a monochromatic electromagnetic wave in the frequency band 100 MHz to 1 GHz with the ground situated between two boreholes. Three different approaches are involved in the design of this EM tomographic method.
- 1 The application of an ‘exact’ theory is used to calculate artificial data, based on an integral equation method. These data are inverted using a tomographic algorithm whose basic assumptions are rather coarse. The results show that, however, cavities can very well be detected and their position recovered.
- 2 Data are obtained with a physical reduced-scale model in a water tank, in which all parameters are known in advance. The inversion process confirms the validity of the method.
- 3 Underground cavities are actually detected.
126.
This paper develops further the case for a foreland basin origin of South Westland Basin, located adjacent to the Southern Alps mountain belt. Geohistory analyses show Middle Miocene initiation of subsidence in the basin, with marked increases at 5–6 Ma. Five seismic reflection horizons, including basement, Middle Miocene (top Awarua Limestone), top Miocene, mid-Pliocene (PPB) and mid-Pleistocene (PPA) have been mapped through the grid of seismic data. A series of five back-stripped structure contour maps taken together with five isopach maps show that prior to the Middle Miocene, subsidence and sedimentation occurred mainly along the rifted continental margin of the Challenger Plateau facing the Tasman Sea; subsequently it shifted to a foredeep trending parallel to the Southern Alps and located northwest of them. Through the Late Miocene–Recent this depocentre has progressively widened, and the loci of thickest sediment accumulation have moved northwestward, most prominently during the Late Pliocene and Pleistocene with the progradation of a shelf–slope complex. At the northern end of the basin the shelf–slope break is currently located over the forebulge, which appears not to have migrated significantly, probably because the mountain belt is not advancing significantly northwestwards. Modelling of the lithospheric flexure of the basement surface normal to the trend of the basin establishes values of 3.1 to 9.8×1020 N m for the flexural rigidity of the Australia Plate. This is at the very low end of rigidities for plates, and 1–2 orders of magnitude less than for the Australia Plate beneath the Taranaki Basin. Maps of tectonic subsidence where the influence of sediment loading is removed also clearly identify the source of the loading as lying within or beneath the mountain belt. The basin fill shows a stratigraphic architecture typical of underfilled ancient peripheral foreland basins. This comprises transgressive (basal unconformity, thin limestone, slope-depth mudstone, flysch sequence) and regressive (prograding shelf–slope complex followed by molasse deposits) components. In addition the inner margin of the basin has been inverted as a result of becoming involved in the mountain building, as revealed earlier by fission track thermochronological data. The timing and degree of inversion fits well with the geometrical and stratigraphic development of the basin. That the inversion zone and the coastal plain underlain by molasse deposits are narrow, and most of the basin is beneath the sea, highlights this as an underfilled active foreland basin. The basin is geodynamically part of the Southern Alps collision zone. 相似文献
127.
Antonio Gómez David Palacios Enrique Luengo Luis M. Tanarro Lothar Schulte Miguel Ramos 《Geografiska Annaler: Series A, Physical Geography》2003,85(2):165-182
The southernmost glacier in Europe formed during the Little Ice Age at the foot of the north wall of Picacho del Veleta (3 398 m) in Sierra Nevada, in the southeast region of the Iberian Peninsula (lat. 37δ03‘N, long. 3δ22‘W). The glacier gradually retreated during the last century, leaving a large talus slope at the base of the wall. The unconsolidated material covering the ice masses acted as a thermal insulator. Recent bottom temperature of snow (BTS) analyses and drillings indicate that the ice still exists within the talus. Evidence from field observations made during the period 1995–2001, revealed that large mass movements occurred during the driest summers (1998 and especially, 1999 and 2000) when the talus was snow free. These conditions suggest a direct relationship between talus stability and thermal insulation from the snow cover in areas where buried ice or decaying marginal permafrost exists. 相似文献
128.
Lothar Schrott Gabi Hufschmidt Martin Hankammer Thomas Hoffmann Richard Dikau 《Geomorphology》2003,55(1-4):45
Spatial patterns of sediment storage types and associated volumes using a novel approach for quantifying valley fill deposits are presented for a small alpine catchment (17 km2) in the Bavarian Alps. The different sediment storage types were analysed with respect to geomorphic coupling and sediment flux activity. The most landforms in the valley in terms of surface area were found to be talus slopes (sheets and cones) followed by rockfall deposits and alluvial fans and plains. More than two-thirds of the talus slopes are relict landforms, completely decoupled from the geomorphic system. Notable sediment transport is limited to avalanche tracks, debris flows, and along floodplains. Sediment volumes were calculated using a combination of polynomial functions of cross sections, seismic refraction, and GIS modelling. A total of, 66 seismic refraction profiles were carried out throughout the valley for a more precise determination of sediment thicknesses and to check the bedrock data generated from geomorphometric analysis. We calculated the overall sediment volume of the valley fill deposits to be 0.07 km3. This corresponds to a mean sediment thickness of 23.3 m. The seismic refraction data showed that large floodplains and sedimentation areas, which have been developed through damming effects from large rockfalls, are in general characterised by shallow sediment thicknesses (<20 m). By contrast, the thickness of several talus slopes is more than twice as much. For some locations (e.g., narrow sections of valley), the polynomial-generated cross sections resulted in overestimations of up to one order of magnitude; whereas in sections with a moderate valley shape, the modelled cross sections are in good accordance with the obtained seismic data. For the quantification of valley fill deposits, a combined application of bedrock data derived from polynomials and geophysical prospecting is highly recommended. 相似文献
129.
Focused infiltration of snowmelt water in partially frozen soil under small depressions 总被引:5,自引:0,他引:5
Ephemeral puddles in small closed depressions can play an important role in the hydrology and ecology of many landscapes, by storing runoff water, recharging soil moisture and shallow groundwater, and by providing food and habitat for many organisms. Infiltration of snowmelt water under small depressions (<1000 m2) has been studied in the St. Denis National Wildlife Area in Saskatchewan, Canada, located within the northern glaciated prairie of North America where numerous depressions of varying sizes exist. The depressions stored most of the snowmelt runoff generated within their respective watersheds. The water level in a typical depression declined at 0.6 mm/h while the underlying frozen soil was thawing. This rate was likely limited by the rate of downward movement of the thawing front, which was functioning as a moving impermeable boundary. The rate of thawing was controlled by the external energy input from the ground surface. Standing water in depressions efficiently trapped incoming radiation and conducted it to the thawing front. The recession rate increased to 1.1 mm/h when the soil under the depression thawed completely. The recession rate at this later stage appears to be limited by the hydraulic conductivity of the subsoil (0.04–4 mm/h), which is much smaller than the topsoil conductivity (10–20 mm/h). 相似文献
130.
Thomas?OberthürEmail author Thorolf?W.?Weiser Lothar?Gast Kari?Kojonen 《Mineralium Deposita》2003,38(3):327-343
The behaviour of platinum-group elements (PGE) in the exogenic cycle was examined in profiles of oxidized Main Sulfide Zone (MSZ) ores, in which the general metal distribution patterns of the pristine MSZ are grossly preserved. However, at similar Pt grades, significant proportions of Pd have been lost from the system. This indicates that Pd is more mobile than Pt and is dispersed in the supergene environment. Sperrylite and cooperite/braggite are stable in the oxidized MSZ. In contrast, the (Pt,Pd)-bismuthotellurides, common in pristine MSZ ores, have disintegrated, and ill-defined (Pt,Pd)-oxides or (Pt,Pd)-hydroxides have formed. The assemblage of detrital PGM present in the Makwiro River close to the Hartley Platinum Mine indicates further mineralogical changes. Sperrylite largely remains stable whereas most cooperite/braggite grains have been partly altered or completely destroyed. Grains of Pt-Fe alloy are ubiquitous in the alluvial sediments. Most likely, these grains are neo-formations that formed either from pre-existing, unstable PGM or via a solution stage under low-temperature conditions. 相似文献