Beitrag zur Regionalmetamorphose des Harzes     

Prof. Dr. G. Müller  Prof. Dr. K. W. Strauss 《International Journal of Earth Sciences》1985,74(1):87-94

Zusammenfassung Im intrusiven spilitisierten Basalt des Mitteldevons südlich von Langeisheim (NW-Harz) wurde die Mineralparagenese: Pumpellyit + Prehnit + Epidot + Aktinolith, welche in einer Matrix von Albit, Chlorit, Calcit und Quarz vorkommt, vorwiegend mit der Mikrosonde untersucht.Diese Mineralgesellschaft des Metabasits hat sich während der Versenkung des heute noch >4 km stratigraphische Mächtigkeit betragenden Sedimentstapels des Wolfshagen-Goslar-Troges gebildet. Durch die Einengung der mitteldevonischen bis oberkarbonischen Sedimentserien bei der Auffaltung des Harzes im Oberkarbon ist deren Mächtigkeit stark erhöht worden.Aufgrund von Untersuchungsergebnissen in anderen Gebieten, welche in der Pumpellyit-Prehnit-Fazies vorliegen (referiert vonMiyashlro 1973), und von experimentellen petrologischen Untersuchungen zu Mineralreaktionen dieser Fazies (Nitsch 1971) läßt sich die maximale Metamorphosetemperatur für die mitteldevonischen Spilite des Wolfshagen-Goslar-Troges zu nahe 400° C bei Drücken 3 Kbar festlegen.Der Wert des geothermischen Gradienten während der Metamorphose hat wahrscheinlich zwischen 40 und 45° C/km Tiefe gelegen, wenn man von einer durch die Faltung bedingten Verdoppelung der Sedimentgesteinsmächtigkeit ausgeht.

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In rock samples of a Middle Devonian spilitized basaltic sill near Langelsheim (Northwestern Harz Mountains) the following mineral assemblage: pumpellyite + prehnite + epidote + actinolite grown in a groundmass of albite, chlorite, calcite and quartz has been studied by use of a microprobe.This mineral assemblage was formed during the Rhenohercynian burial of a Devonian and Carboniferous pile in the Wolfshagen-Goslar through. Nowadays, the remaining metasedimentary rocks still amount to more than 4 kilometers stratigraphical thickness although the Harz mountains suffered two periods of denudation, a Permian one and another Post-Cretaceous one. The real thickness of the Rhenohercynian pile increased strongly by folding in the Upper Carboniferous and is assumed to be more than 8 kilometers.Considering the research results from various areas which have been metamorphosed under the conditions of pumpellyite-prehnite facies (compiled byMiyashiro 1973) and based on petrological data regarding the mineral reactions of the pumpellyite-prehnite facies (Nitsch 1971) the following conclusions can be made: The peak temperatures of the Rhenohercynian regional metamorphism ranged near 400° C.The formation of the assemblage pumpellyite + prehnite took place at pressures (P_f = P_l below 3 kilobars. The geothermal gradient controlling the metamorphic recrystallization was moderate (40–45° C per kilometer depth) assuming a total thickness of the folded beds of more than 8 kilometers.

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Résumé Dans le NW du Harz (R.F.A.), le synclinorium de Wolfshagen Goslar est occupé par une série sédimentaire d'âge dévonien moyen à carbonifère supérieur. La partie de cette série visible aujourd'hui présente encore une puissance de plus de 4 km, après les deux phases d'érosion permienne et post-crétacée. Le raccourcissement dû au plissement du Harz au Carbonifère supérieur a contribué à accroître cette épaisseur jusqu'à une valeur effective de plus de 8 km.Cette série renferme un basalte (métabasite) intrusif spilitisé d'âge givetien, qui affleure au sud de Langelsheim. Cette roche présente, dans une matrice d'albite-chloritecalcite-quartz, une paragenèse à pumpellyite + prehnite + épidote + actinote, engendrée au cours de l'enfouissement de la série. Cette paragenèse a été étudiée à la microsonde. Les résultats de ces mesures ont été comparés: d'une part avec des données provenant de diverses régions de faciès à pumpellyite-prehnite (rapportées parMiyashlro, 1973), d'autre part avec des données de pétrologie expérimentale (Nitsch, 1971). Il en résulte pour les métabasites étudiées une température maximale de près de 400 °C sous une pression inférieure à 3 Kb.Le gradient géothermique au moment du métamorphisme devait être 40° et 45 °C/Km, valeur obtenue en tenant compte de l'augmentation d'épaisseur due au plissement.

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A Geography of trade and development in Malaya: Courtenay, P.P. (1972): 286 S., 27 Fig., 47 Tab. London: Bell & Sons Ltd. £ 3.00     

Harald UhLig 《Geoforum》1974,5(3):86-87

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Nordic Geoscience and the 33rd International Geological Congress： Introduction     

David G. Gee Harald Brekke Raimo Lahtinen Freysteinn Sigmundsson Bjoern Sundquist Hans Thybo Paer Weihed 《《幕》》2008,31(1):4-8

Geology has been of profound importance for the Nordic countries since the Middle Ages. Strong economies were built on an understanding of the occurrence in bedrock of minerals containing metals, e.g., silver, copper, zinc and iron, and eventually led to the establishment of the first Geological Surveys in Norway and Sweden in the middle of the nineteenth century. The geology of Norden ranges from the oldest to youngest rocks on the planet. Based on the papers in this special issue, this introduction provides a brief summary of the geological evolution of Norden, from the Archean of Greenland and northern Fennoscandia to the on-going volcanicity in Iceland on the MidAtlantic Ridge. It also refers to aspects of Geoscience that are particularly important for society in Norden, including geo-resources （petroleum, geothermal energy, nuclear energy, metals, industrial minerals and groundwater） and environmental geology （including natural and anthropogenic processes, medical geology, geo-hazards and climate）. Information on the early history of geology in Norden and the geological surveys is also included and, finally, an outline of the 33rd International Geological Congress with its main theme “Earth System Science： Foundation for Sustainable Development”.  相似文献   

Estimation of irrigation flow by hydrograph analysis in a complex agricultural catchment in subtropical China     

Jia‐Liang Tang  Bin Zhang  Harald Zepp 《水文研究》2007,21(10):1280-1288

Estimating the amount of irrigation water is challenging at the catchment scale because of the difficulties in direct measurement and interactions between the flow components. The objectives of the study were to characterize the catchment flows in an agricultural catchment with an irrigation system in subtropical China and to estimate catchment irrigation flow using hydrograph analysis methods. A weighting model and multiple regression models were established to estimate catchment irrigation outflow according to the hydrographs of the inflows and outflows of the catchment. The multiple regression models took into consideration the drainage time of base flow, resulting in better estimation on an event and annual basis. Using the MR‐6d method, the estimated irrigation outflows amounted to 3700 mm, 2600 mm and 2760 mm during 2001, 2002 and 2003 respectively, which covered 70%, 60% and 64% respectively of the total catchment outflows in the corresponding years. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Recent climatic trends and linkages to river discharge in Central Vietnam   总被引：1，自引：0，他引：1       下载免费PDF全文

Maxime Souvignet  Patrick Laux  Jim Freer  Hannah Cloke  Dang Quang Thinh  Tran Thuc  Johannes Cullmann  Alexandra Nauditt  Wolfgang‐Albert Flügel  Harald Kunstmann  Lars Ribbe 《水文研究》2014,28(4):1587-1601

In this study, change in rainfall, temperature and river discharge are analysed over the last three decades in Central Vietnam. Trends and rainfall indices are evaluated using non‐parametric tests at different temporal levels. To overcome the sparse locally available network, the high resolution APHRODITE gridded dataset is used in addition to the existing rain gauges. Finally, existing linkages between discharge changes and trends in rainfall and temperature are explored. Results are indicative of an intensification of rainfall (+15%/decade), with more extreme and longer events. A significant increase in winter rainfall and a decrease in consecutive dry days provides strong evidence for a lengthening wet season in Central Vietnam. In addition, trends based on APHRODITE suggest a strong orographic signal in winter and annual trends. These results underline the local variability in the impacts of climatic change at the global scale. Consequently, it is important that change detection investigations are conducted at the local scale. A very weak signal is detected in the trend of minimum temperature (+0.2°C/decade). River discharge trends show an increase in mean discharge (31 to 35%/decade) over the last decades. Between 54 and 74% of this increase is explained by the increase in precipitation. The maximum discharge also responds significantly to precipitation changes leading to a lengthened wet season and an increase in extreme rainfall events. Such trends can be linked with a likely increase in floods in Central Vietnam, which is important for future adaptation planning and management and flood preparedness in the region. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Spatio‐temporal variability of water and energy fluxes – a case study for a mesoscale catchment in pre‐alpine environment          下载免费PDF全文

Luitpold Hingerl  Harald Kunstmann  Sven Wagner  Matthias Mauder  Jan Bliefernicht  Riccardo Rigon 《水文研究》2016,30(21):3804-3823

Water and energy fluxes at and between the land surface, the subsurface and the atmosphere are inextricably linked over all spatio‐temporal scales. Our research focuses on the joint analysis of both water and energy fluxes in a pre‐alpine catchment (55 km²) in southern Germany, which is part of the Terrestrial Environmental Observatories (TERENO). We use a novel three‐dimensional, physically based and distributed modelling approach to reproduce both observed streamflow as an integral measure for water fluxes and heat flux and soil temperature measurements at an observation location over a period of 2 years. While heat fluxes are often used for comparison of the simulations of one‐dimensional land surface models, they are rarely used for additional validation of physically based and distributed hydrological modelling approaches. The spatio‐temporal variability of the water and energy balance components and their partitioning for dominant land use types of the study region are investigated. The model shows good performance for simulating daily streamflow (Nash–Sutcliffe efficiency > 0.75). Albeit only streamflow measurements are used for calibration, the simulations of hourly heat fluxes and soil temperatures at the observation site also show a good performance, particularly during summer. A limitation of the model is the simulation of temperature‐driven heat fluxes during winter, when the soil is covered by snow. An analysis of the simulated spatial fields reveals heat flux patterns that reflect the distribution of the land use and soil types of the catchment. The water and energy partitioning is characterized by a strong seasonal cycle and shows clear differences between the selected land use types. Copyright © 2016 The Authors Hydrological Processes Published by John Wiley & Sons Ltd.  相似文献   

Simulation of moisture content in alpine rockwalls during freeze–thaw events          下载免费PDF全文

Matthias Rode  Harald Schnepfleitner  Oliver Sass 《地球表面变化过程与地形》2016,41(13):1937-1950

Rock moisture during freeze–thaw events is a key factor for frost weathering. Data on moisture levels of natural rockwalls are scarce and difficult to obtain. To close this gap, we can benefit from the extensive knowledge of moisture‐related phenomena in building materials, which is incorporated into simulation software, for example the WUFI® package of the Fraunhofer Institute of Building Physics. In this paper we applied and adapted this type of simulation to natural rockwalls to gain new insights on which moisture‐related weathering mechanisms may be important under which conditions. We collected the required input data on physical rock properties and local climate for two study areas in the eastern European Alps with different elevation [Sonnblick, 3106 m above sea level (a.s.l.) and Johnsbach, 700 m a.s.l.] and different lithologies (gneiss and dolomite, respectively). From this data, moisture profiles with depth and fluctuations in the course of a typical year were calculated. The results were cross‐checked with different thermal conditions for frost weathering reported in the literature (volumetric expansion and ice segregation theories). The analyses show that in both study areas the thresholds for frost cracking by volumetric expansion of ice (90% pore saturation, temperature < ?1 °C) are hardly ever reached (in one year only 0.07% of the time in Johnsbach and 0.4% at Sonnblick, mostly in north‐exposed walls). The preconditions for weathering by ice segregation (?3 to ?8 °C, > 60% saturation) prevail over much longer periods; the time spent within this ‘frost cracking window‘ is also higher for north‐facing sites. The influence of current climate warming will reduce effective frost events towards 2100; however the increase of liquid precipitation and rock moisture will promote weathering processes like ice segregation at least at the Sonnblick site. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

A method for the regional estimation of runoff separation parameters for hydrological modelling     

Harald Kling  Hans Peter Nachtnebel 《Journal of Hydrology》2009,364(1-2):163-174

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Banded structure of drifting macroalgae   总被引：3，自引：0，他引：3  

Fangli Qiao  Dejun Dai  John Simpson  Harald Svendsen 《Marine pollution bulletin》2009,58(12):1792-1795

A massive bloom of macroalgae occurred in the western Yellow Sea at the end of May, 2008, and lasted for nearly 2 months. The surface-drifting macroalgae was observed to accumulate in a pattern dominated by linear bands. The maximum length of individual algal bands exceeded 10 km and the distance between neighboring bands ranged from hundreds of meters to 6 km. Seven satellite images were analyzed to determine the distances between neighboring bands. Proportions of about 24%, 38%, and 22% are responsible for the separation distances smaller than 1 km, between 1 and 2 km, and between 2 and 3 km, respectively. The separation of about five percent of the bands exceeds 4 km. The probability distribution of the separation distance is quite close to log-normal which is that found in Langmuir circulation. However, the observed algal band separation greatly exceeds the distances between convergence lines reported in Langmuir circulation.  相似文献   

Flow banding in basaltic pillow lavas from the Early Archean Hooggenoeg Formation, Barberton Greenstone Belt, South Africa     

Brian Robins  Nils Rune Sandstå  Harald Furnes  Maarten de Wit 《Bulletin of Volcanology》2010,72(5):579-592

Well-preserved pillow lavas in the uppermost part of the Early Archean volcanic sequence of the Hooggenoeg Formation in the Barberton Greenstone Belt exhibit pronounced flow banding. The banding is defined by mm to several cm thick alternations of pale green and a dark green, conspicuously variolitic variety of aphyric metabasalt. Concentrations of relatively immobile TiO₂, Al₂O₃ and Cr in both varieties of lava are basaltic. Compositional differences between bands and variations in the lavas in general have been modified by alteration, but indicate mingling of two different basalts, one richer in TiO₂, Al₂O₃, MgO, FeO^t and probably Ni and Cr than the other, as the cause of the banding. The occurrence in certain pillows of blebs of dark metabasalt enclosed in pale green metabasalt, as well as cores of faintly banded or massive dark metabasalt, suggest that breakup into drops and slugs in the feeder channel to the lava flow initiated mingling. The inhomogeneous mixture was subsequently stretched and folded together during laminar shear flow through tubular pillows, while diffusion between bands led to partial homogenisation. The most common internal pattern defined by the flow banding in pillows is concentric. In some pillows the banding defines curious mushroom-like structures, commonly cored by dark, variolitic metabasalt, which we interpret as the result of secondary lateral flow due to counter-rotating, transverse (Dean) vortices induced by the axial flow of lava towards the flow front through bends, generally downward, in the tubular pillows. Other pillows exhibit weakly-banded or massive, dark, variolitic cores that are continuous with wedge-shaped apophyses and veins that intrude the flow banded carapace. These cores represent the flow of hotter and less viscous slugs of the dark lava type into cooled and stiffened pillows.  相似文献