3D coupled fluid and heat transport simulations of the Northeast German Basin and their sensitivity to the spatial discretization: different sensitivities for different mechanisms of heat transport     

Björn Onno Kaiser  Mauro Cacace  Magdalena Scheck-Wenderoth 《Environmental Earth Sciences》2013,70(8):3643-3659

Based on a numerical model of the Northeast German Basin (NEGB), we investigate the sensitivity of the calculated thermal field as resulting from heat conduction, forced and free convection in response to consecutive horizontal and vertical mesh refinements. Our results suggest that computational findings are more sensitive to consecutive horizontal mesh refinements than to changes in the vertical resolution. In addition, the degree of mesh sensitivity depends strongly on the type of the process being investigated, whether heat conduction, forced convection or free thermal convection represents the active heat driver. In this regard, heat conduction exhibits to be relative robust to imposed changes in the spatial discretization. A systematic mesh sensitivity is observed in areas where forced convection promotes an effective role in shorten the background conductive thermal field. In contrast, free thermal convection is to be regarded as the most sensitive heat transport process as demonstrated by non-systematic changes in the temperature field with respect to imposed changes in the model resolution.  相似文献   

Influence of fluid flow on the regional thermal field: results from 3D numerical modelling for the area of Brandenburg (North German Basin)   总被引：1，自引：1，他引：0  

Vera Noack  Magdalena Scheck-Wenderoth  Mauro Cacace  Michael Schneider 《Environmental Earth Sciences》2013,70(8):3523-3544

We analyse the effect of fluid flow on the recent thermal field for the Brandenburg region (North German Basin) which is strongly affected by salt structures. The basin fill is modified by a thick layer of mobilized salt (Zechstein, Upper Permian) that decouples the overburden from deeper parts of the lithosphere and is responsible for thermal anomalies since salt has a distinctly higher thermal conductivity than the surrounding sediments and is impermeable to fluid flow. Numerical simulations of coupled fluid flow and heat transfer are carried out to investigate the influence of fluid flow on the shallow temperature field above the Zechstein salt, based on the finite element method. A comparison of results from conductive and coupled modelling reveals that the temperature field down to the low-permeable Triassic Muschelkalk is influenced by fluids, where the shallow low-permeable Tertiary Rupelian-clay is absent. Overall cooling is induced by forced convective forces, the depth range of which is controlled by the communication pathways between the different aquifers. Moreover, buoyancy-induced effects are found in response to temperature-dependent differences in the fluid density where forced convective forces are weak. The range of influence is controlled by the thickness and the permeability of the permeable strata above the Triassic Muschelkalk. With increasing depth, thermal conduction mainly controls the short-wavelength pattern of the temperature distribution, whereas the long-wavelength pattern results from interaction between the highly conductive crust and low-conductive sediments. Our results provide generic implications for basins affected by salt tectonics.  相似文献   

Controls on the deep thermal field: implications from 3-D numerical simulations for the geothermal research site Groß Schönebeck   总被引：1，自引：1，他引：0  

Yvonne Cherubini  Mauro Cacace  Magdalena Scheck-Wenderoth  Inga Moeck  Björn Lewerenz 《Environmental Earth Sciences》2013,70(8):3619-3642

The deep thermal field in sedimentary basins can be affected by convection, conduction or both resulting from the structural inventory, physical properties of geological layers and physical processes taking place therein. For geothermal energy extraction, the controlling factors of the deep thermal field need to be understood to delineate favorable drill sites and exploitation compartments. We use geologically based 3-D finite element simulations to figure out the geologic controls on the thermal field of the geothermal research site Groß Schönebeck located in the E part of the North German Basin. Its target reservoir consists of Permian Rotliegend clastics that compose the lower part of a succession of Late Carboniferous to Cenozoic sediments, subdivided into several aquifers and aquicludes. The sedimentary succession includes a layer of mobilized Upper Permian Zechstein salt which plays a special role for the thermal field due to its high thermal conductivity. Furthermore, the salt is impermeable and due to its rheology decouples the fault systems in the suprasalt units from subsalt layers. Conductive and coupled fluid and heat transport simulations are carried out to assess the relative impact of different heat transfer mechanisms on the temperature distribution. The measured temperatures in 7 wells are used for model validation and show a better fit with models considering fluid and heat transport than with a purely conductive model. Our results suggest that advective and convective heat transport are important heat transfer processes in the suprasalt sediments. In contrast, thermal conduction mainly controls the subsalt layers. With a third simulation, we investigate the influence of a major permeable and of three impermeable faults dissecting the subsalt target reservoir and compare the results to the coupled model where no faults are integrated. The permeable fault may have a local, strong impact on the thermal, pressure and velocity fields whereas the impermeable faults only cause deviations of the pressure field.  相似文献   

The deep geothermal potential of the Berlin area     

Oliver Kastner  Judith Sippel  Magdalena Scheck-Wenderoth  Ernst Huenges 《Environmental Earth Sciences》2013,70(8):3567-3584

In this study, we model the geothermal potential of deep geological formations located in the Berlin region in Germany. Berlin is situated in a sedimentary geological setting (northeastern German basin), comprising low-enthalpic aquifers at horizons down to 4–5 km depth. In the Berlin region, the temperature increases almost linearly with depth by about 30 K per kilometer, thus allowing for direct heating from deep aquifer reservoirs in principle. Our model incorporates eight major sedimentary units (Jurassic, Keuper, Muschelkalk, Upper/Middle/Lower Buntsandstein, Zechstein Salt and Sedimentary Rotliegend). Owing to lack of available petro-physical rock data for the Berlin region, we have evaluated literature data for the larger northeastern German basin to develop a thermodynamic field model which regards depth-corrected equations of state within statistical intervals of confidence. Integration over the thicknesses of the respective structural units yields their “heat in place”—energy densities associated with the pore fluid and the rock matrix under local conditions in Joule per unit area at the surface. The model predicts that aquifers in the Middle Buntsandstein and in the Sedimentary Rotliegend may well exhibit energy densities about 10 GJ m^?2 for the pore fluids and 20 GJ m^?2 to 40 GJ m^?2 for the rock matrices on average. Referring these figures to the city area of Berlin (about 892 km²), a significant hydrothermal potential results, which however remained undeveloped until today for the reason of present development risks. The model accounts for these risks through statistical intervals of confidence which are in the order of ±60 to ±80 % of the trend figures. To minimize these uncertainties, scientific field explorations were required in order to assess the petro-physical aquifer properties locally.  相似文献   

Report on species of Gyrodactylus Nordmann, 1832, distribution in polar regions     

Magdalena Rokicka 《Polar Science》2009,3(3):203-206

The aim of this study was to compare the Gyrodactylus fauna in the Arctic and Antarctic regions. Fish were collected from waters surrounding the South Shetland Islands in the Antarctic and from the Revelva River and Hornsund Fjord in south Spitsbergen in the Arctic. Eighty-two individual fish representing seven species from three families (Channichthyidae, Harpagiferidae, and Nototheniidae) were found in Antarctica and 2 Gyrodactylus infections with altogether 95 specimens were reported. Two new species were identified: Gyrodactylus sp. 1 Rokicka et al., 2009, from the gills of the black rock cod, Notothenia coriiceps Richardson, 1844, and Gyrodactylus sp. 2 Rokicka et al., 2009, from the gills of the gaudy notothen, Lepidonotothen nudifrons Lönnberg, 1905. No Gyrodactylus were found in the 95 Arctic fish examined, which represented four species from four families (Salmonidae, Gadidae, Cottidae, and Liparidae).  相似文献   

Report on anisakid nematodes in polar regions – Preliminary results     

Joanna Dzido  Agnieszka Kijewska  Magdalena Rokicka  Agnieszka Świątalska-Koseda  Jerzy Rokicki 《Polar Science》2009,3(3):207-211

The aim of this study is to extend our knowledge of the distribution of anisakid nematode parasites in Arctic and Antarctic polar regions. We examined vertebrate (fish) taxa characteristic of the faunas in both polar regions for the presence of parasitic nematodes. The material was collected from Svalbard (Arctic) between July and August 2008 and from King George Island (South Shetland Islands, Antarctic Peninsula) between November 2007 and January 2008. In addition, faecal, bird, and invertebrate samples were collected and examined for the presence of anisakid nematodes or eggs. Anisakis simplex s.s. was found in the body cavity of Arctic cod, and Contracaecum sp. and Pseudoterranova sp. were found in Antarctic notothenioids. Eggs of Anisakis sp. and Contracaecum sp. were recovered from the faeces of Mirounga leonina. We present the first record of the occurrence of A. simplex C in the Antarctic fishes Notothenia coriiceps and Notothenia rossii.  相似文献   

On the use of loss‐on‐ignition techniques to quantify fluvial particulate organic carbon          下载免费PDF全文

Magdalena K. Grove  Gary S. Bilotta 《地球表面变化过程与地形》2014,39(9):1146-1152

The fluvial flux of carbon (C) from terrestrial to marine environments represents an important component of the global C‐cycle, which can transfer C from the atmosphere to sedimentary storage. Fluvial fluxes of C are also an essential resource for freshwater ecosystems, critical for habitat heterogeneity and function. As such it is crucial that we are able to quantify this flux accurately. However, at present there are a number of different techniques used to quantify concentrations of fluvial C, and these techniques vary in their accuracy. In this article, we compare particulate organic carbon (POC) measurements derived from two commonly‐used techniques; a simple combustion and loss‐on‐ignition (LOI) technique, and an oxidative–combustion and carbon dioxide (CO₂) detection technique. The techniques were applied to water samples collected from 10 contrasting reference‐condition, temperate river ecosystems. The POC measurements derived from the LOI technique were up to 16 times higher (average four times higher), than those derived from the oxidative–combustion and CO₂ detection technique. This difference was highly variable both across the different river ecosystems and within each river ecosystem over time, suggesting that there is no simple way of converting the mass measured by LOI to estimates of fluvial POC. It is suggested that the difference in POC measured by these two techniques is a consequence of: (1) the loss of inorganic carbon at LOI combustion temperatures of > 425 °C, (2) the potential during the LOI combustion stage to lose hygroscopic and intercrystalline water, not completely driven off by the drying stage at temperatures of < 150 °C, and (3) the variable C content of fluvial organic matter, meaning that the simple application of a fixed correction factor to values obtained from the LOI technique may not be appropriate. These findings suggest that oxidative–combustion and CO₂ detection techniques are preferential for quantifying fluvial POC. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Magnetic mineralogy and paleomagnetism of serpentinized ultramafic rocks from the Braszowice-Brzeźnica fragment of sudetic paleozoic ophiolite     

Magdalena Kądziałko-Hofmokl  Maria Jeleńska  Katarzyna Delura  Paweł Bylina 《Acta Geophysica》2010,58(2):269-299

Complex paleomagnetic, rock-magnetic and mineralogical studies were performed on serpentinized utramafic rocks from Braszowice-Brze?nica massif (BB) situated at the southern extremity of the Niemcza Shear Zone, close to the Sudetic Marginal Fault. Studies of magnetic minerals revealed presence of several varieties of magnetite grains, and partly altered Cr-spinels. Paleomagnetic studies revealed stable component HS of natural remanence carried by magnetite formed probably during the initial serpentinization. The directions of HS have good grouping within each locality, but differ between localities. Studies of anisotropy of magnetic susceptibility (AMS) have shown that directions of anisotropy axes are steep instead of horizontal as is common within the Niemcza Shear Zone. Taking advantage of the directions of AMS we rotated the directions of HS and brought them to the reference direction for the Sudetes for 372 Ma. We suggest that after acquiring AMS and HS during the Upper Devonian, the BB became divided into multiple units due to tectonic activity in the region.  相似文献   

Early angiosperm diversification: evidence from southern South America     

Sergio Archangelsky  Viviana Barreda  Mauro G. Passalia  Maria Gandolfo  Mercedes Prámparo  Edgardo Romero  Rubén Cúneo  Alba Zamuner  Ari Iglesias  Magdalena Llorens  Gabriela G. Puebla  Mirta Quattrocchio  Wolfgang Volkheimer 《Cretaceous Research》2009,30(5):1073-1082

In this report, we analyze the angiosperm fossil record (micro- and megafossil) from the central and southern basins of Argentina, southern South America, deposited between the late Barremian (128.3 Ma) to the end of the Coniacian (85.8 Ma). Based on this analysis, three major stages in the evolution of the angiosperms in the southernmost region of South America are established as follows: the late Barremian–Aptian, the latest Aptian-earliest Albian, and the middle Albian- Coniacian. The comparison between our fossil data set and those from Australia, North America, Asia and Europe suggest that the evolution and diversification of the angiosperms at mid and high latitudes in both hemispheres occurred roughly synchronously.  相似文献   

Seabed characterization through a range of high-resolution acoustic systems – a case study offshore Oman     

Magdalena Szuman  Christian Berndt  Colin Jacobs  Angus Best 《Marine Geophysical Researches》2006,27(3):167-180

This study uses three acoustic instruments (different in their operating frequencies, 13, 3.5, and 6–10 kHz, and deployment type, hull-mounted, surface-towed and deep-towed) to investigate and characterize the acoustic response of seafloor NE of Oman in a frequency-independent manner. High-resolution control was achieved by having selected areas of our acoustic transects ground-truthed by sampling and/or sea-floor photography. On the regional scale, the greatest degree of change in backscatter amplitude was correlated with major changes of seabed morphology and lithology. However, small-scale roughness had the biggest effect on amplitude on the local scale, i.e. within each area of specific seafloor type. The study also shows that seafloor reflection amplitude changes are far more easily detected by deep-towed instrument than by surface-towed or hull-mounted systems. Whilst there are significant changes in bioturbation types and density along the transects, the suite of instruments deployed was not able to pick up the effect of the bioturbation on acoustic signals.  相似文献