The Lyngen Gabbro: the lower crust of an Ordovician Incipient Arc     

Astri?J.?S.?KvassnesEmail author  Anita?Hetland?Strand  Heidi?Moen-Eikeland  Rolf?Birger?Pedersen 《Contributions to Mineralogy and Petrology》2004,148(3):358-379

We present evidence for the origin of the Lyngen Gabbro of the Ordovician Lyngen Magmatic Complex in Troms, Northern Norway. The two magmatic suites of the Lyngen Gabbro strike parallel NNE-SSW, and have distinct magmatic signatures. We define these signatures by using major and trace-element analyses together with selected major- and trace-element mineral analyses and ¹⁴³Nd/¹⁴⁴Nd-isotope whole-rock analyses of gabbroic to tonalitic plutonic rocks from seven detailed cross-sections from this large gabbro-complex. The Western suite of the Lyngen Gabbro precipitated from magma that may have been derived from the same system as the associated volcanic rocks. The gabbros have high An-content (An_>90) of their plagioclases relative to co-existing mafic minerals. Together with somewhat high _Nd(t) values (+6), this implies that the parental magmas were hydrous tholeiites similar to those found in back arc basins today. The Eastern suite, on the other hand, consist of cumulates that were precipitated from melts resembling those of ultra-depleted high-Ca boninitic magmas found in fore-arcs. Extremely high-An plagioclases (An_>95) co-exist with evolved mafic minerals and oxides, and the _Nd(t) values are lower (+4) than in the Western suite. The Eastern suite has no volcanic counterpart, but dikes intersecting the suites have compositions that possibly represent its parental magma. The oceanic Rypdalen Shear Zone generally separates the two suites in the north, but several non-tectonic transitions from boninitic to tholeiitic signatures southwards advocate that the magmatism happened concurrently. The magmatic proximity between the suites, the hydrous magmatism and the absence of a silicic or calc-alkaline mature arc section, suggests that the Lyngen Gabbro formed in the Iapetus Ocean under conditions presently found in incipient arcs later emplaced as outer arc highs.  相似文献   

The use of bisnorhopane as a stratigraphic marker in the Oseberg Back Basin, North Viking Graben, Norwegian North Sea     

Birger Dahl 《Organic Geochemistry》2004,35(11-12):1551

This paper discusses the occurrence of 28,30-dinor-17α,18α,21β-hopane (bisnorhopane) in stratigraphically, fairly well preserved Viking Group sections from wells in local depressions in the North Viking Graben Area. The results show the presence of high relative amounts of bisnorhopane in the “Syn-rift sections”, whilst the “Post-rift sections” contain little or no bisnorhopane. Since most exploration wells are drilled on structural highs, primarily penetrating the “Post-rift Draupne”, this may explain why many analyzed source rock sections in this area contain little bisnorhopane.As a correlation of Draupne sections using the vertical, relative bisnorhopane distributions, it is suggested to be a potential stratigraphic marker for the area, indicating the presence of “Syn-rift Draupne” sediments.The relative bisnorhopane amounts follow a logarithmic reduction with depth and thermal maturity. The bisnorhopane signal is nearly extinguished at 3700 m depth at a maturity of R_o = 0.9–1.0%.  相似文献   

Gaseous and Particulate Oxidized and Reduced Nitrogen Species in the Atmospheric Boundary Layer in Scandinavia in Spring     

Asgeir Sorteberg  Øystein Hov  Sverre Solberg  Kjetil Tørseth  Hans Areskoug  Martin Ferm  Kit Granby  Heikki Lättilä  Karin Persson  David Simpson 《Journal of Atmospheric Chemistry》1998,30(2):241-271

Observations of the concentration of several nitrogen containing compounds at five rural Scandinavian sites during March–June 1993 are reported. Total nitrate (NO ₃ ^- + HNO₃) and total ammonium (NH ₄ ⁺ + NH₃) were measured by denuder and filter pack. In general the methods agree well. At all sites the particulate fraction dominated, with the largest fraction of NO ₃ ^- and the lowest of NH ₄ ⁺ at the sites which were closest to the emission sources. The fraction of NO ₃ ^- of total nitrate increased with increasing NO₂ concentrations, indicating that the nighttime conversion of NO₂ to NO ₃ ^- is an important route of formation for NO ₃ ^- . A positive correlation was found between HNO₃ and O₃ in June at all sites, while no correlation was found early in the spring. Model calculations were made with a lagrangian boundary layer photooxidant model for the whole period, and compared to the measured concentrations. The calculated ratio between mean observed and modelled daily maximum concentrations of ozone over the measurement period were within +/–10% at all sites. The models ability to describe the daily ozone maximum concentration was satisfactory with an average deviation of 19–22% from the observed concentrations. HNO₃ was underestimated by over 50% at all sites except the one closest to the emission sources. The correlation between modelled and observed concentrations was generally best for the sites with shortest transport distance from the sources of emission.  相似文献   

Carbonyls and nonmethane hydrocarbons at rural European sites from the mediterranean to the arctic     

Sverre Solberg  Christian Dye  Norbert Schmidbauer  Alex Herzog  Robert Gehrig 《Journal of Atmospheric Chemistry》1996,25(1):33-66

Results of regular measurements during 1992–1995 of hydrocarbons and carbonyl compounds for a number of rural European monitoring sites are presented. The measurements are part of the EMEP programme for VOC measurements in Europe. In addition, several years of regular measurements are included from the Norwegian stations Birkenes at the south coast, and Zeppelin Mountain on Spitsbergen in the Arctic. The sampling frequency has been about twice per week throughout the years, implying that a substantial amount of measurement data are available. Almost all the chemical analyses have been performed by one laboratory, the EMEP Chemical Co-ordinating Centre located at NILU, which avoids problems of intercomparison and intercalibration among different laboratories. For the measured concentrations both seasonal and geographical variations are shown and discussed. The diurnal cycles of the hydrocarbon concentrations were studied in detail at one site, where the grab samples by EMEP where compared with a parallel continuous sampler, operated by EMPA, Switzerland. Hydrocarbons linked to natural gas and fuel evaporation become well mixed into the Arctic in the winter, whereas combustion products show a latitudinal gradient. The sum of oxygenated species constitutes about 5–15% of the sum of C₂–C₅ hydrocarbons in winter. In summer they are almost equal in magnitude, consistent with an increasing oxidation of hydrocarbons.  相似文献   

Stress-induced variations of remanent magnetism in Late Quaternary varved clay     

Birger Schmitz 《Earth and Planetary Science Letters》1984,69(2):422-426

A study of the remanent magnetism in Swedish varved clay shows that, even in varves that macroscopically appear to be undeformed, the paleomagnetic record may be seriously altered due to stress-induced deformation of the micro-fabric in the sediment.In the studied area disturbed clays were rather the rule than the exception, but undisturbed sediments were found at two sites, Järna II and III. This clay formed 10,200 years B.P. and shows a declination of about 30° east, a value that could be obtained thanks to excellent lateral control of the magnetism.  相似文献   

The Characterization of a Former World War I Battlefield by Integrating Multiple Signals from a Multireceiver EMI Soil Sensor     

Timothy Saey  Wouter Gheyle  Birger Stichelbaut  Jean Bourgeois  Stephanie Verplaetse  Veerle Van Eetvelde  Nicolas Note  Marc Van Meirvenne 《Geoarchaeology》2016,31(4):267-281

World War I (WWI) battlefields contain a large diversity of buried features that are situated just below the plough layer. A noninvasive interdisciplinary approach is preferred to characterize the buried heritage embedded within its soil landscape. In this study, the potential of integrating both electrical conductivity and magnetic susceptibility measurements from a multireceiver electromagnetic induction (EMI) instrument at a heavily shelled WWI battlefield was evaluated. Primarily, both measurements allowed the attribution of approximate depth interval to the buried trench remains. These remains proved dominantly present within the 0.4–0.8 m depth interval. Subsequently, both apparent electrical conductivity and magnetic susceptibility measurements were separately integrated to improve the contrast between buried features and their surrounding background. Trenches that were ditches filled with topsoil material could be distinguished from trenches that were continuously or partially filled with metal reinforcements or debris. To conclude, integrating multiple signals from a multireceiver EMI system allowed for a more straightforward discrimination of the buried WWI relicts.  相似文献   

Potential impact of albedo incorporation in boreal forest sector climate change policy effectiveness     

Hanne K. Sjølie  Greg S. Latta  Birger Solberg 《Climate Policy》2013,13(6):665-679

Forests have an important role to play in climate change mitigation through carbon sequestration and wood supply. However, the lower albedo of mature forests compared to bare land implies that focusing only on GHG accounting may lead to biased estimates of forestry's total climatic impacts. An economic model with a high degree of detail of the Norwegian forestry and forest industries is used to simulate GHG fluxes and albedo impacts for the next decades. Albedo is incorporated in a carbon tax/subsidy scheme in the Norwegian forest sector using a partial, spatial equilibrium model. While a price of EU€100/tCO₂e that targets GHG fluxes only results in reduced harvests, the same price including albedo leads to harvest levels that are five times higher in the first five years, with 39% of the national productive forest land base being cleared. The results suggest that policies that only consider GHG fluxes and ignore changes in albedo will not lead to an optimal use of the forest sector for climate change mitigation.

Policy relevance

Bare land reflects a larger share of incoming solar energy than dense forest and thus has higher albedo. Earlier research has suggested that changes in albedo caused by management of boreal forest may be as important as carbon fluxes for the forest's overall global warming impacts. The presented analysis is the first attempt to link albedo to national-scale forest climate policies. A policy with subsidies to forest owners that generate carbon sequestration and taxes levied on carbon emissions leads to a reduced forest harvest. However, including albedo in the policy alongside carbon fluxes yields very different results, causing initial harvest levels to increase substantially. The inclusion of albedo impacts will make harvests more beneficial for climate change mitigation as compared to a carbon-only policy. Hence, it is likely that carbon policies that ignore albedo will not lead to optimal forest management for climate change mitigation.  相似文献   

Satellite Monitoring of the Biomass Production in Southern Greenland     

Birger Ulf Hansen M.Sc. 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):94-99

Birger Ulf Hansen: Satellite Monitoring of the Biomass Production in Southern Greenland. Geografisk Tidsskrift 88:94–99. Copenhagen, 1988.

Based on satellite data from Southern Greenland the application of Normalized Difference Vegetation Index (NDVI) for monitoring biomass production has been evaluated. Field measurements of spectral reflectance data are quantitatively correlated with clipped samples of total above-ground biomass production. The relation between NDVI measured on the ground and biomass production is discussed. The seasonal and geographical variation in NDVI is correlated with the climate and water balance. The potential production is estimated as the product of mean NDVI and the length of the growing season. The results suggest that operational satellite monitoring of NDVI provides valuable assistance in agricultural management and forward planning of the potential breeding capacity in an arctic/subarctic environment.  相似文献   

Meteorological Observations in 2000 at the Arctic Station,Qeqertarsuaq (69°15'N), Central West Greenland     

Niels Nielsen  Ole Humlum  Birger Ulf Hansen 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):155-158

An automatic meteorological station has been operating at the Arctic Station (69°15'N, 53°31'W) in West Greenland since 1990. This paper summarizes meteorological parameters during 2000 including snow and sea ice cover, ground temperatures and active layer development, and presents comments on the local permafrost thickness.  相似文献   

Meteorological Observations in 1995 at the Arctic Station,Qeqertarsuaq (Godhavn), Central West Greenland/Concentrational Agriculture: Types,Functions, and Derivation/Den Danske Nationalkomité for Geografi     

Ole Humlum  Niels Nielsen  Morten Rasch  Birger Ulf Hansen  Sofus Christiansen 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):119-129

In October 1990 an automatic meteorological station was established at the Arctic Station (69°15'N, 53°31'W), Qeqertarsuaq (Godhavn), Central West Greenland, The station register parameters each 20 min, and the parameters have been described in an earlier paper in this journal by Nielsen et al. (1995). The present paper summarises main points of the climate during 1995.

Concentrational agriculture, defined as types of agriculture based on local concentration of plant nutrients, encompasses two main types: shifting cultivation and infield-outfield systems. They may ecologically be characterised by their mode of concentration: either by a vertical or a horisontal transfer (‘pumping’) of nutrients, respectively. The use of the general term ‘concentrational agriculture’ for the two forms is advocated by demonstrating that functional substitution of one by the other is possible, and by showing that the one type theoretically can be derived from the other. Historically, infield-outfield systems are supposed to be developed from some form of shifting cultivation.

Kort beretning om virksomheden i 1995

Justering af medlemskredsen. I forbindelse med valg af repræsentanter fandt en justering af repræsentationsområder sled (Århus Universilet har ikke længere fagområdet ‘kulturgeografi’). Videnskabernes Selskab har i samme forbindelse bifaldet, at fire observatører, repræsenterende undervisningstrinene i geografi deltager i møderne.  相似文献