Early Holocene history of the Baltic Sea, as reflected in coastal sediments in Blekinge, southeastern Sweden   总被引：4，自引：0，他引：4  

Bjrn E. Berglund  Per Sandgren  Lena Barnekow  Gina Hannon  Hui Jiang  Gran Skog  Shi-Yong Yu 《Quaternary International》2005,130(1):111

Integrated palaeoecological studies of two fiord sediment sequences in the province of Blekinge, SE Sweden, covering the time span 11,000–5000 cal BP, reveal the timing and the environment for the Ancylus Lake/Littorina Sea transition 9800–8500 cal BP. The first ingression of saline water into the Baltic Sea through the Danish Straits occurred earlier than formerly assumed. New evidence, particularly mineral magnetic and palaeobotanical analyses, demonstrate that on the general trend of the eustatically caused Littorina transgression several minor fluctuations of the water level can be identified between 8500 and 5000 cal years BP. A distinct regression phase around 8100 cal BP is correlated with the Greenland ice-core cold event dated to 8200 ice-core years BP. This is described as a regional climatic catastrophe for the Baltic Sea region. The coastal stratigraphy is compared with the offshore stratigraphy earlier studied. A tentative shore displacement curve for Early and Middle Holocene is presented.  相似文献   

The geology and Re–Os geochronology of the Palaeoproterozoic Vaikijaur Cu–Au–(Mo) porphyry-style deposit in the Jokkmokk granitoid, northern Sweden     

Christina Lundmark  Holly Stein  Pär Weihed 《Mineralium Deposita》2005,40(4):396-408

The Vaikijaur Cu–Au–(Mo) deposit is located in the ca. 1.88 Ga calc-alkaline Jokkmokk granitoid near the Archaean–Proterozoic palaeoboundary within the Fennoscandian shield of northern Sweden. The Skellefte VMS district lies immediately to the south and the northern Norrbotten Fe-oxide–Cu–Au deposits to the north. The Vaikijaur deposit occupies an area of 2×3 km within the Jokkmokk granitoid and includes stockwork quartz-sulphide veinlets and disseminated chalcopyrite, pyrite, gold, molybdenite, magnetite, and pyrrhotite. Porphyritic mafic dykes were emplaced along fractures in a ring dyke pattern. The Jokkmokk granitoid, dykes, and the mineralized area are foliated, indicating that mineralization predated the main regional deformation. The mineralized area is characterized by strong potassic alteration. Phyllic and propylitic alteration zones are also present. A pyrite-rich inner core is surrounded by a concentric zone with pyrite, chalcopyrite, and gold. Molybdenite is distributed irregularly throughout the chalcopyrite zone. Geophysical data indicate a strongly conductive central zone in the mineralized area bordered by conductive and high magnetic zones. Five high precision Re–Os age determinations for three molybdenite occurrences from outcrop and drill core samples constrain the age of porphyry-style Cu–Au–(Mo) mineralization to between 1889±10 and 1868±6 Ma. A younger molybdenite is associated with a much later metamorphic event at about 1750 Ma. These data suggest that primary porphyry-style mineralization was associated with calc-alkaline magmatism within the Archaean–Proterozoic boundary zone at ca. 1.89–1.87 Ga.  相似文献   

Quick clay—A case study of chemical perspective in Southwest Sweden     

Yvonne Andersson-Sköld  J. Kenneth Torrance  Karin Odén  Karin Rankka 《Engineering Geology》2005,82(2):107-118

Quick clay, a soil that changes from normal firm ground to a liquid mass when it is disturbed, has been involved in most of the large and serious clay slides in Sweden, Norway and Canada. The location, time of occurrence and size of quick clay slides are difficult to predict and large slides may cause great devastation. Some geochemical studies of Swedish quick clay were done in the 1960s and early 1970s, but no systematic studies of the interrelationships of pore water chemistry, mineralogy, geotechnical properties and other parameters on quick clays in Sweden have been published. Such studies are of national and general interest because of the many combinations of rock flour source areas and sedimentation conditions that occurred across central Sweden and into the Baltic Sea area during deglaciation. In this study, geotechnical properties related to the in situ chemistry at one quick clay site were extensively studied, and spot sampling was conducted at two other locations in Southwest Sweden. In this area the clay minerals mainly are non-expanding phyllosilicate minerals (illite) and primary minerals (quartz, feldspar), which is consistent with previous studies of quick clay mineralogy. Extensive leaching has occurred at all three locations. At the extensively studied site, Surte, the lowest salinity was found at the greatest depth, inferring that the leaching by fresh water was accomplished by water movement upward and laterally through the sediment from the underlying bedrock. This is consistent with the local setting where bedrock hills rise sharply to over 100 m above the marine sediment surface. An artesian pressure would also be anticipated at this location. There is a correlation (negative) between sensitivity and salinity but there is an indication that the maximum salinity or electrical conductivity consistent with the quick clay behaviour is higher than reported elsewhere. However, for high sensitivities the salinity is about the same as reported elsewhere. In the deepest part of the borehole, there is a higher content of Fe and Al in the pore water, indicating reduced state. Further work is needed to confirm the difference in salinity and to investigate the possible interplay of salinity and potential dispersing agents such as the role of anoxic conditions, in this region. Further work is especially needed in the locations where the sediment accumulation occurred under lower salinity conditions. At all three locations, high remoulded shear strength and low sensitivity have been seen near the surface together with a decrease in pore water cation concentrations.  相似文献   

Palaeomagnetism of 935 Ma mafic dykes in southern Sweden and implications for the Sveconorwegian Loop   总被引：1，自引：0，他引：1  

S. A. Pisarevsky  G. Bylund 《Geophysical Journal International》2006,166(3):1095-1104

New palaeomagnetic results for the 935 Ma Göteborg-Slussen mafic dykes in southern Sweden provide a well-dated high-quality palaeomagnetic pole for Early Neoproterozoic Baltica. New U-Pb geochronological data for several palaeomagnetically studied mafic intrusions yield three additional well-dated palaeopoles and one virtual geomagnetic pole. This set of dated poles suggests minimal drift of Baltica in moderate latitudes between ∼965 and 915 Ma. They also support the hypothesis of a post-900 Ma regional remagnetization event in SW Sweden and SW Norway. The positions of three distinct clusters of ∼1100 to 850 Ma palaeopoles suggest a clockwise time progression of the Baltica apparent polar wander path (the Sveconorwegian Loop) during this time interval. New well-dated palaeomagnetic poles for ∼970 to 900 Ma from Laurentia are required to verify the palaeogeographic reconstructions of Baltica and Laurentia.  相似文献   

A comparison of anthropogenic mercury pollution in Kastela Bay (Croatia) with pristine estuaries in Ore (Sweden) and Krka (Croatia)     

Kwokal Z  Francisković-Bilinski S  Bilinski H  Branica M 《Marine pollution bulletin》2002,44(10):1152-1157

Anthropogenic mercury pollution was studied in Kastela Bay (Croatia), 10 years after chloralkaline plant (PVC) stopped production. The concentration of total mercury determined in sediments which are composed mainly of calcite and quartz, are in the range 14,280-30,400 ng/g. The values are higher than reported in the literature for Elbe and Seine estuaries and also above 25,000 ng/g used for criterion in remediation project in Minamata Bay. The concentration of methylmercury 6.05-36.74 ng/g are typical for slightly to highly contaminated estuarine sediments. The low ratio of methylmercury to total mercury found in sediments of Kastela Bay is in the range 0.04-0.18%. It can be explained that in this region predominate conditions which do not promote in-situ methylation. Sediments were found to be highly anoxic. Concentrations of total mercury in unfiltered surface waters are in the range 69-145 ng/l and in unfiltered bottom waters in the range 230-1,418 ngl(-1). High concentrations found in bottom waters suggest that either resuspension or partial dissolution of sediments takes place. An experiment performed on filtered and unfiltered waters showed that about 85% of total mercury in surface water and almost 100% in bottom water was retained on 45 microm filters. To demonstrate contrasts, two pristine estuaries from norths and south Europe were studied. Silicious sediments of Ore estuary (Sweden) and calcareous sediments of Krka estuary (Croatia) have total mercury concentrations close to accepted background level. The ratio of methylmercury to total mercury is < or = 1% in all samples with one exception. The highest observed ratio (2.70%) was in the surface sediment from E2 station in Krka estuary measured in March 2000. This location is suitable for studying methylmercury formation in pristine environment.  相似文献   

Diatom-based water chemistry reconstructions from northern Sweden: a comparison of reconstruction techniques   总被引：6，自引：0，他引：6  

T. Korsman  H. J. B. Birks 《Journal of Paleolimnology》1996,15(1):65-77

The diatom composition in surface sediments from 119 northern Swedish lakes was studied to examine the relationship with lake-water pH, alkalinity, and colour. Diatom-based predictive models, using weighted-averaging (WA) regression and calibration, partial least squares (PLS) regression and calibration, and weighted-averaging partial least squares (WA-PLS) regression and calibration, were developed for inferences of water chemistry conditions. The non-linear response between the diatom assemblages and pH and alkalinity was best modelled by weighted-averaging methods. The lowest prediction error for pH was obtained using weighted averaging, with or without tolerance downweighting. For alkalinity there was still some information in the residual structure after extracting the first weighted-averaging component, which resulted in a slight improvement of predictions when using a two component WA-PLS model. The best colour predictions were obtained using a two component PLS model. Principal component analysis (PCA) of the prediction errors, with some characteristics of the training set included as passive variables, was performed to compare the results for the different alkalinity predictive models. The results indicate that calibration techniques utilizing more than one component (PLS and WA-PLS) can improve the predictions for lakes with diatom taxa that have broad tolerances. Furthermore, we show that WA-PLS performs best compared with the other techniques for those lakes that have a high relative abundance of the most dominant taxa and a corresponding low sample heterogeneity.  相似文献   

Estimating monthly surface winds for Scania, southern Sweden, using geostrophic wind (1899–1997)     

Marie Ekström 《Geografiska Annaler: Series A, Physical Geography》2002,84(2):113-126

Wind direction conditions during the 20th century in Scania, southern Sweden, are investigated using an estimated series of monthly wind vector components (east–west u component and north–south v component). The series is developed from a regression relationship between pairwise (1973 to 1997) monthly averages of 10–m surface wind from Scania and a monthly geostrophic wind, based on mean sea level (MSL) pressure data from the National Center of Atmospheric Research (NCAR). The wind conditions during the 20th century are dominated by winds from southwesterly and westerly directions, particularly during summer and autumn. From the 1980s onwards, increased frequencies of westerly winds are evident in spring and summer; however, similarly large frequencies of westerly winds are also found during the early part of the 20th century. Analysis of the estimated wind series indicates large variation in wind direction during the investigated time period, particularly during 1930 to 1960 when large increases of easterly winds are evident in spring. Increased frequencies of easterly winds were also found in other months during this period but not to the same extent as during the spring season. Thus, the presence of periods with quite different wind characteristics suggests that the overall atmospheric circulation has experienced some shifts in this region during the 20th century.  相似文献   

A HIGH-RESOLUTION, GRIDDED DATASET FOR MONTHLY TEMPERATURE NORMALS (1971-2000) IN SWEDEN     

DELIANG CHEN  LEBING GONG  CHONG-YU XU  SVEN HALLDIN 《Geografiska Annaler: Series A, Physical Geography》2007,89(4):249-261

A baseline climatology is required in evaluating climate variability and changes on regional and local scales. Gridded climate normals, i.e. averages over a 30‐year period, are of special interest since they can be readily used for validation of climate models. This study is aimed at creating an updated gridded dataset for Swedish monthly temperature normals over the period 1971–2000, based on standard 2‐m air temperature records at 510 stations in mainland Sweden. Spatial trends of the normal temperatures were modelled as functions of latitude, longitude and elevation by multiple linear regression. The study shows that the temperature normals are strongly correlated with latitude throughout the year and especially in cold months, while elevation was a more important factor in June and July. Longitude played a minor role and was only significant in April and May. Regression equations linking temperature to latitude, longitude and elevation were set up for each month. Monthly temperature normals were detrended by subtracting spatial trends given by the regressions. Ordinary kriging was then applied to both original data (simple method) and de‐trended data (composite method) to model the spatial variability and to perform spatial gridding. The multiple regressions showed that between 82% (summer) and 96% (winter) of the variance in monthly temperature normals could be explained by latitude and elevation. Unexplained variances, i.e. the residuals, were modelled with ordinary kriging with exponential semivariograms. The composite grid estimates were calculated by adding the multiple linear trends back to the interpolated residuals at each grid point. Kriged original temperature normals provided a performance benchmark. The cross–validation shows that the interpolation errors of the normals are significantly reduced if the composite method rather than the simple one was used. A gridded monthly dataset with 30‐arcsecond spacing was created using the established trends, the kriging model and a digital topographic dataset.  相似文献   

Emplacement and deformation of the ca. 1.45 Ga Karlshamn granitoid pluton,southeastern Sweden,during ENE-WSW Danopolonian shortening     

Audrius Čečys  Keith Benn 《International Journal of Earth Sciences》2007,96(3):397-414

Anisotropy of magnetic susceptibility and structural geology of the ca. 1.45 Ga Karlshamn pluton (southern Sweden) are used to study its emplacement and structural evolution. The Karlshamn pluton is one of the largest metaluminous A-type granitoid intrusions in southern Sweden. It is a multiphase body made up of two suites that differ in composition but which have similar crystallization ages. The magmatic foliation, ductile shear zones and granite–pegmatite filled fractures were mapped as well as the metamorphic foliation and extension lineation in the metamorphic host rocks. The anisotropy of magnetic susceptibility was used to map the magnetite petrofabric of the pluton, providing a larger data set for both the magmatic foliations and lineations, which could not be mapped in the field. The fabrics within the pluton are continuous with the metamorphic fabrics in the country rocks. Both the pluton and the country rock fabrics were folded during ENE–WSW compression, while the pluton was still a magma mush. The stress field orientation during cooling of the pluton is determined on the basis of magmatic, ductile and brittle structures in the Karlshamn pluton that formed successively as the pluton cooled. The compressional event is referred to as the Danopolonian orogeny and therefore the Karlshamn granitoids, and other plutons of similar composition and age in central and southern Sweden, on the Danish Island of Bornholm, and in Lithuania, may be considered as syntectonic intrusions and not as anorogenic, as was previously thought.  相似文献   

Development of a hydrogeological model description of intrusive rock at different investigation scales: an example from south-eastern Sweden     

Ingvar Rhén  Hans Thunehed  Carl-Axel Triumf  Sven Follin  Lee Hartley  Jan Hermansson  Carl-Henric Wahlgren 《Hydrogeology Journal》2007,15(1):47-69

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