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  • 1551.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geochemistry of the Fellingsbro type granites, Sweden1987In: Proterozoic geochemistry: abstracts, Lund June 3-6 1987, IGCP , 1987, p. 67-68Conference paper (Other academic)
  • 1552.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geological setting, tectonic control and REE geochemistry of Proterozoic Mo and W occurrences in northern Sweden1987In: Vol. 17, no 4, p. 643-Article in journal (Other academic)
  • 1553.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geological setting, tectonic control and REE geochemistry of Proterozoic W occurrences in northern Sweden1987In: Vol. 17, no 4, p. 643-Article in journal (Other academic)
  • 1554.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lantanoidmönstret i några Mo-och W-förekomster i norra Sverige1986In: Abstracts: 17e Nordiska geologmötet, Helsingfors universitet, 12-15.5. 1986, 1986, p. 286-Conference paper (Other academic)
  • 1555.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Proterozoic molybdenite mineralization in northern Sweden1983Doctoral thesis, comprehensive summary (Other academic)
  • 1556.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Proterozoic molybdenite occurrences in northern Sweden: derived from acid volcanics or granites?1984In: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 106, no 1, p. 67-72Article in journal (Refereed)
    Abstract [en]

    Proterozoic molybdenite occurrences in Sweden are spatially associated with acid volcanics. To test if mineralization is caused by remobilization of molybdenum in such rocks, fifty samples from northern Sweden have been analysed for major elements and 15 trace elements. Volcanics from the mineralized Rappen district and Vidsel area, situated on the Proterozoic continental domain north of the Skellefte district, have lower Mo-contents than the calc-alkaline submarine Skellefte volcanics. It is therefore concluded that acid volcanics are not the source for molybdenum mineralization. The association between molybdenite occurrences and acid volcanics in northern Sweden is tectonic, suggesting that the late orogenic development of the Rappen district and the Vidsel area, characterized by block movements and development of rift systems, is favourable for generation and emplacement of the granites responsible for molybdenite mineralization

  • 1557.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Results from the flooded Stekenjokk tailings2001In: 8th Annual British Columbia Ministry of Energy and Mines - MEND, Metal Leaching and Acid Rock Drainage Workshop: Proceedings, D.3, 2001Conference paper (Other academic)
  • 1558.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tectonic control and genesis of Proterozoic molybdenite occurrences in northern Sweden1986In: Vol. 6, no 3, p. 557-Article in journal (Other academic)
  • 1559.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Perez, Nathalie
    Project: Using MicroBes for the Regulation of heavy metaL mobiLity at ecosystem and landscape scAle: an integrative approach for soil remediation by geobiological processes2012Other (Other (popular science, discussion, etc.))
  • 1560.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Axelsson, M.D.
    Luleå tekniska universitet.
    Muller, B.
    Institute of Geotechnical Engineering, Swiss Federal Institute of Technology, Zürich.
    Analyses of trace elements on quartz surfaces in sulfidic mine tailings from Kristineberg (Sweden) a few years after remediation2003In: Environmental Geology, ISSN 0943-0105, E-ISSN 1432-0495, Vol. 45, no 1, p. 98-105Article in journal (Refereed)
    Abstract [en]

    Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been applied to determine the elemental composition of the surface layer, as well as of the first interior layer, of quartz grains from the mine tailings from Kristineberg (northern Sweden) in order to determine concentration gradients between these two layers. The quartz grains were collected from the oxidized and unoxidized zones within the tailings. The aim of this study is to assess the role of quartz surfaces as sites for the attenuation of solutes from the mine-tailings porewater. Concentrations of Cu, Ag, Sb, Pb and Bi are highest near the surface of each grain and decrease towards the interior. The surface concentration of Cu, Zn and Pb is more pronounced within the unoxidized than within the oxidized zone of the tailings. Cu exhibits a distinct concentration peak at the surface of the quartz grains below the pre-remediation oxidation front. For Zn and Ce the trend of high surface concentration is less pronounced than for Cu or Pb. Silver, Bi and As are preferably adsorbed within the uppermost layers of the oxidized zone where the pH is as high as 6.2. The conversion of intensity signals of the elements to concentration values in ppm was done by using external standards (NIST silicate glass).

  • 1561.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Billström, Kjell
    On the origin of the Yxsjöberg Cu-W skarn deposit, central Sweden: evidence from geochemical studies of the skarn and adjacent granitoids1989In: Abstracts / Symposium Precambrian granitoids - petrogenesis, geochemistry and metallogeny: August 14-17, 1989, University of Helsinki, Helsinki, Finland / [ed] Ilmari Haapala; Yrjö Kähkönen, Geological Survey of Finland , 1989, p. 97-Conference paper (Other academic)
  • 1562.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Billström, Kjell
    Regional implications of U-Pb zircon dating of two proterozoic granites associated with molybdenite mineralized aplites in northern Sweden1989In: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 111, no 3, p. 229-238Article in journal (Refereed)
    Abstract [en]

    To contribute to the understanding of the timing of the molybdenite mineralizing events in the Proterozoic of Sweden, two granites associated with molybdenite enriched aplites at Allebuoda and Kåtaberget in northern Sweden have been dated by the U-Pb zircon method. The result is 1892+-62 Ma for the Kåtaberget granite, and 1767+-9 Ma for the Allebuoda granite. As the granitoids in the Svecofennian region generally fall into two major age groups, 1890-1860 Ma and 1800-1770 Ma respectively, this suggests that the Kåtaberget granite belongs to the older group and the Allebuoda granite to the younger group. Sulphur isotopic analyses suggest a larger admixture of sediments in the source material of the Allebuoda granite and aplite than in corresponding rocks at Kåtaberget. The results of this and previous studies suggest that the major Mo- and W-occurrences in the Precambrian of Sweden are associated with granites belonging to the 1800-1770 Ma group.

  • 1563.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Billström, Kjell
    Laboratoriet för Isotopgeologi, Naturhistoriska Riksmuseet, Stockholm.
    Hålenius, Elke
    Sveriges Geologiska AB, Luleå.
    Behaviour of rare-earth elements in highly evolved granitic systems: evidence from Proterozoic molybdenite mineralized aplites and associated granites in northern Sweden1989In: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 23, no 4, p. 267-280Article in journal (Refereed)
    Abstract [en]

    Field relations, mineralogy, major- and trace-element contents (including REE analyses of whole-rock samples and minerals) of three Proterozoic granites and their associated molybdenite mineralized aplites have been studied at Allebuoda, Munka and Kåtaberget in northern Sweden. The granites crystallized from melts that were not saturated with water. The mineralized potassic aplites formed by quenching of residual melts caused by sudden pressure drop...

  • 1564.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Billström, Kjell
    Laboratoriet för Isotopgeologi, Naturhistoriska Riksmuseet, Stockholm.
    Hålenius, Elke
    Sveriges Geologiska AB, Luleå.
    Geochemistry of the Proterozoic wolframite-bearing greisen veins and the associated granite at Rostberget, northern Sweden1989In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 78, no 2, p. 135-150Article in journal (Refereed)
    Abstract [en]

    At Rostberget in northern Sweden, a swarm of thin, undeformed wolframite-bearing greisen veins occurs within the 1.78-Ga-old Joran granite intrusion. This is a microcline-rich porphyritic granite probably generated with sediments as important source materials. When the Joran granite crystallized, an aqueous fluid, rich in volatiles and W, was active in the central and apical parts of the intrusion. This fluid escaped through fractures caused by tectonic rupturing, the immediate surroundings of the fractures became altered, and the greisen veins were formed. The contents of SiO2, Na2O, Sr, V, Zr and LREE decreased during this greisenization, while the contents of Fe2O3, MnO, MgO, CaO, H2O, W, Sn, Mo, Cu, Rb, Sc, Pb, Be, Nb, HREE and probably Ag increased. K2O, TiO2, P2O5, Ba, Zn and Y were not immobile, but no consistent trends of gain or loss were found. Neutralization of the acid vapour by alteration reactions was probably important for controlling the precipitation of wolframite. Accessory minerals contain most of the REE in all sample types. The gain of HREE during the greisenization was caused mainly by deposition of fluorite (and xenotime), and the loss of LREE was the result of dissolution of monazite (and allanite). No change in Eu content was observed. The enrichment of HREE and the presence of fluorite and minor topaz, indicate alteration from a F-rich fluid, but do not necessarily imply that W was transported as F− complexes.

  • 1565.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Carlsson, Erik
    Luleå tekniska universitet.
    Holmström, Henning
    Envipro Miljöteknik AB, Linköping.
    Elander, Pär
    Envipro Miljöteknik AB, Linköping.
    MiMi - Characterization of the tailings and the till cover in impoundments 1 and 1B, Kristineberg mine, northern Sweden2001Report (Other academic)
  • 1566.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Chatwin, Terrence
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Management of sulfide-bearing waste: a challenge for the mining industry2012In: Minerals, ISSN 2075-163X, E-ISSN 2075-163X, Vol. 2, no 1, p. 1-10Article in journal (Refereed)
    Abstract [en]

    Oxidation of iron sulfides in waste rock dumps and tailings deposits may result in formation of acid rock drainage (ARD), which often is a challenging problem at mine sites. Therefore, integrating an ARD management plan into the actual mine operations in the early phases of exploration, continuing through the mine life until final closure might be successful and decrease the environmental impact. A thorough characterization of ore and waste should be performed at an early stage. A detailed knowledge of mineralogical composition, chemical composition and physical properties such as grain size, porosity and hydraulic conductivity of the different waste types is necessary for reliable predictions of ARD formation and efficiency of mitigation measures. Different approaches to prevent and mitigate ARD are discussed. Another key element of successfully planning to prevent ARD and to close a mining operation sustainably is to engage the mine stakeholders (regulators, community and government leaders, non-governmental organization (NGOs) and lenders) in helping develop and implement the ARD management plan.

  • 1567.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Correge, O.
    Luleå University of Technology.
    Evolution of the groundwater geochemistry in sulphide-rich mine tailings remediated by applying soil cover, Kristineberg, northern Sweden2002In: Vol. 66, no 15, Suppl. 1, p. 569-569Article in journal (Refereed)
  • 1568.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Drugge, L.
    Widerlund, Anders
    Ingri, Johan
    Changed transport of weathering products after river regulation: the Lule River, northern Sweden2004In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 68, no 11, p. 31-Article in journal (Other academic)
  • 1569.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Forsberg, Jerry
    Österlund, Helene
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ecke, Frauke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Fractionation of trace metals in a contaminated freshwater stream using membrane filtration, ultrafiltration, DGT and transplanted aquatic moss2012In: Geochemistry: Exploration, Environment, Analysis, ISSN 1467-7873, E-ISSN 2041-4943, Vol. 12, no 4, p. 303-312Article in journal (Refereed)
    Abstract [en]

    Four metal speciation and fractionation techniques – DGT (diffusive gradients in thin films), 1-kDa ultrafiltration, 0.22-µm membrane filtration and aquatic moss – were simultaneously applied to a small, contaminated freshwater stream in northern Sweden to investigate differences and similarities between the methods regarding trace metal speciation and their dependence on geochemical water properties. The investigated metals comprise Al, Cd, Co, Cu, Fe, Mn, Ni, and Zn. The normal DGT devices with Chelex cation exchanger were used. Shoots from the aquatic moss Fontinalis antipyretica L ex Hedw. were collected in a non-polluted brook and transplanted to the sampling site for exposure. It was evident that 0.22-µm membrane filtration, 1-kDa ultrafiltration and DGT generally measured different metal fractions where

  • 1570.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Forsberg, Jerry
    Österlund, Helene
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ecke, Frauke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Alakangas, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Speciation of trace metals in a contaminated stream at the Laver mine by using membrane filtration, ultrafiltration, DGT and transplanted aquatic moss2011Conference paper (Refereed)
  • 1571.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Frietsch, Rudyard
    Luleå tekniska universitet.
    New ore types in northern Fennoscandia: introduction and summary1991In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 113, no 1, p. 39-40Article in journal (Other academic)
    Abstract [en]

    Summarizes proceedings of meeting arranged by Geological Society of Sweden (Geologiska Föreningen) and Department of Economic Geology at Lulea University of Technology (Tekniska Högskolan i Lulea) in Lulea, 26-27 September 1989. Followed (p. 40-72) by twenty brief papers presented at meeting, with several previously unpublished maps of ore deposits

  • 1572.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Frietsch, RudyardLuleå tekniska universitet.
    New ore types in northern Fennoscandia: September 26-28, 1989, Luleå University of Technology, Luleå, Sweden1989Collection (editor) (Other academic)
  • 1573.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Hamilton, P. Joseph
    Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow.
    Fallick, Anthony F.
    Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow.
    Wilson, Michael R.
    Sveriges Geologiska AB, Luleå.
    Crustal reactivation in northern Sweden: the Vettasjärvi granite1987In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 35, no C, p. 277-293Article in journal (Refereed)
    Abstract [en]

    The 1.8 Ga old Vettasjärvi granite belongs to a widespread granite type in northern Sweden and northern Finland. It is a leucocratic, generally massive, pink granite covering a large area but possesses a small vertical extent. Foliated varieties occur and gneissic ghost structures are common. Gradual transitions from biotite-rich gneiss to granite have also been observed. Mineralogy and major and trace element geochemistry demonstrate the minimum-melt character of the Vettasjärvi granite. The low contents of elements such as Nb, Y, Sn and F indicate that it is also undifferentiated. Initial εNd values between −6.2 and −8.2 suggest that the Vettasjärvi granite was generated by crustal anatexis with a major Archaean component as source material. REE contents support this conclusion. Molar proportion ratios Al2O3/Na2O+K2O+CaO lower than 1.1, combined with δ18O values between 8 and 5 suggest that little or no pelitic sedimentary material was involved in the genesis. The Vettasjärvi granite is not a single intrusion, but more likely a zone of remobilisation where granite was generated and gently and irregularly emplaced.

  • 1574.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Holmström, Henning
    Geochemistry of the tailings - pond water interface in the flooded tailings pond at Stekenjokk, northern Sweden2000In: Vol. 5, no 2, p. 753-Article in journal (Other academic)
  • 1575.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Holmström, Henning
    Luleå tekniska universitet.
    Carlsson, Erik
    The geochemical dynamics of a pyrrhotite concentrate deposit, remediated by applying a till cover1999In: Vol. 4, no 1, p. 512-Article in journal (Other academic)
  • 1576.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Land, Magnus
    Andersson, P.S.
    Schönberg, H.
    Fractionation of Sm-Nd isotopes during weathering of till1998In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 62A, p. 1104-1105Article in journal (Other academic)
  • 1577.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Ponter, C.
    Geochemistry of till weathering in the Kalix river watershed, northern Sweden1990In: Chemical Weathering under Field Conditions: reports from a Nordic seminar, 27-28 September 1990, Wik, Uppsala / [ed] Kaj Rosen, Sveriges Lantbruksuniversitet, 1990, p. 1-18Conference paper (Refereed)
  • 1578.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Pontér, Christer
    Luleå tekniska universitet.
    Lead isotopes as tracers of environmental pollution from mining industries1991In: Abstracts: [2nd International Symposium on Environmental Geochemistry], including 3rd International Symposium on Environmental Geochemistry and Health and 9th European Meeting of The Society for Environmental Geochemistry and Health, 16-19 September 1991, Uppsala, Sweden / [ed] O Selinus, Uppsala: Sveriges Geologiska Undersökning , 1991Conference paper (Other academic)
  • 1579.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ingri, Johan
    Pontér, Christer
    Lead isotopes as tracers of lead pollution from various sources: an example from northern Sweden1993In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 8, no Suppl. 2, p. 67-70Article in journal (Refereed)
    Abstract [en]

    The surface sediments in the central Bothnian Bay are contaminated with antropogenic Pb. Preindustrial sources of the Pb pollution are anthropogenic atmospheric Pb, where the main Pb source is combustion of gasoline, and ore from the Laisvall mine which is processed in the smelter Rönnskärsverken. Because the Pb isotope composition of these possible sources are known, an attempt was made to trace the origin of the antropogenic Pb by studying the Pb isotope composition of sediments. The results show unequivocally that Laisvall Pb is not the source of the pollution. The enrichment of Pb in surface sediments is caused by atmospheric deposition of Pb additives from gasoline. Lead emitted from Rönnskärsverken is deposited relatively close to the smelter, and has not reached central Bothnian Bay in traceable amounts.

  • 1580.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lager, Ingemar
    Luleå University of Technology.
    Loberg, Bengt E. H.
    Luleå University of Technology.
    Schöberg, Hans
    Stratigraphical position and Pb-Pb age of lower Proterozoic carbonate rocks from the Kalix greenstone belt, northern Sweden1992In: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 114, no 3, p. 317-322Article in journal (Refereed)
    Abstract [en]

    In the Kalix area, a more than 3600 m thick sequence of continental rift-associated, well-preserved metasedimentary and mafic metavolcanic rocks occurs in a Lower Proterozoic greenstone belt which has no connection to other areas of mafic volcanites. These supracrustals are probably resting on an Archaean basement, and overlain by at least 2000 m of schists of marine prigin. By analysing for Pb isotopes, an attempt was made to date intertidal dolomites with evenly laminated stromatolites and supratidal, pisolitic dolomite calcretes. The resultant age was 2.1 +/- 0.2 Ga. The large uncertainty is partly due to a narrow range of Pb isotopic ratios. Small-scale postdepositional redristribution of lead in the stromatolites is probable. The sample sites are stratigraphically situated just below a 400 m thick sequence of mafic metalavas, which can be correlated with c. 2.1 Ga old mafic metalavas in the Peräpohja Schist Belt in adjacent parts of northern Finland. Despite the large uncertainty of the age obtained, the lithostratigraphical correlations with the Peräpohja Belt suggest that 2.1 Ga is a good approximation of the depositional age of the rocks studied. Later transgression with subsequent deposition of marine sediments is older than the peak of Svecofennian igneous activity at c. 1.9 Ga.

  • 1581.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Land, Magnus
    Stockholms Universitet.
    Ingri, Johan
    Mobility and transport of Nd isotopes during weathering of till in a boreal forest2007In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 71, no 15S, p. A732-Article in journal (Other academic)
  • 1582.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Land, Magnus
    Mistra Council for Evidence-based Environmental Management (EviEM), The Royal Swedish Academy of Sciences.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Widerlund, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Mobility and transport of Nd isotopes in the Vadose zone during weathering of granitic till in a boreal forest2014In: Aquatic geochemistry, ISSN 1380-6165, E-ISSN 1573-1421, Vol. 20, no 1, p. 1-17Article in journal (Refereed)
    Abstract [en]

    There is a broad correlation between the εNd values for rivers (including both the water and the particulate material it carries) and the age of the source terrain. This paper presents Nd isotope distribution data for soil, soil water, groundwater, and stream water samples gathered in a small catchment in northern Sweden. The results show that the release of Nd and Sm from boreal forests into streams and, eventually, into the oceans is more complicated than previously realized. The weathering of till causes changes in both the Nd isotopic composition and Sm/Nd ratios. Both the Sm/Nd ratio and εNd were higher in strongly weathered soils horizons than in less weathered till, since minerals with high Sm/Nd ratios were, on average, more resistant to weathering than those with low Sm/Nd ratios. In contrast to the situation for the main minerals and the major elements, the weathering of rare earth elements (REE) was not restricted to the E-horizon: the measured REE concentrations continued to increase with depth in the C-horizon. In addition, REE released by weathering in the upper parts of the soil profile were partly secondarily retained at deeper levels. Therefore, the dissolved Nd released by weathering in the upper soil horizons was trapped and did not enter the groundwater directly. Rather, the Nd in the groundwater largely originated from weathering within the groundwater zone. However, this was not the only source of Nd in the stream water. The Nd isotope composition and Sm/Nd ratio were determined by the mixing between of Nd and Sm in the groundwater and REE-carrying organic material washed out of the soil profile. The groundwater close to the stream reaches the upper soil horizons during high discharge events such as snowmelts, and organic matter carrying Nd and Sm is washed out of the soils and thus released into the stream. Therefore, the Nd exported from catchment is derived from both the weathering within the groundwater zone, and the organic matter washed out from the soil. If longer timescales with more advanced weathering stages in the groundwater zone are considered, it cannot be ruled out that there will be a shift towards more radiogenic values in the exported Nd. Recorded shifts in the Nd isotopic composition in the ocean may thus not only reflect changed source regions, but also the weathering history of the same source region

  • 1583. Öhlander, Björn
    et al.
    Land, Magnus
    Luleå tekniska universitet.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Widerlund, Anders
    Mobility of rare earth elements during weathering of till in northern Sweden1996In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 11, no 1-2, p. 93-99Article in journal (Refereed)
    Abstract [en]

    Continuous, volume-controlled sampling from the surface down to a depth of 130 cm was conducted at two stations on weathered till (typic haplocryods). All the samples were analysed for major and trace elements including the rare earth elements (REE). Eight thousand seven hundred years of weathering since the glacial ice left the area, has resulted in a strong depletion of REE in the E-horizon. This loss decreases as atomic number increases, so that 80-85% of the La and 54-60% of the Yb have been lost. Europium has been lost to a greater degree than have the neighbouring elements. Possible explanations for the release of REE are: weathering of common silicates such as hornblende and epidote (and plagioclase in the case of Eu); weathering of apatite; weathering of rare but REE-rich minerals such as allanite and monazite; and release of REE adsorbed on clay minerals. Further studies on various size fractions and minerals are needed to quantify the importance of the various possible mechanisms of REE release. The release of REE continues within and below the Bs1-horizon, but the results from one station show that light REE can be enriched in the Bs1-horizon. This secondary enrichment could be caused by adsorption on secondary oxy-hydroxides, on clay minerals or on organic material. However, the net result of the weathering is that all REE have been released to the groundwater.

  • 1584. Öhlander, Björn
    et al.
    Lindvall, Manfred
    Widerlund, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Holmström, Henning
    Carlsson, Erik
    Peinerud, Elsa K
    Correge, Olivier
    A system approach to mine waste remediation, the Kristineberg mine, northern Sweden2003In: Acid rock drainage: application and sustainability of technologies : sixth international conference ; 14 - 17 July 2003, Cairns, Queensland, Australia ; proceedings, Carlton, Victoria: The Australian Institute of Mining and Metallurgy , 2003, p. 81-92Conference paper (Refereed)
  • 1585.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ljungberg, J.
    Holmström, H.
    Luleå tekniska universitet.
    Desorption of metals retained secondarily after release by sulphide oxidation: the main mechanism for groundwater contamination in the tailings at the Laver mine, northern Sweden2001In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 123, no 3, p. 153-162Article in journal (Refereed)
    Abstract [en]

    Geochemical studies of pore water and groundwater in sulphide-bearing tailings have been performed at the Laver mine in northern Sweden. Pore water has been sampled from just above the groundwater table down to the peat and till underlying the tailings. Groundwater has been sampled weekly from April to November in pipes installed at various depths in the tailings. All samples were analysed for major and trace elements by using ICP-AES and ICP-MS. When the oxidation front in the tailings is moving downwards, metals released by weathering in this low-pH environment are to a large extent retained secondarily in the tailings below the oxidation front and do not reach the groundwater, except in areas where the oxidation front is situated close to the groundwater table. Vertical flow of precipitation water contaminated with metals released by sulphide oxidation is, thus, not the major explanation for groundwater contamination. Instead, contamination occurs when the advancing oxidation front pushes the secondary enrichments of metals ahead to meet the groundwater table and the metals are released to the groundwater. The release of metals is caused by desorption due to the low pH in this environment. Areas of the tailings deposit with shallow groundwater table are at present the main sources of metal release. There is a seasonal variation in the composition of groundwater, particularly shallow groundwater. This is caused by changing levels of the groundwater table. Rising groundwater table results in outflush of metals in areas where the groundwater reaches secondarily retained metals. A steady trend with rising groundwater table after snowmelt results in a larger proportion of contaminated water in shallow groundwater, which decreases during the autumn. Concentration peaks of Cu and other metals in shallow groundwater may be the result of small, rapid rises of the groundwater table due to strong precipitation, superimposed on the general seasonal trend.

  • 1586.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lu, Ming
    Alakangas, Lena
    Effect of liming a permanently stratifies pit lake, Rävlidmyran, northern Sweden2007In: Mining and the environment international conference: proceedings, Centre for Environmental Monitoring, Laurentian University , 2007Conference paper (Refereed)
    Abstract [en]

    Rävlidmyran pit lake situated in Northern Sweden had low pH, and a permanent stratification with anoxic water at depth. To improve the water quality, the pit lake was limed by using Ca(OH)2. Before liming, the lake was stratified with low pH (3.0 - 3.4) and high concentration of dissolved oxygen between 0 and 5 m depth, with a transition zone from 5 to 8 m depth, and a zone with pH 3.2 - 5.5 and very low dissolved oxygen from 8 m depth to the bottom. Metals such as Al, Cu and Pb had highest concentrations in the upper zone whereas the concentrations of most other elements including As, Ca, Cd, Fe, Mg, Mn, S and Zn increased with depth. The stratification remained also after the liming treatment. pH increased to about 8 in the whole water column although only one sixth of the Ca(OH)2 was rapidly dissolved, and the remaining part accumulated in the bottom sludge. Redox decreased, especially in the oxygen poor zone at depth. Concentrations of Fe, Mn, Zn and Mg decreased strongly in the upper oxic water, due to formation of oxyhydroxides. In the anoxic bottom water, the concentrations of these elements gradually increased towards pre-liming levels. Aluminium and Cu were almost completely depleted in the entire water column due to pH increase and precipitation of minerals such as gibbsite. The bottom sludge formed after the liming was dominated by Ca(OH)2, calcite and a group of Fe(II)-Fe(III) oxyhydroxides, so called green rust. Metals removed from the dissolved phase of the water column accumulated in the sludge. Although the bottom sludge will have a buffering effect for some time, the poor water mixing in the pit lake will rapidly result in acid water in the upper zones when liming ceases.Key Words: AMD, pit lake, liming, geochemistry, water column, bottom sludge

  • 1587.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Markkula, Heikki
    Luleå University of Technology.
    Alteration associated with the gold-bearing quartz veins at Middagsberget, northern Sweden1994In: Mineralium Deposita, ISSN 0026-4598, E-ISSN 1432-1866, Vol. 29, no 2, p. 120-127Article in journal (Refereed)
    Abstract [en]

    The mesothermal Au deposit at Middagsberget in northern Sweden is associated with irregular stock-works of quartz veins occurring in shear zones across a dioritic intrusion. Alteration in the shear zones is characterized by sericitization, chloritization, the presence of sulphides and several generations of veins and small-scale fractures. Small fractures which are filled with variable amounts of quartz, carbonate, sericite, chlorite, albite and sulphides, are particularly abundant in zones having a high Au content. In general, these fractures are younger than the major quartz veins and were apparently important for strong Au-enrichment. Au is associated with arsenopyrite and it occurs as droplets or interfillings in the arsenopyrite or at the crystal surface; together with pyrrhotite as inclusions in arsenopyrite; as free grains in silicates but close to arsenopyrite; or in very small fractures in carbonates. The Au-mineralization is associated with elevated contents of As, S, Sb and W and depletion of Cu, Zn, Ge and Bi. The entire altered areas are enriched in Au compared with the < 1 to 15 ppb found in the host intrusion. During alteration an initial increase in Na or K was accompanied by a weak enrichment of Au and associated elements together with a depletion of elements such as Ca and Mg. In Au-rich samples this alkali enrichment was overprinted by the carbonate-and sulphide-bearing fractures, which often led to an increased Ca-content. An clear zonation of alteration types has not been found. The host rock has been altered by several generations of fluids: the shear zones were repeatedly ruptured and new small-scale fractures were opened. The different fluids did not, therefore, flow through identical paths although they penetrated the same major zones. This resulted in a complex pattern of variously superimposed alterations.

  • 1588.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Mellqvist, C.
    Skiöld, T.
    Swedish Museum of Natural History.
    Sm-Nd isotope evidence of a collisional event in the Precambrian of northern Sweden1999In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 93, no 1, p. 105-117Article in journal (Refereed)
    Abstract [en]

    The Sm-Nd isotope characteristics of c. 1.9 and c. 1.8 Ga granitoids occurring close to the edge of the Archaean craton in northern Sweden have been studied. Strongly negative εNd(t) values occur farther southwest in the potassic 1.8 Ga granitoids than in the calc-alkaline 1.9 Ga granitoids. Intrusions of the younger granitoids with distinctly negative εNd(t) values are surrounded by granitoids of the older group with positive values. Northeast of the 1.8 Ga granitoids discussed here, the c. 1.9 Ga calc-alkaline intrusions formed within the Archaean continent have the same Sm-Nd isotope characteristics as the 1.8 Ga granitoids to the southwest. Our interpretation is that a juvenile volcanic-arc terrane to the south collided with and was thrust onto the Archaean continent after the formation of the 1.9 Ga granitoids. The outcome was that these juvenile rock masses were obducted onto the reworked Archaean continent. The 1.8 Ga granitoids were formed by remobilisation of continental crust. Partial melting at 1.8 Ga resulted in the intrusion of granitoids carrying the Sm-Nd isotopic signature of the Archaean continent into juvenile rocks. It is probable that the collision discussed here was part of a major accretion and amalgamation to the Archaean craton after the formation of the calc-alkaline 1.9 Ga granitoids, but before the formation of the 1.8 Ga granitoids.

  • 1589.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Müller, Barbara
    Institute of Geotechnical Engineering, ETH Hönggerberg, Zürich.
    Axelsson, Mikael
    Varian Analytical Instruments, Solna.
    Alakangas, Lena
    An attempt to use LA-ICP-SMS to quantify enrichment of trace elements on pyrite surfaces in oxidizing mine tailings2007In: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 92, no 1, p. 1-12Article in journal (Refereed)
    Abstract [en]

    Metals released from oxidation and weathering of sulphide minerals in mine tailings are to a high degree retained at deeper levels within the tailings themselves. To be able to predict what could happen in the future with these secondarily retained metals, it is important to understand the retention mechanisms. In this study an attempt to use laser ablation high-resolution ICP-MS (LA-ICP-SMS) to quantify enrichment of trace elements on pyrite surfaces in mine tailings was performed. Pyrite grains were collected from a profile through the pyrite-rich tailings at the Kristineberg mine in northern Sweden. At each spot hit by the laser, the surface layer was analyzed in the first shot, and a second shot on the same spot gave the chemical composition of the pyrite immediately below. The crater diameter for a laser shot was known, and by estimating the crater depth and total pyrite surface, the total enrichment on pyrite grains was calculated. Results are presented for As, Cd, Co, Cu, Ni and Zn. The results clearly show that there was an enrichment of As, Cd, Cu and Zn on the pyrite surfaces below the oxidation front in the tailings, but not of Co and Ni. Arsenic was also enriched on the pyrite grains that survived in the oxidized zone. Copper has been enriched on pyrite surfaces in unoxidized tailings in the largest amount, followed by Zn and As. However, only 1.4 to 3.1% of the Cd and Zn released by sulphide oxidation in the oxidized zone have been enriched on the pyrite surfaces in the unoxidized tailings, but for As and Cu corresponding figures are about 64 and 43%, respectively. There were many uncertainties in these calculations, and the results shall not be taken too literally but allowed the conclusion that enrichment on pyrite surfaces is an important process for retention of As and Cu below the oxidation front in pyrite rich tailings. Laser ablation is not a surface analysis technique, but more of a thin layer method, and gives no information on the type of processes resulting in enrichment on the pyrite surfaces. Although only pyrite grains that appeared to be fresh and without surface coatings were used in this study, the possibility that a thin layer of Fe-hydroxides occurred must be considered. Both adsorption to the pyrite directly or to Fe-oxyhydroxides may explain the enrichment of As, Cd, Cu and Zn on the pyrite surfaces, and, in the case of Cu, also the replacement of Fe(II) by Cu(II) in pyrite.

  • 1590.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nisca, Dan
    Tectonic control and genesis of Proterozoic molybdenite occurrences in northern Sweden1988In: Proceedings of the Seventh Quadrennial IAGOD Symposium / [ed] Ebbe Zachrisson, Taylor and Francis Group , 1988, p. 603-612Conference paper (Refereed)
  • 1591.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nisca, Dan
    Swedish Geological Co..
    Tectonic control of Precambrian molybdenite mineralization in Northern Sweden1985In: Economic geology and the bulletin of the Society of Economic Geologists, ISSN 0361-0128, E-ISSN 1554-0774, Vol. 80, no 2, p. 505-512Article in journal (Refereed)
    Abstract [en]

    The major molybdenite occurrences of N Sweden are mostly confined to the Proterozoic continental domain. The molybdenite occurrences are in aplites, pegmatites and metamorphosed volcanics, located in narrow supracrustal belts surrounding granites. The Mo deposits are associated with faults and dome structures (apical parts of cupolas), as recognized by geophysical methods

  • 1592.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nordblad, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Lax, Kaj
    Geological Survey of Sweden.
    Ecke, Frauke
    Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Biogeochemical mapping of stream plants to trace acid sulphate soils: A comparison between water geochemistry and metal content in macrophytes2014In: Geochemistry: Exploration, Environment, Analysis, ISSN 1467-7873, E-ISSN 2041-4943, Vol. 14, no 1, p. 85-94Article in journal (Refereed)
    Abstract [en]

    The efficiency of biogeochemical mapping for identifying acid sulphate soils (AS soils) was studied by sampling and analysing water, transplanted aquatic moss (Fontinalis antipyretica) and leaves of the vascular plant Calamagrostis purpurea at two sites in a stream in northern Sweden with AS soils in its drainage area. One upstream sampling station (Mårtsmarken) was situated in an area dominated by till, and a downstream station (Persraningen) was situated in an area where AS soils are common. Metal contents in F. antipyretica and C. purpurea at these sites were compared to those in water (both unfiltered samples, and samples subjected to 0.22 μm membrane filtration and 1 kDa ultrafiltration to obtain data on metal speciation and its effects on uptake). Oxidation of sulphides with associated increases in acidity and release of metals were clearly reflected by differences in the water samples. At Persraningen the pH was lower than at Mårtsmarken, and the unfiltered concentrations of Al, Ca, Cd, Co, Cu, K, Mg, Mn, Ni, P, S, Sr, Y and Zn were higher. At the upstream station, Mårtsmarken, the suspended fraction was an important carrier of Fe and P, and the colloidal concentrations were higher than or similar to the dissolved concentrations for all determined elements except Na and K. At Persraningen the low pH resulted in changes of speciation, so that the dissolved concentrations were higher than the colloidal concentrations for most elements. For Al, As, Cr, Cu, Pb and Y, the dissolved and colloidal concentrations were similar. For Fe, the colloidal concentration was usually higher than the dissolved concentration, and suspended Fe was detected. Aluminium, Cr, Cu, Fe and Y concentrations were significantly higher in Fontinalis antipyretica at Persraningen than at Mårtsmarken. In addition, concentrations of Al and Fe in C. purpurea were significantly higher at Persraningen. Our results highlight the potential of biogeochemical mapping for predicting the occurrence of AS soils. A limitation is the strong pH dependence of the uptake of metals in the aquatic mosses resulting in that only a few of the elements typically occurring at high concentrations in waters draining AS soils are enriched in the macrophytes. A combination of maps showing both absolute concentrations and elemental ratios would be useful for this, including not only ratios of previously suggested utility (e.g. Y:Pb and Ni:Pb), but also others, such as Y:Ca, Al:Ca, Cu:Ca, Y:Mg, Al:Mg and Cu:Mg. © 2014 AAG/The Geological Society of London.

  • 1593.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Romer, Rolf L.
    Luleå University of Technology.
    Zircon ages of granites occuring along the Central Swedish Gravity Low1996In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 118, no 4, p. 217-225Article in journal (Refereed)
    Abstract [en]

    Two major types of late Svecofennian granitoids occur in south central Sweden. Large homogeneous massifs of coarse-grained granite with trace element characteristics typical of granites formed in tensional settings occur along the Central Swedish Gravity Low (CSGL). The other type comprises smaller intrusions of irregular, heterogeneous, locally derived granites (IHLD granites). We present U-Pb zircon ages are presented of one IHLD granite and of three varieties of the homogeneous intrusions. The result for the IHLD granite is 1779+-8 Ma. One of the samples of the homogeneous type yielded an age of 1769.7 +- 3.4 Ma. The remaining two samples have heterogeneous zircon populations. The emplacement age of these rocks is bracketed by the intercept ages of 1770 +- 6 and 1779 +- 23 Ma.The overlapping ages of granite groups of different types show that different types of granites were formed contemporaneously in the same region as a result of melt formation at various depths and from various sources.

  • 1594.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Schöberg, Hans
    Character and U-Pb zircon age of the Proterozoic Ale granite, northern Sweden1991In: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 113, no 2-3, p. 105-112Article in journal (Refereed)
    Abstract [en]

    The Ale granite west of Lule in northern Sweden forms an irregular, almost elliptical exposure covering an area of roughly 30 by 15 km in size. The central part of the intrusion consists of a homgeneous, quartz- and microcline-rich porphyritic granite, whereas its marginal parts are made up of a heterogeneous granite slightly less rich in quartz. Pegmatites and aplites are common in the surroundings. Zircons from two samples, one from the central part of the Ale granite and one from the border zone, were dated at 1802±3 (2σ) Ma and 1796±2 (2σ) Ma, respectively, by using the U-Pb method. An analysis of Sm-Nd istopes of these samples gave initital Nd values of -5.2 and -3.2, respectively, indicating a significant contribution of Archaean crustal material. Thirteen samples were analysed for major and trace elements. The isotopic and geochemical results suggest that the Ale granite was formed in a compressional environment 1.80 Ga ago, and that mature sediments were not an important source material.

  • 1595.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skiöld, T.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Delineation and character of the Archaean-Proterozoic boundary in northern Sweden1993In: Vol. 5, no Suppl. 1, p. 320-321Article in journal (Other academic)
  • 1596.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skiöld, T.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Claesson, S.
    Nisca, D.H.
    Luleå tekniska universitet.
    Delineation and character of the Archaean-Proterozoic boundary in northern Sweden1993In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 64, no 1-4, p. 67-84Article in journal (Refereed)
    Abstract [en]

    Before the deposition of a Proterozoic cover and the repeated Proterozoic reworking of the older rocks, the presently exposed Archaean areas in northern Sweden formed part of a coherent craton. In the present study, we have used Sm---Nd isotopic analyses of Proterozoic granitoids and metavolcanics to delineate the Archaean palaeoboundary. In a regional context, the transition from strongly negative εNd(t) values in the northeast to positive values in the southwest is distinct, and approximately defines the border of the old craton. The Archaean palaeoboundary extends in a WNW direction, and is subparallel to the longitudinal axis of the Skellefte sulphide ore district but it is situated ≈ 100 km farther to the north. The ≈ 1.9 Ga old granitoids on the two sides of the palaeoboundary were all formed in compressional environments, but those situated to the north have higher contents of LILE and LREE at similar contents of Si. This indicates that they were generated in an area with thicker crust and supports the location of the Archaean-Proterozoic palaeoboundary. There is no simple correlation between the Archaean palaeoboundary, as defined by the isotopic results, and any of the major fracture systems as interpreted from regional geophysical measurements. Reflection seismic work indicates that juvenile volcanic-arc terrains to the south have been thrust onto the Archaean craton. Possible thrust faults have been identified from aeromagnetic measurements. Rifting of the Archaean craton created a passive margin ≈ 2.0 Ga ago. Spreading shifted to convergence with subduction beneath the Archaean continent ≈ 1.9 Ga ago. Subsequently, the resulting juvenile volcanic arc collided with the old continent, and the Archaean palaeoboundary as existing today was formed by a collision characterized by overthrusting. The boundary then was disturbed by later deformation predominantly along NNE-trending fracture systems.

  • 1597.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skiöld, T.
    Laboratoriet för Isotopgeologi, Naturhistoriska Riksmuseet, Stockholm.
    Hamilton, P. J.
    IIsotope Geology Unit, Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow.
    Claesson, L. Å.
    Swedish Geological Co..
    The western border of the Archaean province of the Baltic Shield: evidence from northern Sweden1987In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 95, no 4, p. 437-450Article in journal (Refereed)
    Abstract [en]

    Restricted areas of acid to intermediate gneisses in northernmost Sweden are known to be Archaean and several other gneissic granodioritic to tonalitic massifs have been suggested to be of this age. To delimit the western border of the Archaean province of the Baltic Shield, and to characterize the Swedish Archaean, we have studied the 2.83 Ga old Soppero gneiss and 8 of the proposed Archaean massifs in northern Sweden by Sm-Nd isotopic analyses, U-Pb zircon dating (in two cases), and geochemistry. Of the Archaean gneisses proposed thus far, only those from the Soppero and Kukkola areas have Archaean ages (2.83 and 2.67 Ga, respectively). These gneisses have geochemical characteristics such as LREE-enrichment, low U-contents, and low K/Na-ratios, which are typical of Archaean TTG (tonalite-trondhjemite-granodiorite) rocks worldwide. The REE results indicate that the Soppero and the Kukkola gneisses were generated by partial melting of basic rocks, presumably amphibolites. According to the Sm-Nd isotopic data for the Soppero gneiss, this process occurred only a short time after initial segregation from the mantle (εNd values between +0.9 and +3.5). The Kukkola gneiss, however, has longer crustal residence time as indicated by negative εNd values (-1.0 and -2.5) at the U-Pb zircon age of 2.67 Ga. Evidence in support of an important event at that time is given by secondary overgrowth on zircon cores in the 2.83 Ga old Soppero gneiss. The Sm-Nd isotope results show that the Proterozoic granitoids in northern Sweden have a decreasing involvement of Archaean source material with increasing distance from the Archaean areas. Before the Proterozoic reworking, the rather small Archaean areas in northern Sweden presumably belonged to a large continuous Archaean craton. The western palaeoboundary of this craton in Sweden probably follows approximately a line extrapolated from the western limit of the Archaean of central Finland, passing west of Kukkola, and then continues to the Lofoten area in northern Norway.

  • 1598.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skiöld, Torbjörn
    Contrasting 1.8 Ga granitoids in northern Sweden: the Edefors and Lina suites1993In: Abstracts of lectures and posters: 21:a Nordiska geologiska vintermötet 10-13 Januari 1994 Luleå / [ed] Jan-Anders Perdahl, Luleå: Högskolan i Luleå , 1993, p. 235-Conference paper (Other academic)
  • 1599.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skiöld, Torbjörn
    Contrasting 1.8 Ga potassic granitoids in northern Sweden: the Edefors and Lina suites1996In: Jubilee issue: short papers and abstracts for the Jubilee meeting "Current problems, ideas and results in geology" : Stockholm 16th-18th October 1996 at the celebration of the 125th anniversary of the Geological society of Sweden / [ed] Björn Sundquist, Geologiska föreningen , 1996, p. 22-Conference paper (Other academic)
  • 1600.
    Öhlander, Björn
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Skiöld, Torbjörn
    Laboratory for Isotope Geology. Swedish Museum of Natural History, Stockholm.
    Diversity of 1.8 Ga potassic granitoids along the edge of the Archaean craton in northern Scandinavia: a result of melt formation at various depths and from various sources1994In: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 33, no 4, p. 265-283Article in journal (Refereed)
    Abstract [en]

    The edge of the Archaean craton in northern Scandinavia had been intensively reworked during the Svecofennian orogeny 1.93-1.86 Ga ago and was subsequently intruded by potassic granitoids of 1.79–1.80 Ga age. Despite similar or even identical ages and overlapping areas of occurrence, these rocks belong to two different groups, the Edefors and Lina granitoids, which have contrasting geochemistries and Sm---Nd isotopic characteristics. The Edefors granitoids range from syenites to granites, and are alkali-rich and distinctly metaluminous. They crystallized from dry magmas. This is indicated by the scarcity of pegmatites and aplites. The contacts to older rocks are often distinct, but gradual transitions to Lina-type granitoids are common. The Edefors granitoids have high contents of Zr but not of elements such as Y, REE, Ta and Nb, and have low Mg/Mg+Fe ratios. They also frequently have positive Eu anomalies, even in the quartz rich varieties. Initial εNd values range from −2.1 to +1.4, indicating that the Edefors granitoids were formed by the mixing of mantle-derived magmas and continental crustal materials. The amount of crustal component was probably less than 35% in most cases. The Lina granitoids are accompanied by abundant pegmatites and aplites. Ghost structures and remnants of country rock are common. True granites predominate, but also quartz monzonites occur. The content of HFS elements is low and the Mg/Mg+Fe ratios are higher than in the Edefors granitoids. Initial εNd values range from −9.3 to −3.7, reflecting a significant portion of Archaean Nd in the source materials. The Lina granitoids are largely the result of remobilisation of continental crust with a small input of juvenile material. However, the dominant source for these crustally derived granitoids are c. 1.9 Ga old granitoids. These carry a large proportion of Archaean Nd. The most probable environment of the formation of potassic migmatite granitoids, such as the Lina type, is a collision zone between two masses of felsic crust (e.g. arc-continent or continent-continent), but the details of such a collision in the Baltic Shield remain to evaluated. The formation of the Edefors granitoids could have been associated with an extensional zone developed due to delamination caused by separation of the down-dip oceanic lithosphere from the continental lithosphere.

2930313233 1551 - 1600 of 1615
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