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  • 1. Berggren, Robert
    et al.
    Sandrin, Alessandro
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Physical properties of rocks and geophysical data as tools for targeting Fe-oxide Cu-Au mineralisations in northern Sweden2004In: EOS: Transactions, ISSN 0096-3941, E-ISSN 2324-9250, Vol. 85, no 47Article in journal (Other academic)
  • 2.
    Bispo-Santos, F.
    et al.
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    D'Agrella-Filho,, M S
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Paleomagnetism of paleoproterozoic mafic and felsic volcanic rocks of the Rio Negro-Juruena Province, Southwestern Amazonian Craton, Brazil2007Conference paper (Other academic)
    Abstract [en]

    Several paleogeographic configurations for the Amazonian Craton have been suggested along its geological history. Paleomagnetic tests for suggested configurations are however restricted due to very sparce and low quality paleomagnetic data, especially for Paleoproterozoic. In an attempt to improve our understanding of the geodynamic evolution, a paleomagnetic study was performed on felsic volcanic rocks of the Colider Suite, and associated mafic rocks in the Rio Negro-Juruena Province, southwestern Amazonian Craton. These rocks have well dated zircon U-Pb ages between 1.80-1.78 Ga. Very stable northern (southern) directions with moderate to steep negative (positive) inclinations were isolated during AF and thermal demagnetization. Rock magnetism experiments show that the magnetization, which is probably of primary origin, in the felsic rocks is carried by hematite and in the mafic rocks by Ti-poor titanomagnetite. A preliminary mean direction (D=187.4°, I=50.9°, N=16, A95=11.3°, K=11.7) yield a paleomagnetic pole located at 289.4°E, 65.4°S (A95=12.9°), which is classified with quality factor of Q=5. Paleogeographic reconstructions using key Paleoproterozoic poles suggest that Laurentia, Baltica, North China, and Amazonian Craton were located in laterally contiguous positions forming a large continental mass at 1.83-1.77 Ga ago.

  • 3. Bispo-Santos, F.
    et al.
    DÁgrella-Filho, M.S.
    Perillo, B.M.
    Tohver, E.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Janikian, L.
    Trinidade, R.I.
    Pacca, I.I.G.
    Silva, J.A.
    Barros, M.A
    Pinho, F.E.C.
    Preliminary paleomagnetic results from the Guadalupe intrusives, Amazonian craton: tectonic implications2009Conference paper (Refereed)
  • 4.
    Bispo-Santos, Franklin
    et al.
    Universidade de São Paulo.
    D’Agrella-Filho, Manoel S.
    Universidade de São Paulo.
    Pacca, Igor I.G.
    Universidade de São Paulo.
    Janikian, Liliane
    Universidade de São Paulo.
    Trindade, Ricardo I.F.
    Universidade de São Paulo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Silva, Jesué A.
    METAMAT.
    Barros, Márcia A.S.
    Department of Mineral Resources, UFMT.
    Pinho, Francisco E.C.
    Department of Mineral Resources, UFMT.
    Columbia revisited: paleomagnetic results from the 1790 Ma colider volcanics (SW Amazonian Craton, Brazil)2008In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 164, no 1-2, 40-49 p.Article in journal (Refereed)
    Abstract [en]

    In an attempt to improve our understanding of the Paleoproterozoic geodynamic evolution, a paleomagnetic study was performed on 10 sites of acid volcanic rocks of the Colider Suite, southwestern Amazonian Craton. These rocks have a well-dated zircon U-Pb mean age of 1789 +/- 7 Ma. Alternating field and thermal demagnetization revealed northern (southern) directions with moderate to high upward (downward) inclinations. Rock magnetism experiments and magnetic mineralogy show that this characteristic magnetization is carried by Ti-poor magnetite or by hematite that replaces magnetite by late-magmatic cleuteric alteration. Both magnetite and hematite carry the same characteristic component. The mean direction (Dm = 183.0 degrees, Im = 53.5 degrees, N = 10, alpha(95) = 9.8 degrees, K = 25.2) yielded a paleomagnetic pole located at 298.8 degrees E, 63.3 degrees S (alpha(95) = 10.2 degrees, K = 23.6), which is classified with a quality factor Q = 5. Paleogeographic reconstructions using this pole and other reliable Paleoproterozoic poles suggest that Laurentia, Baltica, North China Craton and Amazonian Craton were located in laterally contiguous positions forming a large continental mass at 1790 Ma ago. This is reinforced by geological evidence which support the existence of the supercontinent Columbia in Paleoproterozoic times.

  • 5.
    Bispo-Santos, Franklin
    et al.
    Universidade de São Paulo.
    D’Agrella-Filho, Manoel S.
    Universidade de São Paulo.
    Trindade, Ricardo I.F.
    Universidade de São Paulo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Janikian, Liliane
    Universidade de São Paulo.
    Vasconcelos, Paulo M.
    University of Queensland.
    Perillo, Bruno M.
    Universidade de São Paulo.
    Pacca, Igor I.G.
    Universidade de São Paulo.
    Silva, Jesué A. da
    Companhia Matogrossense de Mineração–METAMAT.
    Barros, Márcia A.S.
    Universidade Federal de Mato Grosso.
    Tectonic implications of the 1419 Ma Nova Guarita mafic intrusives paleomagnetic pole (Amazonian Craton) on the longevity of Nuna2012In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 196-197, 1-22 p.Article in journal (Refereed)
    Abstract [en]

    The Nuna supercontinent was probably assembled in the Paleoproterozoic, but its paleogeography and the timing for its demise are still a matter of debate. A paleomagnetic and geochronological study carried out on the Mesoproterozoic Nova Guarita dyke swarm (northern Mato Grosso State, SW Amazonian Craton) provides additional constraints on the duration of this supercontinent. Paleomagnetic AF and thermal treatment revealed south/southwest (northeast) magnetic directions with downward (upward) inclinations for nineteen analyzed sites. These directions are carried by PSD magnetite with high unblocking temperatures as indicated by additional magnetic tests, including thermomagnetic curves, hysteresis loops and the progressive acquisition of isothermal remanence in selected samples. A positive contact test with the host granite in one of the studied dykes further attests to the primary origin of the characteristic magnetic component. A mean site direction was calculated at Dm = 220.5°, Im = 45.9° (α95 = 6.5°, K = 27.7), which yielded a paleomagnetic pole located at 245.9°E, 47.9°S (A95 = 7.0°). 40Ar/39Ar dating carried out on biotites from four analyzed dykes yielded well-defined plateau ages with a mean of 1418.5 ± 3.5 Ma. The Nova Guarita pole precludes a long-lived Nuna configuration in which Laurentia, Baltica, North China, and Amazonia formed a long and continuous block as previously proposed for the Paleoproterozoic. It is nevertheless fully compatible with a SAMBA (Amazonia-Baltica) link at Mesoproterozoic times.

  • 6.
    Buchan, K. L.
    et al.
    Geological Survey of Canada.
    Mertanen, S.
    Geological Survey of Finland.
    Park, R. G.
    Department of Earth Sciences, Keele University.
    Pesonen, L. J.
    Geological Survey of Finland.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Abrahamsen, N.
    University of Aarhus.
    Bylund, G.
    Lunds universitet.
    Comparing the drift of Laurentia and baltica in the Proterozoic: the importance of key palaeomagnetic poles2000In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 319, no 3, 167-198 p.Article in journal (Refereed)
    Abstract [en]

    Key palaeomagnetic poles are defined as those which pass basic reliability criteria and are precisely and accurately dated. They allow a more rigorous analysis of Precambrian continental drift and continental reconstructions than the traditional apparent polar wander path (APWP) approach using mostly non-key poles. Between ca. 2.45 and 2.00 Ga in the early Palaeoproterozoic, key poles define the drift of the Archaean Superior craton of Laurentia, yielding a result that is quite unlike the drift interpreted in earlier studies using the APWP method. There are no early Palaeoproterozoic key poles for the other Archaean cratons that amalgamated to form Laurentia and Baltica prior to 1.8 Ga, so that a rigorous test of early Palaeoproterozoic reconstruction models is not possible. Key poles from Laurentia between ca. 1.46 and 1.267 Ga and Baltica between 1.63 and 1.265 Ga help to define, in a preliminary fashion, the early Mesoproterozoic drift of the two shields. The key pole age match at ca. 1.265 Ga is consistent with Baltica located adjacent to eastern Greenland, and geological considerations suggest that the most reasonable fit aligns the Labradorian belt of Laurentia with the Gothian belt of Baltica. Although there is limited support from non-key poles and key poles that are not matched in age for such a fit as early as ca. 1.8 Ga, no rigorous assessment will be possible until a match in key pole ages is achieved. In the late Mesoproterozoic to Neoproterozoic, Laurentia's drift is reasonably well documented by seven key poles between 1.235 and 0.73 Ga. There are no key poles in this period from Baltica, however, so that a ≈90° clockwise rotation of Baltica relative to Laurentia between 1.265 and 1.0 Ga, widely used in the literature, cannot be confirmed.

  • 7.
    Buchan, Kenneth
    et al.
    Geological Survey of Canada.
    Ernst, Richard
    Geological Survey of Canada.
    Hamilton, Mike A.
    Geological Survey of Canada.
    Mertanen, Satu
    Geological Survey of Finland.
    Pesonen, Lauri J.
    Geological Survey of Finland.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The 1.7-0.7 Ga paleomagnetic record for Laurentia, Baltica and Siberia and its application to Rodinia reconstructions1999In: Vol. 4, no 1, 114- p.Article in journal (Other academic)
  • 8. Buchan, Kenneth L.
    et al.
    Ernst, Richard E.
    Hamilton, Michael A.
    Mertanen, Satu
    Pesonen, Lauri J.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Rodinia: the evidence from integrated palaeomagnetism and U-Pb geochronology2001In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 110, no 1-4, 9-32 p.Article in journal (Refereed)
    Abstract [en]

    Of many hundreds of well-defined palaeomagnetic poles that have been reported from cratons around the world in the 1700-500 Ma period, only a few are precisely dated. However, such ‘key' palaeopoles are a prerequisite for establishing rigorous palaeomagnetic reconstructions in order to chart the assembly, drift and breakup of the postulated late Precambrian supercontinent of Rodinia. Most key palaeopoles are derived from mafic dykes and sills that have been dated by U-Pb techniques. Most are from Laurentia, the largest and best studied of the continental fragments that are thought to have comprised Rodinia. Thirteen key Laurentia palaeopoles form an incomplete reference set that can be used for comparison with key palaeopoles from other cratons as they become available. Currently, there are four key palaeopoles for Baltica between 1700 and 500 Ma, although only one allows a direct comparison with a similar aged pole from Laurentia. The 1265 Ma match between Baltica and Laurentia is consistent with reconstructions in which Baltica is adjacent to present-day east Greenland, with the ca. 1700-1500 Ma Gothian and Labradorian belts aligned. Few key palaeopoles are yet available from other cratons. However, recent U-Pb dating of dykes, sills, or volcanic rocks in the Siberian, Australian and Kalahari cratons and in Coats Land of Antarctica constrains the ages of individual palaeopoles from each of these areas. Most of these are not key palaeopoles because they have not been conclusively demonstrated to be primary, or local tectonic rotations have not been ruled out. Nevertheless, they are useful in testing Rodinia reconstructions. In this paper, a U-Pb baddeleyite age is reported from the late Gardar magmatic rocks of southwest Greenland. Along with the previously published palaeopole for this unit, this age helps constrain the Mesoproterozoic location of southwest Greenland relative to North America.

  • 9. Bylund, G.
    et al.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Från Söderhavet till Arktis2000In: Har du tid?, Stockholm: Naturvetenskapliga forskningsrådet (NFR) , 2000, 61-74 p.Chapter in book (Other (popular science, discussion, etc.))
  • 10. Bylund, Göran
    et al.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The Dala dolerites, central Sweden, and their palaeomagnetic signature1992In: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 14, no 1, 143-153 p.Article in journal (Refereed)
    Abstract [en]

    New palaeomagnetic results are presented from nine dolerites from central Sweden. Data are also presented from four porphyry sites and one granite site. The data obtained are compared with previously published data from the area. Based on the directions of the characteristic magnetizations isolated in the various rock units a division into five groups, A-E, has been made. Group A consists of dolerites of late Sveconorwegian (c. 1050-850 Ma) age and group B comprises dolerites belonging to the Central Scandinavian Dolerite Group (c. 1250-1150 Ma). Groups C and D are less clearly defined. Group C, with a shallow negative northerly remanence inclination represents the Tuna dykes (c. 1370 Ma). The D direction, with a shallow positive northerly inclination, may represent an older generation of dolerites. The border between groups C and D is diffuse and may be the result of a prolonged mid-Proterozoic period with dolerite intrusions in Dalarna during which significant apparent polar wander occurred. Group E comprises dolerites with a steep positive inclination close to the direction of the Earth's present field. The porphyries and the granite studied carry group D and E remanence directions. This strengthens the evidence for a D-group generation of dolerites contemporary with the porphyries and the granite, c.1650 Ma ago.

  • 11. D´Agrella-Filho, Mabuel S.
    et al.
    Pacca, Igor I. P.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Teixeira, Wilson
    Bettencourt, Jorge Silva
    Geraldes, M.C.
    Preliminary paleomagnetic results from metabasic and sedimentary rocks from the Amazonian craton: tectonic implications for the Rodinia supercontinent2001In: Workshop on Geology of the SW Amazonian Craton: State-of- the-art. Abstracts, Instituto de Geociências-USP , 2001, 155-158 p.Conference paper (Other academic)
  • 12.
    D'Agrella-Filho, Manoel S.
    et al.
    Departamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Tohver, Eric
    School of Earth and Geographical Sciences, University of Western Australia, Crawley.
    Santos, João O.S.
    Redstone Resources Limited, Perth.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Trinidade, Ricardo I.F.
    Departamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Pacca, Igor I.G.
    Departamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Geraldes, Mauro C.
    Faculdade de Geologia, Universidade do Estado do Rio de Janeiro.
    Direct dating of paleomagnetic results from Precambrian sediments in the Amazon craton: Evidence for Grenvillian emplacement of exotic crust in SE Appalachians of North America2008In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 267, no 1-2, 188-199 p.Article in journal (Refereed)
    Abstract [en]

    We apply a new diagenetic dating technique to determine the age of magnetization for Precambrian sedimentary rocks in the SW Amazon craton. Two new palcomagnetic poles are reported from the rocks of the Aguapei Gp.: red beds of the Fortuna Fm. (P-lat = 59.8 degrees N, P-lon = 155.9 degrees E, A(95)=9.5, K= 14, 18 sites, N/n 128/115, Q=5) and the reverse-polarity mudstones of the overlying Vale da Promissao Formation (P-lat=49.5 degrees N, P-lon = 89.3 degrees E, A(95) = 12.5, K=30, 6 sites, N/n=94/80, Q=4). The Fortuna Fm. magnetization is hosted by massive, interstitial hematite cement and constitutes a post-depositional remanence. The age of diagenesis of the red beds is well-constrained by the 1149 +/- 7 Ma U-Pb age of authigenic xenotime rims on detrital zircons determined by SHRIMP analysis. The magnetite-hosted remanence of the Vale da Promissao Fm. may be detrital in origin, but the age of deposition is poorly constrained. The reliable and precisely-dated Fortuna Fun. pateomagnetic pole fixes the paleogeographic position of the Amazon craton near the SE Appalachians portion of North America at 1.15 Ga. These data demonstrate a mobile Grenvillian link between these two cratons, and support the recent identification of Amazon crust in the Blue Ridge province region of North America

  • 13.
    D'Agrella-Filho, Manoel S.
    et al.
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Trindade, Ricardo I.F.
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Teixeira, Wilson
    Instituto de Geociências, Universidade de São Paulo.
    Yokoyama, Elder
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Tohver, Eric
    School of Earth and Geographical Sciences, University of Western Australia, Crawley.
    Geraldes, Mauro C.
    Faculdade de Geologia, Universidade do Estado do Rio de Janeiro.
    Pacca, Igor I.G.
    Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo.
    Barros, Marcia A.S.
    Instituto de Ciências Exatas e da Terra, Departamento de Geologia, Universidade Federal de Mato Grosso.
    Ruiz, Amarildo S.
    Instituto de Ciências Exatas e da Terra, Departamento de Geologia, Universidade Federal de Mato Grosso.
    The 1420 Ma Indiavaí Mafic Intrusion (SW Amazonian Craton): Paleomagnetic results and implications for the Columbia supercontinent2012In: Gondwana Research, ISSN 1342-937X, E-ISSN 1878-0571, Vol. 22, no 3-4, 956-973 p.Article in journal (Refereed)
    Abstract [en]

    The configuration and the timing of assembly and break-up of Columbia are still matter of debate. In order to improve our knowledge about the Mesoproterozoic evolution of Columbia, a paleomagnetic study was carried out on the 1420 Ma Indiavaí mafic intrusive rocks that crosscut the polycyclic Proterozoic basement of the SW Amazonian Craton, in southwestern Mato Grosso State (Brazil). Alternating field and thermal demagnetization revealed south/southwest ChRM directions with downward inclinations for sixteen analyzed sites. These directions are probably carried by SD/PSD magnetite with high coercivities and high unblocking temperatures as indicated by additional rock magnetic tests, including thermomagnetic data, hysteresis data and the progressive acquisition of isothermal remanent magnetization. Different stable magnetization components isolated in host rocks from the basement 10 km NW away to the Indiavaí intrusion, further support the primary origin of the ChRM. A mean of the site mean directions was calculated at Dm = 209.8°, Im = 50.7° (α95 = 8.0°, K = 22.1), which yielded a paleomagnetic pole located at 249.7°E, -57.0°N (A95 = 8.6°). The similarity of this pole with the recently published 1420 Ma pole from the Nova Guarita dykes in northern Mato Grosso State suggests a similar tectonic framework for these two sites located 600 km apart, implying the bulk rigidity of the Rondonian-San Ignacio crust at that time. Furthermore these data provide new insights on the tectonic significance of the 1100-1000 Ma Nova Brasilândia belt –a major EW feature that cuts across the basement rocks of this province, which can now be interpreted as intracratonic, in contrast to previous interpretation. From a global perspective, a new Mesoproterozoic paleogeography of Columbia has been proposed based on comparison of these 1420 Ma poles and a 1780 Ma pole from Amazonia with other paleomagnetic poles of similar age from Baltica and Laurentia, a reconstruction in agreement with geological correlations.

  • 14.
    D’Agrella-Filho, Manoel S.
    et al.
    Universidade de São Paulo.
    Trindade, Ricardo I.F.
    Universidade de São Paulo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Yokoyama, Eder
    Universidade de São Paulo.
    Bispo-Santos, Franklin
    Universidade de São Paulo.
    A new 1.42 GA paleomagnetic pole from the Amazonian craton: implications for the Columbia supercontinent configuration2011In: Proceedings of Second Biennial Meeting of Latinmag: Tandil Argentina, November 2011, 2011Conference paper (Other academic)
    Abstract [en]

    Paleomagnetic studies carried out on the 1.42 Ga Indiavaí mafic intrusive rocks, that crop out in the SW Mato Grosso State provides a great opportunity to test the proposed paleogeographic models for Columbia. Paleomagnetic AF and thermal treatment revealed south/southwest magnetic directions with downward inclinations for sixteen analyzed sites. These directions are probably carried by SD/PSD magnetite with high coercivities and high unblocking temperatures as indicated by additional magnetic tests, including thermomagnetic curves, hysteresis loops and the IRM acquisition curves. A different magnetization obtained for host mafic rocks from the basement ca. 10 km NW away from the Indiavaí intrusive, further attests to the primary origin of the characteristic magnetic component. A mean site direction was calculated at Dm=209.8°, Im=50.7° (α95=8.0°, K=22.1), which yielded a paleomagnetic pole located at 249.7°E, -57.0°N (A95=8.6°). Comparison of this pole with other paleomagnetic poles of similar age from Baltica and Laurentia provides evidence for a link of north-northeastern Amazonian craton, southwestern Baltica and Laurentia, as previously suggested from the similar Mesoproterozoic geological evolution of their margins.

  • 15.
    D'Agrella-Filho, Manoel Souza
    et al.
    Sao Paulo University.
    Trindade, Ricardo I. Ferreira
    Sao Paulo University.
    Tohver, Eric
    University of Western Australia.
    Bispo-Santos, Franklin
    Sao Paulo University.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Pacca, Igor I. Gil
    Sao Paulo University.
    Proterozoic paleogeographic evolution of South American cratons2008Conference paper (Other academic)
    Abstract [en]

    The South American platform is composed of four major cratons (Amazonian, São Francisco, Rio de la Plata and São Luis) and other smaller continental blocks and terrains that may have taken part in supercontinental assemblages. Here, paleogeographic configurations from the Paleoproterozoic up to the Cambrian are tested by means of an updated paleomagnetic and geochronologic record of South America, including new high-quality poles from the Amazonian and São Francisco cratons. These poles are compared to those of other cratons thought to have interacted with South American units in the Proterozoic, such as Baltica and Laurentia. The oldest assemblage of continents to be addressed is the Paleoproterozoic Columbia (~1800 Ma), for which our data support a configuration aligning Laurentia, Baltica, North China and Amazonia through their Paleo-Mesoproterozoic belts. For Neoproterozoic times (~1200-1000 Ma) a connection between Laurentia and the Amazonian craton in an evolving configuration (with relative movement between the two units) is supported by a pole-to-pole comparison. In contrast, striking differences in Laurentia's drift history compared to São Francisco, São Luis (=West Africa) and Kalahari rule-out the effective participation of these cratons in Rodinia. The assembly of Gondwana has probably occurred in different steps, comprising first (~630 Ma) the connection between Sao Francisco, Rio de la Plata, other minor blocks and the African cratons, followed by the collision of these central Gondwanan blocks with the Amazonian craton and adjoining blocks by mid-Cambrian times (~530 Ma), after the opening of the Iapetus ocean basin between Laurentia and the Amazonian craton. In this scenario, the West Gondwana was not a coherent tectonic unit before the end of Precambrian times.

  • 16.
    d'Agrella-Filho, M.S.
    et al.
    University of Sao Paolo.
    Pacca, I I G
    University of Sao Paolo.
    Sigueira, R.
    University of Sao Paolo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Teixeira, W.
    University of Sao Paolo.
    Bettencourt, J.S.
    Geraldes, M.C.
    Amazonian Proterozoic poles: implications to Rodinia paleogeography2001In: From basins to mountains: Rodinia at the turn of the century / Chris Powell Memorial Symposium / [ed] K.N. Sircombe; Z.X. Li, University of Western Australia , 2001, 27-30 p.Conference paper (Other academic)
  • 17.
    D'Agrella-Filho, M.S.
    et al.
    University of Sao Paolo.
    Pacca, Igor Gal
    University of Sao Paolo.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Trinidade, R.I.F.
    University of Sao Paolo.
    Paleomagnetic evidence for oblique collision between Amazonia and Laurentia at about 1.1 Ga2004In: International Geological Congress, Abstracts: 32nd international geological congress, Florence, Italy, Aug. 20-28, 2004, 2004, 1089- p.Conference paper (Other academic)
    Abstract [en]

    The connection between Amazonia and Laurentia at late Meso- proterozoic times through the Grenville/Sunsas-Aguapei collisional belts is a key feature of Rodinia paleogeography.However, at least three different geometries are proposed for such connection, mainly due to the paucity of paleomagnetic data for Amazonia.Connections along Greenland and Labrador were initially proposed based on the fit of geological provinces and scarse virtual geomagnetic poles.More recently, a connection through the Llano belt in Texas was proposed based on a single well dated 1.2 Ga paleopole obtained in mafic rocks from the Nova Floresta Formation. We present a series of poles obtained on sedimentary rocks of the Aguapei Group (western Matto Grosso State-Amazonian Craton) and intrusive mafic rocks, whose evolution is related to the Meso-Neoproterozoic Aguapei-Sunsas orogeny (1.3-0.9 Ga).Together with the 1.2 Ga Nova Floresta pole, they define a straight apparent polar wander path which matches the Laurentia APWP by 1.1 Ga for a connection along the (present day) Labrador region. The pole's trajectories imply a high degree of obliquity for such a collision in agreement with tectonic models put forward for the southwestern margin of Amazonia, the southeastern margin of Laurentia and the southwestern margin of Baltica.

  • 18.
    Donadini, Fabio
    et al.
    Scripps Institution of Oceanography, La Jolla, United States of America.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tauxe, Lisa
    Scripps Institution of Oceanography, La Jolla, United States of America.
    Paleointensity results from the 1.7 GA old hoting Gabbro, Sweden2009Conference paper (Other academic)
    Abstract [en]

    Complete text of publication follows. The Hoting Gabbro is located in the western part of the Central Svecofennian Subprovince, and dates about 1.786+-0.010 Ga. In the Hoting area, dykes intruded at around 1.6 Ga, and partly remagnetized the gabbros. Previous paleomagnetic and geochemical studies indicated that the stable characteristic remanent magnetization was acquired at about 1.7 Ga, when the slow cooling of the gabbro is taken into account. Preliminary palaeointensity studies from gabbros in the Hoting area suggested a very low field of about 5.8+-1.9 muT. Unfortunately, at that stage, only two sites out of nine yielded results. During 2008, we sampled seven sites from the Hoting area in order to perform new palaeointensity experiments. At Scripps, we applied the IZZI method on 60 specimens, and 39 yielded reliable results varying between 3 and 20 muT, and confirm the previous low results. Low field values have been associated with oxyexolution processes that might bias the palaeointensity result towards low values, and so we are currently investigating the mineralogy of the samples with SEM analyses. We will present the details of the palaeointensity and mineralogical results, and infer the evolution of the geomagnetic field during Precambrian.

  • 19.
    Donadini, Fabio
    et al.
    Institut für Geophysik, ETH Zürich.
    Elming, Sten-Åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Tauxe, Lisa
    Scripps Institution of Oceanography, University of California, San Diego.
    Hålenius, Ulf
    Swedish Museum of Natural History, Department of Mineralogy.
    Paleointensity determination on a 1.786 Ga old gabbro from Hoting, Central Sweden2011In: Earth and Planetary Science Letters, ISSN 0012-821X, E-ISSN 1385-013X, Vol. 309, no 3-4, 234-248 p.Article in journal (Refereed)
    Abstract [en]

    Paleointensities from Precambrian rocks are rare and might be biased by remagnetization processes. Here we present new analyses of samples from a 1.786 Ga gabbro near Hoting, Central Sweden. Rock magnetic and mineralogical analyses indicate that one of the sites (site 5) may be pristine, whereas the others exhibit evidence of alteration. Characteristic remanent magnetization was determined using principal component analysis for each sample and was compared with results obtained in a previous study of Elming et al. (2009). Intensity measurements from site 5 show higher values compared to those of the other sites, suggesting that alteration processes may lead to underestimation of the field intensity. After cooling rate and anisotropy correction, the field moment at 1.786 Ga was estimated to be 25.6 ± 3.3 ZAm2 and 15.2 ± 6.1 ZAm2 from site 5 only and from all sites respectively. We consider the result from site 5 to be more accurate owing to the lack of evidence for alteration; our estimates agree well with the Proterozoic VDM values suggested by Biggin et al. (2009).

  • 20. Dyrelius, D.
    et al.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bergarters fysik1985In: Geofysik, Uppsala: Svenska fysikersamfundet , 1985Chapter in book (Other (popular science, discussion, etc.))
  • 21. Edfelt, Åsa
    et al.
    Sandrin, Alessandro
    Luleå tekniska universitet.
    Evins, Paul
    EGRU, School of Earth Sciences, James Cook University.
    Jeffries, Teresa
    Natural History Museum, London.
    Storey, Craig
    Open University, Walton Hall, Milton Keynes.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Martinsson, Olof
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Stratigraphy and tectonic setting of the host rocks to the Tjårrojåkka Fe-oxide Cu-Au deposits, Kiruna area, northern Sweden2006In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 128, no 3, 221-232 p.Article in journal (Refereed)
    Abstract [en]

    The Tjårrojåkka area is located about 50 km WSW of Kiruna, northern Sweden, and hosts one of the best examples of spatially and possibly genetically related Fe-oxide and Cu-Au occurrences in the area. The bedrock is dominated by intermediate and basic extrusive and intrusive rocks. An andesite constrains the ages of these rocks with a U-Pb LA-ICPMS age of 1878±7 Ma. They are cut by dolerites, which acted as feeder dykes for the overlying basalts. Based on geochemistry and the obtained age the andesites and basaltic andesites can be correlated with the 1.9 Ga intermediate volcanic rocks of the Svecofennian Porphyrite Group in northern Sweden. They formed during subduction-related magmatism in a volcanic arc environment on the Archaean continental margin above the Kiruna Greenstone Group. Chemically the basalts and associated dolerites have the same signature, but cannot directly be related to any known basaltic unit in northern Sweden. The basalts show only minor contamination of continental crust and may represent a local extensional event in a subaquatic back arc setting with extrusion of mantle derived magma. The intrusive rocks range from gabbro to quartz-monzodiorite in composition. The area is metamorphosed at epidote-amphibolite facies and has been affected by scapolite, K-feldspar, epidote, and albite alteration that is more intense in the vicinity of deformation zones and mineral deposits. Three events of deformation have been distinguished in the area. D1 brittle-ductile deformation created NE-SW-striking steep foliation corresponding with the strike of the Tjårrojåkka-Fe and Cu deposits and was followed by the development of an E-W deformation zone (D2). A compressional event (D3), possible involving thrusting from the SW, produced folds in the central part of the area and a NNW-SSE striking deformation zone in NE.

  • 22.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    A palaeomagnetic study and K-Ar age determinations of tertiary rocks in Nicaragua1998In: Geoscientific research in Nicaragua: a Swedish-Nicaraguan joint project during the period 1981-1991, Luleå: Luleå tekniska universitet, 1998, 1-19 p.Chapter in book (Other academic)
  • 23.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    A palaeomagnetic study of Svecokarelian basic rocks from northern Sweden1985In: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 107, no 1, 17-35 p.Article in journal (Refereed)
    Abstract [en]

    This palaeomagnetic investigation comprises basic rocks from six localities from the Svecokarelian zone in northern Sweden. Most of the pole positions in this study and other reported poles of Svecokarelian and post-Svecokarelian rocks fall within an approximately 12 degrees wide band running from east to west representing ages of magnetizations from 1880-1700 to ∼ 1530 Ma. Thermal demagnetizations of specimens of the probably oldest massifs indicate a possible backward continuation of the polar wandering path. Mineralogical studies of thin sections of the rocks show ore symplectites and myrmekitic textures indicating a slow rate of cooling at least at the end of the rock formation. Signs of metamorphism are demonstrated by the existence of secondary minerals, including magnetite, not related to late magmatic alterations. The distribution of site means as well as the change of directions of the remanence vectors during thermal demagnetization can be explained by a slow rate of cooling and where signs of metamorphism exist by partial remagnetization of the rock. This study has, apart from the palaeomagnetic results, demonstrated the difficulty of correlating radiometric ages with ages of magnetization

  • 24.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Basic dykes and dyke swarms in central and northern Sweden and the plate tectonic evolution of Fennoscandia: palaeomagnetic and Ar39/Ar40 studies2005In: "Dyke swarms - time markers of crustal evolution": Fifth International Dyke Conference, Pohtimolampi Wilderness Hotel, Polar Circle, Rovaniemi, Finland, 31 June - 3 August 2005 ; abstracts and programme / [ed] Jouni Vuollo; Satu Mertanen, Espoo: Geological Survey of Finland , 2005, 11- p.Conference paper (Other academic)
    Abstract [en]

    Palaeomagnetic and Ar39/Ar40 studies have been performed on basic dykes and dyke swarms in central and northern Sweden. At least five different generations of dykes have been defined and will be discussed in a plate tectonic context. Reliable palaeomagnetic data have been obtained from a big gabbro diabase and a geographically related dyke swarm in the northern part of Sweden from which poles similar to those calculated from Svecofennian gabbros (ca 1.86 Ga) are defined. In another swarm of palaeomagnetically similar age, just north of the Skellefte district, partially remagnetized dykes indicate a possible Subjotnian or Caledonian regional remagnetization. The dykes are younger when moving towards the south and in the central part there is a significant dyke swarm with at least two generations of dykes (ca. 1.7 and 1.6 Ga, respectively), one of which is related with rapakivi magmatism. Palaeomagnetic and anisotropy of magnetic susceptibility (AMS) data from the huge ca 1.25 Ga sill complexes in central Sweden and western Finland and from basic intrusions in Greenland suggest that Baltica and Laurentia were joined at that time. The similar stress field as indicated by the AMS data and the tensional regime reflected by the sill complexes is interpreted related to the break up of Baltica from Laurentia. New data from ca 1.1 Ga dykes in central Sweden confirms a clockwise rotation of Fennoscandia between 1.25 and 1.1 Ga, a rotation that is not seen for Laurentia.

  • 25.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Density and magnetic properties of rocks in the Caledonides of Jämtland, Sweden1980In: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 102, no 4, 439-453 p.Article in journal (Refereed)
    Abstract [en]

    Density and magnetic properties were determined on some 1350 rock samples, taken from the different lithologies in the Caledonides of Jmtland, Sweden. The density determinations showed a strong trend of increasing density when moving from east to west in the investigated area. There was also a general increase in density upwards in the tectono-stratigraphy from the autochthon to the Seve of the Seve-Kli Nappe Complex. The determination of magnetic properties showed that east of the Caledonian Front the dominating high-susceptibility rock was the Rtan granite. In the Eastern Complex, west of the Caledonian Front, high-susceptibility rocks were found in the parautochthonous and allochthonous crystalline basement, whereas in the Western Complex the Ottfjllet dolerite in the Srv Nappe was the dominating high-susceptibility rock.

  • 26.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Evidence for early Proterozoic plate tectonics from seismic reflection profiles in the Baltic Shield1990In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 348, 34-38 p.Article in journal (Refereed)
    Abstract [en]

    Plate tectonics provides the linking framework for all tectonic and magmatic activity seen today, but it is not known when plate tectonics first developed on Earth. New deep seismic reflection and coincident refraction profiles across an exposed, 1.89-Gyr-old volcanic arc complex show a 10-km-thick offset in the Moho and bivergent reflectors in the crust, which were most probably created by plate convergence, subduction and accretion during the Early Proterozoic. Hence, plate tectonic models seem to be applicable for at least the second half of Earth's history.

  • 27.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geological modelling based on gravity data from the central part of the Swedish Caledonides1991In: Vol. 113, no 2-3, 257-258 p.Article in journal (Other academic)
  • 28.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Geological modelling based on gravity data from the central part of the Swedish caledonides1988In: Geologiska föreningens i Stockholm förhandlingar, ISSN 0016-786X, Vol. 110, no 4, 317-327 p.Article in journal (Refereed)
    Abstract [en]

    Gravimetric measurements have been carried out within a c. 500 km2 area of western Jämtland in the Swedish Caledonides. Using different types of regional-residual gravity field separations, various geological models have been tested to fit the measured gravity data. Information on the geology and density of the rocks have reduced the number of possible models which are presented along two profiles. These models confirm the existence of antiforms and synforms running approximately parallel to the mountain range. The main profile crosses the two synforms over which positive anomalies are identified. Both in the western Tnnfors Synform and the eastern re Synform this is explained by the presence of high density Seve rocks, in the former case occurring beneath a cover of Kli Nappes. The depth to the base of the Seve Nappe units in the Tnnfors Synform is calculated at 4.5 km and in the re Synform at 3 km. The maximum depth to the interface between Kli and Seve rocks in the Tnnfors district is 3.2 km. Gravimetric models of the basement rocks in the windows, and difference in physical properties between the crystalline rocks of the windows and those of the autochthonous basement east of the Caledonian thrust front, imply that the basement exposed in the antiforms is allochthonous. A gravity minimum east of the re Synform is interpreted as a southern continuation of low density granites related to the Olden Complex. The inferred thickness of these low density rocks suggests that it may be a part of the autochthonous basement.

  • 29.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Integrated seismic studies of the Baltic shield using data in the Gulf of Bothnia region1993In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 112, no 3, 305-324 p.Article in journal (Refereed)
    Abstract [en]

    In the autumn of 1989 a co-operative experiment involving 12 research institutions in northwestern Europe collected 2268 km of deep seismic reflection profiles in the Gulf of Bothnia and the Baltic Sea. the 121 litre airgun array used for this profiling was also recorded by 62 muiticomponent land stations to provide coincident refraction surveys, fan-spreads, and 3-D seismic coverage of much of the Gulf of Bothnia. We thus have potentially both high-resolution impedance contrast images as well as more regional 3-D velocity models in both P- and S-waves. In the Bothnian Bay a south-dipping, non-reflective zone coincides with the conductive Archaean-Proterozoic boundary onshore in Finland. Between the Bothnian Bay and Bothnian Sea observed reflectivity geometries and velocity models at Moho depths suggest structures inherited from a 1.9Ga subduction zone; the upper crust here appears to have anomalously low velocity. Within the Bothnian Sea, reflectivity varies considerably beneath the metasedimentary/granitoid rocks of the Central Svecofennian Province (CSP) and the surrounding metavolcanic-arc rocks. Numerous dipping reflectors appear throughout the metavolcanic crust, whereas the CSP has little reflectivity. Wide-angle reflections indicate that the metasedimentary crust of the Bothnian Basin is 10 km thicker than the neighbouring Svecofennian subprovinces. Near the Åland archipelago Rapakivi granite plutons exhibit bright reflections, a contrast to the usual non-reflective plutons elsewhere in western Europe. Additional dipping reflections deep in the crust of this area may support models of rifting and crustal thinning during emplacement of the 1.70-1.54 Ga Rapakivi granites. Coeval gabbroic/anorthositic magmatism may explain the high reflectivity and high velocity of these plutons. the c. 1.25 Ga mafic sills and feeder dykes of the Central Scandinavian Dolerite Group also produce clear reflections on both near- and far-offset seismic sections. Continued modelling will produce better velocity models of the crust and better constrained contour maps of crustal thickness in this part of the Baltic shield.

  • 30.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Magnetic properties of pyrrhotite1981In: Vol. 19, no 2, 144- p.Article in journal (Other academic)
  • 31.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Palaeomagnetism of Precambrian rocks in northern Sweden and its correlation to radiometric data1994In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 69, no 1-4, 61-79 p.Article in journal (Refereed)
    Abstract [en]

    A palaeomagnetic study has been performed on Palaeo- to Mesoproterozoic basic intrusions and volcanic rocks from the Fennoscandian shield in northern Sweden. Three, possibly four, different generations of magnetizations were identified, the oldest assigned to a Svecofennian age (1.86-1.89 Ga). A second generation is related to the intrusion of granitoids of 1.80-1.76 Ga. In this geological event probably also the third group of directions has its origin. These different magnetizations may indicate that there are at least two different generations of basic intrusions in northern Sweden. A fourth group of directions is isolated as overprints. This magnetization is interpreted to be a Subjotnian magnetization, reflecting a previously unrecognized regional Subjotnian metamorphic event in the northwestern part of the Fennoscandian shield. The drift history for the Fennoscandian shield during the period 1.88-1.50 Ga has been defined based on these new palaeomagnetic data

  • 32.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Recording marine airgun shots at offsets between 300 and 700 km1991In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 18, no 4, 645-648 p.Article in journal (Refereed)
    Abstract [en]

    This paper demonstrates that - under favorable conditions - by using multichannel recording and subsequent stacking of adjacent records marine airgun shots have been detected at offset distances up to 700 km, the maximum offset at which the authors attempted to record data.^Besides a powerful airgun array, a low noise environment at the recording site and the elimination of static shifts are the prerequisites to obtain refracted and reflected arrivals from the crust and upper mantle at such large offsets.^Primary arrivals detected at offsets between 400 and 700 km image the upper mantle from 70 to about 120 km depth.^Stacking of neighboring shots and/or receivers successfully increases the signal-to-noise ratio, if the traces have been corrected for offset differences, which requires knowledge of the apparent phase velocities.^The data presented here were collected in autumn 1989 during the BABEL Project on the Baltic Shield.

  • 33.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Research in rock magnetism and palaeomagnetism with reference to Caledonian and Precambrian rocks in Sweden1982Doctoral thesis, comprehensive summary (Other academic)
  • 34.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Subjotnian metamorphism in northern Sweden: a palaeomagnetic analysis of rocks from the northern svecofennian province and the Skellefte district1993In: Abstracts of lectures and posters: 21:a Nordiska geologiska vintermötet 10-13 Januari 1994 Luleå / [ed] Jan-Anders Perdahl, Luleå: Högskolan i Luleå , 1993, 44- p.Conference paper (Other academic)
  • 35.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    The definition of the southern extension of the Chortis block: a palaeomagnetic and regional geophysical study in Nicaragua1993In: Abstracts of lectures and posters: 21:a Nordiska geologiska vintermötet 10-13 Januari 1994 Luleå / [ed] Jan-Anders Perdahl, Luleå: Högskolan i Luleå , 1993, 45- p.Conference paper (Other academic)
  • 36.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bylund, Göran
    Palaeomagnetism and the Siljan impact structure, central Sweden1991In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 105, no 3, 757-770 p.Article in journal (Refereed)
    Abstract [en]

    A palaeomagnetic study of rocks, from inside and outside the impact structure has been carried out, with the aim of identifying natural remanent magnetizations (NRMs) related to the impact event. Three different directions of magnetizations, not recognized elsewhere, were identified within the central part of the structure. These three magnetizations are defined in terms of coercivity and blocking temperature. The implications of the results are discussed in relation to ages obtained from Ar-Ar dating of impact melt

  • 37.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bylund, Göran
    Lund University.
    Paleomagnetism and the Siljan impact structure, central Sweden1990In: Programme and abstracts: symposium Fennoscandian impact structures, may 29-31, 1990, Espoo and Lappajärvi, Finland / [ed] L.J. Pesonen; H. Niemisara, Geological Survey of Finland , 1990, 25- p.Conference paper (Other academic)
  • 38.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bylund, göran
    Lund University.
    Paleomagnetism and the Siljan impact structure, Central Sweden1992In: Vol. 114, no 1, 158- p.Article in journal (Other academic)
  • 39.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    D'Agrella-Filho, M.S.
    Universidade de São Paulo.
    Page, L.M.
    University of Lund.
    Tohver, E.
    School of Earth and Geographical Sciences, University of Western Australia, Crawley.
    Trindade, R. I. F.
    Universidade de São Paulo.
    Pacca, I.I.G.
    Universidade de São Paulo.
    Geraldes, M.C.
    Faculdade de Geologia, Universidade do Estado do Rio de Janeiro.
    Teixeira, W.
    Instituto de Geociências, Universidade de São Paulo.
    A palaeomagnetic and Ar-40/Ar-39 study of late precambrian sills in the SW part of the Amazonian craton: Amazonia in the Rodinia reconstruction2009In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 178, no 1, 106-122 p.Article in journal (Refereed)
    Abstract [en]

    A new key palaeomagnetic pole (Plat. = 64.3°S, Plon. = 271.0°E, N = 14, A95= 9.2°; Q = 5) is calculated from a primary magnetization isolated in early Neoproterozoic Aguapei basic sills and dykes hosted by 1.3-1.0 Ga sedimentary rocks from the southwestern part of the Amazon craton. The characteristic remanence carried by stable, pseudo-single domain titanomagnetite shows two antipodal polarities that pass a reversals test. Magnetic anisotropy for most sites shows fabric orientations that are typical of sills, with horizontal magnetic foliations concordant to the flat-lying bedding of the host sedimentary rocks. 40Ar/39Ar analyses for one of the sills reveal a well-defined plateau age at 981 ± 2 Myr. A tectonic reconstruction for Amazonia relative Laurentia based on this new pole 'is consistent with' a position of the present northwestern part of Amazonia attached with eastern Laurentia close to Greenland at ca. 981 Ma. On basis of palaeomagnetic and geological data, we propose a scenario where Amazonia moved northeastwards along the present southeast coast of Laurentia from ca. 1200 to 980 Ma. By 980 Ma, Amazonia is placed alongside Laurentia and Baltica, in a position similar to other reconstructions of Rodinia but with a significantly different orientation.

  • 40.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Enmark, Thomas
    Widenfalk, Lennart
    A combined geological petrophysical and geophysical investigation of the Notträsk gabbro, northern Sweden1983In: Vol. 105, no 4, 386-387 p.Article in journal (Refereed)
  • 41.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Jensen, Mai-Britt Mose
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    A correlation of AMS and rock quality in crystalline and sedimentary rocks in the Kiirunavaara hanging wall2012In: Journal of Applied Geophysics, ISSN 0926-9851, E-ISSN 1879-1859, Vol. 86, 54-69 p.Article in journal (Refereed)
    Abstract [en]

    A study of the magnetic fabric and rock quality has been performed on crystalline and sedimentary rocks from the hanging wall of the Kiirunavaara iron ore deposit, northern Sweden. The rock samples were taken from 12 outcrops and three oriented drillcores and consist of quartzite, siltstone, conglomerate, porphyritic basalts, quartz-bearing porphyry and mylonite.Anisotropy of magnetic susceptibility (AMS) was used to determine the texture of the rocks by defining the shape of the magnetic susceptibility ellipsoids, the orientation of the magnetic foliation planes and the degree of magnetic anisotropy. AMS data from the outcrops as well as data from the uppermost part of two of the drillcores was used to produce a surface contour map which indicates that both the dip of the magnetic foliation plane and the degree of magnetic anisotropy decreases towards the east. These two parameters thus generally follow the major structural features of the Kiruna region.Two classical rock mechanical parameters, RQD (Rock Quality Designation) and F/m (fractures pr. meter), were used to quantify the amount of discontinuities and fractures in the drill cores. RQD and F/m was subsequently correlated with the AMS data, and a correlation was observed, with the correlation coefficient r varying between 0.6142-0.7557. The correlation was limited to just one of the drillcores however it could be traced across rock type boundaries. The correlation indicates that AMS may be used as an indicator tool of the rock mechanical properties in both crystalline and sedimentary rocks.

  • 42.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kravchenko, S. N.
    National Academy of Sciences of Ukraine.
    Layer, P.
    University of Alaska.
    Rusakov, O. M.
    National Academy of Sciences of Ukraine.
    Glevasskaya, A. M.
    National Academy of Sciences of Ukraine.
    Mikhailova, N. P.
    National Academy of Sciences of Ukraine.
    Bachhtadse, V.
    Ludwig-Maximilians-University.
    Palaeomagnetism and AR-40/AR-39 age determinations of the Ediacaran traps from the southwestern margin of the East European Craton, Ukraine: relevance to the Rodinia break-up2007In: Journal of the Geological Society, ISSN 0016-7649, E-ISSN 2041-479X, Vol. 164, no 5, 969-982 p.Article in journal (Refereed)
    Abstract [en]

    A palaeomagnetic study and age determinations have been performed on Ediacaran basalts from the northwestern Ukraine. Whole-rock ^sup 40^Ar/^sup 39^Ar age determination revealed plateau ages at 590-560 Ma and 393 Ma, the latter probably reflecting a resetting of the radiometric system. Palaeomagnetic poles have been calculated from five basalt flows, two of which (A poles) are considered reliable with ages that range from 580 to 560 Ma. Tentative poles (B poles), calculated from most probably primary magnetizations, have ages estimated at 580-545 Ma. Secondary magnetizations, possibly of late Ediacaran or Devonian age, have also been isolated (C poles). Based on the new poles, Baltica drifted together with Laurentia from an equatorial position at c. 750 Ma to occupy high southern latitude positions at c. 580 Ma. Baltica during that time period was joined to Laurentia in a similar relative position to that at 750 Ma. The two shields then split up from each other and from c. 550 Ma Baltica drifted at moderately high latitudes and rotated some 180° during the final opening of the Iapetus ocean. This reconstruction suggests that during the Ediacaran glaciation Baltica occupied high-latitude positions, which contradicts the high-obliquity model to explain low-latitude Neoproterozoic glaciations

  • 43.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kravchenko, Svetlana
    Geophysical Institute, Academy of Sciences of Ukraine, Kiev.
    A palaeomagnetic study of Mesoproterozoic basic dykes from the Ukrainian Shield and the amalgamation of the shield with Fennoscandia2005In: "Dyke swarms - time markers of crustal evolution": Fifth International Dyke Conference, Pohtimolampi Wilderness Hotel, Polar Circle, Rovaniemi, Finland, 31 June - 3 August 2005 ; abstracts and programme / [ed] Jouni Vuollo; Satu Mertanen, Espoo: Geological Survey of Finland , 2005, 12- p.Conference paper (Other academic)
    Abstract [en]

    A palaeomagnetic study has been performed on Palaeo-Mesoproterozoic basic intrusions from three crustal blocks of the Ukrainian Shield. At least three different generations of dykes has been identified and positive field tests can be demonstrated for some of them. A sequence of 2.1 to 1.72 Ga apparent polar wander has been defined on basis of the new palaeomagnetic and Ar/Ar data presented here and on basis of old data from anorthosites. The calculated poles are significantly different from poles of similar age from the Fennoscandian Shield. Although the poles are not perfectly coeval the tectonic reconstructions demonstrate that the Ukrainian Shield collided with Fennoscandia at 1.80-1.85 Ga and then rotated some 45° into its present relative position.

  • 44.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kravchenko, Svetlana
    Institute of Geophysics, Acadamy of Science, Kiev.
    Mikhailova, Ninel
    Geophysical Institute, Academy of Sciences of Ukraine, Kiev.
    The consolidation of the East European Craton: a palaeomagnetic analysis of Proterozoic rocks from the Ukrainian and Fennoscandian shields1999In: Vol. 4, no 1, 151- p.Article in journal (Other academic)
  • 45.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Layer, P.
    Geophysical Institute, University of Alaska.
    Ubieta, K.
    Centro de Investigaciones Geoscientificas (CIGEO), the Autonomous University of Nicaragua (UNAN), Managua.
    A palaeomagnetic study and age determinations of Tertiary rocks in Nicaragua, Central America2001In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 147, no 2, 294-309 p.Article in journal (Refereed)
    Abstract [en]

    Palaeomagnetic, K-Ar and Ar40/Ar39 measurements have been made to elucidate Nicaragua's plate tectonic history. These show that the Nicaraguan Highland rotated 90° counterclockwise between 30 and 18 Myr ago, but the Pacific Coastal Plain has not rotated.A lack of data has prevented a direct comparison with the tectonic history of adjacent areas, in particular, the Chortis Block, which is the part of the Caribbean Plate that is geologically most closely related to the Nicaraguan Highland. However, our data suggest that the Caribbean Plate in this part of Central America was not consolidated until c. 15 Ma.

  • 46.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Leino, M.A.H.
    Pesonen, L.J.
    Khramov, A.N.
    Bylund, G.
    Mertanen, S.
    Krasnova, A.F.
    Terho, M.
    Drift history of Fennoscandia2009In: A continent revealed: the European geotraverse, Cambridge: Cambridge University Press, 2009Chapter in book (Other academic)
  • 47.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maokhar, M.O.
    Razi University, Department of Physics, Faculty of Basic Sciences.
    Layer, P.
    University of Alaska, Institute for Geophysics, Fairbanks.
    Donadini, F.
    Scripps Institution of Oceanography, La Jolla, United States of America.
    Uplift deduced from remanent magnetization of a proterozoic basic dyke and the baked country rock in the Hoting area, central Sweden: a palaeomagnetic and Ar-40/Ar-39 study2009In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 179, no 1, 59-78 p.Article in journal (Refereed)
    Abstract [en]

    Remanent magnetization in dyke contact zones in the Hoting area of the Fennoscandian Shield in the central part of Sweden has been studied in order to establish the ambient temperature of the host rock and the depth of burial of the present erosion surface at the time of intrusion. A positive baked contact test for two Subjotnian dykes demonstrates the primary nature of the dyke magnetization. From the magnetic properties and the palaeomagnetic data, it can be concluded that the overprinting in the hybrid zone of one of the basic dykes is a partial thermoremanent magnetization. Reliable results were also obtained from a palaeointensity study of samples from the hybrid zone in the baked host rock. The study was performed in the laboratories at Luleå and at Scripps and a mean intensity of the Earth's magnetic field of 5.8 ± 1.9 μT was determined. The maximum temperature due to the dyke intrusion in the hybrid zone has been defined and from that an ambient temperature of 375 °C in the host rock at the time of intrusion has been calculated. This calculated temperature is not contradicted by the 40Ar/39Ar data. A palaeothermal gradient in the crust at ca. 1.6 Ga is calculated at ca. 34 °C km-1 and yields a depth of burial of the present erosion surface at ca. 10.4 km. This implies an uplift rate of 0.65 km (100 Ma)-1. A slow cooling of the gabbroic host rock (ca. 3.5 °C Ma-1) has been calculated from the difference in the U-Pb age of zircon (1.786 ± 0.010 Ga) and the 40Ar/39Ar biotite ages (1.648 ± 0.012 Ga; 1614 ± 0.024 Ga) of this study. This slow cooling resulted in a palaeomagnetic age of ca. 1.7 Ga for the gabbro, which is also the age of the determined palaeointensity. The calculated ca. 1.614 Ga palaeomagnetic pole from the basic dykes fulfils most of the criteria for a reliable pole and may be regarded as a new key-pole for Fennoscandia.

  • 48.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Mattsson, Håkan
    Luleå tekniska universitet.
    Post Jotnian basic intrusions in the Fennoscandian Shield, and the break up of baltica from Laurentia: a palaeomagnetic and AMS study2001In: Precambrian Research, ISSN 0301-9268, E-ISSN 1872-7433, Vol. 108, no 3-4, 215-236 p.Article in journal (Refereed)
    Abstract [en]

    A palaeomagnetic and anisotropy of magnetic susceptibility (AMS) study has been performed on dolerite sills of the Central Scandinavian Dolerite Group (CSDG) in the Fennoscandian Shield. The dolerites occur in four previously known complexes in central Sweden and Finland and from the results of this palaeomagnetic study another complex has been identified in northern Sweden. These complexes cover an area of at least 100 000 km2 and the palaeomagnetic data suggest a small difference in time between the intrusion of the dolerites. The measurements of anisotropy of magnetic susceptibility reveal a magnetic fabric with almost horizontal foliation planes and lineations that indicate fairly uniform ca NW or SE directed magma flows. The dolerites of the CSDG are geochemically rather uniform and have compositions typical of mantle derived melts formed in continental tensional settings. In a palaeomagnetic reconstruction of Baltica versus Laurentia at ca 1.27 Ga the two continents were joined, with NE Greenland attached to NW Baltica. AMS data from a few dolerites and a basalt in NE Greenland indicate magma flow directions that in the tectonic reconstruction are more or less parallel to the flow of the dolerites in Sweden. This may suggest a common magma source located at the reconstructed contact between Baltica and Laurentia. Both the dolerites in Greenland and those in Sweden are of tholeitic composition indicating an intraplate origin, which supports the interpretation of joined continents at that time. The tensional regime, that is reflected by the huge sill complexes, is in our interpretation related to the break up of Baltica from Laurentia at ca 1.27 Ga ago.

  • 49.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Mattsson, Håkan J.
    Luleå tekniska universitet.
    A paleomagnetic and AMS study of the Rätan granite of the Transscandinavian Igneous Belt, central Sweden2001In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 123, no 4, 205-215 p.Article in journal (Refereed)
    Abstract [en]

    The 1.85-1.67 Ga Transscandinavian Igneous Belt (TIB) forms a major Paleoproterozoic igneous complex in the western part of the Fennoscandian Shield. Different tectonic models propose that the TIB was formed in a tectonic regime governed either by compression or by extension. This paper presents an analysis of anisotropy of magnetic susceptibility (AMS) and paleomagnetic data from the Rätan granite (1.70 Ga), which forms a large pluton in the central part of the TIB. The major aim of the study is to test the existing tectonic models and to define a paleomagnetic pole position for the Rätan granite. Three contrasting magnetic fabric domains are identified. In the eastern and western domains the AMS fabric is characterized by NW-SE to N-S trending subvertical foliation planes and a girdle distribution of the maximum and intermediate anisotropy axes. The central domain is characterized by subhorizontal magnetic foliation planes and lineations that cluster in a NW-SE trending direction. We suggest that the Rätan granite was emplaced in a tectonic regime governed by NW-SE directed extension and that the pluton was fed obliquely with a magma source situated to the present northwest. A positive baked contact test is demonstrated for a basic dyke suggesting that the Rätan granite has not been remagnetized since c. 1.6 Ga. A paleomagnetic formation mean direction is defined for the granite (decl. = 2°, incl. = 59°) that yields a paleopole position of Plat = 67° and Plon = 190°.

  • 50.
    Elming, Sten-åke
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Mikhailnova, N.P.
    Ukrainian Academy of Sciences.
    Kravchenko, S.
    Ukrainian Academy of Sciences.
    Palaeomagnetism of Proterozoic rocks from the Ukrainian Shield and the consolidation of the East European Craton1998In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 16, no Suppl. 1, 103- p.Article in journal (Other academic)
123 1 - 50 of 131
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