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Delineation and cha...
Delineation and character of the Archaean-Proterozoic boundary in northern Sweden
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- Öhlander, Björn (författare)
- Luleå tekniska universitet,Geovetenskap och miljöteknik
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- Skiöld, T. (författare)
- Laboratory for Isotope Geology, Swedish Museum of Natural History, Stockholm, Sweden
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- Elming, Sten-Åke (författare)
- Luleå tekniska universitet,Geovetenskap och miljöteknik
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- Claesson, S. (författare)
- Laboratory for Isotope Geology, Swedish Museum of Natural History, Stockholm, Sweden
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- Jensen, T. D. (författare)
- Greenland Geological Survey, Copenhagen, Denmark
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- Hobbs, R. W. (författare)
- Department of Geophysics, Stanford University, California, USA
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- Klemperer, S. L. (författare)
- Department of Geophysics, Stanford University, California, USA
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- Matthews, D. H. (författare)
- British Institutions' Reflection Profiling Syndicate (BIRPS), Bullard Laboratories, Cambridge University, Cambridge, UK
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- Snyder, D. B. (författare)
- British Institutions' Reflection Profiling Syndicate (BIRPS), Bullard Laboratories, Cambridge University, Cambridge, UK
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- Long, R. (författare)
- Department of Geological Sciences, Durham University, Durham, UK
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- Matthews, T. (författare)
- Department of Geological Sciences, Durham University, Durham, UK
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- Blundell, D. J. (författare)
- Department of Geology, RHB New College, Egham, UK
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- Lund, C-E (författare)
- Department of Solid Earth Geophysics, University of Uppsala, Uppsala, Sweden
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- Palm, H. (författare)
- Department of Solid Earth Geophysics, University of Uppsala, Uppsala, Sweden
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- Pedersen, L. B. (författare)
- Department of Solid Earth Geophysics, University of Uppsala, Uppsala, Sweden
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- Roberts, R. G. (författare)
- Department of Solid Earth Geophysics, University of Uppsala, Uppsala, Sweden
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- Heikinen, P. (författare)
- Institute of Seismology, Helsinki University, Helsinki, Finland
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- Korhonen, H. (författare)
- Institute of Seismology, Helsinki University, Helsinki, Finland
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- Luosto, U. (författare)
- Institute of Seismology, Helsinki University, Helsinki, Finland
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- Hjelt, S-E (författare)
- Department of Geophysics, Oulu University, Oulu, Finland
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- Komminaho, K. (författare)
- Department of Geophysics, Oulu University, Oulu, Finland
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- Yliniemi, J. (författare)
- Geophysical Observatory, Oulu University, Oulu, Finland
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- Meissner, R. (författare)
- Institute for Geophysics, Kiel, Germany
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- Sadowiak, P. (författare)
- Institute for Geophysics, Kiel, Germany
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- Wever, Th. (författare)
- Institute for Geophysics, Kiel, Germany
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- Dickmann, T. (författare)
- GEOMAR Institute, Germany
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- Flueh, E. R. (författare)
- GEOMAR Institute, Germany
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- Berthelsen, A. (författare)
- Institut for Almen Geologi, Copenhagen, Denmark
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- Tybo, H. (författare)
- Institut for Almen Geologi, Copenhagen, Denmark
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- Balling, N. (författare)
- Department of Earth Sciences, Aarhus University, Aarhus, Denmark
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- Normark, E. (författare)
- Department of Earth Sciences, Aarhus University, Aarhus, Denmark
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- Nisca, D.H. (författare)
- Luleå tekniska universitet
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(creator_code:org_t)
- 1993
- 1993
- Engelska.
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Ingår i: Precambrian Research. - 0301-9268 .- 1872-7433. ; 64:1-4, s. 67-84
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- 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.
Ämnesord
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geokemi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geochemistry (hsv//eng)
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geofysik (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geophysics (hsv//eng)
Nyckelord
- Applied Geology
- Tillämpad geologi
- Applied Geophysics
- Tillämpad geofysik
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- art (ämneskategori)
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Öhlander, Björn
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Skiöld, T.
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Elming, Sten-Åke
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Claesson, S.
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Jensen, T. D.
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Hobbs, R. W.
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visa fler...
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Klemperer, S. L.
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Matthews, D. H.
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Snyder, D. B.
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Long, R.
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Matthews, T.
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Blundell, D. J.
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Lund, C-E
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Palm, H.
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Pedersen, L. B.
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Roberts, R. G.
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Heikinen, P.
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Korhonen, H.
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Luosto, U.
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Hjelt, S-E
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Komminaho, K.
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Yliniemi, J.
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Meissner, R.
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Sadowiak, P.
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Wever, Th.
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Dickmann, T.
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Flueh, E. R.
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Berthelsen, A.
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Tybo, H.
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Balling, N.
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Normark, E.
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Nisca, D.H.
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