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Ulf Söderlund

Ulf Söderlund

Professor

Ulf Söderlund

Paleomagnetic and geochronological studies on Paleoproterozoic diabase dykes of Karelia, East Finland-Key for testing the Superia supercraton

Författare

  • J. Salminen
  • H. C. Halls
  • S. Mertanen
  • L. J. Pesonen
  • J. Vuollo
  • Ulf Söderlund

Summary, in English

Paleomagnetic results are presented for two Paleoproterozoic mafic dykes in the Taivalkoski area in northern Karelia Province of the Fennoscandian shield where, based on K-Ar data, the crust has seen minimal effects of the otherwise pervasive 1.8-1.9 Ga Svecofennian orogeny. Within this study a new U-Pb baddeleyite age of 2339 +/- 18 Ma has been determined for one of the E-W trending dykes (dyke AD13). The paleomagnetic results show that a strong Svecofennian overprinting is pervasive in the area. Upon thermal or AF demagnetization four remanence directions were obtained. Most typical are the secondary Svecofennian remanence direction A (intermediate down to the NNW) and remanence direction B (intermediate down to the NNE). Component D (D = 115.4 degrees, 1=50.5 degrees, alpha(95) =2.6 degrees) yielding a virtual geomagnetic pole (VGP) D (Plat= -19.5 degrees N, Plon= 263.3 degrees, A95 = 3.1 degrees) is obtained from baked rocks for dyke WD, and based on a positive baked contact test is interpreted to represent the primary magnetization dating from about 2.4 Ga. Dyke AD13 carries only secondary A and B components, its unbaked host migmatites carry reversed A (A(R)) component, and the baked host rock carries a component D' (D = 134.5 degrees, 1= -7.3 degrees, alpha(95) = 8.8 degrees), which yields a VGP pole D' (Plat= -20.4 degrees N, Plon = 257.3 degrees, A(95) = 7.6 degrees), possibly representing magnetization at 2.3 Ga. The new paleomagnetic data from the Karelia Province compared to similar-aged paleomagnetic data from the Superior Province does not support the recently proposed Superia configuration, based upon dyke swarm trajectories. (c) 2013 Elsevier B.V. All rights reserved.

Avdelning/ar

  • Berggrundsgeologi

Publiceringsår

2014

Språk

Engelska

Sidor

87-99

Publikation/Tidskrift/Serie

Precambrian Research

Volym

244

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Geology

Nyckelord

  • Supercontinents
  • Paleomagnetism
  • Paleoproterozoic
  • Superia
  • Karelia
  • Mafic dykes

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0301-9268