Abstract
Apparent polar wander paths and the close of late Archean crustal transpression, northern Ontario
Geology and Physics Department, Lakehead University, Thunder Bay, Ontario, Canada
Geology and Physics Department, Lakehead University, Thunder Bay, Ontario, Canada
Geology and Physics Department, Lakehead University, Thunder Bay, Ontario, Canada
Lamprophyre dikes of the southern Superior Province of the Canadian Shield crosscut Archean structures, including a late Archean
unconformity and its overlying younger Archean Timiskaming sedimentary and volcanic rocks. The dikes also cut the single schistosity
that formed in these rocks. Nevertheless, the lamprophyre dikes show a weak internal tectonic fabric that is approximately
parallel to the schistosity in the bedrock and oblique to dike walls. The consistent orientation of this internal tectonic
fabric has been recognized in every lamprophyre dike using anisotropy of magnetic susceptibility (AMS). Thus the lamprophyre
dikes provide a useful chronological marker, trapping the last pulse of Archean tectonism. Unfortunately, our previous attempts
to compare the lamprophyre paleopoles with those of the age-calibrated apparent polar wander path (APWP) failed because it
was not possible to isolate separate young and old components of magnetization. That failure occurred due to the overlap of
blocking temperatures or coercivities for the different characteristic vector components [
Received 30 December 2002; accepted 8 April 2003; published 29 August 2003.
Citation: (2003), Apparent polar wander paths and the close of late Archean crustal transpression, northern Ontario, J. Geophys. Res., 108(B8), 2402, doi:10.1029/2002JB002379.
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