| dc.description.abstract | The metasedimentary rocks along the traverse reveal low to
high grade metamorphism from chlorite schist near Atikokan,
through biotite schist to migmatites in the west within the
centre of the Quetico Belt. Continuing towards the ESE, near
Huronian Lake, the metamorphic grade decreases symmetrically but
with somewhat less steep gradients to Kashabowie. The
metamorphism was syn- to late- tectonic.
Only one pervasive tectonic fabric was observed in the
interior of the belt, with NE-SW striking S1 foliations (mean
direction: 256/85° NW, n=121) and extension lineations L1 plunging shallowly to the NE (mean direction: 70-20°, n=52). In
migmatite and pegmatite zones foliation was often less steep. It
was probably deflected due to the intrusion of pegmatite or
granitoid bodies.
Minerals contributing to ferromagnetic properties are
mostly monoclinic ferrimagnetic pyrrhotite within the belt with
some magnetite in medium grade amphibolite - rich outcrops in
metavolcanics of Shebandowan Belt.
Anisotropy of magnetic susceptibility fabric (AMS} is
mainly controlled by paramagnetic biotite or chlorite and
subordinate ferromagnetic pyrrhotite in metasediments of the
Quetico Belt. In some outcrops of mafic metavolcanics near
Kashabowie, the high magnetite content controls bulk
susceptibility more than its anisotropy. Variations in AMS
fabric are largely due to variations in relative composition of
magnetite, pyrrhotite and paramagnetic sheet silicates, not due
to changes in strain along the traverse. | en_US |
