quetico fault in the superior province of the southern canadian shield
abstract
the quetico fault is a major transcurrent fault in the
southern superior province of the canadian shield. along part of
its length the fault forms the boundary between the
wabigoon subprovinces. dextral motion on the fault
by dextral microfaults and appropriately asymmetrical quartz
c-axis petrofabrics.
the fault comprises a zone of dynamically metamorphosed
rocks - primarily mylonitic rocks with some cataclastic rocks and
pseudotachylite. a transition from predominantly ductile
deformation to brittle deformation occurred during the time the
fault was active.
the ductile deformation of quartz within the fault zone
is the result of crystal-plastic processes,
prism planes in the a-direction and slip on
a-direction, accompanied by dynamic recovery and syntectonic
recrystallization. feldspar grains are commonly deformed in a
brittle manner by fracture processes. particulate flow appears
to have made a significant contribution to deformation in the
fault zone.
the harmonic mean of deformed grain axial-ratios and strain determinations by the all object-object separations method
indicate that flattening strain is predominant within the fault
zone. the magnetic susceptibility anisotropy ellipsoid is also
flat-shaped and coaxial with the strain ellipsoids. the
characteristics of microfaults and folds within the fault zone
indicate that flattening may have been accompanied by or followed
by shearing. the harmonic mean of deformed quartz grain axial
ratios yields a minimum strain estimate of 130% extension in x,
58% extension in y, and 71% shortening in the 1 direction.
collections
- retrospective theses [1604]