The Kapuskasing uplift is an enigmatic northeast
trending belt of high-grade metamorphosed rocks that cuts obliquely
across the dominant east-west trending lower grade lithologic
belts of the southern Archean Superior Province, the central
core of the North American craton. It is shown to be an intact,
west-dipping, 20km thick crustal, soled by an intracrustal
decollement above which 55-70 km of southeastward directed
thrusting brought mid-to-lower crustal rocks to the surface.
The upper crustal deformation was accompanied by the development
of a lower crustal root, up to 200 km wide and 12 km thick.
The shortening was accomplished by brittle faulting and erosion
at levels above 20 km and ductile folding or faulting in
the lower crust. A complex, multi-stage history is inferred:
- an ~2540 Ma event with a large component of east-west shortening
and ~10 km of thrust uplift;
- an ~1900 Ma dextral transcurrent event associated with
an additional ~10 km of uplift.
LITHOPROBE studies have documented the KSZ as being a "window" on
the mid-to-lower crust - an exposed crustal laboratory
from which new insights on the development of cratonic
already been derived.
Synthesis volume: Canadian Journal of Earth Science, V31,
#7, July, 1994
Kapuskasing Transect Reports