REGIONAL KINEMATICS INFERRED FROM MAGNETIC SUBFABRICS IN ARCHEAN ROCKS OF NORTHERN ONTARIO, CANADA

Strain analysis, observations of L-S fabrics and studies of the anisot ropy of magnetic susceptibility (AMS) and of anisotropy of isothermal remanence (AIRM) reveal a sequence of progressive fabric development d uring regional deformation. L-S fabrics of quartz and feldspar grains are most transposed in regional transpression whereas the AMS subfabri cs, controlled by the properties of late metamorphic silicates, record a later orientation of the ambient stress field. Anisotropy of magnet ic remanence is caused by the still younger minerals, magnetite and py rrhotite. Its anisotropy is less transposed than the AMS subfabric. Co nsequently the relative orientations of the three types of fabric yiel d a kinematic sequence of subfabrics developed during transpression. T he L-S fabrics are most transposed, the AMS less transposed and the AI RM fabrics least transposed toward the plane of regional flattening. T he results indicate that the deformation recorded by the three subfabr ics was non-coaxial in the most general sense, with all three principa l directions spinning with respect to the rocks during progressive str aining.