THE MONASHEE DECOLLEMENT AT CARIBOO ALP, SOUTHERN FLANK OF THE MONASHEE COMPLEX, SOUTHERN BRITISH-COLUMBIA, CANADA

The Monashee decollement is a crustal-scale compressional shear zone i n the southern Canadian Cordillera; it is well exposed in alpine terra ne and is imaged in the subsurface by LITHOPROBE seismic-reflection pr ofiles. The decollement separates middle- to upper-crustal allochthono us assemblages from underlying middle- to lower-crustal rocks of the o rogen. Development of the exposed part of the decollement at Cariboo A lp in the southern Thor-Odin culmination has included formation of maj or isoclinal folds, superposition of smaller scale folds during progre ssive deformation, and transposition of early formed fabrics and strat igraphic boundaries into the dominant SW-dipping mylonitic planar fabr ic. Hinge lines of early folds have been rotated toward the strong con sistent SW-plunging mineral stretching lineation. As a result of NE-di rected shearing of fold limbs and thrust-stacking of these folded shee ts between a basal shear zone and overlying allochthonous assemblages, an imbricate zone developed within the middle crust during peak metam orphic conditions.