Paradoxical mid-crustal displacements and stratigraphic continuity: structural evolution of the northeastern Paleoproterozoic Amer belt, Nunavut, Canada

The structural geology of the northeastern Paleoproterozoic Amer belt, central Nunavut, has been evaluated in light new field mapping combined with legacy data and independently acquired subsurface geophysics data. Proterozoic sequences Ps1–Ps4 supergroup unconformably overlie Archean basement. Of these sequences, Ps1–Ps3 have intensely deformed (D 1 ) association Snowbird Orogeny (2.05–1.865 Ga). Ps4 was deposited on first three exhibits none D effects. Deformation within is slight compared to underlying restricted 2 folding that occurred 1.84–1.81 Ga Hudsonian Orogeny. forms core this study. comprises imbricate thrusting, intersequence detachment, generations isoclinal transposition. stratigraphic order maintained many areas by decoupling sequence packages along incompetent units so as not “mix” lithologies; there a fundamental mechanical stratigraphy. Within transposition can be otherwise intense. resultant architecture shallowly southwest-dipping tectonically rotated transposed layering (primary tectonic) similar ways orientation regardless whether preserved original bedding features or completely transposed. characterized recumbent folds, noncylindrical folds are sometimes rooted detachments, verging northeast. controlled pre-existing large-scale fabric, resulting overturned synforms parallel belt. Post-D fault modification northern side belt northwest-trending faults interpreted relate extension exhumation.