Abstract

The Wager shear zone (WSZ) is characterized by progressive bending of northeast–southwest-trending aeromagnetic anomalies to the right as they merge with east–west-trending anomalies characterizing the shear zone. This feature indicates dextral net shear. Mapping of abundant and diverse asymmetrical structural fabric elements within the shear zone where it is well exposed along the south coast of Wager Bay, northwestern Hudson Bay, consistently confirmed dextral shear sense.Pervasive, dextral shear-zone mylonites were deformed by folds with hinges parallel to the shear direction (a folds), as well as by discrete, conjugate sinistral and dextral mylonitic shears. To form a folds in mylonites it is necessary for the mylonitic fabric to rotate out of a stable orientation in the plane of shear and flattening and also to rotate about an axis parallel to the shear direction, for which we have no general explanation.We conclude with the speculation that the WSZ is a strike-slip fault related to terminal collision of the Archean plate of Ungava with the Archean plate to the north marked by the 1.8 Ga Sugluk suture.

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