Structural history of the metamorphic sole of the Bay of Islands complex, western Newfoundland

Displacement of the Early Ordovician ophiolitic Bay of Islands Complex was accompanied by the development of a metamorphic sole. A major foliation is pervasively developed in the greenschists and amphibolites. An extension lineation is widely developed and plunges north in amphibolite and trends east-west in greenschist, consistent with a changing direction of thrust transport from northerly to westerly as the mantle wedge cooled over time. In the SW Blow-Me-Down massif, two sets of folds postdate development of accretion-related S-L fabrics and resulted in a substantial widening of the metamorphic sole. Late disruption by foliation-parallel, low-angle extensional and steep faults have excised parts of the metamorphic sole, resulting in a marked discontinuity of units along strike. Extensional faults were induced by gravitational spreading as the Coulomb thrust wedge, containing the ophiolite, metamorphic sole, and underlying melange unit, became supercritical. -from Authors