THE NORTHEASTERN END OF THE DUNNAGE ZONE IN NEWFOUNDLAND

The northeastern end of the Dunnage Zone comprises the Notre Dame Subz one, bounded to the southeast by the Red Indian Line, and the Exploits Subzone bounded to the southeast by the GRUB Line, the boundary of th e Dunnage Zone against the Gander Zone. The Notre Dame Subzone consist s of diverse, fault-bounded assemblages of Arenig and older rocks empl aced in oceanic settings. The Exploits Subzone includes four fault-bou nded belts distinguished by their Silurian stratigraphies (Badger, Bot wood, Duder [new] and Indian Islands belts). All exhibit Ashgill-Lland overy, southeast-vergent sinistral thrusting which emplaced a fragment of the Botwood Belt on the Indian Islands Belt. Progressive post-Wenl ock Silurian deformation produced dextral faults and upright folds eas t of the Dog Bay Line, a Silurian terrane boundary, whereas west of th e line it produced northwest-vergent folds. Late Silurian to Devonian brittle sinistral motion modified the Red Indian and GRUB lines. Struc tural and stratigraphic observations suggest early Arenig obduction of the margin of the Exploits Subzone onto the Gander Zone followed by e astward subduction of old ocean crust (Notre Dame Subzone), along the Red Indian Line, produced a west-facing volcanic are. Are rifting in l ate Arenig time produced an active back-arc basin. Rapid basin filling and structural inversion, accompanied by eastward thrusting began in Ashgill time, probably due to arrival of Laurentia at the subduction z one. Remnants of the back-are basin were closed by westward subduction in Llandovery and Wenlock time. Continent-continent contact, accompan ied by further compression and extrusion of wedge-shape fragments betw een conjugate faults, occurred in late Silurian time.