Atlantic Geology 227 Structural transect through Silurian turbidites of the Fredericton Belt southwest of Fredericton, New Brunswick: the role of the Fredericton Fault in late Iapetus convergence

Excavations along the 23 km stretch of the Longs Creek to Fredericton section of the new Trans-Canada Highway created new exposures affording a transect through part of the Fredericton Belt west of, and including, the Fredericton Fault. This transect lies entirely in the Burtts Corner beds of the Silurian Kingsclear Group, revealing a multi-deforma-tion history. Earliest structural elements in the turbidites include a slaty cleavage (S1) that is close to being bedding-parallel in most places. No F1 fold closures have been identifi ed, but small enclaves of inverted bedding imply that such structures exist but are of limited scale and restricted occurrence. The most conspicuous structures are upright to overturned, open to tight F2 folds with chevron profi les, a locally well-developed axial planar slaty cleavage (S2) and a related crenulation lineation on S1 (L12). These folds have curvilinear hinge-lines that show an increase in curvilinearity toward the Fredericton Fault, coincident with a tightening of the interlimb angle. Lineations related to layer-parallel slip during F2 fold generation remain constant implying the changing geometry is a consequence of changing bulk strain rather than fold interference. Post-F2 structures include a sparsely developed set of chevron folds with horizontal axial planes (F3) and a poorly developed axial planar slaty cleavage (S3). At least two sets of late kinks have also been noted. Systematic variations in style and form of the F2 folds suggest a relationship with the precursor to the Fredericto