QUATERNARY AND LATE PLIOCENE SEISMIC STRATIGRAPHY OF THE CENTRAL SCOTIAN SLOPE FROM HIGH-RESOLUTION REFLECTION SEISMIC

High-resolution single channel seismic reflection profiles collected by the Geological Survey of Canada Atlantic (GSCA) have been used to define the Quaternary and Late Pliocene seismic stratigraphy of the central Scotian Slope, southwest of Sable Island Bank. Reflection profiles used in this study have a dominant frequency at 180 Hz providing near 1 m vertical resolution. This resolution, approximately tenfold that of industry data, is ideal for describing the seismic facies and seismic stratigraphy of Quaternary and Late Pliocene strata of the central Scotian Slope.

Late Pliocene and Quaternary strata are represented by coherent, laterally continuous reflectors that thin or pinch out down-dip. Draping of reflectors over subsurface irregularities indicate the general mode of sediment deposition is by hemipelagic drape. Pre-glacial, Late Pliocene to early Quaternary sediment was deposited during a period of relative slope stability that is interrupted only by a period of widespread gullying. Glacial, mid- to late Quaternary strata are truncated by numerous slump scars indicating a period of slope instability. Several key reflectors have been identified and correlated throughout the study area. Isochron maps constructed from these reflectors indicate that pre-glacial sediment accumulated uniformly on the slope, whereas glacial sediment accumulated preferentially on the upper slope. In addition, numerous examples of slope instability were observed, including sediment failures, mass transport complexes, and structures related to near surface salt deformation.