Billie‑Jo Gauley

Shallow sediment failures within late Quaternary material are widespread along the Scotian Slope and are a concern for offshore hydrocarbon development. During the Wisconsinan glaciation, slope lithostratigraphy was strongly influenced by outer shelf glacial processes and this probably is a factor in the location and style of sediment failures. This study focuses on a central region of the Scotian Slope between 62^o 34'W and 61^o 20'W, which contains both undisturbed and failed sediment. A seismic stratigraphy has been developed for the region by tracing nine key reflectors throughout Huntec DTS profiles. An associated composite stratigraphic sequence of ~30 meters has been sampled by piston coring specific target areas. A chronology was derived from radiocarbon dating shells and use of ice rafting events (brick red mud and Heinrich layers) of well-documented age. Within the study area, failure within sediment occurs as rotational slumps, retrogressive failure, bedding plane slides, creep blocks over decollement surfaces, debris flows, and turbidity currents. Failures begin at water depths of 500 meters and continue downslope beyond 2500 meters. One prominent decollement surface can be traced upslope where it appears to lie directly above one of several till tongues. At least three of the key reflectors within the seismic profile have acted as either failure planes or as depositional surfaces for failed sediment. Large-scale failures have occurred no more recently than 12 ka. The timing of sediment failures and their relationship to the lithostratigraphy are important to predict future events.

Keywords:
Pages:
Supervisor: D.J.W. Piper