Matt Robichaud


B.Sc. (Honours) Thesis

Late Quaternary Evolution of the Northeast Fan, Offshore Nova Scotia

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Northeast Fan is a submarine fan developed seaward of Northeast Channel, located on the southwestern part of the Scotian Margin. Northeast Channel has been recognized as a major ice-stream outlet during the last glacial maximum (18 ka). Seaward of Laurentian Channel, the other major ice stream outlet off Nova Scotia, is the well known Laurentian Fan. The scope of this study is to explore the late Quaternary architecture of Northeast Fan with the use of six strike seismic lines and four piston cores, to test the hypothesis that Northeast Fan resembles a smaller version of Laurentian Fan. Creation of a detailed contour map of bathymetry for the Northeast Fan showed that the axes of three main channels could be traced, called Western, Central and Eastern channel. The interpretation of acoustic facies within the upper 50 m through the use of the high-resolution reflection seismic profiles (Huntec sparker) provided an acoustic facies distribution map. This map showed that the southwestern and upper slope portion of Northeast Fan is composed mainly of dissected reflectors or stratified and dissected reflectors, while the southeast and northeast portions of the Northeast Fan predominantly comprise of mass-transport deposits (MTDs) and highly stratified and stratified reflectors. Six reflection markers in the Huntec seismic profiles were correlated across most of the Fan, thus creating a stratigraphic framework. Cores showed the existence of one or two distinct units of brick red muds (>b= and >d=) and some contained a small tan mud layer identified as Heinrich layer H1. Turbidite sands found in cores were high above channel floors and some were deposited within the time interval of 18 ka and 14 ka. On the continental slope northeast of the Northeast Fan, three distinct high amplitude reflectors were observed in a Huntec profile, which show similar features to an area off the St. Pierre slope. They were interpreted to represent ice-proximal deposition at glacial maximums and correlated to Marine Isotope Stage (MIS) 4 and MIS 6. The MIS 6 reflector corresponds to the Pink marker of the study, which allowed the dating of two major MTDs in Northeast Fan. Although Northeast Fan does share some features with Laurentian Fan such as the development of channels across the slope and rise, major differences exist. The upper portion of Northeast Fan rather resembles The Gully or Banquereau canyons with the presence of shelf-breaching canyons.

Pages: 109
Supervisors: David J. W. Piper