Sill stratigraphy and sedimentology in marine inundated basins, Sachs Harbour, NWT, Canada

• Main Author: Martin, Bryan G.
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2009
• Subjects: Arctic; Canada; Sachs Harbour; Banks Island
• Online Access: https://research.library.mun.ca/8955/; https://research.library.mun.ca/8955/1/Martin_BryanG.pdf

This study focuses on the seismic interpretation and core-based sedimentology of shallow, coastal marine basins and their sills in the western Arctic to better constrain local relative sea level (RSL) records. -- On transgressive coastlines, sea level rise can be measured using the inundation basin approach, which utilizes former coastal freshwater lake basins that have become inundated by marine water as sea level rises. The amount of sea level rise since inundation occurred is measured as the vertical distance between the lowest part of the former lake basin margin - the sill - and the current sea level position. While the approach has been typically applied to basins with rock-cored sills, this study investigates the opportunities and constraints presented by inundation basins with sediment-cored sills, which are more susceptible to post-inundation modification. Specifically, the study examines the processes acting on sediment-cored sills during transgression and their related sedimentary signatures. -- The study was carried out at Sachs Harbour, located on Banks Island in the western Canadian Arctic. The regional coastline is submergent with extensive evidence of drowned estuaries and inundated lakes. Sills associated with five basins were investigated using sediment coring techniques, airphoto analysis, and seismic profiling. Air photo analysis and field observations of two basins that have experienced relatively recent marine inundation suggest that initial marine penetration took place through the former lake outlets. It was hypothesized therefore that a similar inundation process took place in the deeper basins of Sachs Harbour. -- Two buried channels and an erosion surface were identified on the seismic profiles of two sills and were subsequently targeted for coring. Recovered sediments (80-130 cm thickness) from channels were predominantly mud, which is interpreted to represent post- submergence marine sedimentation by suspension settling. A sediment core from one channel did not penetrate the channel ...