Structure of Bedrock Offshore From Point Aconi, Cape Breton Island, Nova Scotia

Abstract

The Prince Colliery is a major offshore coal mine operated by the Cape Breton Development Corporation (DEVCO) in the Hub coal seam of the Sydney Mines Formation (Upper Carboniferous). This thesis presents the results of a multibeam swath bathymetry and high resolution seismic survey in the area offshore from Point Aconi, Cape Breton Island. The multibeam bathymetric data set generally shows the surface expression of the MacKenzie Syncline, a major structural feature in the study area. The Atlantic Geoscience Centre (AGC, Geological Survey of Canada) designed the seismic survey to delineate more precisely the geological structure of bedrock in the area of anticipated mine development. Seafloor morphology influences the interpretation of the seismic data by producing drawdown effects on the seismic record. The seismic data extend the surface structural trends downwards, defining the three dimensional geometry of the bedrock. In addition, two coal seams (Lloyd Cove and Point Aconi coal seams) correlate with specific bedrock reflectors. The seismic data set shows no evidence of faulting. The conversion of the interpretation of structure from two-way time to depth can account for survey geometry and drawdown resulting from unconsolidated sediments. Mine planning at the Prince Colliery accounts for thickness of bedrock, which varies laterally with the depth of the Hub coal seam and thickness of unconsolidated sediments. This new interpretation is, therefore, of benefit to mine planning activities at the Prince Colliery.

Keywords: hign resolution seismology, coal, Prince Colliery,mine planning, Sydney Mines Formation, Sydney basin, multibeam sonar, seafloor morphology Pages: 99 Supervisor: Robert Courtney