The 1985 and 1986 Hobson's Choice Ice Island reflection experiment produced nearly 2000 field records. The data collection utilized a Sercel SN-358, 120 channel, digital recording system with a 3529 m geophone array and thirteen permanent shotpoints with standard charge sizes of 1 kg of explosive. The field observations were highly contaminated with multiple and fexural wave interferences. Data-dependent trace sorting and multiple suppression routines were developed to improve the signal-to-noise ratios. After implementation of an extensive processing sequence, four reflecting horizons were mapped below the water-bottom interface. The reflection-derived average interval velocities of these rock sequences are 2.75 km/s, 3.65 km/s, 5.18 km/s and 5.85 km/s. Correlation of these acoustic properties to stratigraphically defined wireline log information and comparable geophysical results suggests that, 23 km west of Axel Heiberg Island, the polar continental shelf is formed by Tertiary, Mesozoic and Upper and Lower Palaeozoic rock sequences. Interpretation of the seismic data reveals an average sedimentary rock cover of at least 4.0 km in thickness under the path travelled by the island. The well-distinguishable wave patterns of several seismic sections are interpreted, in correlation with potential field anomalies, as an indication of an offshore extension of the Princess Margaret Arch, west of Axel Heiberg Island.
ASJC Scopus subject areas
- Geochemistry and Petrology