Comparison of quaternary glaciogenic debris flows with blocky mass- Transport deposits in orphan basin, offshore eastern Canada

Abstract

Quaternary deposits in southern Orphan Basin include complex mass transport deposits (MTD) comprising both glaciogenic debris flows (GDF) and blocky MTD. 3D seismic reflection data were used to highlight the difference between the two types of MTD. The main MTD in southern Orphan Basin were sourced from the slope off Trinity Trough in the west of the basin. On the Trinity Trough-mouth Fan, a succession of GDF was deposited above horizon B5, interpreted to date from Marine Isotope Stage (MIS) 12. Beyond the direct influence of Trinity Trough, MTD unit 2 below horizon B5 is confined within pre-existing channels, which are in approximately the same location as the modern Bonanza Channel and Sheridan Channel. Blocky MTD are characterized by linear and divergent basal grooves and chaotic internal facies. Dispersed blocks, less than 1 km2 in area, are commonly present within the blocky MTD on the southern Orphan slope. The tongue of the main Sheridan MTD is sharp-edged, with a series of closely spaced pressure ridges. 3D seismic data of GDFs show few features diagnostic of blocky MTD. Both stacked GDF lobes and channelized GDF are observed on Trinity Trough-mouth Fan. © Springer Science+Business Media B.V. 2012.