Canyon Heads and Channel Architecture of the Gollum Channel, Porcupine Seabight

Abstract

The Gollum channel is one of the few lengthy levéed channel systems on the European NE Atlantic margin (Fig. 1). GLORIA 6.5 kHz long-range sidescan sonar imaging (Kenyon et al. 1978) and single-channel high resolution seismics with air gun source (Gainanov and Volkonskaya 1998; McDonnell et al. 1998) mapped six canyon heads at the shelf break (ca. 300 m) on the western margin of the Celtic Sea (Fig. 2). Channel heads are asymmetric and progressively infilled from the south due to the influence of northerly contouritic sand transport along the upper slope in depths above ca. l,000 m (Fig. 3, Fig. 4). The channel heads feed into an anastamosing channel system that transports turbidity currents into the southern Porcupine Seabight (Wheeler et al. 1998). Dating of turbidites suggests activity was predominantly during glacial stages with very limited or no activity during the last ca.10 ka. (1995) propose that sediments are being transported in the channel by reversing currents causing scour in areas.