Glacigenic debris-flow deposits, Storfjorden Fan

Abstract

Glacigenic debris-flow deposits (Laberg & Vorren 1995; Laberg et al. 2012) are the most prominent component of high-latitude trough-mouth fans (TMFs), which develop off fast-flowing ice streams which occupy cross-shelf troughs during full-glacial periods. Glacial erosion and sediment transport to the shelf edge are most effective during glacial maxima; debris-flow deposits therefore represent short periods of a very high input of glacigenic sediments to the continental slope when the ice front reaches the shelf break. Conversely, relatively limited amounts of mostly hemipelagic sediments accumulate on the continental slope during interglacial periods (Dowdeswell et al. 2002). Storfjorden TMF consists of three coalescent lobes (I–III) produced by three ice streams (Fig. 1a, b). It is dominated by an extensive network of gullies on the upper continental slope (Pedrosa et al. 2011; Lucchi et al. 2013) that do not cut back deeply into the continental shelf and are typically 5–20 km long (Fig. 1c, d). The gullies are nearly straight or have a low sinuosity, and are generally less than …