The occurrence of flow transformations within sandy submarine fans: A case study from the Eocene on Spitsbergen

Abstract

The Van Keulenfjorden transect on Spitsbergen offers valuable insight into submarine processes, with well exposed seismic scale clinoforms of Paleocene and Eocene age, which show the distribution of sediments from deltaic to basin floor environments. Several progradational submarine fans are preserved as cliffs on Hyrnestabben. They serve as an analogues to coarse grained submarine fans in provinces of the Barents Sea margin. The architecture of submarine fan bodies is of importance to petroleum exploration, as the distribution of sand prone lobes impact fluid migration reservoir compartmentalization, and the presence or absence of baffles. Gravity flow processes emplace different deposits affecting deep sea fans that change according to both allogenic and autogenic factors, at scales below the limits of seismic detection.

Detailed sedimentological and stratigraphic study was conducted on three shelf proximal submarine fans, of the Frysjaodden Formation, to record and characterize flow transformations as they occur in the deep sea environment. The fans had similar overall stacking patterns, with thin bedded heterolithic deposits overlain by thick sandy amalgamated lobes. The progradational sandy submarine fans were exposed in an area less than 3km in length, and contained deposits from hybrid flows, turbulent gravity flows, and debris flows. Evidence for flow transformations occurred as linked debrites both proximal to the slope and in distal locations, the result of abrupt slope changes and down flow changes flow process. The occurrence of sandy lobes, heterolithic sheets, and mixed debrites did not follow a well-defined systems tract, rather they were interbedded, expressions of local lateral changes in topography and sediment supply.