SEDIMENTARY PROCESSES IN EPICONTINENTAL SEAS AT HIGH LATITUDES – WHAT HAPPENS TO THE PARADIGM WHEN YOU RESTRICT THE INFLUENCE OF GLACIERS IN THESE SETTINGS?

Fundamental research on the sedimentological processes operating to control lithofacies variability in mud-dominated epicontinental seas has mainly concentrated on low latitude depositional settings. Where high latitude processes have been investigated researchers have mainly observed that melting glaciers have been the dominant process controlling patterns of sedimentation. Melting glaciers in these settings may produce large volumes of sediment, some of which may be fine grained, which is then dispersed by tidal driven suspension settling mechanisms and hyperpychnal currents.

At high latitudes, particularly when iceberg calving activity is limited either because fast shore ice is present or where glaciers are not dumping sediment directly into the sea (e.g. in relatively arid conditions), sedimentary processes may be driven more by the presence of melting sea ice and the effects of storms. Here, sedimentation rates are episodic and may be very low, and a significant fraction of the sediment may be derived from primary production in the photic zone.

The aim of this paper is to illustrate some of the lithofacies present in high latitude settings where sea-ice and storm activity were dominant using the L. Cretaceous (Hauterivian to Barremian) aged succession deposited at paleolatitudes >70°N as an example. Individual depositional units in this fine grained succession commonly crudely upward-fine, contain dropstones, are organic matter- and pyrite-rich, comprise organominerallic aggregates and are variably bioturbated.

These data indicate that not all epicontinental seas at high latitudes are dominated by glacio-marine process, and that primary productivity can be particularly significant when iceberg sedimentation is restricted. In contrast, to regions where glacial processes are dominant, these regions maybe significant sites of organic carbon sequestration and are very different from those associated directly with glacial melting.