High-resolution sequence stratigraphy of clastic shelves IV: High-latitude settings

High-frequency clastic shelf sequences deposited in high-latitude settings display marked differences, in term of facies and stratigraphic architecture, with respect to their lower latitude counterparts. This is due to the presence of ice which (1) leads to the accumulation of glacigenic and glacimarine deposits; (2) provides an additional control on accommodation; and (3) determines the position of the shoreline. Transgressions and regressions in glaciated settings are controlled respectively by the retreat and advance of the ‘ice’ shoreline (i.e., the water/ice contact) irrespective of relative sea-level changes; once the ice retreats across the land, the traditional ‘land’ shoreline is exposed and the control on sequence architecture is exerted by the interplay between relative sea-level changes and sediment supply as in low- and middle-latitude settings. A general model that includes both glacial and non-glacial climatic regimes is provided by this paper. In this frame, the classic sequence stratigraphic model represents one (ice-free) end member, which is opposed to an ice-permanent end member. Between these end members, sequences may accumulate in part under ice-free conditions and in part under conditions dominated by ice on the shelf. The main implication of this is that the classic sequence stratigraphic model may be viewed as only a possible scenario in the stratigraphic record rather than the rule.