Late Cretaceous stratigraphy and sedimentology of Cape Lamb, Vega Island, Antarctica

An important new section for the latest Cretaceous marine sedimentary record is described from Cape Lamb, Vega Island, Antarctica. Some 480 m thick, it has been divided into three lithostratigraphic units of member status. Both micro- and macrofossil evidence indicate that members A and B are of late Campanian to early and mid-Maastrichtian age; the latter unit is unconformably overlain by the late Maastrichtian Member C.

Definition of the lithostratigraphic units will aid local correlations within the James Ross Island area. Partial correlation with the major Cretaceous-Tertiary boundary reference section on Seymour Island has been achieved using both ammonite and dinoflagellate cyst taxa. It is apparent that there are major lithofacies differences between the two localities, which are thought to reflect a proximal to distal depth gradient into the depositional basin.

The macrofauna has been grouped into two broad associations: a lower one based on the ammonite Gunnarites and an upper one based on Maorites. It is hoped that this sequence may form the basis of a formal kossmaticeratid ammonite zonation of the latest Cretaceous of the southern Gondwana margins.

The sedimentology of members A and B reflects deposition in a shelf setting and records a transgressive-regressive pulse. Member C was deposited in shelf, shoreface and marginal marine environments, and shows evidence of both coeval arc volcanism and localized basin uplift.