The role of tectonics and eustasy in the evolution of a marginal basin: Cretaceous-Tertiary Larsen Basin, Antarctica

A 5–6 km thick, Cretaceous–Tertiary, marginal basin succession is exposed in the James Ross Island area (northern Antarctic Peninsula). Deep‐marine fan facies and slope‐apron facies (c. 2.5 km) are succeeded by shallow‐marine shelf‐deltaic deposits (c. 3 km). The deep‐marine sedimentary rocks were deposited adjacent to a tectonically active basin margin and show little evidence of relative sea‐level change. Intra‐ and extra‐basinal tectonics were the major control on sedimentation; eustatic events have not been recognized. During the (?)Coniacian a peak in proximal volcanism increased sediment supply to the basin in the James Ross Island area. Continued tectonic uplift and passive basin filling led to partial shallowing within the basin. Widespread shallow‐marine sedimentation did not develop until the Santonian–Campanian, coinciding with basin uplift, widening of the shelf, and decreased tectonic activity. Post‐Santonian sedimentation was partially controlled by minor base‐level changes, possibly eustatically driven, although the current biostratigraphic resolution does not allow direct correlation.