Infill of a structurally controlled estuary: An example from southern Whanganui Inlet, New Zealand

Abstract

Whanganui Inlet, South Island, New Zealand, is a structurally controlled estuary where most of the accommodation space has been occupied by sediment and expanses of mud/sand flats are exposed at low tide. A flood-tide delta extends 1.5 km from the entrance; however, both a mud basin and surfical fluvial deltas are absent from the inlet. Sedimentological and foraminiferal analysis of vibrocores from the inlet's southern half indicates that the intertidal flats accreted close to modern elevations soon after sea level flooding. The present surfical morphology of Whanganui Inlet therefore appears to be inherited from sedimentation that took place soon after sea level stabilized, with little deposition now occurring on the intertidal flats. © 2008 The Authors Journal compilation © 2008 The New Zealand Geographical Society.