Sea-level Indicators From A Holocene, Tide-Dominated Coastal Succession, Port Pirie, South Australia

Abstract

Peritidal Holocene sediments at Port Pirie in the northern Spencer Gulf of South Australia contain several indicators of sea-level change over the last 7,000 years BP. The elevations of present subtidal, intertidal and supratidal environments and corresponding sediment facies were surveyed in order to establish critical boundaries relative to the tidal spectrum. The subtidal Posidonia facies occurs at or below mean low water spring (MLWS) tide; intertidal sandflat, mangrove and samphire facies occur over specific intervals between MLWS tide and mean high water spring (MHWS) tide. Each facies is clearly identifiable in the subsurface, with intertidal sandflat facies particularly characterised by in situ articulated bivalves Anapella cycladae and Katelysia scalarina or K. peronii. A combination of several palaeosea-level indicators from different tidal facies best defines local sea-level change over the millennial timescale.