A Record of Holocene Benthic Foraminifera in Vibrocore SG#279, Spencer Gulf, South Australia

Abstract

Core SG#279 recovered 1.1 m of Holocene bioclastic sediment from northern Spencer Gulf, South Australia. Benthic foraminifera preserved in these sediments provide proxies for the postglacial marine transgression. Species that are characteristic of tidal dominated, coastal seagrass meadows, Cribrobulimina mixta + Nubecularia lucifuga + Peneroplis planatus + Discorbis dimidiatus decrease in numbers upcore confirming their potential to signify a rising sea. Massilina milletti, which favours the deeper waters of northern Spencer Gulf, increases in abundance upcore, thus also signifying the transgression. Quinqueloculina lamarckiana, which positively correlates with increasing water depth in northeastern Gulf St Vincent, similarly provides evidence of the transgression. Maximum water depth is indicated for the core sediments at 40 cm. Data based on the distributions and relative numbers of Elphidium crispum and Elphidium macelliforme were not in accord with those of the other proxy species. It is concluded that the Elphidium ratio is unreliable when applied to sediments deposited at depths of <15 m. Above 40 cm in the core, the distribution of M. milletti provides evidence of marine regression that has been attributed to hydroisostatic uplift of northern Spencer Gulf. The foraminifera provide no credible evidence of any late Holocene sea level rise.