Holocene relative sea-level reconstruction for the central great barrier reef, Australia: a subtidal foraminiferal approach

Abstract

Contemporary subtidal foraminiferal samples and associated environmental Information were collected from two embayments along the central Great Barrier Reef coastline, Australia, to comprehend the relationship of benthic foraminiferal assemblages with respect elevation and their environment. Subtidal foraminifera from Bowling Green Bay illustrate a strong relationship with elevation (-6.7m to - 48.0m AHD), whereas samples from Cleveland Bay display an arbitrary relationship to elevation (-4.2m to - 9.8m AHD). The datasets were combined to generate a regional training set for the first foraminifera-based subtidal transfer function, subsequently applied to 13 fossil vibracore samples, reconstructing former sea levels. The results show a comparable trend with regional geophysical models, depicting a rapid transgression across the shallow continental shelf to a constrained mid-Holocene highstand and a subsequent late Holocene fall. Analysis of the results reveals that benthic foraminifera can be related to subtidal elevation. Furthermore, the subtidal foraminiferal transfer function can be used to reinterpret subtidal samples to generate more accurate and precise reconstructions. This is the first foraminifera-based subtidal transfer function for environmental interpretations and thus may benefit existing semi-quantitative subtidal reconstructions through reinterpretation with a fully quantitative technique. In addition, combination with an inter-tidal foraminifera-based transfer function may help widen the window of our understanding of contemporary benthic foraminiferal distributions and assemblages, and hence prove a more valuable tool for palaeoenvironmental reconstruction.