Implications of a microfossil-based transfer function in Holocene sea-level studies

Fifty-two sea-level index points are described from samples collected within the Land-Ocean Interaction Study area. The vertical relationship between relative sea-level and a reference water level for each index point was estimated using two contrasting methods: a lithological-based approach, which is routinely employed in sea-level studies, and a foraminiferal-based transfer function. Comparison of the two methods reveals that the range of the former is 0.14 ± 0.09 m smaller than the latter because the foraminiferal-based transfer function takes into account differences in tidal ranges between study sites. Furthermore, the reference water-level estimates of transgressive index points using the foraminiferal-based transfer function are on average 0.19 ± 0.12 m higher than those of the lithological-based approach. This may be due to the rapid response time of foraminiferal assemblages relative to lithological indicators or the uneven spatial sampling within the contemporary foraminiferal data set. Whilst these inter-method differences are small in magnitude, they are comparable in size to the scale of changes under investigation by recent high-resolution sea-level studies. In contrast, the reference water levels of both methods are comparable for regressive and basis index points. Index points from clastic sediments were also produced using the foraminiferal-based transfer function. Calcareous foraminifera from intertidal environments can be used to produce indicative meanings and supply material for accelerator mass spectrometry radiocarbon dating. This method expands the range of stratigraphic sequences that can be employed in sea-level reconstruction by redressing the over-reliance on transgressive and regressive contacts.