High interstadial sea levels over the past 420ka from the Huon Peninsula, Papua New Guinea

Abstract

The history of sea level across the Quaternary is essential for assessing past and future climate and geodynamics. Global sea-level reconstructions are typically derived from oxygen isotope curves, but require calibration with geological constraints that are particularly scarce prior to the last glacial cycle (>130 ka). The exceptionally well-preserved coral reef terrace sequence in the Huon Peninsula (Papua New Guinea) may provide such constraints up to ~420 ka, but has never been analysed in its full extent, or with high-resolution topographic data. Here we apply novel geometric approaches to show that the terrace sequence deformation pattern can be approximated by a northward tectonic tilt, and estimate relative sea-level (RSL) for 31 Late Pleistocene periods, including several periods for which no other RSL data exists elsewhere. Supported by reef modelling, these estimates suggest that global mean sea-level curves derived from oxygen isotopes systematically underestimate interstadial sea-level elevations, by up to ~20m. We propose that this discrepancy is either an effect of incorrect oxygen isotope curve calibrations, or that some short-lived sea-level variations are simply not recorded in oxygen isotope ratios.

Quaternary E‐W Extension Uplifts Kythira Island and Segments the Hellenic Arc

“…The apparent dip of the coastline toward the SE (Figure 7) may imply a true dip approximately S‐, SE‐ or E‐wards. In the case of a simple tilt, stacked swath profiles would show a continuous deformation pattern of paleoshorelines (straight lines) when looking at a perpendicular angle to the tilt (as in De Gelder et al., 2022). Looking at the scale of the whole island along four different projections the rasa is continuously tilted eastward within the northwards view (Figure 4c), varying from ∼400 m elevation in the west to ∼200 m in the east over a distance of ∼15 km, and at a relatively constant ∼400 m elevation in the westwards view (Figure 4f).…”

“…The apparent dip of the coastline toward the SE (Figure 7) may imply a true dip approximately S-, SE-or E-wards. In the case of a simple tilt, stacked swath profiles would show a continuous deformation pattern of paleoshorelines (straight lines) when looking at a perpendicular angle to the tilt (as in De Gelder et al, 2022). Looking at the scale of the whole island along four different projections the rasa is continuously tilted eastward within the 2 with location of samples used for biostratigraphic dating, as well as map of marine terraces for which shoreline angles were determined (Figure 7a), and the location of profile C-C' (Figure 8c) (b) Mediterranean planktic foraminifer biostratigraphic scheme of Pliocene-Quaternary, with the distribution of selected species of planktic foraminifers and ostracods recovered in sample Na.…”

Toward New and Independent Constraints on Global Mean Sea‐Level Highstands During the Last Glaciation (Marine Isotope Stage 3, 5a, and 5c)

“…Past global ice volume variations have been estimated from the oxygen isotope ( δ 18 O) composition of benthic and planktic foraminifer tests preserved in marine sediments (K. M. Grant et al., 2014; Siddall et al., 2008) and geological markers of relative sea level, including erosional and constructional terraces, sedimentary facies, and fossilized corals (de Gelder et al., 2022; Dumitru et al., 2019; G. R. Grant et al., 2019; Hibbert et al., 2016; Lambeck & Chappell, 2001; Medina‐Elizalde, 2013; Yokoyama et al., 2000). However, ice volume inferences from foraminiferal oxygen isotopes ( δ 18 O) are complicated by local variations in seawater δ 18 O, ocean temperature, post depositional calcium carbonate diagenesis/dissolution, and uncertainties in the mean δ 18 O of past ice sheets (Raymo et al., 2018; Siddall et al., 2008; Spratt & Lisiecki, 2016; Waelbroeck et al., 2002), which may introduce tens of meters of uncertainty to global mean sea level (GMSL) estimates.…”

“…No new data is used in this manuscript. Datasets included here publicly available (de Gelder et al., 2022; Gowan et al., 2021; Hibbert et al., 2016; K. M. Grant et al., 2014; Medina‐Elizalde, 2013; Pico et al., 2017; Spratt & Lisiecki, 2016; Waelbroeck et al., 2002; Weiss et al., 2022).…”