School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, New South Wales, Australia.
Palaeontology, Geobiology and Earth Archives Research Centre, and ARC Centre of Excellence for Australian Biodiversity and Heritage, School of Biological, Earth and Environmental Sciences, University of New South Wales, New South Wales, Australia.
PLoS One. 2019 Jul 17;14(7):e0218430. doi: 10.1371/journal.pone.0218430. eCollection 2019.
Reconstructing past sea levels can help constrain uncertainties surrounding the rate of change, magnitude, and impacts of the projected increase through the 21st century. Of significance is the mid-Holocene relative sea-level highstand in tectonically stable and remote (far-field) locations from major ice sheets. The east coast of Australia provides an excellent arena in which to investigate changes in relative sea level during the Holocene. Considerable debate surrounds both the peak level and timing of the east coast highstand. The southeast Australian site of Bulli Beach provides the earliest evidence for the establishment of a highstand in the Southern Hemisphere, although questions have been raised about the pretreatment and type of material that was radiocarbon dated for the development of the regional sea-level curve. Here we undertake a detailed morpho- and chronostratigraphic study at Bulli Beach to better constrain the timing of the Holocene highstand in eastern Australia. In contrast to wood and charcoal samples that may provide anomalously old ages, probably due to inbuilt age, we find that short-lived terrestrial plant macrofossils provide a robust chronological framework. Bayesian modelling of the ages provide improved dating of the earliest evidence for a highstand at 6,880±50 cal BP, approximately a millennium later than previously reported. Our results from Bulli now closely align with other sea-level reconstructions along the east coast of Australia, and provide evidence for a synchronous relative sea-level highstand that extends from the Gulf of Carpentaria to Tasmania. Our refined age appears to be coincident with major ice mass loss from Northern Hemisphere and Antarctic ice sheets, supporting previous studies that suggest these may have played a role in the relative sea-level highstand. Further work is now needed to investigate the environmental impacts of regional sea levels, and refine the timing of the subsequent sea-level fall in the Holocene and its influence on coastal evolution.
重建过去的海平面可以帮助限制围绕 21 世纪海平面变化率、幅度和影响的不确定性。从中地海相对海平面高位期在构造稳定和偏远（远场）位置远离主要冰盖的情况来看，这一点非常重要。澳大利亚东海岸为研究全新世相对海平面变化提供了一个极好的场所。围绕东海岸高位期的峰值水平和时间存在相当大的争议。澳大利亚东南部的Bulli 海滩为南半球建立高位期提供了最早的证据，尽管有人对放射性碳定年用于开发区域海平面曲线的预处理和材料类型提出了质疑。在这里，我们在 Bulli 海滩进行了详细的形态和年代地层学研究，以更好地确定澳大利亚东部全新世高位期的时间。与可能由于内在年龄而提供异常古老年龄的木材和木炭样本相反，我们发现，短命陆生植物大化石提供了一个可靠的时间框架。对年龄的贝叶斯建模为 6880±50 cal BP（公元前）最早的高位期证据提供了改进的年代，比之前报道的大约早了一千年。我们在 Bulli 的结果现在与澳大利亚东海岸的其他海平面重建结果非常吻合，并为从卡奔塔利亚湾到塔斯马尼亚的同步相对海平面高位期提供了证据。我们的精确年龄似乎与北半球和南极冰盖的大量冰体损失同时发生，这支持了先前的研究，即这些冰盖可能在相对海平面高位期中发挥了作用。现在需要进一步研究区域海平面上升的环境影响，并细化全新世随后海平面下降的时间及其对海岸演化的影响。
