Redating the earliest evidence of the mid-Holocene relative sea-level highstand in Australia and implications for global sea-level rise
Redating the earliest evidence of the mid-Holocene relative sea-level highstand in Australia and implications for global sea-level rise
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DOI：
10.1371/journal.pone.0218430
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发表时间：
2019-07-17
期刊：
影响因子：
3.7
通讯作者：
Turney, Chris
中科院分区：
文献类型：
--
作者：
Dougherty, Amy J.;Thomas, Zoe A.;Turney, Chris
重建过去的海平面有助于限制围绕变化率、规模和预计到21世纪的增长影响的不确定性。重要的是中全新世相对海平面高位在构造稳定和远程（远场）的位置，从主要的冰盖。澳大利亚东海岸提供了一个很好的竞技场来研究全新世期间相对海平面的变化。围绕东海岸高地的峰值水平和时间有相当大的争论。澳大利亚东南部的布利海滩遗址提供了南半球高地建立的最早证据，尽管人们对用于绘制区域海平面曲线的放射性碳年代测定的材料的预处理和类型提出了疑问。在这里，我们进行了详细的形态和年代地层学研究在布利海滩，以更好地限制在澳大利亚东部的全新世高位的时间。与木材和木炭样品可能提供的年代非常古老（可能是由于内在的年龄）相反，我们发现短命的陆生植物宏体化石提供了一个强大的年代框架。贝叶斯年龄模型提供了最早的证据，即6，880 +/- 50 cal BP的最高点，比以前报道的晚了大约一千年。我们的结果从布利现在密切配合其他海平面重建沿着澳大利亚东海岸，并提供了一个同步的相对海平面高点，从卡奔塔利亚湾延伸到塔斯马尼亚的证据。我们精确的年龄似乎与北方和南极冰盖的主要冰量损失相吻合，支持了先前的研究，这些研究表明这些可能在相对海平面高位中发挥了作用。现在需要进一步开展工作，调查区域海平面对环境的影响，并完善全新世海平面下降的时间及其对海岸演变的影响。
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.