Submerged bedrock shore platforms, Orkney Islands, UK: A new record of significant, though chronologically uncertain sea-level change and coastal erosion

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Marine Geology Pub Date : 2025-05-08 DOI:10.1016/j.margeo.2025.107577

Dayton Dove , Tom Bradwell , Natasha L.M. Barlow

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引用次数: 0

Abstract

Reconstructions of sea level change in NW Europe are primarily based on records of relative sea level (RSL) recovered from terrestrial environments, above modern sea level. This deficit in marine-based records results from the highly limited number of sea level indicators observed in modern submarine settings, as well as the often-limited absolute chronology information available. This sampling bias introduces significant uncertainty in former RSL predictions, negatively impacting efforts to accurately model ice-sheet histories and isostatic response. Here we present new seabed mapping data (i.e. high-resolution multibeam bathymetry) from northern Scotland to address this data gap. Encircling the Orkney Islands we identify an exceptional sequence of submerged terraces ranging from -5 to -95 m below modern sea level, carved in bedrock. We interpret these bedrock terraces as relict shore platforms, based on their spatial distribution and a range of geomorphological characteristics. Shore platform development was linked to contemporaneous landward coastline erosion and cliff formation, and each landform pair (i.e. terrace = shore platform and accompanying seacliff / escarpment) likely represents a single sea-level stillstand event of considerable duration (possibly millennia). These wide and well-preserved shore platforms attest to formation during multiple, separate periods of RSL stillstand, and we estimate that 5–7 RSL stillstands are recorded offshore Orkney. We discuss their potential age – spanning more than the last glacial cycle (i.e. Middle - Late Pleistocene) – and explore the wider implications for Quaternary coastal erosion and sea-level change in the region. This study shows how marine geological data and geomorphological analysis can be used to identify palaeo-sea-level indicators within a glacio-isostatically complex region. Despite a current lack of absolute chronological constraint, we believe these observations may provide crucial information towards understanding sea level change within the NW European region.

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淹没的基岩海岸平台，奥克尼群岛，英国：一个重要的新记录，尽管在年代上不确定海平面变化和海岸侵蚀

欧洲西北部海平面变化的重建主要基于从现代海平面以上的陆地环境中恢复的相对海平面（RSL）记录。这种海洋记录的不足是由于在现代潜艇环境中观测到的海平面指标数量非常有限，以及通常有限的绝对年代学资料。这种抽样偏差给以前的RSL预测带来了很大的不确定性，对准确模拟冰盖历史和均衡响应的努力产生了负面影响。在这里，我们提出了来自苏格兰北部的新的海底测绘数据（即高分辨率多波束测深），以解决这一数据差距。围绕奥克尼群岛，我们确定了一个特殊的淹没梯田序列，范围从现代海平面以下-5到-95米，雕刻在基岩上。根据其空间分布和一系列地貌特征，我们将这些基岩阶地解释为遗留的海岸平台。海岸平台的发展与同期的陆地海岸线侵蚀和悬崖形成有关，每个地貌对（即阶地=海岸平台和伴随的海崖/悬崖）可能代表了一个相当长时间（可能是几千年）的单一海平面静止事件。这些宽阔且保存完好的海岸平台证明了在多个不同时期的RSL仍然存在，我们估计在奥克尼近海记录了5-7个RSL仍然存在。我们讨论了它们的潜在年龄-跨越超过最后一个冰期旋回（即中-晚更新世）-并探索了该地区第四纪海岸侵蚀和海平面变化的更广泛含义。这项研究显示了如何利用海洋地质数据和地貌分析来确定冰川-均衡复杂区域内的古海平面指标。尽管目前缺乏绝对的时间限制，但我们相信这些观测结果可能为了解西北欧洲地区的海平面变化提供重要信息。

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来源期刊

Marine Geology 地学-地球科学综合

CiteScore

6.10

自引率

6.90%

发文量

175

审稿时长

21.9 weeks

期刊介绍： Marine Geology is the premier international journal on marine geological processes in the broadest sense. We seek papers that are comprehensive, interdisciplinary and synthetic that will be lasting contributions to the field. Although most papers are based on regional studies, they must demonstrate new findings of international significance. We accept papers on subjects as diverse as seafloor hydrothermal systems, beach dynamics, early diagenesis, microbiological studies in sediments, palaeoclimate studies and geophysical studies of the seabed. We encourage papers that address emerging new fields, for example the influence of anthropogenic processes on coastal/marine geology and coastal/marine geoarchaeology. We insist that the papers are concerned with the marine realm and that they deal with geology: with rocks, sediments, and physical and chemical processes affecting them. Papers should address scientific hypotheses: highly descriptive data compilations or papers that deal only with marine management and risk assessment should be submitted to other journals. Papers on laboratory or modelling studies must demonstrate direct relevance to marine processes or deposits. The primary criteria for acceptance of papers is that the science is of high quality, novel, significant, and of broad international interest.