摘要
南海北部是南海向陆地过渡的前锋关键地带和全球变化的敏感地区之一,受海平面变化的影响,该地区海平面标志物广泛发育,是开展过去海平面变化研究的理想区域。目前关于南海北部全新世海平面变化历史的认识依然存在一定分歧。基于此,通过新增6个珊瑚礁数据,并对南海北部已发表的海平面数据进行年代和高程校正,然后进行相互验证和可靠性分析。同时对监测记录较为连续的12个验潮站的现代海平面观测资料进行整理和进一步验证重建结果的可靠性。最后,根据汇编的679个校正和可靠性评估后的海平面数据,重建了南海北部全新世以来,尤其是最近2000 a的海平面变化历史和变化特征。校正和评估后的数据显示:南海北部海平面从早全新世(8211±128)cal a BP的−16.16 m快速上升到6000~7000 cal a BP的1.5~2.5 m,之后波动下降到现今海平面高度。其中在中全新世海平面保持高位震荡约2600 a,而晚全新世南海北部过去2000 a海平面整体呈现出阶段变化过程。首先,在公元0−350年呈下降趋势,然后在公元350−850年海平面快速上升,并在公元880年,海平面处于过去2000 a的最高点(1.05±0.35)m,随后海平面继续下降至公元1850年的(−0.18±0.05)m。之后半个世纪保持水平窄幅波动,直到公元1897年(−0.19±0.05)m后,海平面持续震荡逐渐上升至公元2020年的0.076 m。若以过去百年(公元1925−2020年)和40 a(公元1980−2020年)上升速度(分别为2.35 mm/a和3.55 mm/a)估算,公元2100年南海北部海平面将比现今海平面高0.19~0.28 m。因此,在南海北部沿海低洼地区开展大型工程建设时,需要考虑未来海平面上升因素带来的不利影响。此外,分析发现,基于不同海平面标志物和采用不同重建方法是南海北部全新世以来海平面重建结果区域差异的主要原因。总体上,南海北部中全新世以来海平面呈现出波动下降的趋势。尽管不同地区海平面在时间与高度上存有差异,但是南海北部地区与周边海岸的海平面记录一致,这说明中全新世南海北部高海平面与南海周边地区基本同步,极可能具有全球背景。
The northern South China Sea is one of the key front zones for the transition from the South China Sea to land and one of the sensitive areas of global climate change.Affected by sea level changes,sea-level indicators are widely developed in this area,and offers an ideal area for the study of past sea-level changes.However,there are still some differences in the understanding of the Holocene sea-level change history in the northern South China Sea.Therefore,we first added 6 new and high-quality sea-level index points and reviewed and re-corrected the age and elevation of the published sea-level data obtained from the northern South China Sea,followed by mutual verification and reliability analysis.At the same time,the modern sea level observation data from 12 tide-gauge stations with relatively continuous monitoring records are collated,and the reliability of the reconstructed results are further verified.Finally,based on 679 sea level data compiled after correction and reliability assessment,we reconstructed the history and characteristics of sea level changes in the northern South China Sea since the Holocene,especially in the last 2000 years.The results show that during the early Holocene,the sea level in the northern South China Sea rose rapidly from−16.16 m at(8211±128)cal a BP to 1.5~2.5 m during 6000~7000 cal a BP,and maintained a high sea-level oscillation of 2600 years in the Mid-Holocene,and at last began to fluctuate and drop to the current sea level in the late Holocene.The sea level in the northern South China Sea showed a phased change process in the past 2000 years.First,it showed a downward trend from 0 to 350 CE,and then followed by a rapid sea level rise in 350-850 CE.In 880 CE,the sea level was at its highest point in the past 2000 years(1.05±0.35)m,and the sea-level continued to decline to(−0.18±0.35)m in 1850 CE,then the sea level basically kept a narrow horizontal fluctuation until 1897 CE(−0.19±0.05)m.Since then,the sea level kept continuous oscillation and gradually rises to 0.076 m in 2020 CE.If the sea-level in the northern South China Sea in 2100 A.D.is estimated based on the rising rate in the past 100 years,it would be 0.19~0.28 m higher than the current sea level.Therefore,when carrying out large-scale engineering construction in the coastal low-lying areas in this area,it is necessary to consider the adverse effects of future sea-level rise.In addition,it is further found that different sea-level indicators and different reconstruction methods are the main reason for the regional differences of sea-level reconstruction results in the northern South China Sea since the Holocene.On the whole,the sea-level in northern South China Sea has shown a fluctuating downward trend since the Mid-Holocene.Despite the differences in the time and height of sea-level in different regions,the sea-level records in the northern South China Sea are consistent with those in the surrounding coast,suggesting the high sea-level during the Mid-Holocene in the South China Sea,and it is likely to have a global background.
作者
乐远福
唐立超
YUE Yuanfu;TANG Lichao(Guangxi Laboratory on the Study of Coral Reefs in the South China Sea,Coral Reef Research Center of China,School of Marine Sciences,Guangxi University,Nanning 530004,China)
出处
《海洋地质前沿》
CSCD
北大核心
2023年第2期1-16,共16页
Marine Geology Frontiers
基金
国家重点研发计划项目(2017YFA0603300)
国家自然科学基金(41702182)
广西省自然科学基金(2018GXNSFAA281293)。
关键词
南海北部
全新世
海平面变化
不确定性分析
未来预测
northern South China Sea
Holocene
sea-level change
uncertainty analysis
future sea-level prediction