广西北部湾海岸风沙记录的千年来风暴潮演化的阶段性

本文以广西防城港市江平镇巫头剖面（21°32′8.25″N, 108°06′59.9″E）晚全新世厚393 cm含风暴沉积层的风成沙—潟湖相—弱成壤沉积序列为研究对象,结合野外观测的风暴层沉积特点,在6个AMS-¹⁴C、OSL测年数据和沉积物粒度、重矿物分析的基础上重建了广西北部湾沿海千年来风暴潮演化史。分析结果显示,风暴沉积层平均粒径粗、分选差,重矿物成熟度高、稳定度低,是海岸后滨沙丘向陆一侧受风暴潮增水影响快速堆积的产物;千年来巫头剖面记录的9个风暴潮高发期主要集中于1400 AD之后的小冰期内,风暴潮高发期与西太平洋SST、ENSO活动趋势呈反相关,其中一些风暴潮高发期和历史文献记录的4次“海溢”事件与太阳黑子活动曲线有近乎同步的变化趋势。这意味着巫头剖面风暴潮高发期除受西太平洋暖池、ENSO的影响外,可能还在相当程度上受到太阳活动的强迫。

Evolution stages of storm surges over the past millennia recorded by aeolian sands along the coast of Beibu Gulf,Guangxi

The Wutou (WT) section (21°32′8.25″N, 108°06′59.9″E), with a thickness of 393 cm storm sediments located in Jiangping, Guangxi Zhuang Autonomous Region, consists of dune sands-lagoon facies-weak pedogenic sedimentary sequences of the Late Holocene. Based on sedimentary characteristics of storm strata in the field investigation, 6 AMS-¹⁴C, OSL dating ages and the analyses of grain size and heavy minerals, the evolution history of storm surges has been reconstructed over the past thousand of years along the coast of the Beibu Gulf in Guangxi. The results show that the storm sediments are characterized as coarse mean grain size and poor sorting, with high maturity of heavy minerals and low stability, which results from quick accumulation caused by the storm surge from the land-facing side of the coastal backside dune sands. Nine storm surge peak periods recorded in the WT section over the past millennia are mainly concentrated within the Little Ice Period after 1400 AD, which are inversely correlated with the trends of SST and ENSO activities in the western Pacific. Some of storm surge peak periods recorded in the WT section and 4 "sea overflow" events from historical documents nearly synchronized with the changes of the sunspot activity. This suggests that the storm surge peak periods revealed by the WT section are probably controlled by the solar activity to a great extent, in addition to the impact of the Western Pacific Warm Pool and ENSO.