Sedimentological and microfossil records of modern typhoons in a coastal sandy lagoon off southern China coast  

作　　者：Hong-Shuai Qi Min Chen Lin-Nan Shen Feng Cai Ai-Mei Zhang Qi Fang 

机构地区：[1]Third Institute of Oceanography,Ministry of Natural Resources,Xiamen 361005,Fujian Province,China [2]Southern Marine Science and Engineering Guangdong Laboratory,Zhuhai 519082,Guangdong Province,China [3]Observation and Research Station of Coastal Wetland Ecosystem in Beibu Bay,Ministry of Natural Resources,Beihai 536015,Guangxi Province,China [4]Xiamen Municipal Bureau of Land,Resources and Housing Administration,Xiamen 361013,Fujian Province,China

出　　处：《Journal of Palaeogeography》2021年第4期529-549,共21页古地理学报（英文版）

基　　金：the Key Program of National Natural Science Foundation of China(Grant No.41930538);the National Science Foundation of China(Grant No.41306083);the National Key Research and Development Program of China(Grant No.2019YFE0124700);the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources of China(Grant Nos.2019018,2019026,and 2020017)。

摘　　要：To determine the characteristics and potential indicators of modern typhoon deposition in a sandy lagoon off the coast of Guangdong Province(southern China),we analysed the ^(210)Pb,sedimentology,and microfossils of samples from ten cores obtained before and after the passage of Typhoon Rammasun in 2014.Typhoon deposition showed a thinning trend from internal areas of the lagoon to its mouth,with the maximum thickness inside the lagoon of~35 cm.These typhoon deposits are dominated by overwash and differ from sediments deposited under normal weather conditions.Under normal weather conditions,lagoon sediment has a210 Pb curve that follows a model of exponential decay,has a unimodal granularity frequency curve,and lacks organic matter and microfossils(diatoms and foraminifera).However,210 Pb is low in the typhoon deposits,the grain size is coarse,and the granularity frequency curve is obviously bimodal.There are also abundant foraminifera in the typhoon deposits.We found a clear double-layered structure in the typhoon deposits,which was caused by strong hydrodynamic disturbance that mixed sediments originally from the offshore area with those of the lagoon.The lower layer has coarse-grained particles with medium sorting,low organic matter content,and low diatom content.The upper layer has fine-grained particles with poor sorting,high organic matter content,and abundant diatoms.The rate of fragmentation of diatoms in the upper layer was very high(40%-60%).The diatom assemblage contained offshore and freshwater species carried by storm runoff.Therefore,we believe that the sediments of this typical sand bar-lagoon environment retain evidence of typhoon events along the southern China coast that is displayed in the marked sedimentological and microfossil characteristics.

关 键 词：Sediment record MICROFOSSILS Typhoon Rammasun LAGOON Southern China coast 

分 类 号：Q911.2[天文地球—古生物学与地层学] P736.2[生物学—古生物学]