海南岛东寨港地区3.9万年以来沉积物粒度特征及其环境意义  

ENVIRONMENTAL CHANGES OVER THE LAST 39 KA AS RECONSTRUCTED FROM GRAIN SIZE CHARACTERISTICS OF SEDIMENTS IN DONGZHAIGANG HARBOR,HAINAN ISLAND

作　　者：王玉杰 姜文英[1] 杨肖肖 胡道功[3] WANG Yujie;JIANG Wenying;YANG Xiaoxiao;HU Daogong(Key Laboratory of Cenozoic and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029;University of Chinese Academy of Sciences,Beijing 100049;Institute of Geomechanis,Chinese Academy of Geological Sciences,Beijing 100081)

机构地区：[1]中国科学院地质与地球物理研究所,中国科学院新生代地质与环境重点实验室,北京100029 [2]中国科学院大学,北京100049 [3]中国地质科学院地质力学研究所,北京100081

出　　处：《第四纪研究》2024年第5期1362-1370,共9页Quaternary Sciences

基　　金：国家重点研发计划项目(批准号:2020YFA0607703);中国科学院地质与地球物理研究所重点部署项目(批准号:IGGCAS-201905)共同资助。

摘　　要：海平面变化和沿海地区的海陆变迁是古环境研究的热点。本研究通过对海南岛东寨港ZK13-22钻孔(19 m)AMS14C测年和粒度分析,结合沉积物岩性和化石组合,重建了东寨港地区约3.9万年以来沉积环境的变化,探讨了沉积环境与海平面变化的关系。结果表明:1)39.4~15.3 ka B.P.,ZK13-22钻孔的沉积环境为陆地环境,其中在39.4~32.3 ka B.P.、32.3~21.9 ka B.P.和21.9~15.3 ka B.P.期间,沉积环境分别为河床相、河漫滩相和河床相,与古河道的摆动迁移有关;2)15.3~4.4 ka B.P.,沉积物中值粒径减小,出现大量海月和螺等化石,且保存完好,表明海洋影响增加,钻孔沉积环境为滨海相沉积,与全球增温导致的海平面快速上升有关;3)4.4 ka B.P.之后,沉积物的中值粒径和细砂含量均有增加,反映了研究区可能受海平面下降或者人类活动的影响。In 2020,core ZK13-22(19-m long;20°0'38.10″N,110°38'0.24″E;1.85 m above sea level)was collected from the Dongzhaigang area,Hainan Island.The Dongzhaigang area lies at the border of Haikou,the capital of Hainan Island and Wenchang,situated in a bay area with the Qiongzhou Strait to the north and surrounded by mountains on the other three sides.In this study,an age model was built using 9 AMS 14C dates processed using Bacon software.The base and surface of the core were dated to 39361 a B.P.and 3029 a B.P.,respectively.A total of 518 samples were analysed at 2~10 cm intervals for grain size analysis.The grain sizes are divided into coarse sand(500~2000μm),medium sand(250~500μm),fine sand(63~250μm),silt(4~63μm)and clay(<4μm).Based on lithology,fossil and grain size data,the sediments from core ZK13-22 were classified into three depositional units.Unit 1(19.0~13.5 m;39.4~15.3 ka B.P.):This unit displays a pattern of coarse-fine-coarse deposition rhythm,and the grain size distribution is unimodal and bimodal pattern.The coarse sections,situated at the top(15.00~13.50 m;21.9~15.3 ka B.P.)and the base(19.00~17.08 m;39.4~32.3 ka B.P.),consist of greyish white and greyish brown coarse to fine sand interbedded with pebbles.The average contents of medium and coarse sand are 14.7%at the top and 32.9%at the base.The central fine section(17.08~15.00 m;32.3~21.9 ka B.P.)comprises black clay and black peat layers containing abundant plant debris(wood and leaves).The average content of medium and coarse sand is 3.6%.It is inferred that the deposits during the intervals of 39.4~32.3 ka B.P.,32.3~21.9 ka B.P.and 21.9~15.3 ka B.P.were formed in a fluvial channel,floodplain,and another fluvial channel,respectively.Thus,this unit is interpreted as having been deposited in a terrestrial environment.Unit 2(13.5~2.1 m;15.3~4.4 ka B.P.):This unit is characterized by dark grey clayish silt containing large quantities of well-preserved marine molluscan shells,such as Placuna placenta.The median grain size decreases to 13.4μm at 1

关 键 词：粒度 沉积环境 海南东寨港 海平面变化 

分 类 号：P534.631[天文地球—第四纪地质学] P532[天文地球—古生物学与地层学] P512.2[天文地球—地质学]