粤西琼东海域表层孢粉沉积的形成环境  

Sediment environment of surface pollen in sea area to the west of Guangdong and east of Hainan

作　　者：童国榜[1] 龙江平[2] 李团结[3] 肖霞云[4] 许冬[2] 陈亮[3] 童松梅[1] 

机构地区：[1]中国地质科学院水文地质环境地质研究所,石家庄050061 [2]国家海洋局第二海洋研究所,杭州310012 [3]国家海洋局南海工程勘察中心,广州510300 [4]中国科学院南京地理与湖泊研究所 湖泊与环境国家重点实验室,南京210008

出　　处：《科学通报》2014年第8期687-700,共14页Chinese Science Bulletin

基　　金：中国近海海洋综合调查与评价专项(908-01-ZH2)资助

摘　　要：研究区位于珠江口以西至琼州海峡及琼东海域,是一个开放的海湾.在本海域共采集了400个表层沉积物样品进行孢粉分析,所有样品孢粉丰富.根据孢粉总浓度(重量浓度)及木本植物、陆生草本植物和蕨类植物孢粉浓度的分异程度,可将本海域的孢粉散布划分为10个孢粉区域.此外,根据局部孢粉浓度出现极高值与极低值的现象划分了3个孢粉浓度高值区和3个孢粉浓度低值区.根据海底形态及动力情况,可将10个孢粉区域归纳为4种孢粉沉积环境:临岸带、近岸带、远岸带及海岛陡坡带.研究表明,临岸带(区域Ⅰ,Ⅵ,Ⅸ及Ⅹ)沉积环境较为复杂,存在孢粉高值区与孢粉低值区的分化,该带草本植物花粉含量高,达全区之冠.近岸带(区域Ⅱ,Ⅲ,Ⅴ,Ⅶ)孢粉浓度中等,木本植物花粉及蕨类植物孢子含量略有增多,尤以松属花粉显著.远岸带(区域Ⅳ)孢粉浓度低,组合中以蕨类植物孢子含量较多而突出.海岛陡坡带(区域Ⅷ)孢粉组合中各组分含量中等,具有各带混合的特性.孢粉高值的产生与多水团的活动有关,如:高值区A,位于珠江冲淡水向西扩散过程中与陆架水混合锋面带处;高值区B和C,在雷州半岛以东海域的逆时针环流(低速带)处.孢粉浓度低值区与波浪、潮流活跃有关,如:雷州半岛沿岸波浪强烈冲刷区(区D),琼州海峡东口强潮区(区E),及陆坡内潮、内波高发区(区F).The study area is an open gulf in the west of Pearl River Estuary, and to the Qiongzhou Strait and east coast of Hainan Island. Here, we palynologically analyzed 400 surface sediment samples collected from this sea area. All these samples contain abundant pollen and spores. According to concentration （weight concentrations） distributions of the total pollen, arboreal and terrestrial herbaceous pollen and fem spores, the study area can be divided into 10 pollen regions. In addition, three high-concentration and three low-concentration subregions can be distinguished within these pollen regions, with the consideration of extremely high values and/or low values of pollen concentrations. Based on the submarine topography and marine dynamic conditions, the 10 pollen regions are summarized as four types of depositional environment, namely, along-shore zone, nearshore zone, offshore zone and steep-slope zone of island. Our results show that depositional environment of along-shore zone （I, VI, IX and X pollen regions） is relatively complex with high-concentration and low-concentration sugregions. Herb pollen percentages in the zone are the highest. The pollen concentration of nearshore zone （II, III, V, VII pollen regions） is moderately high, and pollen percentages of trees （especially Pinus） and ferns there increase slightly. The pollen concentration of offshore zone （IV pollen region） is low, and its pollen assemblage is highlighted by high percentages of herbs. In steep-slope zone of the island （VIII pollen region）, pollen assemblages appear as a mixed characteristics of the other three zones with moderately high pollen percentages. High-concentration subregion is related to activities of water masses. For example, high-concentration subregion A is located in oceanic front belt where the Pearl River freshwater diffuses westward and mixes with the shelf seawater, and high-concentration subregions B and C in the counterclockwise circulation （the low-velocity zone） of the eastem water of Leizh

关 键 词：表层孢粉 海洋沉积 沉积动力 海洋锋 粤西琼东海域 

分 类 号：Q914[天文地球—古生物学与地层学]