【作者】 汪卫国； 陈坚；

【Author】 Wang Weiguo;Chen Jian;Third Institute of Oceanography,State Oceanic Administration;

【机构】 国家海洋局第三海洋研究所；

【摘要】 为研究南海中部沉积物的粒度特征及其古气候环境意义,对南海中部中沙以南的陆坡和海盆区表层沉积物及分别位于陆坡和海盆的2根柱样进行了粒度、扫描电镜、CaC O3和生物硅的分析。结果显示,南海中部沉积物由三类颗粒组分构成,其中,第一类颗粒组分的峰值粒径在5~10μm之间,主要由陆源矿物碎屑组成;第二类组分的峰值粒径在40-70μm之间,主要由有孔虫和硅藻组成。第三类颗粒组分的峰值粒径>400μm,由生物骨骼碎屑组成。这三类颗粒组分中第一类在研究区表层沉积物中均存在,第三类则随机分布。第二类颗粒组分多以有孔虫为主,其含量受水深控制,在南海中部碳酸钙临界补偿深度(CCr D)以浅的陆坡区,沉积物粒度曲线多为双峰形态,而在CCr D以下的海盆区,因大部分有孔虫被溶解,沉积物粒度曲线多为单峰形态。无论是陆坡区还是海盆区的柱样沉积,因第二类颗粒组分含量的变化导致柱样中的粒度参数、地球化学等发生显著的变化,因而,第二类颗粒组分含量的变化蕴含重要的古气候环境变化信息。更多还原

【Abstract】 The grain size,contents of carbonate and biogenetic silica,along with scanning electron microscope analysis of surface and core sediments in continental slope and abyssal basin south of Zhongsha(Maccelesfield) Bank were measured,with an attempt to reveal the characteristics of grain size distribution of sediments and its implications of palaeo-climate change.The results shows that there are three grain-size populations in sediments.The first population is mainly composed of terrestrial minerals with a mode of 5~10μm The second population is composed of foraminifera and diatom,and the mode of the population is 40-70μm.The third population is bio-clastic sand with mode larger than 400μm.The first population occurs in all sediments and the content of third population is random.The content of second population is controlled by water depth.The contents of second population are high and the grain-size frequency curves are bimodal in the continental slop where sea bottom above the carbonate critical depth(CCr D),whereas the content of second population is very low due to the resolution of foraminifera in the abyssal basin where sea bottom is under the CCr D,and the grain-size frequency curves are mono-modal.No matter continental slope or abyssal basin did the core of sediments from,the content variation of the second population lead to the changes of grain size parameter,element content of sediments.Therefore the second population composed of foraminifera and diatom contains the important information about palaeo-climate and environment changes.更多还原