摘要
通过对渤海莱州湾GK138、GK111及GK95孔的255个沉积物样品中介形虫定量统计分析及分布特征研究，共鉴定出介形虫16属28种，结合钻孔岩性变化特征，进一步探讨研究区晚第四纪以来的沉积环境演化。根据介形虫的种群分布特征及AMS 14C和光释光（OSL）测年结果，揭示研究区晚第四纪以来共发育3套海相地层，分别是中更新世晚期的第三海相层、晚更新世的第二海相层和全新世的第一海相层，由下向上分别对应于MIS 7、MIS 5和MIS 1的高海面阶段。Q型聚类及主成分分析划分出3个代表不同沉积环境的介形虫化石组合带：第Ⅲ化石组合带为中更新世晚期海侵的产物，沉积环境为潮间带环境；第Ⅱ化石组合为晚更新世海侵的产物，沉积环境为潮间带-潮下带沉积环境；第Ⅰ化石组合带为全新世海侵的产物，沉积环境为潮上带-潮间带沉积环境；介形虫的生态特征统计数据显示晚更新世时期海侵强度要明显强于中更新世和全新世海侵强度。
The Bohai Sea is a semi-enclosed interior continental shelf sea in China which connects to the Yellow Sea by a narrow Bohai Strait.The fluvial and marine sediments were deposited during the Quaternary,which caused the complicated sedimentary evolution and the transgressions,especially Pleistocene transgressions.To clearly reveal the paleoenvironmental changes,255 sediment samples taken from new boreholes GK138（37°28＇N,118°44＇E）,GK111（37°18＇N,118°58＇E） and GK95（37°10＇N,118°45＇E） were studied.16 genera in 28 species of ostracod fossils were identified to the species level in comparison with specimens from published illustrations.This fossil identification result together with change characteristics in lithology and accelerator mass spectrometry radiocarbon 14C and optically stimulated luminescence ages （OSL） revealed three transgressive strata.These three transgressive strata could be interpreted as the third Marine Beds （M3）,the second Marine Beds （M2） and the first Marine Beds （M1） in ascending.M3 deposited in the Later Mid-Pleistocene phase,M2 in the Late Pleistocene phase and M1 in the Holocene phase.According to the chronological framework and the global sea-level change,M3,M2 and M1 corresponded well to the high sea stage of MIS （Marine Isotope Stage）7,MIS 5 and MIS 1.To investigate the relationship between the sedimentary environment and ostracod assemblages,three ostracod assemblages related to different environments were identified based on the quantitative statistical analysis （mainly Q-mode cluster and principal component analysis） of samples in which the ostracods was more than 2%.Assemblage Ⅲ was characterized by the tidal intertidal environment and a relative small scale transgression in Later Mid-Pleistocene.Assemblage Ⅱ was the product of the Late Pleistocene transgression,indicating an intertidal-subtidal environment.Assemblage Ⅰ was characterized by the supratidal-intertidal environment which mainly occurred during Holocene marine transgression.Based on the statistics of ostracod ecological characteristics data,the Late Pleistocene transgression was significantly stronger than the Later Mid-Pleistocene and the Holocene transgression.
出处
《第四纪研究》
CAS
CSCD
北大核心
2016年第6期1475-1488,共14页
Quaternary Sciences
基金
中国地质调查局“山东半岛蓝色经济区地质环境调查评价”项目（批准号：1212011220001）和山东科技大学研究生科技创新基金项目（批准号：YC150320）共同资助
关键词
晚第四纪
介形虫
莱州湾
海相地层
沉积环境演化
Late Quaternary, ostracods, Laizhou Bay, marine sedimentary beds, sedimentary environment evolution
