天津市潮滩活体和埋藏有孔虫群的分布及地质环境意义

DISTRIBUTION AND ENVIRONMENTAL SIGNIFICANCE OF LIVING FORAMINIFERAL ASSEMBLAGES AND TAPHOCOENOSE IN TIANJIN INTERTIDAL ZONE,THE WEST COAST OF BOHAI BAY

对天津市潮滩8条垂直于海岸线剖面的57个表层沉积物样品进行了活体和死体有孔虫分析鉴定、粒度分析、含盐量测定,利用全站仪对剖面进行了水准测量,同时测定了海水盐度。研究了天津市潮滩有孔虫群的组成、数量及分异度等特征;通过聚类分析将天津市潮滩活体有孔虫群分为7个带,埋藏有孔虫群(活体+死体)分为5个带,但除了埋藏群Ⅰ、Ⅳ与活体有孔虫群Ⅰ、Ⅳ组合特征一致外,其他各带的组合特征及分带界线均不一致。通过分析活体有孔虫群分带与沉积物含盐量、海水盐度、潮位、沉积物组成等生态环境参数的关系,探讨了活体有孔虫群的主要控制因素;通过分析埋藏有孔虫群分带与潮位、沉积物粒径、现代沉积速率等沉积环境参数的关系,探讨了埋藏有孔虫群的搬运及沉积作用。指出了天津市海岸带活体有孔虫群和埋藏有孔虫群的关系、环境特征及地质意义,为该区高精度的古沉积环境划分提供了重要指标。

57 surface sedimentary samples taken along 8 profiles perpendicular to the coastline in the intertidal zone of Tianjin area were studied for their significance of living and taphocoenose foraminifera assemblages, grain size,and salinity. Also the profiles were leveled and the seawater salinity was measured. Based on these data, the authors studied characteristics of foraminiferal assemblage component, quantity and diversity. The living foraminiferal assemblages in the tidal flat of Tianjin area were divided into 7 zones, while the foraminiferal taphocoenose （living ＆ dead）has shown 5 zones by clustering analysis. The characters and borderlines were different in the living and buried foraminifera except in zones I and IV. The authors discussed the relation between living foraminiferal assemblages and ecological environmental factors （such as salinity of sediments, seawater salinity, tidal level and sediment composition）of the 5 zones,indi cated dominant elements for living foraminiferal assembages, probed the relation between foraminiferal taphocoenose and sedimentary environmental parameters such as tidal level, grain size of sediment and modern sedimentation rate, and studied transport and sedimentary process of foraminiferal taphocoenose. Finally, the authors gave the environmental and geological significance from the living foraminiferal assemblages and foraminiferal taphocoenose in Tianjin coastal zones.