福建深沪湾潮间带全新世有孔虫及其环境意义

Holocene foraminifera and it's environmental significance in Shenhu Bay, Fujian

本文对深沪湾西部潮间带表层沉积物和两个钻孔岩芯共 3 0个样品的有孔虫组成进行了定性和定量分析 .结果表明 ,表层沉积物中有孔虫群分布规律明显 ,随着离岸向海越远 ,水深越大 ,有孔虫数量从 1位数上升到 5位数 ,种数为 9～ 69种 ,多变度V3 1～ 44,复合分异度H(s) 3 .2 5～ 3 .45.从钻孔岩芯中的全新世有孔虫群特征可看出 ,中全新世以来海面升降和海洋环境可分为 2个阶段 :(1 )海水初到钻孔位置 ,有孔虫数量和种数较少 ,分异度不高 ,海相性程度较低 .(2 )后期 (埋深 1 .8m和 2 .0m以浅 ) ,海面有所升高 ,变为潮间带 (高潮位→中潮位→低潮位 )环境 .

A total of 30 samples from two cores and surficial sediments in tide zone were qualitatively and quantitatively analyzed for their foraminiferal contents,with the aim of determining the distribution of marine or continental facies, analyzing stratigraphic sequences of transgression-regression and understanding the depositional environment of the area. The dominant species and diversity of foraminifera fauna(Tab.1)show that the number of foraminiferal is from ones-place to ten thousand-place,the species from 9 to 69,the variability value from 31 to 44,the information function H(s) value from 3.25 to 3.45,with increasing seaward distance and depth. The characters of the Holocene foraminifera from the Core SSZ1 (Tab.2)show that two stages may be divided for the sedimentary environment and the sea level changes since middle Holocene. (1)Early stage(core depth 3～1.8m and 2.9～2.0m respectively),the sea water just arrived the location of the cores,and the foraminiferal population and species are a little,and the diversity value is lower, and the marine facies degree is lower.The age is about 5 ka,B.P.. (2)Late stage(core depth above 1.8m and 2.0m respectively),the sea level sat higher and the sedimentary environment and foraminifera assemblages changed into the tidal zone(from high to low tidal zone).