渤海湾沿岸贝壳堤对潮滩有孔虫海面变化指示意义的影响

摘要

Based on comparison of the two categories of foraminifera fauna living on the modern open muddy tidal flats in the west coast of Bohai Bay, with or without chenier ridge, the authors thoroughly studied the variability indicating sea level elevations by dif⁃ferent foram assemblages in these two kinds of environment. Each category of forams, consisting of five assemblages and correspond⁃ing to five subzones, i.e., high salt marsh, low salt marsh, upper intertidal, upper-middle intertidal and middle-lower intertidal suben⁃vironments, was separated successively by MHWST, MHW, MHWNT and MSL, and investigated in detail. As a result, the specific forams-attached sediment from each subzone on tidal surface can be recognized as a high-accuracy sea level indicator, of which the reconstructed elevation point lies in the middle of the subzone with an error of half of the vertical range. It is evident that the exis⁃tence of the local chenier body can exert an influence on the composition of foram assemblages, and such an influence tends to de⁃cline gradually from high to low water, and finally fades out seaward beneath the MHWNT.%通过对渤海湾沿岸有贝壳堤发育和无贝壳堤发育的2类现代开放潮滩有孔虫组合的对比，研究了该2类潮滩环境沉积物中有孔虫的海面指示意义。5个有孔虫组合带被MHWST（平均大潮高潮位）、MHW（平均高潮位）、MHWNT（平均大潮低潮位）和MSL（平均海面）分隔，分别对应潮滩的高盐沼、低盐沼、潮间带上部、潮间带中上部和潮间带中下部5个不同亚环境。不同亚环境沉积物因其所含的有孔虫群的独特性，均可作为高精度海面标志物，误差为各亚带高差的1/2。沿岸贝壳堤可对潮滩有孔虫的属种组成产生影响，影响程度从高潮位向低潮位逐渐降低。在MHWNT潮位之下，有孔虫组合不再受到沿岸贝壳堤的影响。