东海底质中钙质超微化石的初步研究

钙质超微化石是颗石(Coccolith)及其相近化石的统称.颗石是颗石藻纲(Coccoli-thophyceae)表面的钙质骨骼,一般只有1-15μ大小,需要用电子显微镜研究.近年来,钙质超微化石在侏罗纪以来海相地层研究中,尤其在大洋沉积物的研究中,起着特别重要的作用.关于太平洋表层沉积物中钙质超微化石和水层中颗石藻类的分布,美国、苏联和日本都作过研究,而关于东海海域中的分布情况尚未见报导.近来,我们通过对东海20个表层沉积样品超微化石的分析、鉴定发现,其数量分布和属种组合与沉积速率、海水温度与海流分布等均有密切关系.目前,东海沉积中超微化石的系统研究工作尚在进行之中,现仅就初步分析的结果,作一简短报导.

A PRELIMINARY STUDY OF CALCAREOUS NANNOPLANKTON IN BOTTOM SEDIMENTS OF THE EAST CHINA SEA

Calcareous nannoplankton from surface sediments of the East China Sea was investigated for the first time.As revealed by the preliminary study,coccoliths are highly concentrated in sediments at the outer edge of the continental shelf and on the continental slope,being decreasing in number towarels deeper(bottom of the Ryukyu Trench)and shallower watef areas.The calcareous nannoplankton of the northern part of the East China Sea is dominated by wide-spred species such as Gephyrocapsa oceanico Kamptner and Emiliunia huxleyi(Lohmann)Hay and Mohler. The species diversity is rising southwards,with appearence of some warm-water species,as Helicopontosphueru kamptneri Hay and Mohler,Umbilicosphaera mirabilis Lohmann,Ceratolithus cristatus Kamptner,Rhabdosphner still fer Lohmann, Thoracosphaera sp.,Syrucosphaerd sp.and Bruarudosphaera bigelowi(Gran and Braarud)Deflandre etc.It is suggested,therefore,the main part of the East China Sea belongs to the North subtropic zone in the pacific biogeography zonation of nannoplankton,but its northernmost part——to the Boreal zone.