Oxygen isotopic and species composition of planktonic foraminiferas in sediment cores from the North Atlantic

Paleotemperature curves were drawn from oxygen-isotope ratios in CaCO3 of planktonic foraminiferal tests and by the micropaleontological method using quantitative relationships of their species. Two series of curves yield similar results. These data confirm that isotope composition of oxygen reflects primarily temperature, and not isotope composition in ocean water. Temperature of the upper layer of ocean water increased from north to south both during the last two glaciations and in the interglacials. All three sediment cores collected from different latitudes show approximately the same amplitudes of fluctuation of mean annual temperature during times of their accumulation, as determined independently by different methods; these amplitudes are estimated as 5-7°C.本研究基于浮游有孔虫壳体（planktonic foraminiferal tests）碳酸钙（CaCO₃）中的氧同位素比值，结合基于其物种数量关系的微古生物学方法（micropaleontological method），重建了古温度曲线。两组曲线得到的重建结果高度一致。上述数据证实，氧同位素组成主要反映海水温度，而非海洋水体的同位素组成。在末次两次冰期以及间冰期阶段，海洋上层水温均呈现由北向南递增的分布规律。从不同纬度采集的三根沉积岩芯（sediment cores）均显示，通过不同方法独立测定的沉积时期年平均气温波动幅度大致相当，经估算该波动幅度约为5-7℃。