氧同位素：追踪陆架海沿岸水团变化的良好标志

对于陆架海而言除了冰体积效应,温度效应外,还有由于大陆淡水注入引起的,使δ＾１８Ｏ值负向偏移的效应,而且在低海平面时期,当沿岸水团盛行时,这种效应起主导作用。笔者将这种效应从广州的盐度效应中分离出来,称为陆架海的负值效应。

OXYGEN ISOTOPE :A GOOD INDICATOR TO TRACE COASTAL WATER MASS MIGRATION OF SHELF SEA

values of Neogene planktonic foraminiferas in the northern shelf of the South China Sea are not only influenced by ice volume and temperature effects,but also by the inflow of the continental fresh water which is the predominant reason for the depleted O values (shift toward negative values ). The influence of continental fresh water influx on O values should be separated from salinity effect in a broad senese and becalled as "negative effect" in shelf sea, it is a key problem to the paleoceanographical conditions incoastal water mass in shelf sea. Although the effects of diagenetic recrystallization,together with shelf exposure and erosion are also factors leading to a decreased O value .they can not be separated from negative effect at the present because of the limits of technical and economic conditions. The magnitude and variations with time and space of negative effect are analyzed for the first time based on the data of oxygen isotope and Neogene micro fossil records (planktonic foraminifera, spora, and dinoflagellate ) from the four wells in the northern part of the South China Sea. It is evident that Oxygen isotope is a good indicator to trace coastal water mass migration of shelf sea.