太平洋中部表层沉积物镁铝含量比的变化

Changes of Mg/Al content ratio in surface sediments from Central Pacific

本文根据中、日调查资料,研究了太平洋中部表层沉积物镁铝含量比的变化,并探讨其影响因素。

The study on Mg/Al content ratio(i, e. the m value,m= 100×MgO/Al_2O_3) in the surface sediments from the sea areas of the Central Pacific reveals that the m value decreases with the increasing water depth. In the sedimentary zone with a water depth less than 55 m, the sea water is characterized by the relatively higher salinity, pH and water temperature and the m value of the sediments is more than 500 with an overage of 2 831.3. In the sedimentary zone under high salinity water layer (transitional layer) ,the salinity, pH and water temperature decrease with the increasing water depth, and the m value of the sediments decreases with the increasing water depth,too. The average m value of the sediments in various water depth range is 287.4 for 910—2000 m, 44.3 for 2588—3475 m, and 26.7 for 4784—5443 m. Moreover, the higher m value in the underlying old strata of the surface sediments exerted the influence on the m value of the surface sediments because the old strata were more or less exposed in the sampling of the surface sediment, In addition, the m value of the surface sediments was also influenced by the Antarctic bottom water with low temperature and low salinity ,of which,the greater the influence, the smaller the m value.