南海深海短柱样的磁性地层学特征

The Magnetostratigraphic Characteristics of some Shorter Cores from the Deep South China Sea Basin

对南海５个深海短柱样的磁性地层学特征进行研究后表明，在陆坡柱样沉积物中位于岩芯深约３ｍ处的反向磁性段可与蒙戈磁偏移相对比。因此，对沉积速率相对较高的陆坡碳酸盐相而言，利用反向磁偏移地层事件，可以对代表地质时限较短的深海短柱样进行等时面分析。

During the-marine comprehensive investigation of the Central South China Basin(12-20°N )from the October 1983 to June 1984. 38 sediment cores were obtained by the piston-sampler. The cores are generally not longer than 4m. The paleomagnetic measurement of 5 sediment cores selecting from the continental slope and deep plain has been carried out. The result shows: (1)all cores are mainly positive polarity and belong to Brunhes epoch; (2)the magnetostratigraphic differences exist between the slope cores and deep plain cores.The lower of slope cores reveals the existence of negative magnetic excursion. The chronology of the excursion has been stuied by various methods, such as 14C, Th-230, δ18O and CaCO3%,etc. We got two satisfying cycle curves of δ18O and CaCO3% in the slope cores. In comparison with the magnetostratigraphy and Quaternary geochronology from the neighbour borehole of Tianyang Lake, it can be seen that the nagative polarity section of studied slope cores is in the lower stage 3 of δ18O and CaCO3% curves,its stratum is approximately equal to that located Mungo magnetic excursion in the borehole from Tianyang Lake.