南海中央海盆条带状磁异常特征与海底扩张

CHARACTERISTICS OF STRIPED MAGNETIC ANOMALIES IN THE CENTRAL SEA BASIN OF THE SOUTH CHINA SEA

在我国南海中央海盆中分布着大范围的规律性很强的条带状磁异常 (近 50万km2 )。对它们进行分析、对比与解释 ,认为这是我国疆界内存在的由中央扩张脊型海底扩张产生的磁条带地层的反映 ,是洋壳增生的一个实例。它发生在新生代第三纪中晚期 ,距今 32 .3Ma～ 1.7Ma ,具有太平洋西部边缘海底扩张型特点。对国内外地学界有争议的南中国海的形成与演化有了进一步的认识 ,对南海深部地质构造。

In the central sea basin of the South China Sea,there are vast prominently regular striped anomalies which occupy an area of nearly 500 000 km 2.On the basis of analytical correlation and interpretation of these anomalies,it is held that they are manifestations of magnetic striped strata produced by seafloor spreading of the central spreading ocean ridge type,and serve as an example of the oceanic crust accretion.It occurred in Middle Late Tertiary(32.3 Ma～1.7 Ma),and exhibits characteristics of seafloor spreading on the western margin of western Pacific Ocean.The above achievement obtained has deepened the understanding of the formation and evolution of the South China Sea,a controversial problem among geologists both in China and abroad,and hence is of great significance in the study of deep seated geological structure of the South China Sea and crustal structure as well as the development of mineral resources.