台湾以东海区磁异常及磁条带研究

Study on the Magnetic Anomalies and Magnetic Bands in the Sea Area East of Taiwan

资料显示,在整个台湾以东海区内磁异常几乎全为负磁异常,磁异常分块现象明显。通过对本海区的磁力资料进行分析和研究,表明本海区的地磁异常表现为明显的条带状异常特征。由于受板块差异性运动的影响,以加瓜海脊为界,东西两侧具有不同的磁条带方向,在加瓜海脊以东,磁条带为NW-SE向(120°),而在加瓜海脊以西则为近东西向(80°)。加瓜脊以西地区的扩张时间为45～38Ma,相当于19～16号磁条带;而加瓜脊以东地区的扩张时间为40～35Ma,相当于17～13号磁条带。加瓜脊以西的磁条带相对于以东的磁条带要老,由此推断出加瓜脊以西相对于东侧发生了北向位移。

It is shown from the observed data that the magnetic anomalies in the sea area east of Taiwan are almost all negative and show significant partitioned phenomena. It is shown from the magnetic data analysis results that the magnetic anomalies in the sea area show significant banded characteristics. Taking the Gagua Ridge as a dividing line, the magnetic band directions on both sides of the Gagua Ridge are different due to the influence of differential plate movement, the magnetic band direction east of the Gagua Ridge is SE(120 °), and that west of the Gagua Ridge is about east(80 °). The spreading duration west of the Gagua Ridge is 45～38 Ma, corresponding to magnetic bands Nos. 19～16, and that east of the Gagua Ridge is 40～35 Ma, corresponding to magnetic bands Nos. 17～13, so the magnetic bands west of the Gagua Ridge are older than those east of the Gagua Ridge, which indicates that the part west of the Gagua Ridge was shifted northward in relation to that east of the Gagua Ridge.