塞舌尔海台北部地形地貌特征及其构造演化

塞舌尔微陆块及其北部区域的形成过程与冈瓦纳大陆解体和马达加斯加-塞舌尔-印度复杂的形成演化过程密切相关。通过对2016年中国-塞舌尔大陆边缘海洋地球科学联合调查航次所取得的高精度多波束数据和重力数据处理分析,首次得到了塞舌尔海台北部的高精度地形图和重力异常图。应用构造地貌学分析方法,结合该区域地形及地质、地球物理等资料,进一步探讨了该区域的构造演化过程。研究发现塞舌尔海台北部发育3条向海方向延伸的狭长条带状海脊和平坦的深海平原,与塞舌尔陆块被阿米兰特海沟所切割,是一独立的构造单元。岩石地球化学证据和构造演化历史表明,塞舌尔海台北部可能在印度洋早期扩张阶段形成,向海方向延伸的海脊是由岩浆沿转换断层薄弱带喷发形成的不连续海脊。

The geomorphological features and tectonic evolution in the Northern Seychelles Plateau

Gondwana breakup and the complex rift of Madagascar-Seychelles-India were associated with the formation and evolution of the Seychelles micro-continent and Northern Seychelles Plateau. Based on the high resolution multibeam and gravity data acquired from the China-Seychelles continental margin marine science joint cruise in 2016, high resolution topographic and gravity anomaly map were drew at the first time. Combined with the topography and other geological and geophysical data, the evolution of the Northern Seychelles Plateau was discussed by using the method of the tectonic geomorphology. Here, three narrow ridges and flat abyssal plain which were separated by Amirante Trench from the Seychelles micro-continent were found at the Northern Seychelles Plateau. These ridges extend seaward and apparent discontinuity on topography, which approve that the studying area is an independent tectonic unit that doesn't belong to the Seychelles micro-continent natural extension part. By reviewing the geochemical evidence from the scraping rock samples and plate tectonic evolution history, we suggest that Northern Seychelles Plateau are likely formed during the early expansion phase of the Indian Ocean and the seaward discontinuous ridges are affected by the magma eruption along the transform fault.