Geomorphology and tectonic interpretation of Zhujiang Submarine Canyon, in the northern South China Sea

Abstract

Zhujiang Submarine Canyon, a large submarine canyon, is located in the northern South China Sea, extending to 300 km southeastward from the shelf break off Zhujiang River estuary, down to deep-sea basin. Based on the full-coverage multi-beam seabed terrain data, the subtle topographic features of Zhujiang Submarine Canyon are analyzed. According to the morphology, trend, and bottom axial gradient, Zhujiang Submarine Canyon is divided into upper, middle and lower segments and deep-sea fan. On the basis of geomorphology, tectonic interpretation indicates that Zhujiang Submarine Canyon is mainly affected by the northeast-trending faulted basin and northwest-trending fault belt since Mesozoic, followed by the east-west-trending fault belt. Zhujiang Submarine Canyon maybe formed by the continuing thermal subsidence and fault depression of northern South China Sea margin caused by South China Sea spreading based on the collision between India-Australian plate and Eurasian plate. The submarine canyon becomes more narrow and deeper at the entrance because of the submarine volcanoes formed by the volcanic eruptions in Neogene. Zhujiang Submarine Canyon is continual eroded and filled by the cyclical sea level changing and massive sediment carried by Zhujiang River. The thick sediments, slump layer and developed fracture are conducive to migration, aggregation and accumulation of hydrocarbon. And the surface hydrocarbon spill formed the seabed pockmark structure on the north slope of the submarine canyon.