论文部分内容阅读
张裂大陆边缘和盆地主要通过岩石圈的伸展作用形成,被动大陆边缘岩石圈的减薄导致了岩浆的减压熔融,最终形成了洋壳和减薄的转换带。处理和分析了2010年中国科学院南海海洋研究所“实验2”号采集的南海北部地球物理调查的多道地震数据(MCS2010-1),总结了南海北部洋陆转换带的地震反射特征。转换带主要由北部裂陷期下沉区段,中部海山或埋藏海山隆起带和靠近海盆一侧的掀斜断块带组成。通过对比以前南海北部采集的反射地震数据和折射地震波速度模型,圈定了洋陆转换带的分布范围,洋陆转换带的宽度在南海东北部是225km,中部是160km,西北部是110km。依据零星的大于6级地震震中分布,揭示了南海北部洋陆转换带目前仍是一个地震构造活跃带。
The fractured continental margin and basin are mainly formed by the extension of the lithosphere. The thinning of the lithosphere at the passive continental margin led to the depressurization and melting of the magma, resulting in the formation of the oceanic crust and the thinning transition zone. The multichannel seismic data (MCS2010-1) collected from the 2010 South China Sea Institute of Oceanology “Experiment 2 ” collected from the North China Sea geophysical survey were processed and analyzed. The seismic reflection characteristics of the ocean-land transition zone in the northern South China Sea were summarized. The conversion zone is mainly composed of the subsidence section in the northern rift period, the central seamount or buried seamount uplift belt and the tilted fault block belt near the basin side. By comparing the reflection seismic data and the refraction seismic velocity model collected in the northern part of the South China Sea, the distribution range of the ocean-land transition zone is delineated. The width of the ocean-land transition zone is 225 km in the northeastern South China Sea, 160 km in the central part and 110 km in the northwest part. Based on the epicenter distribution of scattered earthquakes larger than magnitude 6, it is revealed that the ocean-land transition zone in the northern South China Sea is still an active seismic zone.