【摘要】 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。更多还原

【Abstract】 Rifted continental margins and basins are mainly formed by the lithospheric extension.Thinned lithosphere of passive continental margins leads to decompression melt of magma and created oceanic crust as well as thinned ocean-continent transition zone.A multi-channel seismic Line MCS 2010-1 in the northern South China Sea,acquired by the R/V "Shiyan 2" of the South China Sea Institute of Oceanology in 2010,is processed and analyzed in this study.Reflection characteristics of a continent-ocean transition(COT) zone are summarized and outlined.Results show that the COT zone is mainly composed of the northern syn-rift subsidence zone,central volcanic or buried volcanic uplift zone,and tilt faulted blocks near the South China Sea basin.Compared to the previous seismic reflection data and refraction velocity models,the range of the COT zone is outlined,from about 225 km wide in the northeastern South China Sea,160 km wide in the central to 110 km in the northern-central South China Sea.Epicenter distributions of sporadic and larger than 6 magnitude earthquakes suggest that the COT zone in the northern South China Sea is still an active seismic zone.更多还原