中文摘要：

2013年采集的单道地震剖面揭示了西沙海域的火山结构,有助于理解该区域火山的形成机制和活动性特征。地震剖面显示:西沙南部存在大约10个火山构造,具有不连续强振幅反射特征的熔岩流侵入火山周围上新世和更新世地层。此外,在西沙西部边缘和中部分别发现有单个火山构造,岩浆侵入火山体周围的第四纪地层。根据岩浆侵入体和周围地层的接触关系,推测区内火山活动集中在上新世和第四纪两个时期。上涌的深源地幔岩浆弱化了地幔岩石圈并继续沿着先存断裂向上涌至古海底,可能是该区域火山形成机制。

英文摘要：

Due to data sparsity,volcanic activity in the Xisha waters is poorly understood.Single channel seismic profiles areused to study the volcanoes’structures and their formation mechanisms in this paper.Seismic profiles document10submarinevolcanoes in the south XW.Inside the volcanoes,discontinuous but strong reflections are observed and interpreted as lavaflows.In addition,seismic data show two isolated volcanoes intruding Quaternary strata in the western edge and middle XW,respectively.Stratigraphic contact relationship between the lava flows and surrounding sedimentary strata reveals that Plioceneand Quaternary are two main magmatic activity stages in the XW.We propose the formation mechanism of volcanoes in theXW be that upwelling mantle magma weakens mantle lithosphere,migrates along pre-existing fault,and then erupts to thepalaeo-seabed.