中文摘要：

海底天然气水合物与活动构造关系极为密切,随着近十几年来海底天然气水合物勘探与研究取得的重要进展,相关活动构造也正在逐渐受到关注。通过对断裂、地震、气底辟以及海底火山活动等构造活动的多种表现形式的研究,分析了南海北部活动构造的特征。在南海北部,存在北东向、北东东—东西向、北西向3组活动断裂,其中北西向断裂切割其他两组,形成最晚。这些活动断裂以继承性为主,北东向和北东东向断裂均为切割地壳或岩石圈的大断裂。南海北部的震中呈带状分布,在东部呈北东走向,而西部受红河走滑断裂的影响,震中整体为北西走向分布。气底辟是对天然气水合物形成有重要指示意义的构造,同断裂一样,气底辟为气源垂直向上移动至形成水合物的温压带提供了良好的通道。南海北部分布的火山岩由东到西顺时针旋转。从地震剖面可以看出,岩体明显受张性断裂控制。东部天然气水合物的分布受北西向活动断层的影响较大,而西部则与海底滑坡密不可分。

英文摘要：

Submarine gas hydrates are closely related to active tectonics.Recently submarine active tectonics in the northern South China Sea attract much attention because of exploration of submarine gashydrate in the past decades.We descript the features of faults,earthquakes,and volcanic activity andother active tectonics relating to gashydrate.There are three sets of active faults including NE-,NEEEW-,NW-striking faults in the northern South China Sea,of which NW-trending faults cut the other two groups.Most of these active faults are inherited from pre-existing basement faults.NE-and ENEtrending faults are crustal or lithospheric faults.The earthquake distribution is focused on a NEtrending striped region of the northern South China Sea.However,the NW-trending earthquakes are controlled by the Red River strike-slipping fault.Gas chimneys are related to active structures that play an important role of the formation of the gashydrates,as same as the channel which provides the gas to vertically migrate up to the place under appropriate temperature and pressure for gas-hydrate formation. The distribution of volcanic rocks clockwise rotates from east to west.Based on seismic profile,the volcanic rocks are controlled by tensional fault.The distribution of gashydrates in the eastern part is affected by the NW-trending active faults,however,the west is inextricably linked with the submarine landslide.