南海东北部深水区泥火山的分布与特征

THE DISTRIBUTION AND CHARACTERISTICS OF MUD VOLCANOES IN THE NORTHEASTERN SOUTH CHINA SEA

前人在南海东北部发现许多与天然气渗漏相关的规模大小不一的泥火山。受数据类型和分辨率所限,这些泥火山规模大小存在数据断层。利用多波束地形数据,在研究区域新发现了27个直径在300~1170m、高度在5~120m范围内的泥火山,并且这些泥火山大多发育在海底侵蚀作用强烈的峡谷中。南海东北部海底地层中泥质和烃类来源充足,较快的沉积速率构成的超压体系以及强烈的挤压构造应力作用,使得含气高压泥浆上涌,穿透峡谷较薄的沉积层,这些黏性泥质在海底表面堆积形成了泥火山。

Mud volcanoes in different sizes are found associated with gas seepages in the northeastern South China Sea.Restricted by types and low resolutions of the data,there are gaps in the size of mud volcanoes.Using multi-beam bathymetry data,we find 27 new mud volcanoes in the study area 5~120 min heights with diameters between 300~1170 m.Most of them are found in the canyons of heavy erosion.There are enough mud and gas as sources,and the overpressure system due to the joint actions of rapid sedimentation rate and tectonic compression forced the gas-rich mud to pierce into the thin canyon deposits and form mud volcanoes.