南海北部琼东南盆地中央峡谷成因新认识

A new consideration on the genetic mechanism of the central canyon in the Qiongdongnan Basin,the northern South China Sea

通过对区域构造断裂体系和逐渐连片的高分辨率三维地震资料的精细解析,认识到琼东南盆地中央峡谷的形成机制除了与晚中新世区域构造变动、大规模海平面下降、充足物源供给以及凹槽型古地形特征等因素相关之外,还存在另外一个非常重要因素:峡谷底部早期隐伏断裂带的存在。研究表明:琼东南盆地中央坳陷带发育平行于陆架坡折的大规模深水峡谷,峡谷底部发育大型走滑断层以及走滑断层派生出一系列次级断层形成的地层破碎带,认识到峡谷的形成、规模以及展布方向均受断裂带影响;相应地峡谷的充填及演化亦是受物源、海平面变化、重力流作用等多种因素共同作用和相互叠加的过程。从而为研究经历了裂陷期和坳陷期盆地演化过程形成的大型峡谷提供了科学依据。

Based on regional tectonic fracture system and gradually shape the canyon area high resolution 3Dseismic data of fine resolution,realize the central valley of Qiongdongnan Basin formation mechanism in addition to the late Miocene tectonic changes,large-scale sea level falling,adequate supply source and groove type ancient topography and other related factors,there is another very important factor：the existence of early concealed fault zone at the bottom of the canyon.Research shows that parallel to the development in the central depression belt in Qiongdongnan Basin shelf slope break large-scale deep canyon,at the bottom of the canyon development large strike-slip faults and strike-slip faults to derive a series of secondary fault formation strata fracture zone,to realize the formation of the canyon,scale and distribution direction are affected by faults.Accordingly,the filling and evolution of the canyon,sea level change,is also the source of gravity flow function of the process of interaction and mutual superposition of many factors.To study experienced chasmic stage and basin evolution process is formed during the subsidence stage of the basin is of important guiding significance for large canyon.