块体搬运沉积构型及其对后期浊流沉积的影响——以琼东南盆地陵水凹陷L区为例

Sedimentary architecture of mass transport deposits and its influence on later turbidity deposition——An example from the L area of Lingshui Sag in Qiongdongnan Basin

通过对琼东南盆地陵水凹陷陆坡区高分辨率三维地震资料的精细解释,在研究区发现广泛发育的块体搬运沉积体系(MTDs),表现为:(1)弱振幅、低连续、杂乱或空白的地震反射特征且具有明显的侵蚀作用;(2)在研究区体部和趾部区域发现大量侵蚀擦痕、逆冲推覆构造和挤压脊等内部结构;(3)块体搬运沉积由于内部结构变形发育为逆冲推覆构造等,其表面形态往往呈连续的凸起与凹陷。研究区识别出两期MTDs(MTDs1和MTDs2)和一套浊流沉积,MTDs1所形成的长10~15 km、宽2~3 km的脊,改变了海底形态,阻碍了后期浊流沉积的流向,并影响了浊流沉积的位置。

Through the fine interpretation of high-resolution 3D seismic data collected from the slope area of the Lingshui Sag in the Qiongdongnan Basin,extensively developed mass transport deposits(MTDs)have been discovered with the characteristics as follows:(1)The mass transport deposits usually show weak amplitude,low continuity,chaotic or blank seismic reflection with obvious erosion;(2)A large number of internal structures such as erosional scratches,thrust nappe structures,and squeezed ridges are observed in the body and toe parts of the deposits;(3)Mass transport induced thrust nappe structures caused by internal structural deformation are common and the surface morphology of the deformation is always characterized by continuous protrusions and depressions.Two stages of MTDs,i.e.MTDs1 and MTDs2,are found in the study area together with associated turbidites.The ridges 10~15 km long and 2~3 km wide formed by the MTDs1may change the morphology of seafloor,block the way of later turbidity currents and change the location of turbidites.