Complex Linkage and Transformation of Boundary Faults of Northern Huizhou Sag in Pearl River Mouth Basin

Tian Wei; He Min; Yang Yajuan; Liu Hailun; Yuan Xun; Wu Sen; Zhu Dingwei; Mei Lianfu

doi:10.3799/dqkx.2015.181

Abstract：The formation and tectonic framework of a faulted basin are controlled by boundary fault,which have different types of basin evolution under different boundary connection modes.The purpose of this study is to recognize the linkage model of boundary faults of northern Huizhou sag in Zhu I depression,Pearl River Mouth basin (PRMB),the South China Sea,which is a representative of global passive continental margin basins.Based on well controlling high-precision 3D seismic survey,the geometry of boundary faults and the framework of “four-order sequences”are determined in PRMB.The fault activities of dif-ferent boundary fault sections and the spatial change of depocenters during rift episode I are analyzed.An evolution model of boundary fault system in northern Huizhou sag,PRMB is established in this study.The results show that the northern boun-ding faults of northern Huizhou sag have an offset geometry in Early Eocene,characterized by along-strike and transverse two-way linkage.The along-strike linkage is a composite connection-transformation of “soft and hard”linkage,forming a relay ramp and transverse folds which restrict the structural evolution within Huizhou sag and the migration of its depocenters and sequences.The transverse linkage means the multiple-stage linkage of the transfer faults in relay ramp,including three stages, namely,isolated normal faulting,synthetic overlapping and hard linkage,which control the migration and distribution of depo-sitional system within the relay ramp.This paper presents a unique case of spatial evolution,complex linkage and transforma-tion model of boundary faults in a rift basin,which can facilitate further studies on the response relationship among the bounda-ry fault,sedimentary sequence,sag evolution and regional dynamics mechanism.