Differences of Polygonal Faults with Irregularly Polygonal Geometries: A Case Study from the Changchang Sag of Qiongdongnan Basin, Northern South China Sea  

作　　者：LI Yufeng PU Renhai ZHANG Gongcheng FAN Xiaowei 

机构地区：[1]School of Environment and Resource,Southwest University of Science and Technology,Mianyang 621010,China [2]State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi’an 710069,China [3]Key Laboratory of Marine Mineral Resources,Ministry of Natural Resources,Guangzhou 510075,China [4]CNOOC Research Institute,Beijing 100028,China [5]Research Institute of Yangchang Petroleum(Group)Co.,Ltd.,Xi’an 710075,China

出　　处：《Journal of Ocean University of China》2023年第1期119-135,共17页中国海洋大学学报（英文版）

基　　金：supported by the Key Laboratory of Marine Mineral Resources,Ministry of Land and Resources of China(No.KLMMR-2018-B-07);the National Basic Research Program of China(No.2011ZX05025-006-02);the National Natural Science Foundation of China(No.41672206)。

摘　　要：Polygonal faults(PFs)generally have a classic polygonal geometry in map view.However,under the influence of tectonic faults,diapirs,channels,and slopes,the classic polygonal geometry of PFs is not preserved,demonstrating differences(different characters)in map-view 3D seismic data covering an area of 334km^(2) of the Changchang(CC)sag,are used to document the mapview and cross-sectional characteristics of PFs.These data also help investigate the irregularly polygonal geometries of PFs due to the presence of influence factors,such as transtensional faults,submarine fans,channels,diapirs/gas chimneys,and the basal slope within the lower-middle Miocene strata.Results show that various irregularly polygonal geometries of PFs can be classified into enechelon and arcuate PFs,channel-segmenting and-bounding PFs,radial PFs,and rectangular PFs in map-view.En-echelon and arcuate PFs are induced by transtensional faults and exhibit a unique‘flower’structure in NE-and SE-trending cross-sections in the NW area of the study area.This finding is documented for the first time.Channel-segmenting PFs occur in the(northwest)low-amplitude muddy channel and are inhibited in the(southeast)high-amplitude sandy channel in the SW area.Radial PFs are radially aligned around a gas chimney/diapir containing some high-amplitude anomalies(HAAs)in the middle area.The presence of intrusive sandstones with HAAs along the periphery of the diapirs restricts the occurrence of PFs.Two high-amplitude submarine fans act as a mechanical barrier to the propagation of PFs.Meanwhile,the(moderate)slope in the NE area induces rectangular PFs.Additionally,the geneses of the PFs in the current study are comprehensively discussed.This study adds to our understanding of the differences between PFs with irregularly polygonal geometries.

关 键 词：channel DIAPIR GENESIS influence factors northern South China Sea polygonal fault slope transtensional faults 

分 类 号：P736[天文地球—海洋地质]