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LI Yuhan,ZHU Rongwei,LIU Hailing,QIU Xuelin,HUANG Haibo. 2019. The Cenozoic activities of Yangjiang-Yitongdong Fault: insights from analysis of the tectonic characteristics and evolution processes in western Zhujiang (Pearl) River Mouth Basin. Acta Oceanologica Sinica, 38(9):87-101
The Cenozoic activities of Yangjiang-Yitongdong Fault: insights from analysis of the tectonic characteristics and evolution processes in western Zhujiang (Pearl) River Mouth Basin
阳江-一统东断裂的新生代活动:从珠江口盆地西部构造特征与演化过程分析得到的启示
Received:August 17, 2018??
DOI:10.1007/s13131-019-1477-x
Key words:Yangjiang-Yitongdong Fault??Zhujiang (Pearl) River Mouth Basin??tectonic evolution??strike slip movement??Cenozoic
中文关键词:??阳江-一统东断裂??珠江口盆地??构造演化??走滑活动??新生代
基金项目:The National Natural Science Foundation of China under contract Nos 41776072, 41476039, 41674092 and 41676045; the Geotectonic Evolution of China and Compilation of International Asian Geotectonic Map under contract No. DD20190364; the Marine Basic Geological Survey Project under contract No. DD20190627.
Author NameAffiliationE-mail
LI Yuhan?Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
University of Chinese Academy of Sciences, Beijing 100049, China?
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ZHU Rongwei?Guangzhou Marine Geological Survey, Guangzhou 510760, China??
LIU Hailing?Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China?liuh82@126.com?
QIU Xuelin?Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
University of Chinese Academy of Sciences, Beijing 100049, China?
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HUANG Haibo?Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China??
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Abstract:
??????The Yangjiang-Yitongdong Fault (YJF) is an important NW-trending regional fault, which divides the Zhujiang (Pearl) River Mouth Basin (ZRMB) into western and eastern segments. In Cenozoic, the northern continental margin of the South China Sea (SCS) underwent continental rifting, breakup, seafloor spreading and thermal subsidence processes, and the Cenozoic activities of YJF is one part of this series of complex processes. Two long NW-trending multichannel seismic profiles located on both sides of the YJF extending from the continental shelf to Continent-Ocean Boundary (COB) were used to study the tectonic and sedimentary characteristics of western ZRMB. Using the 2D-Move software and back-stripping method, we constructed the balance cross-section model and calculated the fault activity rate. Through the comprehensive consideration of tectonic position, tectonic evolution history, featured structure, and stress analysis, we deduced the activity history of the YJF in Cenozoic. The results showed that the YJF can be divided into two segments by the central uplift belt. From 65 Ma to 32 Ma, the YJF was in sinistral motion as a whole, inherited the preexisting sinistral motion of Mesozoic YJF, in which, the southern part of YJF was mainly in extension activity, controlling the formation and evolution of Yunkai Low Uplift, coupled with slight sinistral motion. From 32 Ma to 23.8 Ma, the sinistral motion in northern part of YJF continued, while the sinistral motion in southern part began to stop or shifted to a slightly dextral motion. After 23.8 Ma, the dextral motion in southern part of YJF continued, while the sinistral motion in northern part of YJF gradually stopped, or shifted to the slightly dextral motion. The shift of the YJF strike-slip direction may be related to the magmatic underplating in continent-ocean transition, southeastern ZRMB. According to the analysis of tectonic activity intensity and rift sedimentary structure, the activities of YJF in Cenozoic played a regulating role in the rift extension process of ZRMB.
中文摘要:
??????阳江-一统东断裂是珠江口盆地西部一条重要的NW向区域大断裂,是盆地东西分块的重要分界线。南海北部陆缘在新生代经历了大陆裂谷-裂离-海底扩张-热沉降的过程,阳江-一统东断裂在新生代的活动是这一复杂过程的一部分。对分处断裂两侧的从陆架延伸至洋陆边界的两条NNW向多道地震剖面进行了地质解释,研究了珠江口西部的构造和沉积特征。利用2D-Move软件及构造回剥法建立了平衡剖面模型,计算了断层活动速率,结合构造位置、构造演化史、标志构造和应力分析推断了阳江-一统东断裂在新生代的活动史。结果表明,阳江-一统东断裂可以中部坳陷带为界分为两段,从65Ma到32Ma,断裂整体表现为左旋活动,继承了断裂在中生代时期的先存左旋走滑,其中,在此时期断裂南段主要表现为伸展活动,伴随着轻微的左旋走滑,这种伸展活动控制了云开低凸起的形成和演化;从32Ma到23.8Ma,断裂北段的左旋走滑活动持续,而南段逐渐转为轻微的右旋走滑或左旋活动停止。在23.8Ma之后,断裂南段的右旋走滑活动持续,北段的左旋走滑逐渐停止,或转为轻微的右旋走滑。阳江-一统东断裂的这种走滑旋向的转变可能与在珠江口盆地南部洋陆过渡带区域的岩浆底侵作用有关。根据对盆地构造活动强度和裂谷格架的分析,认为阳江-一统东断裂的新生代活动在珠江口盆地裂谷伸展过程中起到了应力调节的作用。
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