摘要
琼东北的1605年琼州7.5级大地震曾导致大面积陆陷成海。前人研究多关注陆陷成海机制,但对该区晚新生代断裂活动及其控制下的沉降过程与构造机制一直缺乏深入研究。在地质调查基础上,结合钻孔揭露和大地电磁探测(EH4)结果等资料发现,东寨港地区自西向东可分为演丰火山岩台地、东寨港潟湖平原和锦山剥蚀台地三个构造地貌单元,并且不同地貌单元间明显受到区域上北西向正断层活动的控制。根据86个钻孔资料制作的东寨港地区新近纪以来不同时期沉积物等厚度图显示,该区的沉积中心从新近纪以来存在由西向东迁移过程,沉积速率也存在明显的变化。中—上新世、早更新世、晚更新世和全新世平均沉积速率分别为12 mm/ka、10 mm/ka、67 mm/ka和1 922 mm/ka,显示中更新世之后沉积速率骤然增大,并在全新世达到最大。综合分析认为,北西向铺前—清澜断裂第四纪正断层活动控制了东寨港地堑的发育与东寨港陆陷成海及其震后地壳持续下沉;东寨港凹陷晚更新世以来处于快速加积过程中;相邻的锦山剥蚀台地长期以来处于相对稳定或微隆升状态,并很可能属于雷琼凹陷之外的构造地块,雷琼凹陷是否应囊括锦山剥蚀台地值得进一步研究和商榷。
The Qiongzhou great earthquake of magnitude 7.5 in 1605 caused extensive land subsidence into the sea.Previous studies have paid much attention to the land subsidence mechanism,but there is still a lack of in-depth study of the fault activities as well as the process and the mechanism of tectonic subsidence since the Late Cenozoic.Based on field investigation,drill hole data and EH4 inversion analysis,the authors divided the Dongzhai port area into three tectonic geomorphologic units,namely,Yanfeng volcanic platform,Dongzhai lagoon plain and Jinshan eroded platform,which are controlled by the regional NW-trending faults.The sedimentation thickness map based on data of 86 drill holes at different stages since the Neogene was compiled,which shows that the sedimentation center is transferred from the west bank to the east bank and the average deposition rates also have significant change.The average deposition rates of the Mesozoic–Pliocene,Early Pleistocene,Late Pleistocene and Holocene were 12 mm/ka,10 mm/ka,67 mm/ka and 1 922 mm/ka respectively,which suggests that the deposition rate was slow before the Middle Pleistocene,began to increase suddenly in the Late Pleistocene,and probably reached the maximum since the Holocene.Some conclusions have been reached:(1)The Dongzhai port graben was mainly controlled by NW-trending Quaternary normal Puqian–Qinglan fault that also controlled the development of Dongzhai port graben,its subsidence into the sea and its continuous sink.(2)The subsidence of Dongzhai port depression has been accelerated since the Late Pleistocene.(3)Jinshan eroded platform has been long in a stable or slightly uplift state,and is likely to belong to the tectonic block outsidethe Lei–Qiong Depression.The problem whether the Leiqiong depression includes Jinshan eroded platform deserves further study.
作者
丁莹莹
赵希涛
胡道功
张绪教
王超群
胡正旺
夏蒙蒙
吴环环
游报捷
常鹏渊
DING Ying-ying;ZHAO Xi-tao;HU Dao-gong;ZHANG Xu-jiao;WANG Chao-qun;HU Zheng-wang;XIA Meng-meng;WU Huan-huan;YOU Bao-jie;CHANG Peng-yuan(School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083;Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029;Key Laboratory of Neotectonic Movement&Geohazard,Ministry of Land and Resources,Beijing 100081;Institute of Geophysics&Geomatics,China University of Geosciences(Wuhan),Wuhan,Hubei 430074)
出处
《地球学报》
EI
CAS
CSCD
北大核心
2018年第2期155-166,共12页
Acta Geoscientica Sinica
基金
中国地质调查局地质调查项目"泛珠三角地区活动构造与区域地壳稳定性调查"(编号:DD20160269)资助~~
关键词
海南岛
雷琼凹陷
新构造运动
活动断裂
铺前—清澜断裂
Hainan Island
Leiqiong depression
neotectonic movement
active fault
Puqian–Qinglan fault
