摘要
晚第四纪以来,黄河、长江都曾经江苏中部海岸注入南黄海,河海交互作用形成一系列沉积,全新世海侵后发育岸外辐射沙脊群。沙脊群西北部、由岸滩与沙脊所夹持的西洋潮流通道,位于北侧废黄河三角洲和南侧长江三角洲两大地貌单元间的过渡区,成为揭示不同大河交互作用下的海岸、陆架晚第四纪沉积层序模式的重要窗口。最近通过更多晚第四纪钻孔对比和浅层地震剖面集成研究发现:①由于混乱的测年结果和陆相硬黏土层对比不当,造成之前基于07SR01孔和Y1孔构建的辐射沙脊群西洋潮流通道浅部沉积(标高-60 m以内)的年代框架有误,其主体应是晚更新世沉积且发育两个沉积旋回,末次冰盛期硬黏土层多被潮流侵蚀而缺失,表层全新世沉积厚度在水下沙脊处基本不足10 m,其余普遍不足5 m,甚至缺失;②仅在西洋西北段稳定分布的浅层地震单元U3指示了MIS 3古黄河三角洲的南缘,自晚更新世以来西洋所在的江苏中部海岸可能深受古黄河物源的影响,这尚需在西洋西北段的关键位置钻取新孔,并结合已有浅层地震剖面和东南段钻孔来进一步研究证实。提出下一步工作将基于层序地层学方法,通过对已有控制性浅层地震剖面进行地震层序格架的三维可视化、提取地震单元和反射界面的空间分布特征,结合已有及新增控制性钻孔的沉积学和年代学研究,构建可靠年代框架、判识大河物源,并参考邻区钻孔资料,来探明西洋潮流通道的浅部沉积层序,反演其形成演化。
Since the Late Quaternary,both the Yellow River and Changjiang River entered into the South Yellow Sea flowing through the middle Jiangsu coast.As a result,a series of sediments have been deposited in this area controlled by the river-sea interactions.The Radial Sand Ridge Field(RSRF)off the middle Jiangsu coast has been formed after the Holocene transgression.The Xiyang tidal channel in the northwestern RSRF is constrained by the tidal flat coast and tidal ridges.It is located in the transition zone between the northern Abandoned Yellow River delta and southern modern Changjiang River delta.Therefore,it becomes the important window area to reveal the sedimentary sequence formed in the coast and continental shelf under the active interactions between different large rivers during the Late Quaternary.As to the upper strata with the depth less than 60 m below the current mean sea-level in the Xiyang tidal channel,there are still different viewpoints on its sedimentary sequence,chronology framework and evolution,while the concerned studies are still pretty limited.Recently,the results of further Late Quaternary stratigraphic correlations and synthesis study on shallow seismic profiles showed that,(1)Due to disordered dating results and improper correlation of terrigenous stiff mud layers,the chronology framework of Xiyang upper strata built previously based on core07SR01 and Y1 is incorrect,the main part of the upper strata including two sedimentary cycles are the Late Pleistocene deposits and the stiff mud layer of the Last Glacial Maximum is often missing due to the tidal scouring,the thickness of surficial Holocene sediments are generally less than 10 m in the submerged sand ridges,and extensively less than 5 m in other places,or even zero in some places;(2)The shallow seismic unit 3(U3)only steadily located in the northwestern part of the Xiyang tidal channel indicates the southern margin of the old Yellow River delta developed during MIS 3,and the middle Jiangsu coast in which the Xiyang tidal channel is located was probably influenced deeply by the old Yellow River sediments since the Late Pleistocene,however it is still necessary to recover a new sedimentary core in the key position of northwestern part,plus further study and verification based on the new core and other acquired shallow seismic profiles and cores in the southeastern part should be done.Thus,this paper proposed the further study plan as follows,based on the 3D visualization of the seismic sequence framework,the spatial characteristics of the seismic units and main reflection interfaces would be extracted.Furthermore,combined with the sedimentology and chronology studies of the existing and designed cores,the reliable chronology framework would be set up expectedly,and the provenance from large rivers would be identified.Applying the sequence stratigraphy method,referencing the adjacent published core data,it is targeted to ascertain the shallow sedimentary sequence in the Xiyang tidal channel,and to reveal its evolution.
作者
夏非
张永战
刘德政
XIA Fei;ZHANG Yongzhan;LIU Dezheng(School of Urban,Resource and Environmental Sciences,Jiangsu Second Normal University,Nanjing 211200,China;The Key Laboratory of Coast and Island Development of Ministry of Education,School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China)
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2021年第4期13-26,共14页
Marine Geology & Quaternary Geology
基金
国家自然科学基金青年科学基金项目“辐射沙脊群西洋潮流通道的浅部沉积层序及其形成演化”(41901107)
江苏省高等学校自然科学研究面上项目“辐射沙脊群东北翼浅层沉积结构南北分异研究”(18KJB170003)
江苏第二师范学院引进高层次人才科研启动经费项目(919801)。
关键词
南黄海
江苏中部海岸
辐射沙脊群
潮流通道
沉积层序
晚第四纪
South Yellow Sea
middle Jiangsu coast
Radial Sand Ridge Field
tidal channel
sedimentary sequence
Late Quaternary
