江苏如东潮滩微地貌及现代沉积速率  

Micro-morphology and contemporary sedimentation rate of tidal flat in Rudong,Jiangsu Province

作　　者：李海清[1] 殷勇[1] 施扬[1] 何华春[1] 刘昕洋[1] 

机构地区：[1]南京大学海岸与海岛开发教育部重点实验室,江苏南京210093

出　　处：《古地理学报》2011年第2期150-160,共11页Journal of Palaeogeography：Chinese Edition

基　　金：国家自然科学基金项目(编号:40776023);国家大学生创新训练计划项目"如东紫菜养殖对沿海滩涂地貌以及沉积作用的影响"联合资助

摘　　要：在江苏如东洋口港东侧长沙镇外宽10余千米的粉砂质潮滩上进行潮滩微地貌调查,在低潮滩设置3个沉降板,在中、低潮滩采集4个柱状样(长度92～151cm),并对其进行垂向上的粒度和微相分析及210Pb测量。希望通过上述调查,揭示研究区近几十年来由于强烈的人类活动导致的潮滩冲淤调整状态。调查结果表明,低潮滩尤其是低潮滩下部是微地貌变化最活跃的场所,表现为潮滩表面凹凸不平、多冲蚀洼槽,沉降板试验结果显示低潮滩约2个月的沉积量向水边线方向显著减小;中潮滩表面平坦,微地貌相对比较稳定。柱状样研究结果显示,低潮滩早期为向上变细的进积层序,但近期沉积物粗化,呈现退积层序,且该现象在低潮滩下部尤其明显;中潮滩柱状样显示向上细化层序,反映稳定持续的加积和进积。柱状样的210Pb测试结果表明,中潮滩中部(米草滩中部)沉积速率为4.40cm/a,中潮滩下部(米草滩前缘)为1.85cm/a,低潮滩中部为1.54cm/a,低潮滩下部无法获得沉积速率。该沉积速率结果还显示低潮滩退积层序的开始时间和研究区米草的引种时间基本吻合。上述研究结果反映近30a来在人类活动尤其是米草的作用下,研究区中潮滩稳定淤积,但低潮滩却因缺乏充足泥沙而加剧侵蚀。The present study investigated the micro-morphology,measured the deposition thickness by the method of setting 3 settlement plates on low-tidal flat,and obtained four short vibrocores（92-151cm long）from low to mid-tidal flat in Changsha coastal area,Rudong County.Grain size,microfacies and 210Pb of these vibrocores were analyzed to reveal the adjustment of tidal flat accretion/erosion responding to the increasing human activities during recent decades.The survey shows that surface of low-tidal flat,especially the lower part of low-tidal flat is rough with lots of scouring groves,which indicates the most active place of micromorphological change.The settlement plate experiments show that the deposits accumulated within two months distinctly decrease towards the water sideline.The micro-morphology in mid-tidal flat is relatively stable.Vertical micro-facies from vibrocores on low-tidal flat shows an upward-fining progradational sequence in early stage,but recently it became coarsening upward and shows characteristics of retrogradational sequence,especially in the lower part of low-tidal flat.Results of 210Pb show that sedimentation rate is 4.40 cm/a in the middle part of mid-tidal flat,1.85 cm/a in the lower part of mid-tidal flat,and 1.54 cm/a in the middle part of low-tidal flat.The sedimentation rate is not available in the lower part of low-tidal flat.The sedimentation rates show that the time when the retrogradational sequence began to appear in low-tidal flat is in agreement with the time when the Spartina angilica was introduced about 30 years ago.The above results reflect human activities,especially the Spartina angilica colonization have led to the continous progradation of mid-tidal flat,but intensive erosion in the low-tidal flat.

关 键 词：潮滩 米草促淤 低潮滩侵蚀 人类活动 

分 类 号：P512.2[天文地球—地质学]