日本地球惑星科学連合2019年大会

講演情報

[E] ポスター発表

セッション記号 H (地球人間圏科学) » H-CG 地球人間圏科学複合領域・一般

[H-CG26] デルタとエスチュアリー:複雑な河口システムへの学際的取り組み

2019年5月27日(月) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:齋藤 文紀(島根大学エスチュアリー研究センター)、Guan-Hong Lee(Inha University)、David L Dettman(University of Arizona)、堀 和明(名古屋大学環境学研究科地理学講座)

[HCG26-P01] Deltafront Clinoform of Abandoned Yellow River Delta in Jiangsu Province, China

*LIANGYONG ZHOU1 (1.Qingdao Institute of Marine Geology China Geological Survey)

キーワード:Abandoned Yellow River Delta, Deltafront clinoform, C-14 ages, OSL ages

The abandoned Yellow River delta in Jiangsu province is a major sediment supplier to the South Yellow Sea and East China Sea. In this study, comparison of historical maps, two cores and three seismic profiles were used to examine its deltafront clinoform (nearshore clinoform). The original historical maps and nautical charts since AD 1750s were collected and compared after calibration, showing the accretion of the shoreline before 1855, when the Yellow River shifted to the Bohai Sea. Near Sheyang River mouth, two 20m-long cores onshore (1 m above present sea level ) and offshore (6 m bellow present sea level) were on a line normal to the shoreline. Samples og both cores were dated using AMS 14C and OSL(Optical Stimulated Luminescence) dating technologies. Ages in bottoms of the cores are 43000 to 44000 cal yr BP. At approximate 17.5m bellow present sea level in both cores, yellow and younger (younger than 5000 yr BP) silt sediment occurs. Several young ages in upper part of two cores were obtained, and these show a clear clinoform pattern. Furthermore, seismic profiles across the offshore core show the deltafront clinoform. The upper part weak reflector or transparent part in seismic profiles become thinner seaward and the lower part is strong reflectors. Sea bottom nearshore show a convex shape, but the seaward low gradient part show erosional gullies. The evolution of the deltafront clinoform was revealed in profiles and in plan view.