Evolution of fan delta systems in temperate-humid and tectonically active region

温带湿润构造活动区扇三角洲系统演化

• 批准号: 19700677
• 负责人: HORI Kazuaki
• 金额: $ 2.54万
• 依托单位: Meijo University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Young Scientists (B)
• 财政年份: 2007
• 资助国家: 日本
• 起止时间: 2007 至 2009
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-19700677/
• 关键词: ファンデルタ; 沖積層; 完新世; 海進・海退サイクル; 後背地

This research obtained sediment cores (TR1 and TR2) from the fan delta developed at the lower reaches of the Tenryu River, central Japan to clarify stratigraphy and sedimentary environments of the fan delta. Two sediment cores are similar to each other, and are divided into three depositional units, units 1 to 3. Unit 1 consists of alternation of pebble to pebbly sand, which is interpreted as fluvial sediments. Unit 2 is characterized by organic-rich, sand-mud alternation. Electric conductivity suggests that the unit was formed under marine influence. Unit 3 is composed of clast-supported gravels underlain by mud. Radiocarbon dates show that each unit was deposited almost simultaneously between the both sites. Large accumulation rates, approximately 12 m/kyr, occurred between about 11000 and 8000 cal BP. In contrast, accumulation rates decreased considerably after about 8000 cal BP. The change is probably related to the rate of post-glacial sea-level rise. Moreover, upward-coarsening successions observed at both cores around 8000 cal BP suggest the beginning of regression.

本研究从日本中部天龙川下游发育的扇三角洲获得沉积物岩心（TR 1和TR 2），以阐明扇三角洲的地层和沉积环境。两个沉积岩芯彼此相似，分为三个沉积单元，即单元1至单元3。单元1由卵石到含砾砂的交替组成，解释为河流沉积物。2单元以有机质丰富、砂泥交替为特征。电导率表明该单元是在海洋影响下形成的。单元3由碎屑支撑的砾石组成，下伏泥浆。放射性碳年代测定表明，每个单元几乎同时沉积在两个地点之间。大的积累率，约12米/kyr，发生在约11000和8000卡BP。相反，积累率大大降低后，约8000卡BP。这种变化可能与冰后期海平面上升的速度有关。此外，在两个核心8000 cal BP左右观察到向上粗化的继承表明回归的开始。

项目成果

完新世における氾濫原の堆積速度

全新世期间的漫滩沉积速率

• 发表时间: 2009
• 作者: Tamamura,S.;Sato,T.;Ota,Y.;Aota,Y.;Kashiwaya,K.;Kumagai,M.;長澤重信・堀和明;堀和明
• 通讯作者: 堀和明

天竜川河口域にみられるファンデルタ堆積物

天龙川河口地区发现扇三角洲沉积物

• 发表时间: 2009
• 作者: Tamamura,S.;Sato,T.;Ota,Y.;Aota,Y.;Kashiwaya,K.;Kumagai,M.;長澤重信・堀和明
• 通讯作者: 長澤重信・堀和明

天竜川扇状地で得られたコア堆積物の堆積相と堆積速度.

天龙河扇的沉积相和岩心沉积物的沉积速率。

• 发表时间: 2009
• 期刊: 地形 30(4)
• 作者: 山口実里・福留邦洋・岡崎篤行;福留邦洋;福留邦洋・山口実里・岡崎篤行;新潟NPO協会;福留邦洋;長澤重信・堀和明
• 通讯作者: 長澤重信・堀和明