河成低地堆積システムの第四紀環境変動への応答

河流低地沉积体系对第四纪环境变化的响应

• 批准号: 16700594
• 负责人: 堀 和明
• 金额: $ 2.05万
• 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: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16700594/
• 关键词: 河成低地; 沖積層; 後背湿地; 河道変遷; 海進・海退サイクル; 完新世

河成層の累重様式と平野微地形の形成過程を,堆積物のボーリング調査にもとついて論じた.今年度は,濃尾平野の河成低地を構成する旧河道と自然堤防上で採取された堆積物コア(AP1およびAP2)を解析し,堆積物の特徴や堆積時期,堆積速度などを検討した.調査地点は岐阜県安八町である.その結果,以下のことがわかった.約3200yrBP以降,両地点は後背湿地の環境となり,植物遺体を多く含む泥の堆積が続いた.その後,揖斐川がAP1コア採取地点の上を流れるようになり,AP1コアの後背湿地堆積物の一部は侵食を受けた.一方,AP2コア採取地点では,砂質の自然堤防堆積物が後背湿地堆積物を覆って急速に堆積するようになった.堆積物の年代測定結果によれば,この地点が揖斐川の流路となったのは,約400cal BP以降と考えられる.歴史記録によると,揖斐川の流路がAP1を通過するようになったのは慶長年間(1596-1615年)の洪水時とされている.したがって,本研究で得られた年代測定結果は,歴史記録とも矛盾しない.年代測定結果にもとついて,河川成堆積物の堆積速度を推定した.後背湿地堆積物の堆積速度は,AP1コアで約0.1cm/yr, AP2コアで約0.2cm/yrとなる.一方,自然堤防堆積物の堆積速度は約1.5cm/yrであり,後背湿地堆積物の堆積速度に比べて約4-15倍大きい.河成層の厚さは,AP1コアで7m, AP2コアで10m程度となっており,河成層の下限の標高は約-3mとなり,現在の海水準よりも明らかに低い.これは濃尾平野が養老断層の活動に関係して沈降傾向にあるためだと考えられる.なお,研究成果については,2006年夏の国際堆積学会および2007年春の日本地形学連合春季大会で発表した.

The process of Hecheng heavy-duty Hirano micro-topography is formed, and the accumulation of active materials is very difficult. At the end of this year, the Hirano river lowland in Yuewei was selected from the natural embankment of the old river course to analyze the AP1 active matter (AP2). During the special period of the reactor, the speed of the reactor was very high. The location is Kanabachi, Gifu, and the city of Anba. The results show that the following results are correct. As a result of 3200yrBP, the wetlands at the back of the site have a poor environment, and most of the plants contain sediment deposits. After the scraping, he bowed to Fichuan AP1 to pick up the location, and the AP1 to collect food from the wetlands on the back. On the one hand, the AP2 will pick up the location, and the sand will cover the wetland on the back of the natural embankment. The results of the dating of the active material in the pile show that the location of the reactor is very high, and the location of the reactor is about 400cal BP. In the history of the past, there was a long history of suffering from floods in the middle of the year (1596-1615). During the long years (1596-1615), the Feichuan Riverside Road was in the middle of the storm. In this study, we have obtained the results of dating, and historical records are full of contradictions. The results of chronological determination show that the velocity of active materials in rivers is inferred. The composting speed of back wetlands is about 0.1cm/yr for AP1 and 0.2cm/yr for AP2. On the one hand, the stacking speed of the active material of the natural dike is about 1.5cm/yr, while that of the back wetland is about 4-15 times higher than that of the natural dike. The thickness of the river is about 7m, AP1 is 7m, AP2 is 10m, the lower limit of the river is about-3m, and the sea level is now low. At the end of the day, there was an old train in Hirano, and there was a lot of activity, and there was a lot of trouble. In the summer of 2006, the International Institute of International stacking, the Spring Conference of Topographic Connectivity in Japan in the spring of 2007, the table.