SEDIMENTATION AND ENVIRONMENTAL CHANGE FROM SEDIMENTOLOGICAL ANALYSIS OF BOTTOM SEDIMENT OF LAKE KAMO,SADO ISLAND

佐渡岛加茂湖底部沉积物的沉积学分析及环境变化

基本信息

批准号：
07640598
负责人：
TAKEISHI Masaaki
金额：
$ 1.41万
依托单位：
NIIGATA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Lake Kamo is a coastal lagoon separated from Ryotsu Bay by a sand bar formed at the transgressional stage after the last. To make clear the sedimentation and environmental change of Lake Kamo, echo sounding profiles by SH20 and uniboom were firstly investigated, and diatom and pollen in core dorring samples were secondarily analyzed.The lake is divided into two parts from the geomorphological feature, that is, the southern and northern part. The geomorphology of the southern lake shows the form like a bottom of the ship, which is a broad plain with steep margin. The plain bottom is 7 to 8m in depth. A long and narrow depression with 2 m depth is observed along the eastern margin. On the other hand, the northern bottom slopes gentlly from north to south.The southern bottom is covered by broad dispersive layrs. A sounding basement is cropped out on the lake bottom along the lake coast. In the northern lake the sounding basement is extended to the central part from the eastern margin. The echo sounding profiles by uniboom and boring cores showsthat the sounding basement was formed by progradation of sand bar, which developed after last glacial stage.The base of alluvium sediments is observed at 37 m in depth under the lake bottom. Terrestrial sediment underlying the alluvium sediment is considered to be Upper Pleistocene terrace deposits. The analysis of diatom assemblage about the alluvium sediments show the environmental change of the lake from brackish/fresh through marine to brackish.

Kamo湖是一条沿海泻湖，在上一场后通过在违法阶段形成的沙杆分离。为了清除Kamo湖的沉积和环境变化，首先研究了SH20和Uniboom的回声音调，然后对核心Dorring样品中的硅藻和花粉进行了研究。其次是分析的。该湖分为两部分，分别为“地貌”特征，即南部和北部。南部湖的地貌学表现出船底的形式，这是一个宽阔的平原，边缘陡峭。平原的深度为7至8m。沿东边缘观察到长而狭窄的凹陷，深度为2 m。另一方面，北部的底部从北向南倾斜。南部的底部被广泛的分散层覆盖。沿湖海岸的湖底上裁剪了一个响起的地下室。在北部湖泊中，响起的地下室从东边缘延伸到中部。 Uniboom和无聊的核心的回声响应曲线呈现出声音的地下室是由砂棒的前列形成的，该棒在最后一个冰川阶段后开发。在湖底下方，在37 m的深度下观察到了冲积物沉积物的基础。冲积液沉积物的底层沉积物被认为是上更新世露台沉积物。关于冲积层沉积物的硅藻组合的分析表明，湖中的环境变化从咸淡的/新鲜到海洋到咸咸水。