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Palaeolimnological Study on Coastal Closed Lake Inferred from Frequency of Overflow

从溢流频率推断的沿海封闭湖古湖泊学研究

基本信息

批准号：
60302027
负责人：
AKAO Kinshiro
金额：
$ 3.52万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Co-operative Research (A)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60302027/
关键词：
maritime coastal lake frequency of overflow mechanism of water budget sediments core of lake bottom granulometric analysis strarification specified by soft X-ray origin of lake basin 安定同位体比による古環境変遷

项目摘要

A purpose of this study is to clarify how a hydrological regime has changed during a drastic, climatic change, that is, from the last glacial age to the postglacial age. In this connection, Lake Horokayanto at the Tokachi district in Hokkaido was subjected to a co-operative research on the subject of" Palaeolimnological Study on Coastal Closed Lake Inferred from Frequency of Overflow" by the members of the research headed by Professor Kinshiro Nakao; the research was conducted for three years of 1983 (preliminary study) and 1985 - 1986 (principal studies). This lake is located on the seashore and is a closed lake dammed up by a sand bar in the estuary. The interaction between the climatic change and hydrological regime could be shown by recognizing the frequency with which the lake will overflow into the sea. The overflow of the lake can raise a breakdown of the sand bar, followed by an inflow of sea water. In the beginning, a survey on a water budget of the lake was performed in 1983. … More As a result, the lake was seen to have the overflow at the rate of one time per four or five years in the present climatic condition. The frequency of the overflow can be also traced as the number of coarse-grained laminae in the sedimentary facies below the lake bottom. These results gave preparatory recognition to trace the change in the hydrological regime of Lake Horokayan-to.A long sediment core was sampled in Lake Horokayan-to in August 1985 to reconstruct a history of the paleoenvironment. Its coring was performed on a raft fixed at the center of the sub-basin. The core sampler reached a fluvial gravel bed at a depth of 12 m below the bottom. The core sample obtained was 10.8 m long. The gravel bed consists of bed materials of a river which would have discharged into the sea through the valley of the present lake basin during a period of low sea-level. The following conclusion through inspection of the core can be led: The river was dammed up in the estuary about 8,400 years ago, when a postglacial transgression caused the sea level to rise. In the Jomon transgression, the higher sand bar by 2 m than today had dammed the mouth of the river valley at the same site as that in the present day. Various analyses for the sediment core show the fact that the hydrological regime of Lake Horokayan-to has been varied under the interaction of the changes in sea-level and climate. Less

本研究的一个目的是澄清如何水文制度发生了巨大的变化，气候变化，也就是说，从末次冰期到冰后期的年龄。在这方面，北海道十胜区的幌冈延渡湖受到了以Kinshiro Nakao教授为首的研究成员关于”从溢流频率推断的沿海封闭湖的古湖沼学研究”主题的合作研究;该研究进行了三年，1983年（初步研究）和1985 - 1986年（主要研究）。这个湖位于海滨，是一个封闭的湖泊，由河口的沙洲阻塞。气候变化和水文情势之间的相互作用可以通过识别湖泊溢入大海的频率来显示。湖水的溢出会引起沙洲的破裂，随后是海水的流入。1983年开始对该湖的水量进行了调查。 ...更多信息结果表明，在目前的气候条件下，该湖以每四、五年一次的速度溢出。溢流的频率也可以追踪到湖底以下沉积相中粗粒纹层的数量。1985年8月，在霍罗卡延陶湖采集了一个长柱状沉积物样品，重建了古环境的历史。取芯是在固定在子盆地中心的筏上进行的。岩芯取样器到达底部以下12 m深处的河流砾石层。获得的岩心样品长10.8 m。砾石床由河流的河床物质组成，这些物质在低海平面时期通过现在湖盆的山谷排入大海。通过对岩芯的考察可以得出以下结论：大约8,400年前，冰后期的海侵导致海平面上升，河流在河口堵塞。在绳文海侵中，比今天高出2米的沙坝在与今天相同的位置阻塞了河谷口。对沉积物岩芯的各种分析表明，在海平面和气候变化的相互作用下，霍罗卡延托湖的水文状况发生了变化。少