2024-03-29T13:15:13Z
https://soar-ir.repo.nii.ac.jp/oai
oai:soar-ir.repo.nii.ac.jp:00011859
2022-12-14T04:13:13Z
1169:1170
Grain Size Distribution of the Surface Sediments in Lake Biwa, Japan
琵琶湖底表層堆積物の粒径分布
公文, 富士夫
紙谷, 敏夫
須藤, 浩一
井内, 美郎
Lake Biwa
grain size distribution
circular current
hydrometer
Ane River
Biwako
Grain size analysis by the modified hydrometer method was performed on the bottom surface sediments sampled from 164 localities every 2km interval in Lake Biwa. The systematic survey enable to make up a grain size distribution map of the lake for the first time. Sandy sediments coarser than 4 phi in median size is limited to the zones shallower than about 10 meters, and the most area of the lake is covered by clayey silt or silty clay which is finer than 6 phi in median diameter. Based on the median size, there appears a concentric pattern of grain size distribution between the mouths of Ado and Amano Rivers, about the central portion of northern basin of North Lake Biwa. The grain size become finer in the inner zone of the concentric circle, but the center is a slightly coarser than the surrounding parts. The location of the concentric circle well corresponds to that of the circular current, Gyre I, which was revealed recently by the water temperature distributions and the radar trackings of drifters. Convergent circular currents of Gyre I in the epilimnion, can explain well the concentric distribution of sediments. The grain size and modal analyses of the surface sediments at 39 localities near the mouth of Ane River revealed that there may be two directions of the inflows from the river to the lake, namely, northwest and southeast. The former seems to be dominant in thermal-stratified seasons, and the later in non-stratified seasons. The grain size distribution of lake sediments should play an important role to clarify the major movements of lake water.
Article
地質学論集. 39:53-60 (1993)
journal article
日本地質学会
1993-03-29
application/pdf
地質学論集
39
53
60
0385-8545
AN00141779
https://soar-ir.repo.nii.ac.jp/record/11859/files/chishitsuron_39-1.pdf
jpn
http://ci.nii.ac.jp/naid/110003022645/
日本地質学会
本文データは学協会の許諾に基づきCiNiiから複製したものである