烏丸半島学術ボーリング試料の堆積相と粒度分析からみた琵琶湖南湖周辺の古環境変遷

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The scientific deep drilling was carried out at the eastern margin of Nanko, southern part of Lake Biwa and well-preserved core samples were collected for the first time in 1992. Detailed lithological research and grain-size analysis were performed on the upper part of the drilled sediments. The sediments are composed mostly of pebble, sand, silt and clay beds with fining-upward or coarsening-upward sequence. A part of the core sample have good similarity to the braided river sediments or meandering river sediments. Grain size characters were interpreted on the basis of comparison with the recent sediments collected from various sedimentary environments around Lake Biwa. These results indicate that the southern part of Lake Biwa have been in mid-fan to fluvial environments partly with shallow lake condition during more than 330,000 years. This contrasts with the northern part of the lake where deep water environments have been developed for 400,000 years.
滋賀県立琵琶湖博物館の論文