関東平野中央部、猿島台地宝木台地の珪藻分析に基づく古環境復元

Environmental changes in the center of the Kanto plane around the Sashima and Takaragi uplands based on diatom analysis

野口 真利江*; 宮本 樹*; 須貝 俊彦*; 中西 利典*; 小松 哲也  ; 杉中 佑輔*; 遠藤 邦彦*

Noguchi, Marie*; Miyamoto, Tatsuki*; Sugai, Toshihiko*; Nakanishi, Toshimichi*; Komatsu, Tetsuya; Suginaka, Yusuke*; Endo, Kunihiko*

関東平野中央部、猿島台地宝木台地のボーリングコアGC-NG-1, GC-OY-1, GC-OY-2を用いた堆積相解析に基づく地殻発達史の議論が進んでおり、本研究では珪藻分析に基づく古環境復元を行った。これらのコア試料には、MIS9以降の海水準変動と陸化の過程が保存されている可能性が高い。珪藻の群集解析の結果から、各コアにおける古環境が、内湾,汽水淡水,淡水,湖沼,河川環境,陸域環境など、掘削地点に応じた変遷が捉えられた。また、珪藻分析結果のクラスター分析により、群集組成変化の客観的提示を試みた。

Discussions on the history of crustal development based on sedimentary facies analysis using the boring cores GC-NG-1, GC-OY-1, and GC-OY-2 in the central Kanto Plain, from the Sarushima Plateau to the Takaragi Plateau, are underway. In the study, paleoenvironmental restoration based on diatom analysis was performed. These core samples are likely to preserve sea-level changes and landing processes since MIS9. From the results of the diatom community analysis, the paleoenvironment in each core was found to change according to the boring site, such as inner bay, brackish water to freshwater, freshwater, lakes, river environment, and land environment. We also attempted to objectively present changes in community composition by cluster analysis of diatom analysis results.