「しんかい6500」に搭載されたサブボトムプロファイラを用いたマリアナトラフ背弧拡大軸付近の表層堆積物観察  [in Japanese] Observation of sediments in a back-arc basin spreading center of the Mariana Trough using a subbottom profiler installed on the <i>Shinkai 6500</i>  [in Japanese]

Access this Article

Author(s)

Abstract

マリアナトラフ背弧拡大軸17°N付近では, 枕状溶岩とシート状溶岩の2種が分布しており, それぞれ拡大軸谷端, 中央に分布している. これらは, 溶岩噴出量の違いを示唆しているとともに, 形成年代の変化も示している可能性がある. 本稿では, YK08-08 Leg.1航海で行われた, 「しんかい6500」に搭載したサブボトムプロファイラの観測結果を報告する. 行われた3潜航 (拡大軸西側斜面でのDive #1088と#1090, 拡大軸東側斜面での#1089) のSBPデータと潜水船外写真を照らし合わせ, 表層堆積物を観測した. その結果, #1088は, 表層堆積物をほとんど認識できないことから, 新しい溶岩流であることが推定できた. #1089は, 堆積層厚も明瞭に観測され, 堆積層中に基盤面と平行な反射面も識別できた. #1090では, 各地点の目視観察で堆積物の被覆を認識できたが, SBPでは堆積層厚を識別できなかった. したがって#1089の斜面より堆積層が薄いと考えられる. これら3潜航測線下の溶岩流は#1089, #1090, #1088付近の順に形成された可能性がある.

Both pillow and sheet lava flows are distributed in the Mariana Trough back-arc basin axis at 17°N. These flows suggest different eruption rates, and they may indicate age variation in the lava. In this report we present observational results of sediments using a subbottom profiler (SBP) installed on the <i>Shinkai 6500</i> during the YK08-08 Leg1 cruise. Observations from three dives (#1088 and #1089 on the western slope, #1090 on the eastern slope) with the SBP with visual observations and camera photos taken by the <i>Shinkai 6500</i> were conducted to observe sediment on the lava flows. We estimate that the lava flow is new in dive #1088 because the SBP and visual observation cannot find sediment cover. In dive #1089 the sedimentary layer can be observed distinctly; moreover we can find a reflection within the sedimentary layer parallel to the basement. In dive #1090 we can find sediment cover by visual observation, but cannot determine sediment thickness by SBP observation. We consider the sediment coating in the dive #1090 survey area to be thinner than that in dive #1089. Therefore, it is possible to consider that these lava flows formed in the order #1089, #1090, and #1088.

Journal

  • JAMSTEC Report of Research and Development

    JAMSTEC Report of Research and Development (8), 75-89, 2008

    Japan Agency for Marine-Earth Science and Technology

Codes

  • NII Article ID (NAID)
    130002148903
  • Text Lang
    JPN
  • ISSN
    1880-1153
  • Data Source
    J-STAGE 
Page Top