13:45 〜 15:15
[SCG52-P12] Characteristics and evolution process of the tectonic regions in the Antarctic Sea as based on marine geophysical data (Part 2)
キーワード：南極海、南極プレート、テクトニクス
The Antarctic Plate including the continental region is known to be classified into 11 tectonic regions. And also, the area south of 30°S including the Antarctic Plate and its adjacent area is classified into more than 20 tectonic regions (Hayes, et al., 2009). Each tectonic region has experienced proper tectonic history and evolution process after the break-up of the Gondowanaland, cooling after the accretion of the oceanic crust at the mid-ocean ridges, subsidence of the seafloor due to the cooling and the oceanic sedimentation, and transition of the oceanic plate motion by the fluctuation of the Euler pole location for past 200 million years.
The current study is proposed in order to clarify the uniqueness of each tectonic region in the Antarctic Plate, the possible interaction with adjacent plates and tectonic regions and its transition, and finally to estimate the driving force that led the evolution of each region. This study is based on analysis of marine geophysical data, seafloor topography, gravity, geomagnetic anomaly, seafloor age, total sediment thickness, etc., which are available at NCEI (National Centres for Environmental Information, NOAA) database. Marine geophysical data acquired by R/V MIRAI and Icebreaker SHIRASE, and other research vessels are also examined in this study.
The total sediment thickness based on the NCEI database of Globsed Ver.2, and the distribution of seafloor age (Müller et al., 2020), are examined in order to verify the sedimentation rate (sediment thickness over seafloor age) variations around the Antarctica. The sedimentation rate shows more than 100 m/million years around the Antarctic Peninsula, at 70 degrees south. However, in the Weddel Sea, just east of the Antarctic Peninsula, the sedimentation rate is drastically low, totally 20 m/million years. The area north of the Weddel Sea near the South Sandwich Islands shows several local high sedimentation rate spots, more than 80 m/million years. The variation of these sedimentation rate may due to the supply of the different soil from the land nearby and the status of the glaciers at these continets.
The current study is proposed in order to clarify the uniqueness of each tectonic region in the Antarctic Plate, the possible interaction with adjacent plates and tectonic regions and its transition, and finally to estimate the driving force that led the evolution of each region. This study is based on analysis of marine geophysical data, seafloor topography, gravity, geomagnetic anomaly, seafloor age, total sediment thickness, etc., which are available at NCEI (National Centres for Environmental Information, NOAA) database. Marine geophysical data acquired by R/V MIRAI and Icebreaker SHIRASE, and other research vessels are also examined in this study.
The total sediment thickness based on the NCEI database of Globsed Ver.2, and the distribution of seafloor age (Müller et al., 2020), are examined in order to verify the sedimentation rate (sediment thickness over seafloor age) variations around the Antarctica. The sedimentation rate shows more than 100 m/million years around the Antarctic Peninsula, at 70 degrees south. However, in the Weddel Sea, just east of the Antarctic Peninsula, the sedimentation rate is drastically low, totally 20 m/million years. The area north of the Weddel Sea near the South Sandwich Islands shows several local high sedimentation rate spots, more than 80 m/million years. The variation of these sedimentation rate may due to the supply of the different soil from the land nearby and the status of the glaciers at these continets.