ボレアリス盆地と火星の地殻の二分法の起源
Jeffrey C Andrews-Hanna1, Maria T Zuber, W Bruce Banerdt
1Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. jhanna@mit.edu
Nature
|June 27, 2008
まとめ
惑星の主要な特徴である火星の地殻の二分性は円形であり,巨大な衝突が火星の北の低地と南の高地との間にこの古代の違いを生み出したことを示唆しています.
科学分野:
- 惑星科学は惑星科学である.
- 地質物理学 地質物理学とは地質物理学です.
- 地質学 地質学 地質学
背景:
- 火星は,南の高地と北の低地との間に顕著な近半球二分法を示しています.
- この二分法は,その境界に沿った地殻の厚さの大きな変化によって特徴づけられ,それは惑星の最も古い特徴の1つであることを示唆しています.
- この二分論の起源は不明であり,巨大衝突やマントルのコンベクションを含む仮説がある.
研究 の 目的:
- 火星上のタルシス火山の上昇の下の二分界の位置を制限するために.
- 重力と地形データを用いて,タルシスの補償と二分法の効果を区別する.
主な方法:
- 火星の重力と地形データの分析.
- タルシスの上昇と地殻の二分化のイソスタティック補償効果を分離するためのモデリング.
- 二分法の境界を円モデルに合わせる.
主要な成果:
- タルシスの下の二分界の境界は成功裏に位置付けられました.
- 境界線は,約10,600×8,500kmの円で正確に表されており,その中心は67°N,208°Eにあることが判明しました.
- この円形の形状は,二分法の起源に強い制約を与える.
結論:
- 火星の地殻の二分法の円的性質は,巨大な衝突イベントによって最も簡単に説明されます.
- この衝撃は,太陽系でこれまでに発見された最大の構造物である可能性が高い.
- この発見は,火星の古代の二分論の主な原因として巨大な衝突を裏付けている.
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