熱化学マントルのコンベクションによって駆動された初期の月のコアダイナモ
Dave R Stegman1, A Mark Jellinek, Stephen A Zatman
1Department of Earth and Planetary Science, University of California, Berkeley, California 94720, USA. dstegman@eps.berkeley.edu
Nature
|January 10, 2003
まとめ
月の磁場を生成する初期の月のダイナモは,核の熱流の一時的な増加によって電力を供給されていた可能性があります. この増加は,放射性物質に富んだ層が月のマントルの中で転覆した結果でした.
科学分野:
- 月科学 月科学 月科学
- 地質物理学 地質物理学とは地質物理学です.
- 惑星のダイナミクス
背景:
- 古磁気データとアポロ探査のサンプルは,月が39億年から36億年前に磁場を持っていたことを示唆し,古代の月のダイナモを暗示しています.
- 既存の熱進化モデルは,42億年前のダイナモを動かすのに十分なコア熱流を説明できません.
研究 の 目的:
- 初期の月のダイナモの存在とタイミングを説明するために.
- 古磁気証拠と熱進化モデルを調和させるため.
主な方法:
- 立体球形コンベクションモデルを使用した.
- 放射能に富んだ基礎層を持つ分層化された月面マントルの役割を調査した.
主要な成果:
- 月面マントルの底辺にある密集した放射性"熱毛布"は,当初,核の冷却とダイナモの作用を抑制していた.
- その後の放射性加熱により,毛布の浮力性が増加し,毛布が上昇し,マントルに転覆した.
- 転覆のイベントは一時的にコア熱流を増加させ,短命の月のダイナモに電力を供給するのに十分であった.
結論:
- 月面マントルの転覆によって引き起こされた,核の熱流の一時的な増加は,初期の月のダイナモを説明することができます.
- この転覆の出来事は,トリウムとチタンに富んだ月面のマールベースルトの噴火も説明できるかもしれない.
- 提案されたメカニズムは,古磁気観測と月の熱史を調和させるものである.
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