氷河 の 静止 調節 は 火星 の 内面 の 粘度 構造 を 明らかに し て い ます
A Broquet1, A-C Plesa2, V Klemann3
1Institute for Planetary Research, German Aerospace Center, DLR, Berlin, Germany. adrien.broquet@dlr.de.
Nature
|February 26, 2025
まとめ
火星
科学分野:
- 惑星科学
- 地理学
- 氷河学
背景:
- 氷河の静止調整 (GIA) は惑星の粘度を理解する鍵です.
- GIAの研究は観測データが限られているため,他の惑星では稀です.
- 火星の北極帽はGIA分析の ユニークな特徴です
研究 の 目的:
- 火星の北極の氷の位置を調べる
- 火星の現在の内粘性構造を決定する.
- 新しいデータを用いてGIAモデルを制限する.
主な方法:
- 組み合わせた熱進化モデル
- 粘着弾性変形計算
- レーダー観測,重力場データ,地震データの分析.
主要な成果:
- 火星の北部の地域では 進行中の下降運動です
- 高粘度 (500 km 以下の2-6 × 10^22 Pa·s) が求められる.
- 厚い地殻 (> 40 km) と枯渇したマントル (> 90% の放射性元素) と一致するモデル.
結論:
- 火星の北極帽は 17億2千万年前に形成された.
- リトスフィアの変形は年0.13mm未満である.
- 将来の重力ミッションは,火星のGIAをさらに制限します.
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