三次元磁気帯は,急速に広がる下層の海殻でゆっくりと冷却する必要があります
Sarah M Maher1, Jeffrey S Gee2, Michael J Cheadle3
1Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA. s1maher@ucsd.edu.
Nature
|September 23, 2021
まとめ
地球の磁場は 海殻の冷却を記録しています 新しい発見は,ゆっくりとした冷却と,急激に広がる地殻の軸外8kmの広大な熱帯を示し,以前の水熱冷却モデルに挑戦しています.
科学分野:
- 地理学
- 海洋地質学
- プレート構造
背景:
- 地球の磁場は 海殻の冷却に刻み込まれ 磁気異常が形成され 極性の逆転が 1億6000万年以上に渡ります
- 地殻の下部の極性境界はイソテルムとして機能し,地殻の冷却と蓄積プロセスを理解するために重要です.
- 急速に広がる地殻の既存の地震,地速度測定,熱モデリングの研究は,中海の山脊の近くの熱損失メカニズムについて矛盾する見解を提供します.
研究 の 目的:
- 熱的構造と冷却過程を調査する 磁気的に堅固で急速に広がる海洋の地殻の下部.
- 熱の損失と溶融輸送メカニズムの 矛盾する解釈を調和させるため
- 海洋地殻の増殖と磁気異常形成のモデルを改良する.
主な方法:
- 2つの異なる領域で下部磁化溶液を使用した磁気異常の分析.
- オリエンテッド・ロック・サンプルの古磁気分析により,極性成分と冷却速度を決定する.
- 磁気データの統合と既存の地震と熱モデリングの制約
主要な成果:
- ダイク-ガブロの移行の近くの地殻の温度は,0.1百万年間約500°Cにとどまります.
- ダイク-ガブロの移行から200メートル以内のサブホリゾントの極性境界が特定され,軸外で7〜8キロメートルに及ぶ.
- 3つの極性間隔でゆっくりとした冷却の直接的な証拠が発見され,軸外約8kmの広い熱い軸帯が確認されました.
結論:
- 急速に広がる地殻の磁気構造は,ゆっくりと冷却し,広大な熱帯地帯を示し,山脊軸の近くの急速な水熱冷却と矛盾しています.
- これらの発見は,熱がよりゆっくりと 急速に広がる海洋環境の下層層で失われることを示唆しています
- この研究は,海洋の活発な広がりの中心における 溶融輸送,結晶化,地殻の蓄積過程の理解を 洗練しています
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