地球で最も長い大陸のホットスポット線に沿ったマグマの組成に関する石層制御
D R Davies1, N Rawlinson2, G Iaffaldano1
1Research School of Earth Sciences, The Australian National University, Canberra 2601, Australia.
Nature
|September 15, 2015
まとめ
岩層の厚さは大陸のホットスポットでのマグマの構成と量を制御します 厚い石層は火山の隙間や独特のルシチートを含む火山に繋がり,マントルの羽根融解への影響を示しています.
科学分野:
- 地理科学
- 火山学
- 地化学
背景:
- ホットスポットとは プレート境界とは無関係な火山地帯であり,しばしばマントルの羽根によって説明される.
- マントルの羽根は 地球の深いマントルから 熱い物質を表面に運ぶ浮遊水源です
- 石層の厚さは,羽根の上昇高さやマグマの地化学に影響を及ぼすと理論化されているが,証拠は限られている.
研究 の 目的:
- オーストラリアのコスグローブ線に沿って石層の厚さとマグマの組成の関係を調査する.
- 統合された地質学と地質学的データを用いて,大陸のホットスポット軌道の下のプラムの融解深度を決定する.
- 岩層の厚さによる噴出によるマグマへの影響に関する観測上の制約を示す.
主な方法:
- 表面地質学,地年代学,プレート運動再構築の統合
- 微量元素の濃度を含む地化学データの分析
- 岩層の厚さを評価するために地震データを解釈する.
主要な成果:
- コスグローブ線に沿って石層の厚さとマグマの組成の間に強い相関関係がある.
- 塩基岩マグマは,石層が110km未満で形成され,火山の隙間は石層が150km以上で発生する.
- 中間の石層の厚さは,低体積でルシチットを含む火山活動と相関しています.
結論:
- リトスフィアの厚さは,マントルの部分的な溶解の度合いの主要な制御です.
- この研究は,亜大陸の羽根の融解深度に関する最初の観測的制約を提供します.
- 岩層の厚さは,ホットスポットにおける火山の体積と化学的構成に大きな影響を与える.
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