コルディレラの変形制御における地殻クォーツの役割
Anthony R Lowry1, Marta Pérez-Gussinyé
1Department of Geology, Utah State University, Logan, Utah 84322-4505, USA. Tony.Lowry@usu.edu
Nature
|March 18, 2011
まとめ
大陸の地殻のクォーツの豊富さは,温度と変形に影響を与え,大陸の山帯形成と地震活動を説明します. この研究は,クォーツに富んだ地殻,熱,および弱まりを含むフィードバックループを明らかにしています.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- テクトニクス (地質学) とは
- ミネラル物理学 ミネラル物理学
背景:
- 大陸の変形メカニズムは,プレート構造の革命から数十年後,ほとんど理解されていません.
- 強度や密度などの岩の性質は,ストレスに影響しますが,温度,水,岩の種類に複雑に依存しています.
- 山岳帯と裂け目地帯の周期的形成は,大陸変形の基礎的な制御を示唆しています.
研究 の 目的:
- 大陸の温度と変形における地殻のクォーツの豊富さの役割を調査する.
- 地震速度比 (vP/vS) と,変形地帯における地殻特性との関連を理解する.
- 大陸変形の静止的性質と空間的分布を説明するために.
主な方法:
- 米国西部でEarthScopeの地震受信機能,重力,熱流量データを活用した.
- 大陸地殻の厚みと地震速度の比率 (vP/vS) を推定する.
- 低vP/vS,高層岩層温度,地殻変形との相関を分析した.
主要な成果:
- 低地殻のvP/vSと高層岩層の温度とコルディレラの変形との間に強い相関が見られた.
- 地震速度比 (vP/vS) は,岩の弱さの重要な要因であるクォーツの豊富さに敏感です.
- 低いvP/vSは,クォーツが豊富な大陸の地殻を示しています.
結論:
- 地殻のクォーツの豊富さは,大陸の温度と変形を大きく左右する.
- ダイナミックなフィードバックメカニズムが提案されている:柔らかいストレンは弱い,クォーツに富んだ地殻に定着し,温暖化,水分補給,さらに弱まりを促します.
- このフィードバックは,大陸の変形,熱上昇,流体活動の空間的分布とタイミングを説明します.
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