パプアニューギニア東部でプレート構造の速度でプリオセンのエコロギット発掘
Suzanne L Baldwin1, Brian D Monteleone, Laura E Webb
1Syracuse University, Department of Earth Sciences, Syracuse, New York 13244, USA. sbaldwin@syr.edu
Nature
|September 17, 2004
まとめ
この研究は,パプアニューギニアで430万年前に形成された最も若い知られているエクロジットを明らかにしています. これらの高圧岩の急速な発掘は,プレート境界地帯での拡張によるプレート構造の速度で発生しました.
科学分野:
- 地質学 地質学 地質学
- テクトニクス (地質学) とは
- メタモルフ Petrology メタモルフペトロロジー
背景:
- エクロギットは,石層板の沈下過程で高圧および超高圧条件下で形成されます.
- エクロジットの鉱物集合と質感は,沈殿と発掘のP-T-D条件を記録する.
- 鉱物内の放射性同位体変異は,変形現象の年代付けに役立ちます.
研究 の 目的:
- これまでのところ,パプアニューギニア東部のエクロジットのメタモルフィズムに直面している.
- 若いエコロギットの発掘率とメカニズムを調査する.
主な方法:
- シトウジルコンのU/Pbイオンマイクロプローブ用デッティング.
- ミネラル・アセンブリとテクスチャの分析.
- プレート境界地帯の地質的地図作成.
主要な成果:
- エクロジットの顔の変形は,4.3 +/- 0.4百万年前に遡る.
- これは,地球表面に露出している最も若い記録されたエコロギットを表しています.
- ~75キロメートルの深さから非常に急速な発掘 (>1cm yr(-1)) はプレート構造の速度で発生しました.
結論:
- 高圧/超高圧岩の急速な発掘は,一時的なプレート境界地帯内の拡張によって促進されます.
- ウッドラーク流域の拡張は,斜板収束時に急速な発掘に対応しました.
- この研究は,活発なプレート境界プロセスに関連した若い,急速に発掘されたエコロギットの新しい例を提供します.
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