4He/3He熱クロノメトリーによって明らかになった1.8 Maの急速な氷河侵食
David L Shuster1, Todd A Ehlers, Margaret E Rusmoren
1Division of Geological and Planetary Science, California Institute of Technology, 100 23, Pasadena, CA 91125, USA. dshuster@bgc.org
Science (New York, N.Y.)
|December 13, 2005
まとめ
氷河の侵食は,180万年前から,ブリティッシュ・コロンビア州のクリナクリニ渓谷を急速に深めた. この加速された山の侵食は,約190万年前,地球規模の気候の不安定性とのつながりを示唆しています.
科学分野:
- ジオモルフォロジー ジオモルフォロジー
- 四季地質学 四季地質学
- サーモクロノロジー サーモクロノロジー
背景:
- アルプス山脈の氷河化と川の切断が,山の地形を形作っている.
- これらのプロセスの相対的な貢献は,まだ議論されている.
- 氷河の侵食率を理解することは,景観の進化を再構築する上で鍵となる.
研究 の 目的:
- クリナクリニ渓谷,南海岸山脈,BCの氷河侵食のタイミングと速度を制限するために.
- 氷河の侵食と気候変動の関係を調査する.
- 四年期のデヌデーション率を定量化する.
主な方法:
- アパタイト4He/3He熱クロノメトリーは,岩石サンプルを年代測定するために使用されました.
- クリナクリニ渓谷から採取した5つの近接サンプルを分析した.
- 熱クロノメトリックデータに基づく脱毛率の計算.
主要な成果:
- クリナクリニ渓谷の急速な脱毛は,約1.8 +/- 0.2百万年前に始まった.
- 2キロメートル以上の岩石が,年間5ミリメートルを超える速度で除去されました.
- 氷河渓谷の深化率は,氷河以前の侵食率よりも少なくとも6倍速かった.
結論:
- 氷河の侵食は,クリナクリニ渓谷で約1.8万年前に著しく加速した.
- この強烈な侵食は,地球規模での気候変動の変動と関連し,気候の不安定性が190万年近く増加する可能性がある.
- この発見は,氷河の景観の動態と気候強制への反応に関する重要な洞察を提供します.
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