北米におけるファネロゾイク時代の大陸の排水は,Nd同位体から発生した
1P. J. Patchett, Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA. E-mail: patchett@geo.arizona.edu. G. M. Ross, Geological Survey of Canada, 3303 33rd Street NW, Calgary AB T2L 2A7, Canada. J. D. Gleason, Lunar and Planetary La.
Science (New York, N.Y.)
|January 29, 1999
まとめ
ネオジムイソトープデータは,北米の堆積岩源が時間とともに大きく変化したことを明らかにしています. 古代の盾が早期に支配され,続いてカレドニア・アパラチア山脈,そして後に西部のコルディレラが続いた.
科学分野:
- 地質化学 地質化学
- 堆積地質学的地質学 堆積地質学的地質学
- 同位体地質学とは,同位体地質学のことです.
背景:
- 堆積岩は,その起源地域の歴史を記録しています.
- 堆積物の起源を理解することは,古地理学と構造的出来事を再構築するための鍵です.
研究 の 目的:
- ネオジミウム (Nd) イソトープを用いて北米の堆積岩の起源を追跡する.
- 過去6億年にわたる主要な堆積物供給の変化のタイムラインを確立するために.
主な方法:
- 堆積岩におけるネオジミウム (Nd) の同位体組成物の分析.
- 同位体シグネチャーを解釈し,堆積物の源と輸送経路を特定します.
主要な成果:
- 一貫したNd同位体パターンは,北米の大陸規模の堆積物採取を示しています.
- 古代大陸のシールド源は6億年から4億5000万年前 (Ma) の間に優勢であった.
- カレドニア・アパラチア山脈からの破片は,約450万年前頃に支配的になり,約150万年前まで存在し,おそらく堆積岩のリサイクルによるものである.
- 150万年前ごろに西部のコルディレラの出現は,新しい破片をシステムに導入した.
結論:
- ネオジムイソトープは,沈殿物の起源の長期的な変化を追跡するための強力なツールを提供します.
- 北米の堆積物源の歴史は,主要な構造的出来事と古地理学的再建を反映しています.
- 堆積物のリサイクルは,主要な堆積物源の信号を遮断または延長する上で重要な役割を果たします.
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