ハフニウムイソトープは,フェロマンガネスの地殻の層図である
1Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109, USA. Institut fur Isotopengeologie und Mineralische Rohstoffe, Department fur Erdwissenschaften, ETH-Zentrum, NO C61, Sonneggstrasse 5, CH-8092 Zurich, Switzerland.
Science (New York, N.Y.)
|August 14, 1999
まとめ
中央太平洋の深水ハフニウムイソトープは,おそらく海洋アドベクションから,エオセン-オリゴセンの大きな変動を示しています. 過去2千万年間,ハフニウムの同位体組成は均一であり,太平洋の孤立が増加したことを示唆しています.
科学分野:
- 地質化学 地質化学
- 海洋学 海洋学 海洋学
- パレオセアノグラフィー
背景:
- フェロマンガンの殻は,過去の海洋化学の貴重なアーカイブを提供します.
- ケノゾイク時代の海洋循環と同位体組成を理解することは,古気候の再構築に不可欠です.
研究 の 目的:
- 中央太平洋の深い水域におけるハフニウム (Hf) の同位体組成のケノゾイク史を再構築する.
- 深海のHf同位体記録に海洋循環の変化の影響を調査する.
主な方法:
- ケノゾー紀にわたる2つの地理的に分離したフェロマンガネスの地殻からのHf同位体組成の分析.
- Hfの同位体データを,既知の海洋学および地質学的な事象と比較.
主要な成果:
- フェロマンガンの殻は,Hfイソトープが3000km以上離れているにもかかわらず,同様の世俗的な変化を明らかにしています.
- 重要なHf同位体変動は,エオセーンとオリゴセーン中に発生し,インド洋と大西洋からの誘導と関連している可能性がある.
- Hfの同位体組成は,過去2000万年にわたって比較的一定であり続け,中央太平洋の孤立が増加したことを示しています.
結論:
- 中央太平洋の深い水域のHfの同位体成分は,過去の海洋学的な変化に対応して大きく変化しています.
- 過去2千万年の間,Hfイソトープの長期的均一性は,より孤立した中央太平洋を指している.
- 海水におけるストロンチウム (Sr) の同位体変動を駆動するメカニズムは,ケノゾーイク時代に中央太平洋の深海のHf同位体に有意な影響を及ぼさなかった.
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