ゆっくりと広がる山脊の海殻の成長を年代付けする
Joshua J Schwartz1, Barbara E John, Michael J Cheadle
1Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071, USA.
Science (New York, N.Y.)
|October 29, 2005
まとめ
アトランティス銀行からのガブロスのウラン鉛ジルコンの年代測定は,海洋の地殻形成の洞察を明らかにします. いくつかのガブロは,予測された海底の年齢で形成され,他のものは,岩層圏内のより深く,より古い結晶化を示唆しています.
科学分野:
- 地質学 地質学 地質学
- 地質化学 地質化学
- テクトニクス (地質学) とは
背景:
- ゆっくり広がる山脊の海殻形成は複雑である.
- 地殻の成長過程を理解することは,プレート構造学にとって極めて重要です.
研究 の 目的:
- 南西インド山脈における海洋地殻の成長のタイミングとメカニズムを制限する.
- 下層海洋の地殻にある異常に古いガブロスの起源を調査するために.
主な方法:
- 下層地殻ガブロスのウラン鉛ジルコン年代測定.
- アトランティス・バンク,南西インディアン・リッジからのガブロサンプル分析.
主要な成果:
- ガブロス用のウラン・鉛・ジルコンの年齢は19歳であった.
- ガブロスの約75%は,予測された海底磁気年齢の近くで蓄積した.
- ガブロスの約25%は,予測されたよりかなり古い年齢をもたらしました.
結論:
- この発見は,軸内収縮と,海洋地殻の構成要素のより深く,より古い結晶化の組み合わせを示唆しています.
- 異常な古いガブロは,地殻より5〜18kmの深さで形成され,後に上昇した可能性が高い.
- この研究は,ゆっくり広がるセンターでの海洋地殻の構造のモデルを洗練しています.
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