ミオセンの中期,中米海路の閉鎖
C Montes1, A Cardona2, C Jaramillo3
1Universidad de los Andes, Bogotá, Colombia. cmontes@uniandes.edu.co.
まとめ
中米海路はミオセンの半ば以前に閉鎖され,パナマと南米の間の陸路接続が可能になった. この発見は,アンデス山脈北部の層におけるデトリタルジルコンの指紋に基づいています.
科学分野:
- 地質学 地質学 地質学
- パレオジオグラフィー パレオジオグラフィー
- ジオクロノロジー (Geochronology) について
背景:
- 中米海路の閉鎖は,世界の海洋学,大気学,生物学的パターンに重大な影響を及ぼしました.
- この閉鎖の正確なタイミングを理解することは,これらの世界的な出来事を相関させる上で極めて重要です.
研究 の 目的:
- 中央アメリカ海路の閉鎖のタイミングを決定する.
- パナマ・アークと南米との間の古地理的つながりを調査するために.
主な方法:
- デトリタルジルコンのウラン鉛地質年代測定.
- ストラティグラフィック断面と掘削穴のデータによる産地分析.
主要な成果:
- パナマに特有のエオセンの独特のジルコンの痕跡は,アンデス山脈北部のミオセンの中期層で確認された.
- このパナマのジルコンの指紋は,より古い,下層のオリゴセーンと下層のミオセーン層には存在しなかった.
- この指紋の存在は,ミオセンの中期にパナマと南米の間の海路ではなく,河川の接続を示しています.
結論:
- 中米海路はミオセンの半ばまでには閉鎖されていた.
- この時期,陸上の陸上橋が北米と南米の動物と花の交換を容易にした.
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