プレカンブリア/カンブリアの境界で地表水に硫化水素が放出される

Martin Wille¹, Thomas F Nägler, Bernd Lehmann

¹Institute of Geological Sciences, University of Bern, Baltzerstrasse 3, 3012 Bern, Switzerland. martin.wille@anu.edu.au

Nature

|May 30, 2008

まとめ

カンブリア爆発は,動物の生命の急速な増加であり,海洋循環の変化によって引き起こされた可能性があります. プレカンブリア/カンブリア移行期に続く深海水の激しい上流は,海洋環境を変化させました.

科学分野:

地質化学地質化学
パレオセアノグラフィー
パレオントロジー・パレオントロジー

背景:

プレカンブリア/カンブリア移行期 (約5億4200万年前) は,動物のような多細胞化石の出現と"カンブリア爆発"を目撃しました.
この移行期の環境の変化はカンブリア爆発の原因として議論されている.
この時期の海洋状態を理解することは,初期の動物の多様化を説明するために極めて重要です.

研究の目的:

プレカンブリア時代からカンブリア時代への移行期における環境条件を調査する.
カンブリア爆発の引き金となる可能性を理解するために.

主な方法:

プレカンブリアとカンブリアの境界からのブラックシェールにおけるモリブデン同位体シグネチャーの分析.
海洋モリブデン循環のボックスモデルを用いて.

主要な成果:

前カンブリア時代からカンブリア時代への移行直後に,一時的なモリブデン同位体信号が検出されました.
観測された信号は,硫化水素に富んだ深海水の激しい上流によって最もよく説明されます.
これは,海洋循環に大きな変化が起きたことを示唆しています.

結論:

初期のカンブリア期の動物放射は,海洋循環の大きな変化によって引き起こされたのかもしれません.
この変化により,長い期間にわたる層状の硫化深海の状態が終結した.
この発見は,初期の動物進化の環境的要因について新たな視点を提供している.

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