26億年前の地上の生態系の地化学的証拠
Y Watanabe1, J E Martini, H Ohmoto
1Astrobiology Research Center and Department of Geosciences, The Pennsylvania State University, University Park 16802, USA. yumiko@essc.psu.edu
Nature
|December 16, 2000
まとめ
南アフリカの古代土壌で発見された化石化した微生物マットが,26~27億年前の地上の生命の存在を証明しています. この発見は,地上の最も初期のバイオマスのタイムラインを14億年以上後退させる.
科学分野:
- 地質科学は地質科学である.
- パレオントロジー・パレオントロジー
- 微生物学 微生物学とは
背景:
- 微生物の生命は38億年以上前に海で誕生した.
- 陸上の生命の植民地化のタイミングは不明である.
- 初期の陸上の生命 (2.3-2.7 Gyr) の以前の証拠は,潜在的な外来的な起源または海洋/淡水の曖昧さのために論争されています.
研究 の 目的:
- 南アフリカの異常な炭酸性の古代土壌 (パレオソール) を調査する.
- これらのパレオソール内の有機物質の起源と年齢を決定する.
- 陸上のバイオマスの最古の決定的な証拠を確立するために.
主な方法:
- 有機物質の発生を分析する.
- 元素比分析 (炭素,水素,窒素,リン).
- 有機物質と宿主岩の同位体組成分析.
主要な成果:
- 南アフリカの古太陽で有機物質を特定した.
- 基本的および同位体データは,固有の微生物起源を強く示唆しています.
- オーガニック物質の年代は26~27億年前とされています.
- 有機物を土壌表面の微生物マットの残骸として解釈した.
結論:
- この発見は,地球上の微生物が26~27億年前に存在していたことを示しています.
- この発見は,これまで最も古いと認められていた地上の微生物化石よりも14億年以上前のものです.
- 陸上のバイオマスの早期発達の新たな証拠を確立する.
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