古代の枕の溶岩に記録された初期の生活
Harald Furnes1, Neil R Banerjee, Karlis Muehlenbachs
1Department of Earth Science, University of Bergen, Allegaten 41, 5007 Bergen, Norway. Harald.Furnes@geo.uib.no
Science (New York, N.Y.)
|April 24, 2004
まとめ
微生物の生命は,約35億年前に存在していたことが,南アフリカの枕の溶岩の鉱化管で証明されています. これらの古代の微生物は火山のガラスを刻み,有機炭素の痕跡と軽い炭素同位体を残した.
科学分野:
- * 地質学と古生物学
- * 初期の地球環境と微生物の進化
背景:
- *枕の溶岩は,海底環境で形成された火山岩です.
- * 微生物の活動が地質学的構造に影響を及ぼします.
- *バーバートン・グリーンストーン・ベルトは,地球の歴史の初期に洞察力を与えてくれます.
研究 の 目的:
- *メソアケアの枕の溶岩における初期の微生物生命の証拠を調査する.
- *古代火山岩の鉱化管の形成メカニズムを理解する.
- * 潜在的生体シグネチャーの年齢と起源を決定する.
主な方法:
- *枕の溶岩縁の内にあるマイクロメートルスケールの鉱化チューブの顕微鏡分析.
- * 管の縁の有機炭素含有量の地化学分析.
- * 大量岩炭酸の同位体分析 (デルタ13C)
- * 放射線年代測定法により,マグマ的および変形現象を相関させる.
主要な成果:
- *メソアケアの枕の溶岩輪の中に微米規模の鉱物化した管を発見.
- * 管の縁に関連した有機炭素の識別.
- * 枕縁炭酸で同位体的に軽いデルタ13C値が検出され,生物学的プロセスを示す.
- * メタモルフィックとマグマティック年代が重なり,噴火後の急速な植民地化を示唆している.
結論:
- * 鉱物化した管は,約35億年前の海底微生物の活動に対する強力な証拠を提供します.
- * 火山ガラスの微生物によるエッチングは,チューブ形成の合理的なメカニズムである.
- * 初期の生命は,噴火直後の間もなく,水中の火山岩を植民地化し,回復力と適応力を示した.
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