ネオアルカイアの酸素ベースの窒素循環は,大酸化イベントへの道
Alice Pellerin1, Christophe Thomazo2,3, Magali Ader4
1Laboratoire Biogéosciences, UMR CNRS 6282, Université de Bourgogne, Dijon, France. alice.pellerin-lefebvre@u-bourgogne.fr.
Nature
|August 21, 2024
まとめ
初期の地球
科学分野:
- 地化学
- 古生物学
- 地球 の 初期 史
背景:
- 沈殿性窒素同位体 (δ15N) は,酸化還元過程と初期の酸素化を追跡する.
- 大酸化現象 (~2.45 Ga) は大きな δ 15 N 変化を示せず,脱された窒素と酸素のサイクルを示唆している.
- 陽性 δ15N値 (2.82.6 Ga) は酸化の前駆体を示しているが,その起源は不明である.
研究 の 目的:
- プレカンブリア時代の岩石における正の δ 15 N 値の起源を調査する.
- 初期の窒素サイクル進化のタイミングと影響を決定する.
- 大気中の酸素の蓄積前の 謎の酸素循環の証拠を特定する.
主な方法:
- 2.68Gyrの堆積岩における窒素同位体組成 (δ15N) の分析
- セラ・スル・フォーメーションの地化学研究,アマゾンのクレートン.
- 初期の地球における窒素循環の解釈
主要な成果:
- 2.68-Gaの海洋沈殿物で強く陽性 δ15N値 (> 30 ‰) が発見された.
- 謎の酸素循環に関連した地域のアンモニア酸化による発見.
- 証拠によると,酸素の光合成は 2.7 億年ほど前に活発であった.
結論:
- "窒素同位体現象"は 初期の生地化学的再編成を示しています
- この出来事は 大気中の有酸素化に先行した.
- 大酸化イベントへの最初のステップを示します.
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