金鉱床の形成におけるCO2の役割
1CSIRO Division of Exploration and Mining, PO Box 3, Central Park, Victoria 3145, Australia. neil.phillips@csiro.au
Nature
|June 25, 2004
まとめ
二酸化炭素 (CO2) は,金貨の輸送において重要な役割を果たしています.
科学分野:
- 地質化学 地質化学
- 経済地質学 経済地質学
- ミネラル埋蔵地
背景:
- 世界的な金産出は,多くの場合,有意な基礎金属濃度が欠けている鉱床から発生します.
- これらの"金だけ"の鉱床は,二酸化炭素 (CO2) に富んだ熱水流体から形成されるという理論があります.
- これらのシステム内の金輸送におけるCO2の正確な役割は,歴史的に過小評価されてきた.
研究 の 目的:
- "金のみ"の埋蔵地における黄金の形成と輸送における二酸化炭素 (CO2) の役割を調査する.
- 金を含む熱水流体におけるpHバッファとしてのCO2の間接的な役割の重要性を再評価する.
- 特定の地質環境における金輸送機構の改訂モデルを提案する.
主な方法:
- 地化学データと流体含有研究を分析し,過去の熱水流体状態を推論する.
- 異なる条件下で金,硫黄,CO2の振る舞いをシミュレートするための地化学モデリング.
- 金を輸送する液体の以前に計算されたpH値の再評価.
主要な成果:
- 黄金を含有する液体に対する以前に推測されたpH値は,金運搬中の条件を正確に反映していない可能性があります.
- 二酸化炭素 (CO2) は,特定の液体の状態を維持し,重要なpHバッファとして作用する可能性があります.
- これらの緩衝状態は,硫黄の種類が減少した複合体による高濃度の黄金を促進します.
結論:
- CO2は,熱水流体のpHをバッファリングすることによって,黄金の輸送に重要な間接的な役割を果たします.
- このバッファリングメカニズムは,黄金の複合を減少した硫黄で可能にし,より高い濃度につながる.
- この発見は",金のみ"の鉱床の探査のための新しい地化学的枠組みを提供します.
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