ファネロゾイク海水化学における振動:流体インクルージョンからの証拠
T K Lowenstein1, M N Timofeeff, S T Brennan
1Department of Geological Sciences and Environmental Studies, State University of New York, Binghamton, NY 13902, USA. lowenst@binghamton.edu
まとめ
海水化学は,地球の歴史を通じて変化しており,海洋ハライトに含まれる液体の含有物によって証明されています. これらの変化は地質学的な出来事と,支配的な海洋鉱物の変化と相関しています.
科学分野:
- 地質化学 地質化学
- パレオセアノグラフィー
- 堆積地質学 堆積地質学とは
背景:
- 海水の組成は,地球の気候と地質学的プロセスを理解するために重要である.
- ハライトの原流体含有物は,古代の海水化学のユニークなアーカイブを提供します.
研究 の 目的:
- ファネロゾイク海水化学の変動を再構築する.
- 海水化学と主要な地質学的出来事との関係を調査する.
主な方法:
- 海洋ハライトの原流体含有物内の蒸発した海水における体系的な化学変化の分析.
- 地化学データと地質学的記録の相関 (海底の広がり,火山活動,海面,鉱物学).
主要な成果:
- 海水の化学成分,特にMg2+/Ca2+比,Na+濃度などは,ファネロゾーイク時代に体系的に変動していた.
- 高いMg2+/Ca2+比とNa+は,アラゴニットとMgSO4の降水と一致する,プレカンブリア後期,ペルミア期,そして三次期を特徴づけた.
- 低Mg2+/Ca2+比とNa+がカンブリア,シルウリア,白亜紀の特徴で,カルシートと特定のポータシュ蒸発石の形成と一致しています.
結論:
- 海水の化学は恒定ではなく,地質的な時間尺度で著しい振動を示します.
- これらの変動は,構造的活動や海面の変化を含む主要な地質学的なサイクルと同期しています.
- 海水のMg2+/Ca2+比とNa+濃度は,海洋蒸発物と炭酸塩の鉱物学を制御する重要な要因である.
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