マントルの羽ばたきで長期にわたる冷却に関する石器学的な証拠
Claude Herzberg1, Esteban Gazel
1Department of Earth and Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854-8066, USA. herzberg@rci.rutgers.edu
Nature
|April 3, 2009
まとめ
海洋島の玄武岩 (OIBs) と大火山地帯 (LIPs) は,異なる噴火率を示しています. Petrological モデリングは,マントルの羽根が過去により熱く,より広範に溶けたことを明らかにし,これらの違いを説明します.
科学分野:
- 地質化学 地質化学
- ペトロロジー・ペトロロジーとは
- ジオクロノロジー (Geochronology) について
背景:
- 海洋島の玄武岩 (OIBs) と大火山地帯 (LIPs) は,異なる噴火率を示しています.
- 以前の研究では,OIBとLIPのマントルの温度と融解の範囲に関する量的な石油学的比較が欠けていました.
研究 の 目的:
- OIBとLIPのマントル源の間の定量的な石油学的比較を行うために.
- ガラパゴス諸島に関連するラバのマントルの源温度と融解範囲の変化を時間とともに調査する.
主な方法:
- 地質地図作成とジオクロノロジック研究.
- ガラパゴス諸島に関連する溶岩とその原始的なマグマにおけるMgOとFeOの含有量の Petrologicalモデリング.
- アイスランドの長期的な冷却傾向の分析.
主要な成果:
- ガラパゴス諸島に関連する溶岩は,白亜紀以来,MgOとFeOの含有量が減少したことを示しています.
- Petrologicalモデリングは,ガラパゴスマントルの羽根の冷却を1,560-1,620°C (クレタセアス) から1,500°C (現在) に示しています.
- アイスランドも,世俗的な冷却の証拠を示しています.
結論:
- 古いLIP (ペルミア紀・ペルミア紀) に関連するマントルの羽根は,現代のOIBよりも熱く,より広範に溶けました.
- 低マントルの異質な領域からのエピソディックフローが,これらの羽根の変動を誘発している可能性が高い.
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