ブリッジマニートの結晶学的な好み向きから推論されたマントルの動態
Noriyoshi Tsujino1, Yu Nishihara2, Daisuke Yamazaki1
1Institute for Planetary Materials, Okayama University, 827 Yamada, Misasa, Tottori 682-0193, Japan.
Nature
|November 4, 2016
まとめ
ブリッジマニット
科学分野:
- 鉱物物理学
- 地震学
- 地力学
背景:
- 最上層の下層マントルのシーザー波アニソトロピーは,沈殿したスラブと関連しています.
- ブリッジマニートの結晶学的な好み向き (CPO) が原因である可能性が高いが,その変形メカニズムは不明である.
- 以前の研究では 変形質が特定されましたが 主要な滑り系は特定されていません
研究 の 目的:
- 最上下マントルの条件下におけるブリッジマニートの支配的な滑り系を決定する.
- 沈殿したスラブの近くの地震アニソトロピーの観測を説明します.
主な方法:
- 単軸変形実験は以前行われていた.
- カワイ型変形-DIA装置を用いた単純な切断変形実験が行われた.
- ブリッジマニットCPOは25GPaと1,873Kで分析された.
主要な成果:
- ブリッジマニトの支配的な滑り系は [001] だった.
- CPOパターンは,切断平面に垂直 [100],切断方向に平行 [001] を示した.
- このCPOは,トンガ・ケルマデック,クリル,ペルー,ジャワなどの沈殿板の近くの地震性アニソトロピーを説明します.
結論:
- [001](100) スリップシステムは,最上下のマントルのブリッジマニット変形を制御します.
- マントルの流れによって誘発されたブリッジマニットCPOは観測された地震アニソトロピーを説明します.
- この発見はマントルの地力学と 地震波の伝播に関する理解を深めるものです
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