コア・マントルの境界にある超低速帯の源泉として,亜熱帯鉄の形成物

David P Dobson¹, John P Brodholt

¹Department of Earth Sciences, University College London, Gower Street, London, WC1E 6BT, UK. d.dobson@ucl.ac.uk

Nature

|March 18, 2005

まとめ

地球上の超低速帯 (ULVZs)

科学分野:

地質物理学地質物理学とは地質物理学です.
ミネラル物理学ミネラル物理学
地球科学地球科学地球科学

背景:

超低速帯 (ULVZs) は,コアマントルの境界にある明確な領域で,地震波の速度が低下し,密度が増加することが特徴です.
ULVZの起源に関する既存の仮説には,シリケート溶融の貯水池,コア-マントルの反応,およびコア沈殿が含まれています.
厚さ約1~10kmのこれらのゾーンでは,圧縮波の速度が10~20%減少し,シア波の速度が10~30%減少しています.

研究の目的:

超低速ゾーン (ULVZ) の新たな起源を提案する.
ULVZsの源泉として潜水帯状鉄の形成の可能性を調査する.
ULVZの観測された地震および密度特性を説明する.

主な方法:

地質学的仮説の形成. 地質学的な仮説の形成.
帯状鉄の形成の組成と堆積環境の分析.
核-マントルの境界における潜水過程と物質の振る舞いのモデリング.

主要な成果:

鉄酸化物とシリカから成る鉄の帯状構造は,古代の海に堆積していた.
これらの構造は,沈下すると,コア-マントルの境界に到達する可能性があります.
サブダクトされた帯状鉄の構造の性質は,観測されたULVZの特徴と一致しています.

結論:

亜圧帯状鉄の形成は,超低速度ゾーン (ULVZ) の妥当な起源を表しています.
この仮説は,ULVZで観察された地震と密度の異常を潜在的に説明します.
提案されたメカニズムは,古代の地球プロセスと現在の深層マントルの構造を結びつける.

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