熱化学的石層の微分化とクラトンマントルの起源

Fabio A Capitanio¹, Oliver Nebel², Peter A Cawood²

¹School of Earth Atmosphere and Environment, Monash University, Clayton, Victoria, Australia. fabio.capitanio@monash.edu.

Nature

|December 3, 2020

まとめ

初期の地球における解圧溶解と溶解抽出のメカニズムによって形成されたクレートン

科学分野:

地理科学
地球科学
構造学

背景:

クラトンは古くから安定した大陸の地殻を表しますが,その形成と長期の安定性は十分に理解されていません.
初期の地球のマントルはより熱く,よりダイナミックで,石層形成プロセスに影響を与えていた.

研究の目的:

融解したクラトニック・リトスフィアマント (CLM) の形成のための新しいメカニズムを提案し,調査する.
地質学的スケールで安定したクレートンの進化を説明するために

主な方法:

初期の地球条件下でマントルの動態と石層の進化をシミュレートするために数値モデリングを使用した.
マントルの枯渇と安定化に対する解圧溶解,溶融抽出,石層強さの影響を調査した.

主要な成果:

モデルでは,伸縮する石層の下での大規模解圧融解は,かなりの量の枯渇したマントルを生成することを示しています.
ストレスの局所化とマントルの硬化との間の負のフィードバックは,枯渇したマントルの石層への同化を促進し,長期的な安定性を促進します.
低地層の強度を含む初期の地球の条件は,広範囲の枯渇とクレートンの限界の形成に不可欠です.

結論:

提案されたメカニズムは,大量で枯渇したCLMの形成とその後のクラトンへの安定化を説明する.
初期の地球の大規模な融解と再利用は,原始的な石層の生成と喪失に決定的であり,後の安定化は,アルカイア期のクラトン形成の舞台となった.

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