大陸の衝突が遅いのは,地形ではなく粘着性マントルの石層による
1Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA. marinkc@umich.edu
Nature
|March 3, 2012
まとめ
プレート速度は,プレート境界にある力によって導かれる. 大陸のマントルの石層変形はプレート運動に影響し,インド-ユーラシアの衝突以来,チベットでは恒常的な緊張率を示しています.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- テクトニクス (地質学) とは
- プレートダイナミクス プレートダイナミクス
背景:
- プレート速度は,マージンとベースの力によって決定され,大陸変形が推進力を影響する.
- 衝突後のプレート運動速度はあまり理解されていないが,収束の減速はしばしば地形に起因する.
- プレート運動における大陸マントルの石層の変形の役割は,以前は調査されていなかった.
研究 の 目的:
- 大陸マントルの変形する石層がプレート運動に及ぼす影響を調査する.
- 衝突後,インドがユーラシアに浸透する速度を分析する.
- 衝突後の収束率を制御する要因を理解する.
主な方法:
- 過去のプレート運動を再構築するために,海洋磁気異常の分析.
- テキトニックプレート力と変形のモデリング.
- インド・ユーラシア衝突地帯における収束率とストレスの割合の検討.
主要な成果:
- インドのユーラシアへの収束率は,衝突以来指数関数的に減少しています.
- 衝突以来,チベット全域で7.03 × 10−16 s−1の恒常収縮ストレスの速度.
- 証拠は,チベットの下のマントル・リトスフィアの無傷性を示唆しており,その変形の歴史を反映しています.
結論:
- 変形する大陸のマントルの石層は粘着抵抗を行使し,板の動きに影響を与えます.
- チベットの恒常的な散発ストレートレートは,深さの恒常的な平均ストレートによる抵抗を意味します.
- トポグラフィの進化は,衝突後のプレート運動抵抗を制御する唯一の要因ではありません.
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