在哥斯达黎加和尼加拉瓜下方的地幔中,弧形平行流
Kaj Hoernle1, David L Abt, Karen M Fischer
1SFB 574, University of Kiel, Wischhofstrasse 1-3, Kiel 24148, Germany. khoernle@ifm-geomar.de
Nature
|January 29, 2008
概括
中美洲下方的沟平行地幔流挑战了传统的俯冲区模型. 同位素地质化学揭示了来自科科斯板块的火山起源,表明与板块构造速率相比,地幔向西北运动显著.
科学领域:
- 地质物理学 地质物理学
- 地质化学 地质化学
- 构造学 构造学 构造学 构造学
背景情况:
- 了解地幔流对于潜水带动态至关重要,包括板块脱水,融化和弧形火山.
- 经典模型预测了沟正常的地幔流动,由引板驱动.
研究的目的:
- 在哥斯达黎加和尼加拉瓜下面调查地幔形流动几何.
- 为了使火山岩的地化学特征与地幔动力学相协调.
主要方法:
- 在火山岩中分析同位素地质化学.
- 测量地震速度的异质性测量.
- 地质年代和运输距离估计.
主要成果:
- 证据表明,在哥斯达黎加和尼加拉瓜下方存在沟平行地幔流.
- 火山岩石显示出源于加拉帕戈斯热点海底山的同位素标志,这些岩石位于可可斯板块上.
- 估计的西北地幔流速 (63-190毫米/年) 与科科斯板块运动 (~85毫米/年) 相当.
结论:
- 这些发现与沟正常流动的经典模型相矛盾.
- 沟沟平行流必须纳入潜水带热和化学结构以及融的模型.
- 这种流动会影响火山活动和相关的气候影响.
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