中央安第斯山脉的俯冲和碰撞过程受到转换的地震阶段的限制
1GeoForschungsZentrum Potsdam, Telegrafenberg, Germany.
Nature
|January 5, 2001
概括
深度地震成像显示,石质层地幔的稀薄,而不仅仅是地的加厚,导致了高处的中央安第斯山脉. 这项研究还提供了证据,证明了纳斯卡板块的延迟变态反应.
科学领域:
- 地质物理学 地质物理学
- 构造学 构造学 构造学 构造学
- 地震学 地震学
背景情况:
- 中央安第斯山脉是一个主要的山脉,是由海洋与大陆的碰撞形成的.
- 升起主要归因于过去2000万年来大陆地的加厚.
研究的目的:
- 为了描绘中央安第斯山脉下的深层地和地幔结构.
- 调查导致该地区大幅上升的构造过程.
- 为了了解纳斯卡板块沉降的行为.
主要方法:
- 使用P-to-S (压缩到剪切) 转换的远震波.
- 在Altiplano和Puna高原上部署了临时的地震网络.
- 分析了Moho深度变化和潜浮板结构.
主要成果:
- 莫霍的深度有很大的差异,从阿尔蒂普拉诺高原下75公里到普纳高原下50公里.
- 普纳高原下方的薄薄地表明,石层地幔稀薄有助于升起.
- 纳斯卡板块被降低到120公里的图像,在那里由于gabbro-eclogite转变,它变得在地震上看不见.
- 一个地内低速区表明正在进行的变形和在高原下部分融化.
结论:
- 石质层地幔变薄是普纳高原升起的一个关键因素.
- 延迟的变态反应,特别是加布罗-生态石的转变,控制了纳斯卡板块的行为和地震性.
- 一个内地内的低速度区域将上层和下层地的变形过程分开.
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