上层地幔橄的氧影响的地震性能
C J Cline Ii1, U H Faul2, E C David1
1Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory, Australia.
Nature
|March 16, 2018
概括
上层地幔的地震波速度和衰减对水含量有惊人的不敏感性. 而不是水, 显著影响地震特性, 挑战以前的假设.
科学领域:
- 地质学
- 矿物物理
- 地震学
背景情况:
- 地震波速的侧向变化和地球上层地幔的衰减可以揭示温度,组成,融化和水含量的信息.
- 了解影响地震波传播的微机械过程对于解释地质数据至关重要.
- 结构上结合的水 () 对地震性能的影响已被假设,但未经实验量化.
研究的目的:
- 通过实验量化水含量对橄的地震性能的影响.
- 研究氧化还原条件和缺陷化学对上层地幔地震波传播的影响.
- 重新评估水在解释观测到的地震结构中的作用,例如低速度区域和石层-石层边界.
主要方法:
- 在橄石样本上进行低频强制振荡实验.
- 系统地改变了与地球内部相关的低和状态中的水含量.
- 使用不同的金属外套材料控制和变化的氧化还原条件.
主要成果:
- 地震波速度和衰减对水含量变化显示出显著的不敏感性.
- 由于金属外套和由此产生的缺陷化学物质, 反氧条件对地震性能产生了重大影响.
- 没有证据支持在石化层-石化层边界的水增加了谷物边界的滑动.
结论:
- 高含水量不太可能是上层地幔低速或高衰减结构的主要原因.
- 在水性和氧化上层地幔区域的高衰减可能与占主导地位的氧气流动性有关,而不是水本身.
- 这项研究挑战了水在清晰的岩层-岩层界限中的作用, 表明其他因素更为主导.
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