克拉石层的平均物理结构,来自全球表面波数据的热力学反转
Yihe Xu1,2, Sergei Lebedev2, Javier Fullea3
1Department of Geophysics, School of Earth Sciences, Yunnan University, Green Lake North Road 2, Kunming, 650091 Yunnan China.
概括
克拉顿拥有地球上最厚的石化层,但其精确的结构仍然不确定. 这项研究使用地震热学测量模拟了克拉顿石质层,揭示了平均石质层-石质层边界深度为228公里.
科学领域:
- 地质物理学 地质物理学
- 固体地球科学 固体地球科学
- 地震学 地震学
背景情况:
- 众所周知,克拉顿拥有地球上最厚,最冷的石化层.
- 温度,地震速度和密度的定量深度分布在克拉顿岩石层中没有很好的约束.
- 来自断层模型的地震速度概况在相关深度尺度上表现出非唯一性.
研究的目的:
- 确定克拉石层内的平均物理性质和深度分布.
- 建立一个量化,平均模型的克拉顿石质层结构.
- 为克拉顿的地质物理和地质化学研究提供参考.
主要方法:
- 利用地震热学来将全球克拉顿平均表面波测量与物理性质联系起来.
- 执行雷利和爱情波相速曲线的热力学反转.
- 假设平均耗尽的矿组成和对流开始温度为1290°C,以定义石灰岩层-石灰岩层边界 (LAB).
主要成果:
- 开发了一种平均克拉顿石质层模型,包括温度,S波和P波速度,密度和辐射异构形状.
- 估计了石化层-石化层边界 (LAB) 的平均深度为228公里 (不确定性为211-242公里).
- 该模型与观察到的相位速度,地形和表面热流密切匹配,证实了克拉顿是异构的.
结论:
- 衍生出来的克拉顿-平均石层模型作为地质物理和地化学数据集成的有价值的参考.
- 证实了克拉顿岩石层是平均而言,同热带,上层地幔密度形状与非克拉顿地区相似.
- 突出的是,许多地幔色诺石P-T数据在150公里以下显示的温度高于克拉平均值,为克拉演变提供了洞察力.
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