THERMO-CHEMICAL STRUCTURE OF THE LOWER MANTLE: SEISMOLOGICAL EVIDENCE AND CONSEQUENCES FOR GEODYNAMICS
THERMO-CHEMICAL STRUCTURE OF THE LOWER MANTLE: SEISMOLOGICAL EVIDENCE AND CONSEQUENCES FOR GEODYNAMICS
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下地幔的热化学结构：地震证据和地球动力学后果
DOI：
10.1007/978-1-4020-5750-2_11
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
P. Tackley
中科院分区：
文献类型：
--
作者：
F. Deschamps;J. Trampert;P. Tackley
我们结合联合收割机在地震层析成像和热化学对流数值模拟方面的最新进展来推断地幔结构和动力学的鲁棒特征。首先，我们将观测到的密度异常分为它们的热贡献和成分贡献。热化学变化的层析成像图计算使用一种新的方法，结合了一个仔细的状态方程建模的下地幔，独立的约束密度从概率层析成像，和一个完整的统计处理的不确定性分析。然后，我们测试模型的热化学对流对这些密度组件。我们计算合成异常的热和成分的密度从模型的热化学对流计算的滞弹性近似。这些合成分布被过滤，以与观测到的密度异常进行有意义的比较。我们的比较表明，浮力比B≥ 0.3的致密材料的稳定层（即，没有圆顶或桩从它产生）不太可能存在于地幔底部。从密度大但不稳定的层（浮力比B <0.2）中向上夹带的桩模型对观测结果的解释明显更好，但在下地幔顶部仍存在差异。这些差异可能与1000公里左右的板块偏转有关，或者与670公里处的相变有关，但尚未包括在热化学计算中。
We combine recent progress in seismic tomography and numerical modeling of thermochemical convection to infer robust features on mantle structure and dynamics. First, we separate the observed density anomalies into their thermal and compositional contributions. The tomographic maps of thermo-chemical variations were computed using a new approach that combines a careful equation of state modeling of the lower mantle, independent constraints on density from probabilistic tomography, and a full statistical treatment for uncertainties analyses. We then test models of thermo-chemical convection against these density components. We compute synthetic anomalies of thermal and compositional density from models of thermo-chemical convection calculated with the anelastic approximation. These synthetic distributions are filtered to make meaningful comparisons with the observed density anomalies. Our comparisons suggest that a stable layer (ie, that no domes or piles are generated from it) of dense material with buoyancy ratio B≥ 0.3 is unlikely to be present at the bottom of the mantle. Models of piles entrained upwards from a dense, but unstable layer with buoyancy ratio B∼ 0.2, explain the observation significantly better, but discrepancies remain at the top of the lower mantle. These discrepancies could be linked to the deflection of slabs around 1000 km, or to the phase transformation at 670 km, not included yet in the thermo-chemical calculations.
影响因子：
2.3
作者：
Dapeng Zhao
通讯作者：
Dapeng Zhao
影响因子：
2.3
作者：
T. Yagi;Kouichi Okabe;N. Nishiyama;A. Kubo;T. Kikegawa
通讯作者：
T. Yagi;Kouichi Okabe;N. Nishiyama;A. Kubo;T. Kikegawa
影响因子：
56.9
作者：
Murakami, M;Hirose, K;Ohishi, Y
通讯作者：
Ohishi, Y