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Inferring nonlinear mantle rheology from the shape of the Hawaiian swell

机译：从夏威夷隆起的形状推断非线性地幔流变

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摘要

The convective circulation generated within the Earth's mantle by buoyancy forces of thermal and compositional origin is intimately controlled by the rheology of the rocks that compose it. These can deform either by the diffusion of point defects (diffusion creep, with a linear relationship between strain rate and stress) or by the movement of intracrystalline dislocations (nonlinear dislocation creep)1'2. However, there is still no reliable map showing where in the mantle each of these mechanisms is dominant, and so it is important to identify regions where the operative mechanism can be inferred directly from surface geophysical observations. Here we identify a new observable quantity-the rate of downstream decay of the anomalous seafloor topography (swell) produced by a mantle plume-which depends only on the value of the exponent in the strain rate versus stress relationship that defines the difference between diffusion and dislocation creep. Comparison of the Hawaiian swell topography with the predictions of a simple fluid mechanical model shows that the swell shape is poorly explained by diffusion creep, and requires a dislocation creep rheology. The rheology predicted by the model is reasonably consistent with laboratory deformation data for both olivine3 and clinopyroxene4, suggesting that the source of Hawaiian lavas could contain either or both of these components.
机译：由地热和成分起源的浮力在地幔内部产生的对流循环受构成它的岩石的流变学的影响。这些可以通过点缺陷的扩散（扩散蠕变，在应变速率和应力之间具有线性关系）或晶体内位错的移动（非线性位错蠕变）1'2发生变形。但是，仍然没有可靠的地图显示这些机制中每种机制占主导地位，因此重要的是要确定可从地表地球物理观测直接推断出其工作机制的区域。在这里，我们确定了一个新的可观测量-由地幔柱产生的异常海底地形（膨胀）的下游衰减率-它仅取决于应变率与应力关系的指数值，该值定义了扩散与扩散之间的差异。位错蠕变。将夏威夷膨胀地形与简单流体力学模型的预测结果进行比较表明，膨胀扩散很难解释膨胀形状，并且需要位错蠕变流变学。该模型预测的流变学与橄榄石3和斜柏石4的实验室变形数据相当一致，这表明夏威夷熔岩的来源可能包含这两种成分中的一种或两种。

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  • 来源
    《Nature》 |2011年第7348期|p.501-504|共4页
  • 作者

    N. Asaadi; N. M. Ribe; F. Sobouti;

  • 作者单位

    Institute for Advanced Studies in Basic Sciences (lASBS),Zanjan 45137-66731 ,lran;

    Universite Pierre et Marie Curie (Paris6),UniversiteParis-Sud,CNRS, Lab FAST, Batiment 502, Campus Universitaire,91405 Orsay, France;

    Institute for Advanced Studies in Basic Sciences (lASBS),Zanjan 45137-66731 ,lran;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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