Effects of compositional and rheological stratifications on small‐scale convection under the oceans: Implications for the thickness of oceanic lithosphere and seafloor flattening
Effects of compositional and rheological stratifications on small‐scale convection under the oceans: Implications for the thickness of oceanic lithosphere and seafloor flattening
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DOI：
10.1029/2008gl035419
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发表时间：
2008-10
影响因子：
5.2
通讯作者：
J. Afonso;S. Zlotnik;Manel Fernández
中科院分区：
文献类型：
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作者：
J. Afonso;S. Zlotnik;Manel Fernández
洋中脊的压力释放熔融在海洋地幔中产生成分和流变分层，这可能控制海洋岩石圈的演化。我们使用动力学模型结合熔融和岩石学模型来探索1）这种分层对海洋下小尺度对流发展的影响，2）它在确定海洋岩石圈厚度方面的作用，以及3）它作为海底和表面热流偏离成熟海洋岩石圈传导模型预测的可行性。在这里，我们表明，小尺度对流的存在与实验蠕变参数和流动定律完全兼容，并且由于熔体萃取（即，H2O的去除）是控制该板块热演化、渐近厚度、海底平坦化和地表热流的主要因素。富铝相变和成分分层的影响较小。
Pressure‐release melting at mid‐ocean ridges generate compositional and rheological layering in the oceanic mantle that may control the evolution of the oceanic lithosphere. We use dynamic models coupled with melting and petrological models to explore 1) the influence of this layering on the development of small‐scale convection under the oceans, 2) its role in determining the thickness of oceanic lithosphere, and 3) its feasibility as responsible for the deviations of seafloor and surface heat flow from predictions by conductive models in mature oceanic lithosphere. Here we show that the existence of small‐scale convection is entirely compatible with experimental creep parameters and flow laws, and that the viscosity stratification due to melt extraction (i.e., H2O removal) is the main factor controlling the plate's thermal evolution, its asymptotic thickness, and the flattening of seafloor and surface heat flow at ages ≳70 Ma. The effects of Al‐rich phase transitions and compositional layering are minor.