当前位置: X-MOL 学术Phys. Earth Planet. Inter. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Effects of rheology and mantle temperature structure on edge-driven convection: Implications for partial melting and dynamic topography
Physics of the Earth and Planetary Interiors ( IF 2.3 ) Pub Date : 2020-06-01 , DOI: 10.1016/j.pepi.2020.106487
Dae-Hee Kim , Byung-Dal So

Abstract Edge-driven convection, which affects partial melting, intraplate volcanism, and dynamic topography, is small-scale convection that occurs along a lithospheric keel with a sharp contrast in lithospheric thickness. Various factors, including Rayleigh number, lateral mantle temperature heterogeneity, and geometry of the keel, influence the edge-driven convection, and the correlation between edge-driven convection and surface expressions (dynamic topography and volcanism) is complicated. We performed a finite element study to quantify the effects of these factors on dynamic topography and partial melting. We found that the dynamic topography is more prominent when a strong edge-driven convection cell develops, which corresponds to homogeneous mantle temperatures and the absence of mantle wind. In contrast, the development of edge-driven convection cells and dynamic topography near the lithospheric keel are hindered when the mantle temperature is strongly heterogeneous (laterally varying ~280 K). This indicates that a large lateral contrast in mantle temperature results in a strong mantle wind that may prevent the development of edge-driven convection cells. An increase in the Rayleigh number results in more vigorous convection and enhances partial melting. Our study shows that the location of volcanic activity at craton edges and passive margins can be reproduced in models with weakly heterogeneous mantle temperature for given mantle viscosity. The existence of a strong mantle wind (e.g., related to subducting slabs or mantle plumes) may inhibit the formation of an edge-driven convection cell and its related partial melt near a lithospheric keel. However, mantle conditions with weak temperature heterogeneity ( 17×1019 Pa∙s), which corresponds to the Rayleigh number of 1.8×106, do not induce partial melts despite the development of edge-driven convection cells. Our model parametrized the condition and location of edge-driven convection cells and partial melts, which can contribute to understanding anomalous intraplate volcanisms, such as in Jeju Island south of the Korean Peninsula and the Tanzania Craton near the East African Rift.

中文翻译:

流变学和地幔温度结构对边缘驱动对流的影响:对部分熔融和动态地形的影响

摘要 边缘驱动对流影响部分熔融、板内火山作用和动态地形,是沿岩石圈龙骨发生的小规模对流,岩石圈厚度对比强烈。各种因素,包括瑞利数、横向地幔温度非均质性和龙骨的几何形状,都会影响边缘驱动对流,并且边缘驱动对流与表面表现(动态地形和火山作用)之间的相关性很复杂。我们进行了一项有限元研究,以量化这些因素对动态地形和部分熔化的影响。我们发现,当强大的边缘驱动对流单元发展时,动态地形更加突出,这对应于均匀的地幔温度和没有地幔风。相比之下,当地幔温度强烈不均匀(横向变化~280 K)时,边缘驱动对流单元和岩石圈龙骨附近动态地形的发展受到阻碍。这表明地幔温度的大横向差异会导致强烈的地幔风,这可能会阻止边缘驱动对流单元的发展。瑞利数的增加导致更剧烈的对流并增强部分熔化。我们的研究表明,对于给定的地幔粘度,克拉通边缘和被动边缘火山活动的位置可以在具有弱异质地幔温度的模型中重现。强地幔风的存在(例如,与俯冲板片或地幔柱有关)可能会抑制边缘驱动对流单元及其在岩石圈龙骨附近的相关部分熔体的形成。然而,尽管边缘驱动对流单元的发展,具有弱温度异质性(17×1019 Pa∙s)的地幔条件(对应于 1.8×106 的瑞利数)不会引起部分熔化。我们的模型参数化了边缘驱动对流单元和部分熔体的条件和位置,这有助于了解异常的板内火山活动,例如在朝鲜半岛南部的济州岛和东非裂谷附近的坦桑尼亚克拉通。
更新日期:2020-06-01
down
wechat
bug