Mantle convection with continental drift and heat source around the mantle transition zone
Mantle convection with continental drift and heat source around the mantle transition zone
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DOI：
10.1016/j.gr.2013.02.001
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发表时间：
2012-12
影响因子：
6.1
通讯作者：
H. Ichikawa;M. Kameyama;K. Kawai
中科院分区：
文献类型：
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作者：
H. Ichikawa;M. Kameyama;K. Kawai
地质研究表明，由于海陆融合边缘的分层、大陆碰撞和俯冲作用，大量的地壳物质已经从地表流失。如果是这样，那么俯冲的地壳物质可能被困在中地幔中，这是由于由硅长石向辉长石相变引起的橄榄岩物质密度差所致。为了研究俯冲花岗岩物质在地幔过渡带周围漂移的影响，我们在地幔过渡带底部放置一个热源，进行了包含大陆漂移的地幔对流二维数值实验。模拟在高度为2900公里、宽度为11,600公里的二维矩形盒模型中处理扩展的Boussinesq近似下的随时间变化的流体对流，其中施加了长度为2900公里的大陆和大陆下方的热源。研究发现，地幔过渡带热源的增加大大增强了上地幔上升流柱的发生，进一步缩小了大陆漂移的时间尺度。热源还引起了大量的机械混合，特别是在上地幔。结果表明，地幔过渡带附近的热源可能是诱发超大陆旋回的一个候选热源。
Geological studies have suggested that a significant amount of crustal material has been lost from the surface due to delamination, continental collision, and subduction at oceanic–continental convergent margins. If so, then the subducted crustal materials are expected to be trapped in the mid-mantle due to the density difference from peridotitic materials induced by the phase transition from coesite to stishovite. In order to study the effect of the subducted granitic materials floating around the mantle transition zone, we conducted two-dimensional numerical experiments of mantle convection incorporating a continental drift with a heat source placed around the bottom of the mantle transition zone. The simulations deal with a time-dependent convection of fluid under the extended Boussinesq approximation in a model of a two-dimensional rectangular box with a height of 2900 km and a width of 11,600 km, where a continent with a length of 2900 km and heat source below the continent are imposed. We found that the addition of heat source in the mantle transition zone considerably enhances the onset of upwelling plumes in the upper mantle, which further reduces the time scale of continental drift. The heat source also causes massive mechanical mixing, especially in the upper mantle. The results suggest that the heat source floating around the mantle transition zone can be a possible candidate for inducing the supercontinent cycle.