Spherical dynamic models of top‐down tectonics
Spherical dynamic models of top‐down tectonics
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自上而下构造的球形动力学模型
DOI：
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
R. Müller
中科院分区：
文献类型：
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作者：
G. Morra;L. Quevedo;R. Müller
我们使用多极边界元法（MP-BEM）在球面三维环境中模拟区域和全球地球动力学。我们首先模拟了一个孤立的俯冲矩形板，其长度（Llitho）和宽度（Wlitho）在地球半径（REarth）的0.5倍和2倍之间变化，粘度η litho在上地幔（η UM）的100倍和500倍之间变化，下沉到分层地幔中，其特征在于下-上地幔粘度比λ = η LM/η UM在1和80之间变化。在上/下粘度差较小的地幔中（λ < 1），海沟和板块运动对Wlitho的依赖性较弱;如果Llitho ≤ REarth，板块运动受板片拉拽控制，而对于较长的板块，由于板块基底摩擦和流动重组，板块运动速度显著降低。粘度比λ的增加逐渐打破了这一模式，当λ = 10时，结合Wlitho的REarth（或更大），可以同时观察到海沟的前进和后退。这些结果为过去1.5亿年来观测到的最大板块的大小（Llitho Wlitho Wlitho REarth）的起源提供了一级解释。最后，分别对25Ma前和100Ma前重建的板块和板片进行了两次全球板块构造模拟。结果表明，如果对最长的板块（Llitho> REarth）采用板幔解耦，MP-BEM预测了现今的板块运动学。100 Ma的模型表明，印度板块和Izanagi板块在100 Ma时的板-板相互作用可以解释板块重组从印度板块到太平洋板块的传播。
We use the Multipole–Boundary Element Method (MP‐BEM) to simulate regional and global geodynamics in a spherical 3‐D setting. We first simulate an isolated subducting rectangular plate with length (Llitho) and width (Wlitho) varying between 0.5 and 2 times the radius of the Earth (REarth) and with viscosity ηlitho varying between 100 and 500 times the upper mantle (ηUM), sinking in a layered mantle characterized by lower‐upper mantle viscosity ratioλ = ηLM/ηUM varying between 1 and 80. In a mantle with small upper/lower viscosity contrast (λ ≅ 1), trench and plate motions are weakly dependent on Wlitho; plate motion is controlled by slab pull if Llitho ≤ REarth, while for longer plates plate speed strongly decreases because of the plate basal friction and flow reorganization. An increasing viscosity ratio λ gradually breaks this pattern, and for λ ≅ 10 combined with Wlitho ≈ REarth(and greater) trench advance and retreat are simultaneously observed. These results offer a first‐order explanation of the origin of the size (Llitho ≈ Wlitho ≈ REarth) of the largest plates observed over the past 150 Myr. Finally, two global plate tectonic simulations are performed from reconstructed plates and slabs at 25 Ma before present and before 100 Ma, respectively. It is shown that MP‐BEM predicts present plate kinematics if plate‐mantle decoupling is adopted for the longest plates (Llitho > REarth). Models for 100 Ma show that the slab‐slab interaction between India and Izanagi plates at 100 Ma can explain the propagation of the plate reorganization from the Indian to the Pacific plate.
新生代板块运动中板块浮力驱动的下行俯冲特征
影响因子：
2.3
作者：
Goes S
通讯作者：
Goes S