俯冲板块的动力学性质对平板俯冲的影响：数值模拟

平板俯冲是地球上一种独特的俯冲模式，主要发生在南美洲地区，与该地区的地震、火山等构造地质现象有着密切联系。平板俯冲的形成机制和影响因素仍然需要进一步地研究。文章通过数值模拟的方法，研究了俯冲板块的动力学性质对于平俯冲板片形态的影响。模拟实验结果表明，俯冲板块的厚度和密度差（与地幔）对平板俯冲的形成有着决定性的影响。合适的俯冲板块厚度（70 km 左右）有利于在俯冲过程中形成平板片。厚度较大的板片难以发生弯曲，阻碍了平板片的形成。俯冲板块与地幔的密度差越小，越容易形成平板俯冲，平板片的长度也越长。俯冲板片的密度差太大也不利于形成平板片。此外，高粘度的俯冲板块容易形成平板俯冲，俯冲板块的粘度与形成的平板片的长度也成正比。研究还发现，平板俯冲的形成伴随着海沟后撤速率的减小。参考模型重现了智利中部平板俯冲的形态，为研究该地区的平板俯冲机制提供了新认识。

Influence of Subducting Plate Dynamic Properties to Flat-slab Subduction by Numerical Modeling

This particular phenomenon of flat-slab subduction mainly occurs in South American,which is closely related to the structural geological phenomena such as earthquakes and volcanoes in this area.However,mechanics of flat-slab subduction is not yet well understood.By numerical modeling,we investigate influences of subducting plate dynamic properties to the geometry of flat-slab subduction.The model results show that subducting plate thickness and density contrast between slab and mantle have great impacts to flat-slab formation.The appropriate slab thickness(around 70 km)facilitate slab flattening,while thicker slab is difficult to bend and hesitates to flatten.The smaller the density anomaly of subducting plate,the easier slab flattens and the longer flab-slab length.When density anomaly is very large,no flat-slab is predicted.In addition,strong plate promotes flat-slab formation.Flat-slab length increases with plate viscosity increasing.We also find that trench rollback velocity decreases during the slab flattening episode.Our reference model REF_MODEL has comparable flat-slab geometry with central Chile subduction,which provides the insight of flat subduction formation in this area.