Numerical modelling of spontaneous slab breakoff and subsequent topographic response
Numerical modelling of spontaneous slab breakoff and subsequent topographic response
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DOI：
10.1016/j.tecto.2010.05.024
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发表时间：
2011-04-13
期刊：
影响因子：
2.9
通讯作者：
May, Dave A.
中科院分区：
文献类型：
--
作者：
Duretz, Thibault;Gerya, Taras V.;May, Dave A.
我们进行了一组数值实验，研究俯冲碰撞系统的演化受到自发板片断裂。该研究考虑了复杂的流变行为，包括塑性，粘性蠕变和Peierls蠕变。通过改变大洋板块年龄和初始板块收敛速率，观察到四种不同的端元。在这一参数空间中，断裂深度可从40公里到400公里不等。这些断裂模式中的每一种在断裂期间显示复杂的流变行为。橄榄石中的Peierls蠕变是板片破裂的关键机制，通常导致板片在较浅的深度较早地破裂。涉及不同破裂深度的模型受到不同的地形演化，但总是显示出尖锐的破裂信号。前陆盆地和腹地盆地的断裂后隆升速率在深拆离的0.1 km/My和浅拆离的0.8 km/My之间。我们的系统研究表明，断裂深度与隆升速率之间近似呈线性关系，在断裂实验中观察到了大陆地壳俯冲作用，这些实验涉及年龄大于30 My的大洋岩石圈。根据断离深度的不同，发生了板片后退和排出等不同的折返过程。如果俯冲洋板足够古老，这些模型很可能在断裂和板块分离之后经历大的反弹。(C)2010 Elsevier B. V.保留所有权利。
We conducted a set of numerical experiments to study the evolution of a subduction-collision system subject to spontaneous slab breakoff. The study takes into account complex theological behaviour including plasticity, viscous creep and Peierls creep.By varying the oceanic slab age and initial plate convergence rate, four different end-members were observed. In this parameter space, breakoff depth can range from 40 to 400 km. Each of those breakoff modes displays complex rheological behaviour during breakoff. Peierls creep in olivine turns out to be a key mechanism for slab breakoff, generally causing slabs to break earlier and at shallower depths.Models involving different depths of breakoff are subject to different topographic evolution, but always display a sharp breakoff signal. Post breakoff uplift rates in foreland and hinterland basins range between 0.1 km/My for deep detachment and 0.8 km/My for shallow detachment. Our systematic study indicates an approximately linear relationship between the depth of breakoff and the rate of uplift.Continental crust subduction was observed in breakoff experiments involving oceanic lithosphere older than 30 My. Different exhumation processes such as slab retreat and eduction occur according to the depth of breakoff. These models are likely to undergo large rebound following breakoff and plate decoupling if the subducted oceanic slab is old enough. (C) 2010 Elsevier B.V. All rights reserved.