The effect of metastable pyroxene on the slab dynamics
The effect of metastable pyroxene on the slab dynamics
复制标题
DOI：
10.1002/2014gl062159
复制
发表时间：
2014-12-28
影响因子：
5.2
通讯作者：
Goes, Saskia
中科院分区：
文献类型：
--
作者：
Agrusta, Roberto;van Hunen, Jeroen;Goes, Saskia
地震研究表明，一些俯冲板块直接进入下地幔，而另一些板块似乎在地幔过渡带底部附近变平。板块停滞通常归因于橄榄石系统中粘度的增加和相变。然而，最近的矿物物理研究表明，由于极低的相变扩散速率，低密度亚稳态辉石可能会持续存在于冷却板坯的过渡区。在这里，我们使用一个动态的完全自洽俯冲模型来研究亚稳辉石对大洋岩石圈俯冲动力学的影响。我们的结果表明，亚稳辉石对板坯浮力的影响至少与橄榄石亚稳一样大。然而，与亚稳橄榄石不同的是，亚稳辉石只对冷的、老的和快的板岩才能阻止板岩在下地幔中的穿透，亚稳辉石可能也会影响相对年轻和缓慢的板岩的下沉。
Seismic studies show that some subducting slabs penetrate straight into the lower mantle, whereas others seem to flatten near the base of the mantle transition zone. Slab stagnation is often attributed to an increase in viscosity and phase transformations in the olivine system. However, recent mineral physics studies showed that due to extremely low transformational diffusion rates, low-density metastable pyroxene may persist into the transition zone in cool slabs. Here we use a dynamically fully self-consistent subduction model to investigate the influence of metastable pyroxene on the dynamics of subducting oceanic lithosphere. Our results show that metastable pyroxene affects slab buoyancy at least as much as olivine metastability. However, unlike metastable olivine, which can inhibit slab penetration in the lower mantle only for cold, old, and fast slabs, metastable pyroxene is likely to also affect sinking of relatively young and slow slabs.