Menant Armel, Angiboust Samuel, Gerya Taras, Lacassin Robin, Simoes Martine, Grandin Raphael
CNRS, Institut de physique du globe de Paris, Université de Paris, 75005, Paris, France.
GFZ Helmholtz Centre Potsdam, German Research Centre for Geosciences, Telegrafenberg, 14473, Potsdam, Germany.
Nat Commun. 2020 Apr 14;11(1):1823. doi: 10.1038/s41467-020-15580-7.
Topography in forearc regions reflects tectonic processes along the subduction interface, from seismic cycle-related transients to long-term competition between accretion and erosion. Yet, no consensus exists about the topography drivers, especially as the contribution of deep accretion remains poorly constrained. Here, we use thermo-mechanical simulations to show that transient slab-top stripping events at the base of the forearc crust control uplift-then-subsidence sequences. This 100s-m-high topographic signal with a Myr-long periodicity, mostly inaccessible to geodetic and geomorphological records, reflects the nature and influx rate of material involved in the accretion process. The protracted succession of stripping events eventually results in the pulsing rise of a large, positive coastal topography. Trench-parallel alternation of forearc highs and depressions along active margins worldwide may reflect temporal snapshots of different stages of these surface oscillations, implying that the 3D shape of topography enables tracking deep accretion and associated plate-interface frictional properties in space and time.
弧前区域的地形反映了俯冲界面沿线的构造过程，从与地震周期相关的瞬变到增生与侵蚀之间的长期竞争。然而，关于地形驱动因素尚无共识，尤其是深部增生的贡献仍受严格限制。在这里，我们使用热机械模拟表明，弧前地壳底部的瞬态板片顶部剥离事件控制着先隆升后沉降的序列。这种具有百万年级周期性、高达数百米的地形信号，大地测量和地貌记录大多无法获取，它反映了增生过程中物质的性质和流入速率。长期的剥离事件序列最终导致大型正海岸地形的脉冲式上升。全球活跃边缘沿线弧前高地和洼地的平行于海沟的交替可能反映了这些表面振荡不同阶段的时间快照，这意味着地形的三维形状能够在空间和时间上追踪深部增生及相关的板块界面摩擦特性。
