Southward propagation of Nazca subduction along the Andes
Southward propagation of Nazca subduction along the Andes
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DOI：
10.1038/s41586-018-0860-1
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发表时间：
2019-01-24
期刊：
影响因子：
64.8
通讯作者：
Suppe, John
中科院分区：
文献类型：
--
作者：
Chen, Yi-Wei;Wu, Jonny;Suppe, John
安第斯边缘是板块构造的范例，长期存在，持续俯冲，但其地质自中生代晚期（过去1亿年左右）一直远离稳定状态。这种阶段性的变形和岩浆活动被归因于俯冲板片倾角的周期性变化、板片断裂和板片渗入下地幔;由于纳斯卡-法拉隆板块的广泛俯冲（导致5 500多公里的岩石圈消失在地幔中），板块构造的作用仍然不清楚。在这里，使用断层扫描数据，我们重建板块构造几何的俯冲纳斯卡板，这使我们能够重建安第斯板块构造自中生代晚期。我们的模型表明，目前阶段的纳斯卡俯冲开始于北方安第斯山脉（5度S）在白垩纪晚期（约80万年前），并向南传播，到达南部安第斯山脉（40度S）的新生代早期（约55万年前）。因此，与当前的范式相反，纳斯卡俯冲自中生代以来并不是完全连续的，而是包括幕式分离阶段。此外，我们发现，前渊沉积和安第斯山脉压缩的启动都与纳斯卡板块和下地幔之间的相互作用，与以前的建模一致。
The Andean margin is the plate-tectonic paradigm for long-lived, continuous subduction, yet its geology since the late Mesozoic era (the past 100 million years or so) has been far from steady state. The episodic deformation and magmatism have been attributed to cyclic changes in the dip angle of the subducting slab, slab break-off and the penetration of the slab into the lower mantle; the role of plate tectonics remains unclear, owing to the extensive subduction of the NazcaFarallon plate (which has resulted in more than 5,500 kilometres of lithosphere being lost to the mantle). Here, using tomographic data, we recreate the plate-tectonic geometry of the subducted Nazca slab, which enables us to reconstruct Andean plate tectonics since the late Mesozoic. Our model suggests that the current phase of Nazca subduction began at the northern Andes (5 degrees S) during the late Cretaceous period (around 80 million years ago) and propagated southwards, reaching the southern Andes (40 degrees S) by the early Cenozoic era (around 55 million year ago). Thus, contrary to the current paradigm, Nazca subduction has not been fully continuous since the Mesozoic but instead included episodic divergent phases. In addition, we find that foredeep sedimentation and the initiation of Andean compression are both linked to interactions between the Nazca slab and the lower mantle, consistent with previous modelling.