India-Asia convergence driven by the subduction of the Greater Indian continent
India-Asia convergence driven by the subduction of the Greater Indian continent
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DOI：
10.1038/ngeo725
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发表时间：
2010-02-01
影响因子：
18.3
通讯作者：
Moresi, L.
中科院分区：
文献类型：
--
作者：
Capitanio, F. A.;Morra, G.;Moresi, L.
地球上板块汇聚事件最显著的例子是印度板块以超过18厘米/年的速度向欧亚大陆移动（参考文献1）以及随后发生的碰撞。大陆的浮力通常会在碰撞后不久使俯冲停滞，这在阿尔卑斯 - 喜马拉雅山脉链的大部分地段都能看到。然而，在该山脉链的印度段，当印度大陆边缘在约5000万年前撞击欧亚海沟时，板块速度仅降低了约三分之一。板块汇聚伴随着欧亚大陆的凹陷，在整个新生代一直持续（1 - 3），这表明汇聚的驱动力在大陆碰撞时并没有消失。在此，我们估算了大印度大陆在上地壳在喜马拉雅前缘被刮掉后的密度，发现该大陆板块很容易发生俯冲。通过数值模型，我们表明这样一个高密度大陆的俯冲使汇聚降低的程度与所观测到的相似。此外，洋脊推力和板块拉力之间可能会出现不平衡，从而导致海沟前进和凹陷。我们得出结论，高密度的印度大陆板块的俯冲为当前印度 - 亚洲的汇聚提供了一个重要的驱动力，并解释了大陆碰撞后有记录的板块速度的演变。
The most spectacular example of a plate convergence event on Earth is the motion of the Indian plate towards Eurasia at speeds in excess of 18 cm yr(-1) (ref. 1), and the subsequent collision. Continental buoyancy usually stalls subduction shortly after collision, as is seen in most sections of the Alpine-Himalayan chain. However, in the Indian section of this chain, plate velocities were merely reduced by a factor of about three when the Indian continental margin impinged on the Eurasian trench about 50 million years ago. Plate convergence, accompanied by Eurasian indentation, persisted throughout the Cenozoic era(1-3), suggesting that the driving forces of convergence did not vanish on continental collision. Here we estimate the density of the Greater Indian continent, after its upper crust is scraped off at the Himalayan front, and find that the continental plate is readily subductable. Using numerical models, we show that subduction of such a dense continent reduces convergence by a factor similar to that observed. In addition, an imbalance between ridge push and slab pull can develop and cause trench advance and indentation. We conclude that the subduction of the dense Indian continental slab provides a significant driving force for the current India-Asia convergence and explains the documented evolution of plate velocities following continental collision.