Lithospheric foundering and underthrusting imaged beneath Tibet.
Lithospheric foundering and underthrusting imaged beneath Tibet.
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DOI：
10.1038/ncomms15659
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发表时间：
2017-06-06
影响因子：
16.6
通讯作者：
Ribeiro J
中科院分区：
文献类型：
--
作者：
Chen M;Niu F;Tromp J;Lenardic A;Lee CA;Cao W;Ribeiro J
关于青藏高原隆升的时间和机制，特别是岩石圈演化与高原隆升和火山作用的地表表现之间的关系，存在着长期的争论。在这里，我们显示了一个T形的高波速结构，在我们的新的层析成像模型下，西藏中南部，解释为上地幔残留早期岩石圈沉降。其与超钾质和埃达克质岩浆作用的空间相关性支持了渐新世西藏岩石圈加厚的对流迁移导致藏南主要隆升的假说。岩石圈沉降引起软流圈拖曳力，驱动印度大陆岩石圈继续俯冲和北方藏北岩石圈缩短和增厚。藏北北方地表隆升受较晚的软流圈上涌和增厚岩石圈的热侵蚀作用的影响，这与现代钾质火山作用和上地幔中一个狭窄的低速带在空间上是一致的。青藏高原隆升的时间和机制仍然是一个争论的来源。在这里，作者提出了一个新的层析成像模型，揭示了西藏中南部的T形高波速结构，并解释这是岩石圈沉降的上地幔残留。
Long-standing debates exist over the timing and mechanism of uplift of the Tibetan Plateau and, more specifically, over the connection between lithospheric evolution and surface expressions of plateau uplift and volcanism. Here we show a T-shaped high wave speed structure in our new tomographic model beneath South-Central Tibet, interpreted as an upper-mantle remnant from earlier lithospheric foundering. Its spatial correlation with ultrapotassic and adakitic magmatism supports the hypothesis of convective removal of thickened Tibetan lithosphere causing major uplift of Southern Tibet during the Oligocene. Lithospheric foundering induces an asthenospheric drag force, which drives continued underthrusting of the Indian continental lithosphere and shortening and thickening of the Northern Tibetan lithosphere. Surface uplift of Northern Tibet is subject to more recent asthenospheric upwelling and thermal erosion of thickened lithosphere, which is spatially consistent with recent potassic volcanism and an imaged narrow low wave speed zone in the uppermost mantle. The timing and mechanism of uplift of the Tibetan plateau continues to be a source of debate. Here, the authors present a new tomographic model revealing a T-shaped high wave speed structure beneath South-Central Tibet and interpret this an upper-mantle remnant from lithospheric foundering.