The crust-mantle interaction in the Qiangtang terrane is significant to study continental rheology and evolution. Its mechanism remains a subject of considerable debate for the reason of lack of sufficient geophysical evidence. The effective elastic thickness (Te) of the lithosphere can provide important constraints on this issue because it is sensitive to the state of mechanical coupling between the crust and the lithospheric mantle. We present new high-resolution Te of the Qiangtang terrane by using the multitaper admittance method with fusion of different window, based on satellite gravity and topographical data. Thus, a detailed study of the lithosphere is conducted, for the first time to utilize the spatial variations of Te and associated parameters, including thermal structures of the lithosphere, uppermost mantle seismic Pn-velocity, and crustal deformation. The results indicate that crust-mantle interaction in the Qiangtang terrane primarily occurs in the middle Qiangtang terrane (87°E ∼ 95°E, 32°N ∼ 34°N), where Te values are lower. In the eastern and western Qiangtang terrane, Te values are higher, implying weaker late-stage modification. Due to Rayleigh-Taylor instability, lithospheric delamination occurred beneath the south Qiangtang terrane. Based on the extent of these low Te values (Te < 50 km), we conclude that the delaminated lithospheric slab sinking into the mantle is ∼400 km in length and elongated in shape. The delamination induces the upwelling of mantle material, upward stress, volcanic activity, extensional faults, and hot springs in the Qiangtang terrane.

中文翻译：

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羌塘地层的地壳-地幔相互作用：来自岩石圈有效弹性厚度的新证据


Qiangtang 地层中的地壳-地幔相互作用对研究大陆流变学和演化具有重要意义。由于缺乏足够的地球物理证据，其机制仍然是一个相当多的争论话题。岩石圈的有效弹性厚度 （Te） 可以为这个问题提供重要的约束，因为它对地壳和岩石圈地幔之间的机械耦合状态很敏感。我们基于卫星重力和地形数据，使用多锥度导纳法融合不同窗口，提出了新的强塘地层高分辨率 Te。因此，对岩石圈进行了详细的研究，首次利用了 Te 的空间变化和相关参数，包括岩石圈的热结构、最上部地幔地震 Pn 速度和地壳变形。结果表明，羌塘地层中的地壳-地幔相互作用主要发生在羌塘中地层（87°E ∼ 95°E，32°N ∼ 34°N），其中 Te 值较低。在东部和西部的 Qiangtang 地层中，Te 值较高，这意味着后期改性较弱。由于 Rayleigh-Taylor 不稳定性，岩石圈分层发生在南 Qiangtang 地层下方。根据这些低 Te 值（Te < 50 km）的范围，我们得出结论，沉入地幔的分层岩石圈板长约 400 公里，形状细长。分层作用诱发了地幔物质的上升流、向上应力、火山活动、伸展断层和羌塘地层的温泉。