The Crust-Mantle Interaction of the Qiangtang Terrane: New evidence from the Effective Elastic Thickness of the Lithosphere

IF 2.7 3区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS
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Abstract

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.
羌塘地壳-地幔相互作用:岩石圈有效弹性厚度的新证据
羌塘地块的地壳与地幔相互作用对研究大陆流变和演化具有重要意义。由于缺乏足够的地球物理证据,其作用机理仍存在较大争议。岩石圈的有效弹性厚度(Te)对地壳与岩石圈地幔之间的力学耦合状态非常敏感,因此可以为这一问题提供重要的约束条件。我们基于卫星重力和地形数据,采用融合不同窗口的多锥体导纳法,给出了羌塘地层新的高分辨率Te。从而首次利用岩石圈热结构、最上层地幔地震Pn-速度和地壳变形等Te及相关参数的空间变化,对岩石圈进行了详细研究。结果表明,羌塘地块的地壳与地幔相互作用主要发生在Te值较低的羌塘地块中部(87°E ∼ 95°E,32°N ∼ 34°N)。在羌塘阶地东部和西部,Te值较高,意味着晚期改造作用较弱。由于雷利-泰勒不稳定性,羌塘南部地层下发生了岩石圈分层。根据这些低 Te 值(Te < 50 千米)的范围,我们得出结论,沉入地幔的脱层岩石圈板块长度为 400 千米,形状拉长。分层导致地幔物质上涌、应力上升、火山活动、延伸断层和羌塘地层中的温泉。
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来源期刊
Tectonophysics
Tectonophysics 地学-地球化学与地球物理
CiteScore
4.90
自引率
6.90%
发文量
300
审稿时长
6 months
期刊介绍: The prime focus of Tectonophysics will be high-impact original research and reviews in the fields of kinematics, structure, composition, and dynamics of the solid arth at all scales. Tectonophysics particularly encourages submission of papers based on the integration of a multitude of geophysical, geological, geochemical, geodynamic, and geotectonic methods
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