High-resolution lithospheric structures of the Qinling-Dabie orogenic belt: Implications for deep subduction and delamination of continental lithosphere
High-resolution lithospheric structures of the Qinling-Dabie orogenic belt: Implications for deep subduction and delamination of continental lithosphere
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DOI：
10.1016/j.tecto.2021.228799
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发表时间：
2021-02
期刊：
影响因子：
2.9
通讯作者：
K. Zhao;Yinhe Luo;Yingjie Yang;Xiaozhou Yang
中科院分区：
文献类型：
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作者：
K. Zhao;Yinhe Luo;Yingjie Yang;Xiaozhou Yang
秦岭-大别造山带是在北中国克拉通与扬子地块碰撞过程中形成的。大别山东部出露大量高压和超高压变质岩。为了更好地了解高压/超高压岩石的碰撞过程和折返机制，我们处理了秦岭-大别造山带及周边地区台站记录的环境噪声数据，提取了S时期8-95年的宽带瑞利波频散曲线。利用这些频散曲线，我们建立了秦岭-大别造山带及周边地区的高分辨率三维横波速度模型。我们的三维模型揭示了大别山西部和秦岭西部之下的最高地幔中的高速度，这表明存在过去大陆俯冲的残余大陆岩石圈。东秦岭和大别东部下地壳和上地幔的低速运动图像表明，大陆岩石圈在过去曾发生过拆沉。我们的三维模型支持大别造山带东部HP/UHP岩石的两阶段折返模式，即第一阶段HP/UHP岩石首先折返到中下地壳，然后在岩石圈拆沉引起的上地幔上涌的驱动力下进一步折返到地表。
The Qinling-Dabie orogenic belt was formed during the collision between the North China Craton and the Yangtze Block. A large volume of the high-pressure (HP) and ultra-high-pressure (UHP) metamorphic rocks are exposed in the eastern Dabie Mountains. In order to better understand the collision processes and the exhumation mechanism of the HP/UHP rocks, we process ambient noise data recorded at stations in the Qinling-Dabie orogenic belt and surrounding areas to extract broadband Rayleigh wave dispersion curves at 8–95 s periods. Using these dispersion curves, we construct a high-resolution 3-D shear wave velocity model of the Qinling-Dabie orogenic belt and surrounding regions. Our 3-D model reveals high velocities in the uppermost mantle beneath the western Dabie Mountains and also beneath the western Qinling Mountains, suggesting the presence of remnant continental lithosphere from the past continental subduction. Low velocities in the lower crust and uppermost mantle beneath the eastern Qinling and eastern Dabie are imaged, suggesting the continental lithosphere delaminated in the past. Our 3-D model supports a two-stage exhumation model of the HP/UHP rocks in the eastern Dabie orogenic belt, in which HP/UHP rocks were first exhumed to the mid/lower crust in the first stage and were then further exhumed to the surface under the driving force of the upper mantle upwelling induced by the lithosphere delamination.