Geophysical constraints on the nature of lithosphere in central and eastern Tibetan plateau
Geophysical constraints on the nature of lithosphere in central and eastern Tibetan plateau
复制标题
青藏高原中东部岩石圈性质的地球物理约束
DOI：
10.1016/j.tecto.2021.228722
复制
发表时间：
2021-04
期刊：
影响因子：
2.9
通讯作者：
Shixian Dong
中科院分区：
文献类型：
--
作者：
Lun Li;Xuezhen Zhang;Jie Liao;Yanling Liang;Shixian Dong
岩石圈的结构和流变学是理解青藏高原岩石圈变形的基础，因此对大陆动力学具有重要意义。然而，其中一些方面在西藏仍然没有受到很好的限制。在这项研究中，我们构建了新的各向同性平均剪切波速度和径向各向异性从以前公布的瑞利波和洛夫波相速度在8-143秒的周期。结合其他先前发表的地球物理数据，我们表明，一个薄弱的中下地壳是普遍的高原内，直接推断出地震低速度和高导电性在这些深度沿着与高莫霍面温度。结合正径向各向异性图象（Vsh > Vsv）的观测，我们推测这种较弱的中下地壳可能向西藏东南部流动，而在秦岭造山带这种地壳流动是不存在的。这种软弱的中-下地壳可以使上地壳和下地壳/上地幔分离，适应了印度-亚洲会聚的活动变形。此外，我们的研究结果表明，印度岩石圈地幔（LM）的俯冲前锋可以达到班公湖-怒江缝合线（BNS）在西藏中部和金沙江缝合线（JRS）在西藏东部。我们没有发现预期的高速度下北方西藏支持南俯冲的亚洲LM。相反，北方西藏的特点是连续的低速异常从莫霍面到200公里。结合居里点深度较浅和莫霍面温度较高的观测结果，我们推断西藏北部上地幔温度高于南部，这可能是由于印度LM俯冲引起的地幔上涌，或者是由于西藏岩石圈拆沉增厚，以及来自西藏地壳增厚的剪切加热和放射性加热的贡献。本研究突出了青藏高原岩石圈的性质，相关的动力学过程和整体变形。
The structure and rheology of lithosphere are fundamental to understanding lithospheric deformation operating within the Tibetan plateau and hence holds significant implications for continental dynamics. Yet, some of these aspects remain less well constrained in Tibet. In this study we construct new models of isotropic-average shear-wave velocity and radial anisotropy from previously published Rayleigh-wave and Love-wave phase velocities at periods of 8–143 s. Integrating with other previously published geophysical data, we demonstrate that a weak mid-to-lower crust is pervasive within the plateau, as directly inferred from seismically low velocity and high conductivity at these depths along with high Moho temperature. When combining with the observation of positive radial anisotropy patterns (Vsh > Vsv), we speculate that this weak mid-to-lower crust could probably flow towards southeastern Tibet, whereas in the Qinling Orogen this crustal flow is absent. This weak mid-to-lower crust in Tibet could decouple upper crust and lower crust/upper mantle, accommodating active deformation in response to the Indian-Asian convergence. Additionally, our results show that the subduction front of Indian lithospheric mantle (LM) could reach to the Bangong-Nujiang-Suture (BNS) in central Tibet and to the Jingsha-River-Suture (JRS) in eastern Tibet. We find no expected high velocity beneath northern Tibet to support southward subduction of the Asian LM. Instead, the northern Tibet is characterized with a continuous low-velocity-anomaly from Moho to 200 km. Coupled with the observations of shallow Curie-point depths and high Moho temperature, we infer that the Tibetan upper mantle in the north is hotter than that in the south, probably resulting from mantle upwelling due to either the Indian LM subduction, or thickened Tibetan lithosphere delamination with some contributions of shear heating and radioactive heating from the thickened Tibetan crust. This study highlights the nature of lithosphere, associated dynamic processes and the overall deformation within the Tibetan plateau.
登录
查看更多内容
影响因子：
16.6
作者：
Wang T;Martin S;Nguyen TH;Harper CB;Gormal RS;Martínez-Mármol R;Karunanithi S;Coulson EJ;Glass NR;Cooper-White JJ;van Swinderen B;Meunier FA
通讯作者：
Meunier FA
接收函数图像揭示藏西地区俯冲印度岩石圈的详细结构
影响因子：
3.9
作者：
Xu Qiang;Zhao Junmeng;Yuan Xiaohui;Liu Hongbing;Pei Shunping
通讯作者：
Pei Shunping
根据S接收函数和SKS分裂测量推断青藏高原东北部岩石圈厚度和上地幔变形
影响因子：
2.8
作者：
Zhang, Hongshuang1, 2;Teng, Jiwen2;Tian, Xiaobo2;Zhang, Zhongjie2;Gao, Rui1;Liu, Jiaqi2
通讯作者：
Liu, Jiaqi2
影响因子：
--
作者：
S. Ceylan;J. Ni;John Chen;Qie Zhang;F. Tilmann;E. Sandvol
通讯作者：
S. Ceylan;J. Ni;John Chen;Qie Zhang;F. Tilmann;E. Sandvol
影响因子：
2.8
作者：
E. Devi;P. Kumar;M. Kumar
通讯作者：
E. Devi;P. Kumar;M. Kumar