Small-scale convection of the upper mantle beneath the Chinese Tian Shan (Tien Shan) is investigated in terms of numerical modeling. The finite element method combined with the marker-in-cell technique is used to describe the flow of the heterogeneous upper mantle. The density model is derived from the P-wave velocity structure of the crust and upper mantle along the Kuche-Kuitun profile across the Chinese Tian Shan, which is obtained using the seismic travel time tomography technique. Our computational results reveal the southward-counterclockwise and northward-clockwise upper mantle convective cells underneath the Junggar-north Tian Shan and Tarim-south Tian Shan, respectively. Our results also show the convective scale reaches to ∼500 km and the convective speed at the top of the upper mantle should not be less than 20 mm/year for a normal viscosity model. The northward extrusion of the Tarim block plays a key role in the Tian Shan mountain building since the Cenozoic period, but it nearly does not influence the upper mantle convection. The present-day tectonic deformation in the Chinese Tian Shan is related to the small-scale convection of the upper mantle.
Bibliographical noteFunding Information:
This study is supported by National Nature Science Foundation of China to Liu Qi-Yuan (grant # 40234043) and is also supported by U.S. National Science Foundation under the auspices of the ITR program. We would like to thank Prof. Deng Qidong, Prof. Shi Yaolin and Dr. Zhang Huai for their suggestions, and Prof. Gan Weijun for providing the GPS data. The manuscript has benefited from the comments of two reviewers, Dr. Sandrine Quéré and Dr. Weronika Gorczyk.
Copyright 2008 Elsevier B.V., All rights reserved.
- Finite element method
- Marker-in-cell method
- Mountain building
- Tian Shan
- Upper-mantle convection