﻿ 天山地区均衡剩余地形特征及其地质意义
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 大地测量与地球动力学  2024, Vol. 44 Issue (3): 267-271  DOI: 10.14075/j.jgg.2023.05.110

引用本文

KONG Fanliang, ZHANG Xingyu, LIANG Qing, et al. Characteristics of Isostatic Residual Topography in the Tianshan Area and Their Geological Significance[J]. Journal of Geodesy and Geodynamics, 2024, 44(3): 267-271.

Foundation support

National Key Research and Development Program of China, No.2018YFC0604000; National Natural Science Foundation of China, No.41774091, 42174090.

Corresponding author

LIANG Qing, associate professor, majors in satellite gravity and lithosphere structure, E-mail: qliang@cug.edu.cn.

第一作者简介

KONG Fanliang, senior engineer, majors in solid minerals and environmental engineering geophysical survey, E-mail: 179643628@qq.com.

文章历史

1. 中国地质大学(北京)地球物理与信息技术学院，北京市学院路29号，100083;
2. 新疆维吾尔自治区地质矿产勘查开发局地球物理化学探矿大队，新疆维吾尔自治区昌吉市延安南路119号，831100;
3. 新疆维吾尔自治区地质矿产勘查开发局第八地质大队，新疆维吾尔自治区阿克苏市北京路55号，843000;
4. 中国地质大学(武汉)地球物理与空间信息学院地球内部多尺度成像湖北省重点实验室，武汉市鲁磨路388号，430074

 图 1 天山地区地形与构造单元示意图 Fig. 1 The schematic diagram of topography and tectonic units of the Tianshan area

1 方法理论

 $\begin{gathered} H_{\text {res }}=\frac{1}{\rho_{\text {res }}} \rho_{\text {top }} H_{\text {obs }}+ \\ \frac{1}{\rho_{\text {res }}} \int_0^z \Delta \rho(z)\left(\frac{R-z}{R}\right)^2 \mathrm{~d} z \end{gathered}$ (1)

 $\begin{gathered} H_{\text {res }}=\left(\frac{1}{\rho_{\text {res }}} \rho_{\text {top }} H_{\text {obs }}+\right. \\ \left.\frac{1}{\rho_{\text {res }}} \int_0^Z \Delta \rho(z)\left(\frac{R-z}{R}\right)^2 \mathrm{~d} z\right) Q \end{gathered}$ (2)

 $\begin{gathered} D \nabla^2 \nabla^2 H_{\text {output }}+2 \frac{\partial D}{\partial x} \frac{\partial}{\partial x} \nabla^2 H_{\text {output }}+ \\ 2 \frac{\partial D}{\partial y} \frac{\partial}{\partial y} \nabla^2 H_{\text {output }}+\nabla^2 D \nabla^2 H_{\text {output }}-(1-v) \\ \left(\frac{\partial^2 D}{\partial^2 x} \frac{\partial^2 H_{\text {output }}}{\partial^2 y}-2 \frac{\partial^2 D}{\partial x \partial y} \frac{\partial^2 H_{\text {output }}}{\partial x \partial y}+\right. \\ \left.\frac{\partial^2 D}{\partial^2 y} \frac{\partial^2 H_{\text {output }}}{\partial^2 x}\right)+\rho_{\text {output }} g H_{\text {output }}=\rho_{\text {input }} g H_{\text {input }} \end{gathered}$ (3)

2 数据计算与分析

 图 2 天山地区重力异常及地形重力效应 Fig. 2 Gravity anomalies and topographic gravity effects of the Tianshan area

 图 3 岩石圈密度异常 Fig. 3 Density anomalies of the lithosphere
3 结果与讨论 3.1 均衡剩余地形特征

 图 4 天山地区剩余地形 Fig. 4 Residual topography of the Tianshan area

3.2 均衡剩余地形对岩石圈形变的启示

4 结语

1) 天山地区显示出复杂的均衡剩余地形特征，且与各构造单元具有良好的对应性，不同块体的均衡剩余地形幅值均较高，表明研究区中新生代以来经历了复杂的演化过程。

2) 区内山脉(天山中西部、阿尔泰山和青藏高原)主要为负值均衡剩余地形，而塔里木盆地、吐哈盆地和哈萨克斯坦等较老块体主要为正值均衡剩余地形。这说明在板块碰撞和挤压过程中，较老块体岩石圈整体发生抬升，而年轻造山带岩石圈形变主要表现为地表抬升和更为剧烈的下地壳增厚。

3) 天山各段均衡剩余地形存在差异，中部(80°~88°E)和西部(约74°~80°E)基本为负值，反映出俯冲导致的下地壳增厚，且西部幅值相对较小，可能与软流圈上涌有关；而天山东部(>88°E)则为低幅值的正值，表明岩石圈形变主要以地表抬升为主。

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Characteristics of Isostatic Residual Topography in the Tianshan Area and Their Geological Significance
KONG Fanliang1,2,3     ZHANG Xingyu4     LIANG Qing4     CHEN Chao4
1. School of Geophysics and Geoinformation Technology, China University of Geosciences, 29 Xueyuan Road, Beijing 100083, China;
2. Geophysical and Geochemical Prospecting Brigade, Geology and Mineral Exploration and Development Bureau of Xinjiang Uygur Autonomous Region, 119 South-Yan'an Road, Changji 831100, China;
3. The Eight Geological Brigade, Geology and Mineral Exploration and Development Bureau of Xinjiang Uygur Autonomous Region, 55 Beijing Road, Aksu 843000, China;
4. Hubei Subsurface Multi-Scale Imaging Key Laboratory, School of Geophysics and Geomatics, China University of Geosciences, 388 Lumo Road, Wuhan 430074, China
Abstract: The distal effect of continuous collision and subduction of the Indian plate onto the Eurasian continent during the Cenozoic reached the entire Tianshan region, strongly modifying the lithospheric structure of the Tianshan and adjacent blocks. To better understand the lithosphere evolution and deformation process in the Tianshan area, we first use a combined inversion method of gravity and seismic data to obtain the lithospheric density anomalies in the study area, and then calculate the isostatic residual topography considering the lateral variation of effective elastic thickness. The results show that the amplitude of isostatic residual topography ranges from -1.6 to 0.9 km and corresponds well with each tectonic unit. The isostatic residual topography of different parts of the Tianshan is characterized by different features, with higher negative values in the central part, indicating a strongly thickened lower crust, and with lower negative values in the west part, possibly related to asthenosphere upwelling, and with low positive values in the east part, suggesting that lithospheric deformation is dominated by surface uplift.
Key words: Tianshan area; isostatic residual topography; lithosphere deformation