| 青藏高原东南缘南段现今变形特征研究 |
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| 引用本文： | 李长军,甘卫军,秦姗兰,郝明,梁诗明,杨帆.青藏高原东南缘南段现今变形特征研究[J].地球物理学报,2019,62(12):4540-4553. |
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| 作者姓名： | 李长军 甘卫军 秦姗兰 郝明 梁诗明 杨帆 |
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| 作者单位： | 1. 中国地震局地质研究所, 地震动力学国家重点实验室, 北京 100029;2. 中国地震局第二监测中心, 西安 710054 |
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| 基金项目： | 国家重点研发计划（2018YFC1503304），国家自然基金项目（41604078，41874017）和国家重点研发计划（2018YFC1503403）联合资助. |
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| 摘 要： | 本文以青藏高原东南缘南段1999—2017年的GPS速度场为主,结合小震分布、历史地震和活断层探测等资料,首先,基于Okada断层位错模型反演了研究区域主要活断层的滑动速率;其次,以断层滑动速率和GPS速度场观测资料作为约束,利用DEFNODE负位错方法反演了研究区域的块体内部变形及主要活断层的闭锁程度和滑动亏损;最后,计算研究区域现今应变率场,并结合Pms和XKS剪切波分裂结果,探讨分析了青藏高原东南缘的动力学特征.研究结果表明:(1)红河断裂带现今滑动速率明显低于南华—楚雄—建水断裂和无量山断裂;(2)红河断裂带的元江—元阳段、鹤庆—洱源段和小江断裂带北段处于强闭锁状态,南华—楚雄—建水断裂带和无量山断裂带中—北段的闭锁程度强于南段;(3)青藏高原东南缘南段现今地壳变形表现为近E-W向的拉张和近N-S向的挤压,最大剪切方向与Pms和XKS剪切波分裂的快波方向呈一定角度,表明地壳与地幔处于完全解耦状态,而中-下地壳低速层可能是壳幔解耦的主要原因之一;(4)青藏高原东南缘的整体变形受控于印度板块的推挤、印缅俯冲带的深源俯冲以及缅甸微板块与巽他板块的后撤/回退的共同作用.
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| 关 键 词： | 断层滑动速率 断层闭锁 块体永久变形 剪切波分裂 |
| 收稿时间： | 2018-12-17 |
Present-day deformation characteristics of the southeast borderland of the Tibetan Plateau |
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| LI ZhangJun,GAN WeiJun,QIN ShanLan,HAO Ming,LIANG ShiMing,YANG Fan.Present-day deformation characteristics of the southeast borderland of the Tibetan Plateau[J].Chinese Journal of Geophysics,2019,62(12):4540-4553. |
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| Authors: | LI ZhangJun GAN WeiJun QIN ShanLan HAO Ming LIANG ShiMing YANG Fan |
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| Institution: | 1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;2. Second Monitoring and Application Center, Xi'an 710054, China |
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| Abstract: | Based on GPS observations from 1999 to 2017, small earthquakes, historic events, and geologic fault slip rates in southeastern borderland of Tibetan Plateau (STP), we firstly determined active fault slip rates using Okada dislocation model. Constrained by fault slip rates determined and GPS velocity, we inverted internal deformation of active blocks, locking parameters and slip deficit of main active faults in STP based on DEFNODE method. Subsequently, we calculated strain rates in study area and combined with Pms and XKS splitting observations, we analyzed dynamic characteristics of STP. Our results are as follows:(1) The Red River fault has a lower slip rate than the Nanhua-Chuxiong-Jianshui fault and the Wuliangshan fault. (2) There are some strong coupling fault segments in STP, such as the Yuanjiang-Yuanyang and Heqing-Eryuan portions of the Red River fault and the northern part of the Xiaojiang fault. The central-to-northern portions have a higher coupling coefficients in the Nanhua-Chuxiong-Jianshui and the Wuliangshan faults. (3) Present-day crustal deformation in STP are nearly with E-W dilatation and N-S compression. Direction of the maximum shear deformation in upper crust are different from Pms and XKS fast wave direction, which indicate a completely decoupling between crust and upper mantle since the existence of middle-to-lower crustal low velocity layer. (4) Deformation in STP is mainly controlled by the intrusion of the Indian plate, the subduction of Indian-Burma plate, and the rollback/retreat of the Burmese platelet and the Sunda block. |
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| Keywords: | Fault slip rate Fault locking Block internal permanent deformation Shear wave splitting |
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