Study on the Tectonic Geomorphology and Fault Activity Characteristics of the Zhongba Rift, Southern Tibet
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摘要: 仲巴裂谷位于藏南裂谷系的西侧，其断层发育、断错地貌清晰. 但目前，该断裂活动性研究尚属空白，制约了对整个藏南裂谷系变形机制的探索.基于GIS空间分析技术，利用数字高程模型数据系统提取该区的河流地貌参数，包括地形坡度、地形起伏度、河流陡峭指数和裂点等. 对该裂谷两侧36个流域盆地的地形参数结果进行统计和分析后发现：地形坡度与ksn之间具有一致性，仲巴裂谷西侧北、中段坡度陡峭，ksn值较高，南段支流中间部分陡峭，两端较缓，对应ksn值中间高两端低；东侧坡度和ksn分布呈现中段陡峭，两端变缓的特征. 河流纵剖面上表现出裂点上下陡峭系数的差异，东西两侧河流均在出水口处河段有最高河道陡峭系数，向上游段减小，总体上西侧河道陡峭系数大于东侧. 综合地形坡度、河流纵剖面及裂点分析结果，认为仲巴裂谷西侧断裂的构造活动性可能强于东侧.Abstract: The Zhongba rift zone located on the west side of the southern Tibet rift system has well⁃developed faults and clear faulted landforms. However, the study on the activity of the fault is still lacking, which hinders our understanding of the deformation mechanism of the entire southern Tibet rift system. Based on GIS spatial analysis technology, we used the Digital Elevation Model data system to extract geomorphic parameters in this area, including topographic slope, topographic relief, channel steepness index, and knickpoints. We analyzed 36 basins on both sides of the Zhongba rift. The results show that the topographic slope is consistent with ksn. On the west side of the Zhongba rift, tributaries located on the north and middle sections have steeper slopes and higher ksn; tributaries in the south have steeper middle section with higher ksn value. On the east side, the slope and ksn are steep at the middle part and gentle at both ends. The river profiles display that the channel steepness are different on both sides of the knickpoints. The rivers of the east and west sides have the highest channel steepness near the outlets, and decrease towards the upstream. Generally, the river channels on the west sides are steeper than ones on the east side. Based on the analysis results of the topographical slope, river profiles, and knickpoints, we suspect that the tectonic activity of the faults on the west side of the Zhongba rift may be stronger than that on the east side.
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Key words:
- Zhongba rift zone /
- geomorphic parameter /
- tectonics
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图 1 青藏高原内部活动断裂分布图
Fig. 1. Distribution map of active faults in the Tibetan Plateau
图 3 仲巴流域地貌简图
根据30 m分辨率SRTM生成的仲巴裂谷带区域地形，A⁃A′、B⁃B′、…、H⁃H′、I⁃I′为横跨裂谷带条带状剖面的位置
Fig. 3. The map of topography and major drainage in the study area
图 4 裂点的类型
引自Kirby and Whipple（2012）；a. 垂阶型裂点河流纵剖面，上下游河道陡峭度无明显差异；b. 垂阶型裂点logA⁃logS散点图表现为高程的突变；c. 坡断型裂点河流纵剖面，上下游河道陡峭度有明显差异；d. 坡断型裂点logA⁃logS散点图表现为明显的错位.
Fig. 4. Classification of knickpoints
图 5 横跨仲巴裂谷带条带状剖面
剖面位置见图 3，虚线为裂谷带左右山脉最高位置，红色实线箭头为断裂位置
Fig. 5. The swath profiles across the Zhongba rift
图 6 仲巴裂谷带坡度分布
根据裂谷带走向及几何不连续，将裂谷带由北向南分为3段，记为北段、中段和南段
Fig. 6. Slope map of the Zhongba rift
图 9 河流纵剖面分析结果
a. 仲巴裂谷西侧1-20号流域距塔若错出口距离的主干道河流剖面图河流纵剖面及裂点：显示了每条河流在本次研究中确定的主要河流裂点及出水口位置，即断层. b~g. 图为西侧河流χ与海拔图的典型示例(蓝色粗线). 蓝色线表示原始的χ⁃z分布，红色虚线表示回归的χ⁃z分布；坡度的突变被归类为裂点，用蓝色三角形标记. h. 仲巴裂谷东侧21~36号流域距塔若错出口距离的主干道河流剖面图河流纵剖面及裂点；i~l. 图为东侧河流χ与海拔图的典型示例
Fig. 9. Analysis results of trunk channel river profiles
图 10 沿裂谷带不同河段的标准化陡峭指数
仲巴裂谷东西两侧流域距塔若错出口距离的主干道河流裂点ksn值，蓝色区域为裂谷中段，其左右部分分别对应北段和南段；a. 各流域第一代裂点下游河流段ksn值；b. 菱形为只有一个裂点流域的裂点上游河流段ksn值（如图 10c~10g、10j~10l）；方形为含有两个裂点流域的第一代裂点与第二代裂点之间的河流段ksn值（如图 10b、10i）；c. 菱形为只有一个裂点流域的裂点上游河流段ksn值（同图b中的菱形）；圆形为含有两个裂点流域的第二代裂点上游河流段ksn值
Fig. 10. Normalized steepness index for different channel segments along the rift zone
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[1] Basangciren, Guo, C. M., Deng, G. Y., et al., 2009. Analysis on Seismic Disaster Characteristics of Dangxiong Ms6.6 and Zhongba Ms6.8 Earthquakes in Xizang. Plateau Earthquake Research, 21(3): 64-69 (in Chinese with English abstract). [2] Berlin, M. M., Anderson, R. S., 2007. Modeling of Knickpoint Retreat on the Roan Plateau, Western Colorado. Journal of Geophysical Research, 112(F3): S06. https://doi.org/10.1029/2006jf000553 [3] Burbank, D. W., Anderson, R. S., 2012. Tectonic Geomorphology, Second Edition. Environmental & Engineering Geoscience, 19(2): 198-200. https://doi.org/10.2113/gseegeosci.19.2.198 [4] Ding, L., Yue, Y. H., Cai, F. L., et al., 2006. 40Ar/39Ar Geochronology, Geochemical and Sr-Nd-O Isotopic Characteristics of the High-Mg Ultrapotassic Rocks in Lhasa Block of Tibet: Implicationsin the Onset Time and Depth of NS-Striking Rift System. Acta Geologica Sinica, 80(9): 1252-1261(in Chinese with English abstract). [5] Du, Z. B., Shen, Q., He, C. J., et al., 2010. Analysis of Deformation of Zhongba, Tibet 2004 MS6.7 and 2005 MS6.5 Earthquakes as Constrained by InSAR Measurement. Journal of Geodesy and Geodynamics, 30(4): 12-18 (in Chinese with English abstract). [6] Flint, J. J., 1974. Stream Gradient as a Function of Order, Magnitude, and Discharge. Water Resources Research, 10(5): 969-973. https://doi.org/10.1029/wr010i005p00969 [7] Forte, A. M., Whipple, K. X., 2019. Short Communication: The Topographic Analysis Kit (TAK) for Topo Toolbox. Earth Surface Dynamics, 7(1): 87-95. https://doi.org/10.5194/esurf-7-87-2019 [8] Gallen, S. F., Wegmann, K. W., 2017. River Profile Response to Normal Fault Growth and Linkage: An Example from the Hellenic Forearc of South-Central Crete, Greece. Earth Surface Dynamics, 5(1): 161-186. https://doi.org/10.5194/esurf-5-161-2017 [9] Godard, V., Bourlès, D. L., Spinabella, F., et al., 2014. Dominance of Tectonics over Climate in Himalayan Denudation. Geology, 42(3): 243-246. https://doi.org/10.1130/G35342.1 [10] Kirby, E., Whipple, K., 2001. Quantifying Differential Rock-Uplift Rates Via Stream Profile Analysis. Geology, 29(5): 415. https://doi.org/10.1130/0091-7613(2001)029<0415:qdrurv>2.0.co;2 doi: 10.1130/0091-7613(2001)029<0415:qdrurv>2.0.co;2 [11] Kirby, E., Ouimet, W., 2011. Tectonic Geomorphology along the Eastern Margin of Tibet: Insights into the Pattern and Processes of Active Deformation Adjacent to the Sichuan Basin. Geological Society, London, Special Publications, 353(1): 165-188. https://doi.org/10.1144/sp353.9 [12] Kirby, E., Whipple, K. X., 2012. Expression of Active Tectonics in Erosional Landscapes. Journal of Structural Geology, 44: 54-75. https://doi.org/10.1016/j.jsg.2012.07.009 [13] Korup, O., 2006. Rock-Slope Failure and the River Long Profile. Geology, 34(1): 45. https://doi.org/10.1130/g21959.1 [14] Li, Y. L., Wang, C. S., Dai, J. G., et al., 2015. Propagation of the Deformation and Growth of the Tibetan-Himalayan Orogen: A Review. Earth-Science Reviews, 143(3-4): 36-61. https://doi.org/10.1016/j.earscirev.2015.01.001 [15] Liang, S. M., 2014. Three-Dimensional Velocity Field of Present-Day Crustal Motion of the Tibetan Plateau Inferred from GPS Measurements (Dissertation). Institute of Geology, China Earthquake Administration, Beijing (in Chinese with English abstract). [16] Molnar, P., Tapponnier, P., 1978. Active Tectonics of Tibet. Journal of Geophysical Research, 83(B11): 5361. https://doi.org/10.1029/jb083ib11p05361 [17] Molnar, P., England, P., Martinod, J., 1993. Mantle Dynamics, Uplift of the Tibetan Plateau, and the Indian Monsoon. Reviews of Geophysics, 31(4): 357-396. https://doi.org/10.1029/93RG02030 [18] Murphy, M. A., Sanchez, V., Taylor, M. H., 2010. Syncollisional Extension along the India-Asia Suture Zone, South-Central Tibet: Implications for Crustal Deformation of Tibet. Earth and Planetary Science Letters, 290(3/4): 233-243. https://doi.org/10.1016/j.epsl.2009.11.046 [19] Qiu, J. T., Liu, L., Liu, C. J., et al., 2019. The Deformation of the 2008 Zhongba Earthquakes and the Tectonic Movement Revealed. Seismology and Geology, 41(2): 481-498 (in Chinese with English abstract). [20] Sanchez, V. I., Murphy, M. A., Robinson, A. C., et al., 2013. Tectonic Evolution of the India-Asia Suture Zone since Middle Eocene Time, Lopukangri Area, South-Central Tibet. Journal of Asian Earth Sciences, 62(20): 205-220. https://doi.org/10.1016/j.jseaes.2012.09.004 [21] Schwanghart, W., Kuhn, N. J., 2010. TopoToolbox: A Set of Matlab Functions for Topographic Analysis. Environmental Modelling & Software, 25(6): 770-781. https://doi.org/10.1016/j.envsoft.2009.12.002 [22] Schwanghart, W., Scherler, D., 2014. Short Communication: TopoToolbox 2-MATLAB-Based Software for Topographic Analysis and Modeling in Earth Surface Sciences. Earth Surface Dynamics, 2(1): 1-7. https://doi.org/10.5194/esurf-2-1-2014 [23] Shen, T.Y., Wang, G.C., , 2020. Detrital Zircon Fission-Track Thermochronology of the Present-Day River Drainage System in the Mt. Kailas Area, Western Tibet: Implications for Multiple Cooling Stages of the Gangdese Magmatic Arc. Journal of Earth Science, 31(5): 896-904. https://doi.org/10.1007/s12583-020-1285-y [24] Styron, R. H., Taylor, M. H., Sundell, K. E., et al., 2013. Miocene Initiation and Acceleration of Extension in the South Lunggar Rift, Western Tibet: Evolution of an Active Detachment System from Structural Mapping and (U-Th)/He Thermochronology. Tectonics, 32(4): 880-907. https://doi.org/10.1002/tect.20053 [25] Styron, R., Taylor, M., Sundell, K., 2015. Accelerated Extension of Tibet Linked to the Northward Underthrusting of Indian Crust. Nature Geoscience, 8(2): 131-134. https://doi.org/10.1038/NGEO2336 [26] Sundell, K. E., Taylor, M. H., Styron, R. H., et al., 2013. Evidence for Constriction and Pliocene Acceleration of East-West Extension in the North Lunggar Rift Region of West Central Tibet. Tectonics, 32(5): 1454-1479. https://doi.org/10.1002/tect.20086 [27] Tapponnier, P., Mercier, J. L., Armijo, R., et al., 1981. Field Evidence for Active Normal Faulting in Tibet. Nature, 294(5840): 410-414. https://doi.org/10.1038/294410a0 [28] Tapponnier, P., Xu, Z. Q., Roger, F., et al., 2001. Oblique Stepwise Rise and Growth of the Tibet Plateau. Science, 294(5547): 1671-1677. https://doi.org/10.1126/science.105978 [29] Taylor, M., Forte, A., Laskowski, A., et al., 2021. Active Uplift of Southern Tibet Revealed. GSA Today, 31(8): 4-10. https://doi.org/10.1130/gsatg487a.1 [30] Taylor, M., Yin, A., 2009. Active Structures of the Himalayan-Tibetan Orogen and their Relationships to Earthquake Distribution, Contemporary Strain Field, and Cenozoic Volcanism. Geosphere, 5(3): 199-214. https://doi.org/10.1130/ges00217.1 [31] Wang, H., Wright, T. J., Liu, L., et al., 2019. Strain Rate Distribution in South-Central Tibet from Two Decades of InSAR and GPS. Geophysical Research Letters, 46: 1-10. https://doi.org/10.1029/2019GL081916 [32] Wang, J. Y., He, Z. T., 2020. Responses of Stream Geomorphic Indices to Piedmont Fault Activity in the Daqingshan Area of China. Journal of Earth Science, 31(5): 978-987. https://doi.org/10.1007/s12583-020-1321-y [33] Wang, W., Godard, V., Liu, Z. J., et al., 2021. Tectonic Controls on Surface Erosion Rates in the Longmen Shan, Eastern Tibet. Tectonics, 40(3): e2020TC006445. https://doi.org/10.1029/2020tc006445 [34] Wang, Y. Z., Zhang, H. P., Zheng, D. W., et al., 2016. Coupling Slope-Area Analysis, Integral Approach and Statistic Tests to Steady-State Bedrock River Profile Analysis. Earth Surface Dynamics, 5(1): 145-160. https://doi.org/10.5194/esurf-5-145-2017 [35] Whipple, K. X., 2001. Fluvial Landscape Response Time: How Plausible is Steady-State Denudation? American Journal of Science, 301(4/5): 313-325. https://doi.org/10.2475/ajs.301.4-5.313 [36] Whipple, K. X., 2004. Bedrock Rivers and The Geomorphology of Active Orogens. Annual Review of Earth and Planetary Sciences, 32(1): 151-185. https://doi.org/10.1146/annurev.earth.32.101802.120356 [37] Whipple, K. X., DiBiase, R. A., Crosby, B. T., 2013. Bedrock Rivers. Treatise on Geomorphology, 9: 550-573. https://doi.org/10.1016/B978-0-12-374739-6.00254-2 [38] Whittaker, A. C., 2012. How do Landscapes Record Tectonics and Climate?. Lithosphere, 4(2): 160-164. https://doi.org/10.1130/rf.l003.1 [39] Wolff, R., Hetzel, R., Dunkl, I., et al., 2019. High-Angle Normal Faulting at the Tangra Yumco Graben (Southern Tibet) since ~15 Ma. The Journal of Geology, 127(1): 15-36. https://doi.org/10.1086/700406 [40] Wu, Z. H., Zhao, X. T., Wu, Z. H., et al., 2004. Quaternary Geology and Faulting in the Damxung-Yangbajain Basin. Acta Geologica Sinica-English Edition, 78(1): 273-282. https://doi.org/10.1111/j.1755-6724.2004.tb00700.x [41] Wu, Z. H., Zhang, Y. S., Hu, D. G., et al., 2008. The Quaternary Normal Faulting of the Cona-Oiga Rift. Seismology and Geology, 30(1): 144-160 (in Chinese with English abstract). [42] Yin, A., Harrison, T. M., 2000. Geologic Evolution of the Himalayan-Tibetan Orogen. Annual Review of Earth and Planetary Sciences, 28(1): 211-280. https://doi.org/10.1146/annurev.earth.28.1.211 [43] Yin, A., 2000. Mode of Cenozoic East-West Extension in Tibet Suggesting a Common Origin of Rifts in Asia during the Indo-Asian Collision. Journal of Geophysical Research: Solid Earth, 105(B9): 21745-21759. https://doi.org/10.1029/2000jb900168 [44] Zhang, J. J., 2007. A Review on the Extensional Structures in the Northern Himalaya and Southern Tibet. Geological Bulletin of China, 26(6): 639-649 (in Chinese with English abstract). [45] Zhou, X. Y., Zhang, Y. X., Zhang, J. H., et al., 2021. Petrogenesis of Early Paleocene Dengtong Volcanic-Plutonic Complex in Central Lhasa Terrane and Evolution of Crustal High-Silica Magma. Journal of Earth Science, 46(2): 474-488 (in Chinese with English abstract). [46] 巴桑次仁, 郭春明, 邓桂英, 等, 2009. 西藏当雄6.6级地震与仲巴6.8级地震震害特征分析. 高原地震, 21(3): 64-69. https://www.cnki.com.cn/Article/CJFDTOTAL-GYDZ200903011.htm [47] 丁林, 岳雅慧, 蔡福龙, 等, 2006. 西藏拉萨地块高镁超钾质火山岩及对南北向裂谷形成时间和切割深度的制约. 地质学报, 80(9): 1252-1261. doi: 10.3321/j.issn:0001-5717.2006.09.003 [48] 杜志彪, 沈强, 何婵军, 等, 2010. 仲巴2004年MS6.7和2005年MS6.5地震的InSAR观测及形变分析. 大地测量与地球动力学, 30(4): 12-18. https://www.cnki.com.cn/Article/CJFDTOTAL-DKXB201004005.htm [49] 梁诗明, 2014. 基于GPS观测的青藏高原现今三维地壳运动研究(博士学位论文). 北京: 中国地震局地质研究所. [50] 邱江涛, 刘雷, 刘传金, 等, 2019. 2008年仲巴地震形变及其揭示的构造运动. 地震地质, 41(2): 481-498. https://www.cnki.com.cn/Article/CJFDTOTAL-DZDZ201902014.htm [51] 吴中海, 张永双, 胡道功, 等, 2008. 藏南错那-沃卡裂谷的第四纪正断层作用及其特征. 地震地质, 30(1): 144-160. https://www.cnki.com.cn/Article/CJFDTOTAL-DZDZ200801010.htm [52] 张进江, 2007. 北喜马拉雅及藏南伸展构造综述. 地质通报, 26(6): 639-649. https://www.cnki.com.cn/Article/CJFDTOTAL-ZQYD200706003.htm [53] 周逍遥, 张玉修, 张吉衡, 等, 2021. 拉萨地体中部古新世早期灯垌火山-侵入杂岩成因及地壳硅质岩浆演化. 地球科学, 46(2): 474-488. doi: 10.3799/dqkx.2019.073 -
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