可可西里东部活动断裂的地质特征
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摘要
通过大比例尺地质勘测、路线观测、探槽揭露和综合分析,在青藏铁路可可西里段沿线鉴别出14条活动走滑断层,组成五道梁活动断裂、可可西里山北活动断裂和可可西里山南活动断裂,构成可可西里东部活动走滑断裂系。典型断层F_(16),F_(16-4),F_(17-2),F_(17-3),F_(18-4)切割最新地层的年龄分别为4500a,5.33万a,3700 a,1.53万a,6000 a,反映可可西里东部走滑断裂系在晚更新世晚期—全新世具有强烈活动;估算断层平均走滑运动速度分别为1.50 mm/a,0.39 mm/a,7.76 mm/a,6.76 mm/a,3.27mm/a。部分活动走滑断层发育砂质构造楔、地震陡坎和砂土液化现象,反映可可西里东部走滑断裂系具有强烈的地震活动性。断裂活动能够产生多种不同类型的地质灾害,对青藏公路、青藏铁路及永久性重大工程安全具有不良影响。
Fourteen strike-slip active faults were discovered based on detail geological surveys and trench cross-sections, constituting the left-lateral strike-slip fault zones of Wudaoliang, of North Hohxil, South Hohxil, and the active fault system of east Hohxil Mts. Typical active faults F16 , F16-4 ,F17-2 ,F17-3 and F18-4 cut and offset sediments of 4. 5 ka, 53. 3 ka, 3. 7 ka, 15. 3 ka and 6 ka, and have average slip rates of 1. 50 mm/a, 0. 39 mm/a, 7. 76 mm/a, 6. 76 mm/a, 3. 27 mm/a respectively, illustrating the regional active faulting of east Hohxil Mts. in late Pliocene-Holocene. Some strike-slip faults resulted in strong earthquakes in Holocene and formed different related remains in the field. Active faults of Hohxil Mts. induced many kinds of geological hazards, giving negative effects to Golmud-Lhasa highway, railway and permanent engineering constructions.
Fourteen strike-slip active faults were discovered based on detail geological surveys and trench cross-sections, constituting the left-lateral strike-slip fault zones of Wudaoliang, of North Hohxil, South Hohxil, and the active fault system of east Hohxil Mts. Typical active faults F16 , F16-4 ,F17-2 ,F17-3 and F18-4 cut and offset sediments of 4. 5 ka, 53. 3 ka, 3. 7 ka, 15. 3 ka and 6 ka, and have average slip rates of 1. 50 mm/a, 0. 39 mm/a, 7. 76 mm/a, 6. 76 mm/a, 3. 27 mm/a respectively, illustrating the regional active faulting of east Hohxil Mts. in late Pliocene-Holocene. Some strike-slip faults resulted in strong earthquakes in Holocene and formed different related remains in the field. Active faults of Hohxil Mts. induced many kinds of geological hazards, giving negative effects to Golmud-Lhasa highway, railway and permanent engineering constructions.
引文
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[3] TAPPONNIER P, MOLNAR P. Active faulting and tectonics of China[J]. Journal of Geophysical Research, 1977, 82: 2905-2930．
[4] MOLNAR P, TAPPONNIER P. Active tectonics of Tibet [J]. Journal of Geophysical Research, 1978, 83: 5361-5375．
[5] YI M C. The neotectonic movements along the Qinghai Xizang highway and their influence on route construction[A]. Ministry of Geology and Mineral Resources. Proceeding of Geology of the Tibetan Plateau[C]. Beijing: Geological Publishing House, 1982． 119-129(in Chinese). [易明初.青藏线格尔木-不冻泉挽近构造及其对道路工程的影响[A].地质矿产部青藏高原地质文集编委会.青藏高原地质文集[C].北京:地质出版社,1982． 119～129． ]
[6] AMIJO R, TAPPONNIER P, MERCIER J L, et al. Quaternary extension in South Tibet: Field observations and tectonic implications[J]. Journal of Geophysical Research. 1986, 91 (B14) : 13803-13872．
[7] HAN T L. Active Tectonics of Tibet [M]. Beijing: Geological Publishing House, 1987． 76-94(in Chinese). [韩同林.西藏活动构造[M].北京:地质出版社,1987． 76-94． ]
[8] KIDD W S F, MOLNAR P. Quaternary and present active faults of Lhasa-Golmud of the Tibetan Plateau[A]. Chinese-British Tibetan Plateau Geotraverse Team. Geological Evolution of the Tibetan Plateau[C]. London: Roy Soc, 1988, 327:332-352．
[9] WU Z M, WANG Y P, REN J W. Late Quaternary activity of Jinsha and Nujiang suture of north Tibetan Plateau[J]. Seismic Geology,1993,15(1) :28-31(in Chinese). [吴章明,汪一鹏,任金卫.青藏高原北部金沙江、怒江缝合带晚第四纪的活动性[J].地震地质,1993,15(1) :28-31． ]
[10] HU H T, XU G S. The structural system of the southern Qinghai-northern Xizang Plateau and its control over ground-water[A]. Ministry of Geology and Mineral Resources. Proceeding of Geology of the Tibetan Plateau[C]. Beijing: Geological Publishing House, 1982． 1-40(in Chinese). [胡海涛,许贵生.青南-藏北高原的构造体系及其对地下水的控制[A].地质矿产部青藏高原地质文集编委会.青藏高原地质文集[C].北京:地质出版社,1982． 1-40． ]
[11] BIAN Q T,ZHENG X S, YE J Q, et al, Active tectonics and earthquakes[A]. ZHANG Y F, ZHENG X S. Geological Evolution of Hohxil Region of Qinghai Province [C]. Beijing: Science Press, 1996． 100-117(in Chinese). [边千韬,郑祥身,叶建青,等.活动构造与地震[A].张以弗,郑祥身.青海可可西里地区地质演化[C].北京:科学出版社,1996． 100-117． ]
[12] MA Z J. Basis of Active Tectonics and Seismic Engineering [M]. Beijing: Seismological Press, 1992． 180-182 (in Chinese). [马宗晋.活动构造基础与工程地震[M].北京:地震出版社.1992． 180-182． ]
[13] MATSUDA T, OTA Y, ANDO M, et al. Fault mechanism and recurrence time of major earthquakes in southern Kanto district, Japan, as deduced from coastal terrace data[J]. Geol Soc America Bull, 1978,89:1610-1618．
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