可可西里东部活动断裂的地质特征

GEOLOGICAL FEATURES OF ACTIVE FAULTS IN EAST HOHXIL MOUNTAINS OF NORTHERN TIBETAN PLATEAU

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.