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位于华北克拉通中部、沁水含煤构造盆地核心部位的榆社盆地,是一个上新世至早更新世河湖相沉积的内陆小型盆地,浊漳河的侵蚀导致大量新生界剖面出露地表。野外地质调查发现,榆社群高庄组中发育大量泄水构造,包括砂泥岩脉、砂岩脉、泥岩脉、粘土质团块、片状钙质胶结岩脉、结核等,且相互间渐变过渡。基于饱和松散岩土体,在大于一定强度的外动力扰动下,沿岩层软弱结构面发生逃逸,形成泄水构造。基于泄水构造在本区大范围发育的调查结果以及现代地震诱发砂土液化的研究成果类比可知,地质历史时期的高庄组沉积物(地震发生时高庄组沉积物处于饱和松散状态、中值粒径变化范围在O.055~O.159mm区间、级配良好且富含CaCO_3,FeO和MnO等矿物质),是在遭受地震震级M_s=5~6的动力扰动下,沿岩层弱面泄水灌入形成了上述泄水构造。地表揭露的各种震积构造关联证据与地震导致饱和松散岩土体液化射流的水动力以及粘粒、砂粒、矿物质等物源供应量变化的形成条件相匹配,构建了表征其成因的“地震液化射流分异模型”。地震液化射流形成不同形态的泄水构造,可作为相变剧烈小型盆地地层识别与对比的良好标志。
Yushe Basin, located in the central part of North China Craton and the core part of Qinshui coal-bearing tectonic basin, is an inland small basin that was deposited from Pliocene to Early Pleistocene by lacustrine facies. The erosion of Zhuozhanghe River resulted in a large number of exposed sections of Cenozoic table. Field geological survey found that a large number of drainage structures developed in Gaozhuang Formation of Yushe Group, including sandstone and mudstone veins, sandstone veins, mudstone veins, clay mass, lamellar calcareous veins, tuberculosis and so on, and the gradual transition between them . Based on saturated loose soil and rock mass, under the external dynamic perturbation greater than a certain intensity, escape occurs along the weak structural plane of the rock formation to form a drainage structure. Based on the findings of the large-scale development of the drainage structure in this area and the analogies of the researches on sand liquefaction induced by modern earthquakes, it is clear that the sediments of the Gaozhuang Formation during the geological history (the sediments of the Gaozhuang Formation were in a saturated and loose state during the geological epoch The values of particle size ranged from O.055 to O.159mm with well-graded and rich in CaCO_3, FeO and MnO and other minerals. Under the disturbance of earthquake magnitude M_s = 5-6, Drainage poured into the formation of the drainage structure. The evidences associated with the various seismites revealed by the surface match the formation conditions of the hydrodynamic force of the liquefied jets caused by earthquakes and the changes in the supply of clay, sand and minerals and so on, “Earthquake Liquefaction Jet Differentiation Model”. Seismic liquefied jets forming different types of drainage structures can be used as a good marker for the identification and comparison of stratums in the small phase basin.