Yushe basin,located in the central North China Craton and the center of Qingshui coal-bearing basin,is a small scale Pliocene to Early Pleistocene fluvial-lacustrine basin and good outcrops of Cenozoic strata were exposed by erosion of Zhuozhang River.Many water escape structures,including sand-mud vein,sandstone vein,mud vein,mud ball,calcium sheet,concretion,and the gradual transition characteristics among them were observed in Gaozhuang Formation of Yushe Group.Based on theory that when the intensity of outer dynamic disturbance is larger than a threshold,saturated and loose rock mass will escape along the soft rock structural plane and form the water escape structures,and in comparison with the water escape structures induced by contemporary earthquakes,it was suggested that the water escape structures in Gaozhuang Formation were formed along the soft rock structural planes by a Ms5～ 6 earthquake under the condition that sediments were saturated and loose,with 0.055 ～ 0.159mm median diameter,good gradation and abundant CaCO3,FeO,MnO minerals.A genesis model,called as earthquakeinduced liquefaction jet differentiation model,was proposed according to the matching of the seismic structures in the outcrops with water power of earthquake-induced liquefaction jet for saturated and loose materials and the distribution of clay particle,sand particle and minerals in strata,which controls the supply of material for formation of various water escape structure.Different water escaped structures formed by earthquake liquefaction jet could be acted as the good symbols of strata identification and correlation in small scale basin with fierce face transformation.
Gaozhuang Formation of Yushe Group
water escape structure
model of jet differentiation
赵金贵 男 39岁 工程师/在读博士 矿产普查与勘探专业 E-mail：firstname.lastname@example.org