Study On Quaternary Activity Of Main Buried Faults And Strata Mineral Composition In Xiong'an New Area And Neighboring Areas

Xiong'an New Area,established by the Party Central Committee and the State Council in 2017,is another national new district in China.In order to build this new state-level district,Xiong'an is planning to build a large number of infrastructures.It plans to build four stations,six railways,and improve six highways.In addition,a large number of urban infrastructures are also being planned.The research on the activity of the buried faults in Xiong'an New District and its adjacent areas can help to select the location of major projects and build urban infrastructure,which has very important economic and social significance.The paper first collected the previous data and conducted a field geological survey to roughly understand the specific location and basic shape of the fault.Then,based on the previous data,the controllable source audio-frequency magnetotelluric sounding(CSAMT),shallow seismic,and high-density resistance were arranged.The rate method is used to study the number,location,deep extension state,shape,and approximate upper breakpoint buried depth of buried faults in the study area.In order to verify the reliability of the comprehensive geophysical survey conclusions,a series of boreholes are arranged on the upper and lower disks of the fault.Through the cataloging of borehole cores,study the specific age of fracture activity;at the same time,the borehole cores are sampled at different depths and XRD powder crystal diffraction is performed to study the Cenozoic strata mineral formations in the study area.Achieved the following knowledge:(1)The occurrence of Baoding-Shijiazhuang fault(F1)is NE-SW trending,SE-prone,with an inclination angle of 45 °-75 °.The shape is steep upward and downward,shovel-shaped,and there is an upper breakpoint with a burial depth of 350 m.In addition,a secondary fault F1-1 is also developed,with a trend of NE-SW and SE trend,with an inclination angle of 45 ° to 75 °.The shape is steep upward and downward,shovel-shaped,and there is an upper fault with a burial depth of 360 m.point.(2)The occurrence of Xushui-Dacheng fault(F2)is toward NWW-SEE,with a tendency of S,an inclination angle of 70 °,a shape with a steep upward and downward slope,a shovel shape,and an upper breakpoint with a burial depth of 240 m.In addition,there is a secondary fault F2-1,which is towards NE-SW,tends to N,and has an inclination angle of 70 °.(3)The occurrence of the Rongcheng fault(F3)is toward NE-SW and tends to SE,and there is an upper break point with a burial depth of 370-685 m.(4)The thickness of the stratum in the study area is determined by the borehole exploration.The thickness of the Neogene in the vicinity of Taishang Village is 410 m for the F1 fault lower plate,F1 for the upper plate F1-1 for the lower plate for 440 m,and F1-1 for the upper plate for 530m;The thickness of the Neogene near Cuizhuang Town is 710 m below the F2 fault and 760 m above the F2 fault,respectively.The thickness of the Neogene near Rongcheng is 680 m below the F3 fault and 720 m above the F3 fault.(5)Research on the activity of the fault,the Baoding-Shijiazhuang fault(F1)has no activity in the Quaternary,the latest active period is the Neogene,and the slip rate in the Neogene is 0.02 mm / a;the Xushui-Dacheng fault(F2)There is activity in the Early-Middle Pleistocene of the Quaternary,the sliding rate in the Early Pleistocene is0.02 mm / a,and the sliding rate in the Middle Pleistocene is 0.01 mm / a;the Rongcheng fault(F3)has no activity in the Quaternary,the latest The active era is Neogene,and the sliding rate in Neogene is 0.016 mm / a.(6)The mineral composition of the Quaternary strata is mainly divided into clastic minerals and clay minerals,the average content of clay minerals is 58.76%,mainly montmorillonite and illite,the average content is 53.41%,kaolinite and chlorite The content is relatively small,the average content is 5.35%;the detrital minerals are mainly quartz,with an average content of 26.23%,and the other detrital minerals are relatively small,namely potassium feldspar(5.32%),plagioclase(3.57%),Calcite(2.05%)and dolomite(4.06%).(7)By sampling near the bottom formation interface of the Quaternary Holocene,the bottom formation interface of the Upper Pleistocene,the bottom formation interface of the Middle Pleistocene,and the bottom formation interface of the Lower Pleistocene in different boreholes,the mineral composition and percentage content of the sample were investigated There was no significant change in mineral composition and percentage content near the stratigraphic interface,which verified the accuracy of stratigraphic division.In addition,there is no significant difference in the depth of thestratigraphic interface in the combined borehole section.From this,it can be judged that the Baoding-Shijiazhuang fault(F1)has not caused the fault segment of the Quaternary strata,and the F1 fault has not been active since the Quaternary.