A Study On The Magnetic Susceptibility And Mineral Composition Of The Cenozoic Strata Related With Active Faults In Baoding, East Of The Taihang Mountains

Baoding is located at the east of the Taihang Mountains in the hinterland of Hebei Province.The human activities in this area are relatively concentrated,and plenty of projects have been built and more over are under construction.As the faults in front of the Taihang Mountains traverse this area along the NE direction,it is of great significance for future engineering construction to strengthen the investigation and evaluation of the activity of the piedmont faults in this region.The thesis is wroted according to the research data,which is made by predecessors,and the investigation results in the field.After systematic cataloging of drilling cores in engineering geology,the large spacing magnetic susceptibility measurement and X-ray powder diffraction(XRD)phase analysis were made.Based on the results of geophysical exploration,a comparison of the upper and lower strata of the Baoding-Shijiazhuang fault,the main fault in this area,is made in detail,and the following main understandings and conclusions are obtained.1.According to the formation of the emergence of conglomerate under the loose capping layer of the Quaternary in the upper plate and the absence of the gravel strata in the lower plate of the boreholes(XSZK02 and XSZK01),whose straight distance distance is only 1.5km,it is infered that the Baoding-Shijiazhuang fault has been formed since the Cenozoic.2.According to the significant difference of the thickness and exposure elevation of the lower Pleistocene of the two boreholes(XSZK02 and XSZK01),it is believed that the Baoding-Shijiazhuang fault is still active in the early Pleistocene.3.The results of magnetic susceptibility measurement show that the variation amplitude of the Quaternary strata,which revealed by the drill hole XSZK02 and the drill hole XSZK01,is obviously different.The variation amplitude of the magnetic susceptibility of the two borehole cores in Holocene is relatively small,while the variation amplitude of the upper Pleistocene is the largest.And the variation amplitude of the magnetization rate of the middle Miocene is larger than the Holocene.The variation amplitude of the susceptibility of the Pleistocene is the smallest.It reflects the difference of hydrodynamics of Quaternary strata in different ages.4,XRD phase analysis results show that the content of quartz and main clay minerals(illite,smectite,chlorite and kaolinite),which varies with the depth,have certain differences in the two boreholes of Quaternary strata.It reflects the movement of strata,so it is also one of the evidence for the existence of fault activities between the two drill holes..The above understanding provides a basis for evaluating the engineering geological stability appropriately in Baoding area.