Research And Application Of Deep Exploration In The Panxi Area With Long-period Magnetotelluric Method

Magnetotelluric method has been played an important role in the detection of the crust and upper mantle structure,make the long-period and broadband magnetelluric method combines the land of ultra-wideband electromagnetic magnetotelluric method is a further increase detection depth of the new techniques.In this paper, combining a new type of ultra-long period magnetotelluric sounding instrument LEMI417 with multifunction instrument V8 to carry out the broad-band ultra-long period for magnetotelluric observation in outlying Panxi area, and use of advanced data processing and interpretation of electromagnetic technology to analyses outlying Panxi area profile, which has gained very credible outlying Panxi area deep fault electrical structure, and summed up the results of previous work. At the same time, the Panxi area with a number of hot issues were discussed and researched according to the advantage of magnetotelluric sounding.First of all,the paper introduces some workings of panxi area section, which west Yanyuan and east Meigu,spans 180km; Looking back on the research history of panxi region and the development of magnetotelluric, we set the work stations along survey line considering the features of long cycle instruments.In total,we have finished 37 MT sounding points and 10 long-term sounding points , each long-cycle sounding point synchronously finished the collection work with conventional magnetotelluric sounding instrument (V8) and long-cycle magnetotelluric sounding instrument (LEMI417).This paper introduces the data processing of long-cycle data and splices the data collceted by that two instuments and then we get the bandwidth magnetotelluric data.Secondly this paper introduces the stratigraphic distribution of this research area with the background of reserch history and the rupture structural geology condition and the geophysical characteristics of panxi area. And also we explain the details of the specific research background.Rotate the tensor impedance to get the best electrical spindle direction of the profile,and using the Mohr circle and polarization analysis method, qualitative analysis the broadband data.In research of that two instruments, we correct the data after comparing the resistivity curves measured by V8 and LEMI417 at the same point.Then the credible broad-bandwidth magnetotelluric sounding curves are available;Summarizing the predecessor's precious experience, the paper introduces the current situation of the development of the inversion method and 1-D inversion, and briefly introduces the basic principle and implication of MTsoft2D. Finally we choose OCCAM inversion method and TE inversion to obtain the profile of broad-spectral-bandwidth inversion results.Finally, based on the measured resistivity, phase curve types and characteristics of the section map, the further interpretation of the profile data and electrical analysis is available .In this paper the mainly electrical characteristics of this geologic structure and the deep electrical tectonic features is studied. And then the paper discusses the relationship between the electrical structures and earthquake in this area.