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The Study on Application of the Audio Frequency Magnetotelluric Method in Azelik Area of Niger
Author(s) -
ZHANG Ruliang
Publication year - 2014
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12381_43
Subject(s) - beijing , library science , citation , computer science , magnetotellurics , key (lock) , zhàng , china , history , engineering , archaeology , computer security , electrical engineering , electrical resistivity and conductivity
The work area is located in Azelik area in Niger. Outcropping strata include Izegouandane formation of Permian system, Agadez group of Jurassic-Triassic, Assaouas formation, Irhazer formation , and Tegama formation of Cretaceous system. The Irhazer formation widely exposed in the region, and other strata is scattered outcrops . AMT method is adopted in the work; its principle is same with that of the conventional magnetotelluric sounding method. Multi-purpose Electroprospecting Data Acquisition Station (V8) which was produced by Phoenix company of Canada was used to collect the data by using tensor method, which recorded time series of electric field and magnetic field along the direction of survey line and perpendicular to the survey line. The frequency range of data is from 5 HZ to 10400 HZ. Time series of each point must be record more than 30 minutes to make sure the apparent resistivity and impedance phase is useful. The software used for data processing was SSMT2000 provided by Phoenix Company. First, auto-power spectrum and cross-power spectrum were derived from time series data by Fourier transform. Second, magnetotelluric tensor impedance was estimated based on robust technique. Last, resistivity section diagram were derived by inversion calculation.