The Research On Geological Mapping Method For Low Energy Spectrum Of Gamma-ray Spectrometry

Compared with the traditional method of geological mapping, gamma-ray spectrum geological mapping method has the advantage of convenient, economic and rapid, but the research on geological mapping method for low energy spectrum of gamma-ray spectrometry was limited. Due to the low energy spectrum little affected by the statistical fluctuations, and change with the stratum lithology regularly, study on the geological mapping method will greatly improve the utilization rate of gamma-ray full spectrometry data, have great significance and practical value to expand the scope of application of gamma-ray spectrometry and rich geological the mapping method.This paper combined the method of theory analysis, simulation and ground validation, studying the geological mapping method for low energy spectrum of ground gamma-ray spectrometry and airborne gamma-ray spectrometry respectively. Firstly, theoretical analyzing the relationship between spectrum characteristics and stratum lithology, then using Monte Carlo simulation in the ground environment to establish and verify the stratum lithology inversion method of low energy spectrum, and validate of the feasibility of the inversion solution in the field, evaluate the efficacy of the geological mapping, evaluate the efficacy of the geological mapping,finally, using the same method research the geological mapping method for low energy spectrum of airborne gamma-ray spectrometry.In the research on the geological mapping method for low energy spectrum of ground gamma-ray spectrometry, using 390Kev-550 Kev as Compton scattering energy interval and 60Kev-160 Kev, 0-260 Kev, 390Kev-550 Kev as Photoelectric effect energy interval to inversion the density and equivalent atomic number respectively, simulations have verified that the relative error is less than 8%.The ground validation results showed that using 60Kev-160 Kev to inversion the equivalent atomic number can identify the siltstone of 41.82 o N and biotite diorite and potassic granite below 41.82 o N well, and able to distinguish the ferruginous quartzite on the upper left corner and lower left corner of the measurement surface location of some rocks. Same method to inverse the stratum lithology in geological mapping for low energy spectrum of airborne gamma-ray spectrometry introduced, with the high after the correction, the relative error of the simulation is within 6%, reliable inversion results are obtained.In this paper, research has shown that both in the ground gamma or airborne gamma measurement, with low energy spectrum of 390Kev-550 Kev and 60Kev-160 Kev can effectively realize the geological mapping of gamma-ray spectrometry, this lays the foundation for the application of ground gamma-ray spectrometry and airborne gamma-ray spectrometry.