Comprehensive geophysical prediction method of basement lithology—Example of Binbei area,Songliao basin

Estimating the basement lithology of basin not only is significant for investigating deep geological structure and evolution of basin,but also has instructive role to exploration of the matrix weathering crust reservoir.On the basis of comprehensively analyzing the cause of gravity and magnetic anomalies of basin,in this paper a series of processing and interpretation methods and techniques of integrated geophysical data for estimating the basement lithology were introduced.The formation-separating technique constrained by the seismic structural interface with gravity data can acquire the gravity anomalies caused by basement lithology,which is affected by density difference between interfaces.The method for calculating equivalent-density difference is neatly presented.The plane-to-surface technique can normalize the magnetic anomalies generated by the basement lithology closely related to the relief of basement to the magnetic anomalies with the same height as the basement,which can effectively improve the capacity of characterizing the basement lithology body.Three parameters composed of apparent density and apparent susceptibility and correlation coefficient between them can effectively describe the characteristics of basement lithology.The neural network method can well discriminate and classify the basement lithology.These methods above presented are applied to comprehensively estimate the distribution characteristics of basement lithology of Benbei area in Songliao Basin,which proves that these methods are effective.This series of methods and techniques provide the referential experience for other basins in the basement geolog'ical mapping.