A non-parametric approach to the estimation of plasma turbulence spectra is propesed in the paper. The basic model for description of the fine structure of stochastic processes is a finite location-scale normal mixture. The classical EM-algorithm is used for estimating the unknown parameters. The explanation of empirical results are given for the evolution of one-side Fourier spectra obtained in different modes of low-frequency plasma turbulence. Such kind of analysis allows to identify typical structures of processes forming plasma turbulence.