In the present talk, we will show that plasmon resonances in disordered nanocomposites can be studied by means of equivalent random impedance networks. A special attention is paid to the case of thin-film nanocomposites (or disordered metasurfaces) consisting of a mixture of conductor and insulator. As we will show, a widely used representation of such systems with square-lattice impedance networks implies two-dimensional Coulomb interaction and thus should be corrected. A new model is proposed, which takes into account three-dimensional nature of Coulomb interaction in thin films. Resonances in ordered films of finite thickness within this model correspond to a surface plasmon-polaritons, whereas resonances in systems, strongly confined to the plane, represent 2d-plasmons. Applying this model to a case of two-dimensional disordered systems we show, that at volume fractions of conductive phase below percolation threshold spectral gaps in the form of Lifshitz tails are present, whereas for fillings higher than percolation threshold a crossover between 2d-plasmons and localized resonances is observed. Lifshitz tail edge, as well as the crossover frequency, are both obey scaling relations near the percolation threshold.