  In order to analyze the effect of chaos or order on the rate of decoherence
in a subsystem we aim to distinguish effects of the two types of dynamics from
those depending on the choice of the wave packet. To isolate the former we
introduce a random matrix model that permits to vary the coupling strength
between the subsystems. The case of strong coupling is analyzed in detail, and
we find at intermediate times a weak effect of spectral correlations that is
reminiscent of the correlation hole.
