Despite its complicated history the Ivrea Zone is considered to be
a representative surface exposure of extended continental crust.
We have digitized two standard 1:25,000 geological maps from this
area and evaluated their structural statistics. Because of the subvertical
orientation of the Ivrea Zone these maps can be considered as small-scale
cross sections through the lower continental crust. The autocorrelation
functions of the digitized lithologies measured from these maps show
a clear self-similar or fractal rather than a Gaussian or deterministic
trend. We found that an anisotropic von Karman correlation function
with an aspect ratio around 4 and a Hurst number of 0.3, corresponding
to a fractal dimension of 2.7, matches the observed data. Our results
represent an explicit confirmation of previous indirect evidence
for the fractal nature of lithospheric heterogeneities and provide
the means to construct realistic crustal-scale seismic models of
Ivrea-type lower continental crust.