Based on petrophysical data, geologic maps, and a well log, we present
statistical descriptions of likely upper-, middle-, and lower-crustal
rocks to characterize the fine-scale heterogeneity observed in crustal
exposures and inferred from deep-crustal seismic data. The statistical
models, developed for granitic and metamorphic upper crust, and for
an extended metamorphic lower crust, are used to construct whole-crustal
models of seismic velocity heterogenity. We present finite-difference
synthetic CMP data from several models which compare favorably with
field data. The statistical models also permit classification of
the seismic reflection experiment and the crustal heterogeneity according
to scattering regime. The ''optical'', or scattering properties of
importance for classification are the velocity fluctuation intensity,
the horizontal and vertical correlation lengths of the medium, the
correlation function of the medium, and the velocity population function.
For the crustal properties we measured, the bandwidth of a typical
deep crustal experiment overlaps from the weak to the strong scattering
regime, with implications for crustal seismic data processing and
imaging. Notably, deep-crustal signals are likely to have experienced
multiple scattering, making common seismic imaging techniques of
questionable value. Moreover, the details of the unmigrated CMP stacked
section bears little resemblance to the underlying medium.