I. Kay et al., Imaging the Moho and V-p/V-s ratio in the Western Superior Archean craton with wide angle reflections, GEOPHYS R L, 26(16), 1999, pp. 2585-2588
A refraction/wide-angle reflection survey in northwestern Ontario investiga
ted the Archean Superior Province of the Canadian Shield. Images of apparen
t Moho topography were produced from both the PmP and SmS Moho wide angle r
eflections. The average Moho depth is 41 km, and average P- and S-wave velo
cities 6.6 and 3.8 (+/- 0.05) km/s respectively. The Moho dips southward fr
om 39.5 to 42 km depth over roughly 400 km. From ratios of S and P travel t
imes to the Moho, profiles of V-p/V-s were constructed. The average V-p/V-s
ratios are 1.74 and 1.76 for on the E-W and N-S lines (Poisson's ratio sig
ma = 0.253 and 0.262 respectively). V-p/V-s profiles show a sharp increase
from west to east and a gradual increase from north to south, correlating w
ith the distribution of more felsic continental crust and composite crust i
n the Western Superior.