Three-dimensional seismic traveltime tomography across the Red Lake greenstone belt using LITHOPROBE Western Superior line 2B.

摘要

The Red Lake greenstone belt, located in Uchi Subprovince of western Ontario, comprises mainly Mesoarchean basaltic tholeiite and komatiite lavas, and Neoarchean metavolcanic rocks. LITHOPROBE Western Superior reflection line 2B was shot north to south across the belt employing a 4-vibrator source array and a 963-channel symmetric split-spread with crooked geometry. 3-D seismic traveltime tomography was employed to construct a velocity model and to correlate it with different lithologies.; The dimension of the grid of the 3-D velocity model is 48 x 87 x 1.5 km. A cell size of 100 m was used for forward modeling of travel times using a finite-difference solution to the Eikonal equation, and a cell size of 100 m was also used in the regularized inversion. Starting models with varying surface velocity and velocity gradients were employed to test the effects of starting model on the final model. (Abstract shortened by UMI.)