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Abstract:

Four regional seismic reflection profiles totalling 153 line km were acquired near Timmins, Ontario, within the southern Abitibi greenstone belt. Five additional high-resolution lines targeted specific metallogenically important features such as the Porcupine-Destor deformation zone. Interpretation of these profiles individually and in a composite north-south transect reveals a number of prominent bands of reflectors within the upper 15 km of the crust that define a series of folds or antiformal stacks of thrust nappes. Structures and stratigraphy mapped at the surface confirm structural culminations in these locations. At depths greater than 10 km the reflectors have generally shallower dips implying broad folding. Major ore deposits such as those at the Kidd Creek, Hollinger, McIntyre, and Dome mines are located on the northern, steeply dipping limbs of these antiformal stacks, implying that the fold structures focused post tectonic mineralizing fluids within the upper crust into the near surface. The Porcupine-Destor deformation zone is proximal to the large gold deposits near Timmins and is revealed by the new seismic data to be a composite of early fold structures and late transpressive fault arrays.