EAGE E-Lecture: 3D Seismic Imaging of Volcanogenic Massive Sulphide... by Gilles Bellefleur

This E-Lecture: "3D Seismic Imaging of Volcanogenic Massive Sulphide Deposits in Metamorphosed and Deformed Rocks - Two Case Studies from Canada" presents two case studies on the application of 3D seismic data for mineral exploration in the Snow Lake (Manitoba) and Bathurst (New Brunswick) mining camps, Canada. Both 3D data sets were acquired over deep volcanogenic massive sulphide (VMS) deposits hosted in metamorphosed and deformed rocks. The two deposits investigated are the Lalor (Manitoba) and Halfmile Lake (New Brunswick) VMS deposits. At Lalor, collocated petrophysical and lithogeochemical measurements, and a 3D geological model are used to explain strong and continuous reflections observed in intensely hydrothermally-altered and metamorphosed rocks in the footwall of the deposit. The strong reflections are found at contacts between metamorphosed rocks with felsic and mafic protoliths, some being a proxy for the most prospective horizon in the mining camp. At Halfmile Lake, a 3D seismic survey acquired in the late 1990s led to the discovery of a deep mineralized zone at a depth of 1.2 km. A new anomaly identified on recently re-processed data is the possible continuation at depth of the deep mineralized zone discovered on the original data. Reflections suggest that the deep mineralized zone and its possible continuation are offset by a shallowly dipping fault. The two case studies demonstrate the value of 3D seismic data for mineral exploration, even in areas where geological conditions are complexified by deformation and metamorphism.