HR: 1340h
AN: S53B-0209    [Abstracts]
TI: Large Proterozoic Upper Crustal Intrusions Within the Eastern Athabasca Basin of Northern Saskatchewan, Canada
AU: * Hajnal, Z
EM: Zoltan.Hajnal@usask.ca
AF: University of Saskatchewan, Department of Geological Sciences, Saskatoon, SK S7N5E2 Canada
AU: Takacs, E
EM: takacs@elgi.hu
AF: University of Saskatchewan, Department of Geological Sciences, Saskatoon, SK S7N5E2 Canada
AU: Annesley, I R
EM: annesley@src.sk.ca
AF: Saskatchewan Research Council, 15 Innovation Blvd., Saskatoon, SK S7N 2X8 Canada
AU: Robertshaw, P
EM: phil@explorationGIS.com
AF: Robertshaw Geophysics Ltd., 111 Middleton Crescent, Saskatoon, SK S7J 2W5 Canada
AB: Regional and high-resolution reflection surveys, in three separate areas of the eastern part of the Paleoproterozoic Athabasca Basin, have identified zones of anomalously high reflectivity. These bright reflections extend through all the seismic profiles, some with lengths of over 160 km. The depths of these reflective bodies range form ~ 6 to 13.5 km (2.0 - 4.0 sec TWT). In several locations, the reflector is offset by shear/fault zones. In some localities, these shear/fault zones ascend to or approach the surface. The highly comparable seismic signatures of the isolated surveys, suggest that these are tabular bodies that extend over at least 25,000 km2. The anomalous large amplitude of the seismic signal indicates significant acoustic contrast in a vertical zone of 50 to 150 m. The origin of these enigmatic sheet-like complex zones is not resolved. One interpretation is that they are sill-like bodies, subsurface expressions of the circa 1.265 Ga (post-Hudsonian) Mackenzie diabase suite. However, instantaneous frequency, amplitude strength, and other seismic signal attribute analyses, reveal that a variety of geologically acceptable acoustic contrasts, including remnant brine fluids, cannot be ruled out. The region of the anomalous subsurface reflectivity property is under extensive exploration for unconformity-type uranium deposits, thus resolution of the true nature of this complex interval of the upper crust is of major importance.
DE: 9619 Precambrian
DE: 8015 Local crustal structure
DE: 8105 Continental margins and sedimentary basins
DE: 8109 Continental tectonics--extensional (0905)
DE: 8125 Evolution of the Earth
SC: Seismology [S]
MN: 2004 AGU Fall Meeting