Breccia pipe and sinkhole linked fluidized beds and debris flows in the Athabasca Oil Sands: dynamics of evaporite karst collapse-induced fault block collisions

摘要: Abstract The Middle Devonian hypogene evaporite dissolution, karst collapse resulted in the fragmentation of Upper strata into a mosaic differentially subsided fault blocks underlying northern area Athabasca Oil Sands Deposit. Regional salt dissolution developed structural troughs up to 50 km long on sub-Cretaceous unconformity. depressions formed above collapsed collinearly aligned, brine-filled, chimneys extending 100 m high within Prairie Evaporite beds. Individual and coalesced arrays along lineament trends that dissected 10 wide scarp. 3D seismic images chimney structures basin depocenter across central Saskatchewan are analogues used interpret evident succession overlying Lower Cretaceous McMurray Formation. Devonian-Cretaceous bound located were gravity driven structures. These included oblique rotational trajectories during descents towards voids. Breccia pipes impinged deeper reaches inter-block planes as adjacent obliquely rotated apart each other, resulting zones with compressional extensional bed deformations variable but often rapid rates vertical descent. breccia pass upward, planes, shear twisted beds zigzag suture welding between blocks. collision zone, blocks, dominated by sinkhole development one side plane. Continued compression deformed fragmented many Some these collapse-induced block collisions suggest cataclysmic events, caused seismicity triggered fluidization upper intervals mobilization debris flows spread surfaces.