Bureau of Economic Geology, The University of Texas at Austin (www.beg.utexas.edu).
Bureau Seminar, February 11, 2005
An Allochthonous Salt Canopy in the Sverdrup Basin, Arctic Canada
Martin Jackson and Christopher Harrison (Geological Survey of Canada)
Axel Heiberg Island is second only to Iran in the number and concentration of exposed evaporite diapirs. However, the tectonic geology of the island has hardly been explored until our visit in 2004. The polar desert provides spectacular exposure of diapirs of Carboniferous evaporites and associated minibasins. We infer the presence of an evaporite canopy within a distinctive, enigmatic area known as the “wall-and-basin structure”. The only other known exposed evaporite canopy is in the Great Kavir of Iran; all other known canopies are buried. The evaporite canopy comprises an allochthonous coalescence of evaporite diapirs that spread during the Hauterivian (mid-Cretaceous, ~130 Ma). Since then, the canopy has yielded second-generation diapirs, now exhumed and exposed by modest Tertiary shortening (Eurekan Orogeny). Outcrops record the emplacement and subsequent fate of the canopy, including its subaerial exposure, deltaic onlap of diapiric evaporite, and off-diapir debris flows.