Axel Heiberg Island (northern Nunavut) contains the thickest Mesozoic
section in the Sverdrup Basin. The ~370-km-long island is second only
to Iran in its concentration of exposed evaporite diapirs. However,
the tectonics of this remote region is not well known. A polar desert
on the island provides excellent exposure of 46 diapirs of Carboniferous
evaporites and associated minibasins. Paleogene (Eurekan) anticlines
trend roughly north on a regular ~20 km wavelength and probably detach
on autochthonous Carboniferous Otto Fiord evaporites. In contrast,
a 60-km-wide area, known as the wall-and-basin structure (WABS) province,
has bimodal fold trends and irregular wavelengths of ~10 km. Here,
crooked walls of diapiric anhydrite crop out in the cores of tight
anticlines. Wider synclinal minibasins separate the diapiric walls.
We interpret the WABS province to detach on a shallow evaporite canopy.
This comprises an allochthonous coalescence of evaporite diapirs that
spread extrusively during the Hauterivian (Early Cretaceous, ca. 130
Ma), close to the onset of seafloor spreading in the Arctic Ocean
and of flood basalt volcanism associated with Alpha Ridge. Since then,
the evaporite canopy has yielded second-generation diapirs, now exhumed
and exposed by modest Eurekan shortening. Strata record minibasin
evolution and diapirism since at least the Late Triassic. Stratigraphic
thinning against diapirs and spectacular angular unconformities at
four levels are present between the Jurassic and Paleocene. The most
widespread is the Early Cretaceous event marking the time of canopy
emplacement. Outcrops record the later fate of the canopy, including
exposure, onlap of diapirs, and off-diapir debris flows.