Bouguer gravity anomalies and speculations on the regional crustal structure of the Eurekan Orogen, Arctic Canada

Bouguer anomaly-topography profiles crossing three major structural elements of the Tertiary Eurekan Orogen in Arctic Canada have been constructed: the southwestern extension of Grantland Uplift on western Ellesmere Island and Princess Margaret Arch on north-central Axel Heiberg Island (from detailed gravity measurements taken along two transects in 1987), and Cornwall Arch on Cornwall Island (from pre-existing gravity data).
Gravity signatures beneath the three major uplifts, analyzed in the context of the gravitational effects of the observed near-surface geology of Cornwall and Princess Margaret arches, are consistent with a model of gradational change from isostatic compensation beneath the Grantland Uplift to antithetic isostatic compensation beneath Cornwall Arch. These signatures correspond to increasing distances westward, from the zone of maximum Eurekan compression. Thus, the area of Grantland Uplift has been tectonically thickened, whereas Cornwall Arch is underlain at depth by a broad crustal/mantle upwarp. Princess Margaret Arch is considered to be transitional between these two end-members, possibly being cored by a deep crustal upwarp, but also involving tectonic thickening, perhaps by stacking of thrust slices.
It is speculated that Cornwall and Princess Margaret arches may be the manifestation of crustal scale “folding” in response to in-plane compressional stresses developed during the Eurekan Orogeny. The distance between these two arches is about 200 km and is similar to the expected wavelength of deep crustal folding, given typical flexural rigidities for continental lithosphere.