Crustal structure of the Innuitian region of Arctic Canada and Greenland from gravity modelling: Implications for the Palaeogene Eurekan orogen

摘要: SUMMARY New gravity observations collected over Ellesmere Island and Axel Heiberg have been integrated with existing Canadian Danish data sets to produce a comprehensive regional compilation the Innuitian Region of Greenland High Arctic. This has provided quantitative assessment geometry plate boundary between northern crustal structures across Cretaceous‐Palaeogene Eurekan Orogen. A large amplitude linear low—Nares Strait Gravity Low (NSGL) (<‐160 mGal)— extends obliquely Nares from Island. feature closely correlates distribution Palaeozoic Franklinian Margin sequences is cross-cut by Cenozoic Frontal Thrust (EFT), which represents mappable western limit undeformed Plate associated Newly identified features occur north NSGL: Hazen Plateau (HPGH), corresponding low-lying topography Trough Grantland (GGL), elevated Uplift. models for profiles crossing NSGL, HPGH GGL indicate that long-wavelength component anomalies produced systematic variations in Moho depth. Although significant Eurekan-age thrusting thickening low-density strata observed on Island, locally contributing mass-deficit generating equivalent are undeformed. The NSGL interpreted be primarily signature remnant (Early Palaeozoic) margin downwards flexure crust beneath northwards sedimentary wedge rather than purely result Orogeny. Digital bathymetry sediment thickness were used determine residual ‘crustal’ field, turn was calculate depth-to-Moho thicknesses. These terms affinity thinning processes Late tectonics area. Significant Lancaster Basin, Baffin Devon 40 km separation. failed rift-arm Eocene spreading system Bay. Fourier-domain transfer function analysis (Q) determined an intermediate average strength (flexural rigidity 10 22 N m) region. Comparisons theoretical models, based simple thin elastic model, suggest relatively (30 km) near-isostatic equilibrium—that is, not flexurally supporting or topographic load. clearly defined anisotropy identified, correlating direction convergence, suggesting collisional forces yet dissipated at least partially large-scale orogenic structures.