Evolution of the Kap Cannon Thrust Zone (north Greenland)

Abstract

In North Greenland, early Paleozoic metamorphic successions of the north Greenland fold belt are carried along the Kap Cannon Thrust Zone northward over the Late Cretaceous Kap Washington Group and Permo-Carboniferous strata. Ellesmerian deformations and metamorphism occurred prior to ductile deformation in the Kap Cannon mylonites, which developed from shear zones in the hanging wall metamorphics. Heterogeneous shearing affects the Ellesmerian structures, with shear sense indicators suggesting top-to-north displacements in the mylonites. Late Cretaceous mafic dikes and sills record intense ductile deformation in the mylonites and incipient shearing within distinct zones of the hanging wall metamorphics. In the footwall of the mylonite zone, approximately NW directed thrusting with the formation of imbricates in Permo-Carboniferous strata on Lockwood ∅ is related to an oblique ramping beneath and in front of the Kap Cannon Thrust Zone. Since the Kap Washington volcanics are mostly affected by brittle deformation, the onset of thrusting occurred in a deeper crustal level. Condensed ductile deformation within the mylonites, shear zones, and an additional oblique to lateral ramp suggest that shear/strain heating contributed to a local rise in temperature. Continuing displacement led to uplift of the thrust zone bounded block of metamorphic rocks with a final emplacement over the northern volcanics under brittle conditions. According to the age of the magmatic rocks in the footwall, the evolution of the Kap Cannon Thrust Zone probably took place during early Tertiary (Eurekan) times. The regional implications are briefly discussed.