Polyphase deformation at the Harder Fjord Zone (North Greenland)

In North Greenland, the E-W-trending Harder Fjord Fault Zone represents a m ajor lineament which cuts through Cambrian to Silurian deep-water sediments of the Franklinian Basin over a distance of 300 km. On both sides of the f ault zone, these successions were affected by two stages of folding (F1, F2 ) during Devonian to Early Carboniferous (Ellesmerian) deformation. No fiel d evidence was found that the Harder Fjord Fault Zone was active prior to E llesmerian folding. Early movements along the fault zone are indicated by p ost-Ellesmerian sedimentation of coarse red-beds (Depot Bugt conglomerate) which represent the oldest of the Wandel Sea Basin sediments. They were pro bably deposited in narrow, fault-controlled (?)Late Carboniferous basins si milar to those described from Svalbard. During Late Cretaceous times, 500 m thick fluvial and marine elastic sediments were unconformably deposited ov er the folded Cambro-Ordovician units. Although no direct field evidence su ggests that sedimentation was controlled by displacements along the Harder Fjord Fault Zone, the intrusion of Upper Cretaceous mafic sills and dykes i ndicates a phase of important crustal extension related to reactivation of the fault zone during this period of time, This stage was followed by post- late Santonian (Eurekan) N-S compression (D3) which affected the Franklinia n Basin deposits, Wandel Sea Basin sediments and mafic intrusions. In gener al, it was concentrated along the Harder Fjord Fault Zone and probably caus ed the reactivation of pre-existing (?)Carboniferous and younger fault line s. The entire deformation and its timing are comparable with the Eurekan st ructures found at the Kap Cannon Thrust Zone in northernmost Greenland and are related to intracontinental compression prior to the separation of Sval bard from Greenland.