Abstract

The offshore sedimentary basin between Kap Farvel and Melville Bugt has onshore equivalents between lat 68°50′N and lat 72°15′N, where a sequence of sediments of Early Cretaceous to middle Paleocene age rests on the Precambrian basement. The sedimentary facies onshore indicates deposition in a deltaic to prodeltaic marine environment with a transition from a fluviatile marine environment in the south, to marine in the north. The sediments are overlain by a thick sequence of subaqueous and subaerial Tertiary basalts. A series of approximately N-S trending normal faults with downthrow to the west affects the sedimentary area. There is evidence for major movements during early Tertiary time with only limited synsedimentary faulting. Sedimentation may have been controlled by ancient basement topography.

Offshore between lat 64° N and lat 68°N the basement is known in detail, but farther north it can only be seen sporadically owing to the Tertiary basalt cover. Generally the basement dips smoothly to the west. A prominent N-S trending structural high, the Kangamiut Structural High, interrupts the westward dip, and the eastern parts of the basin are characterized by complex block faulting. Three seismic markers of reasonable areal extent are recognized in the overlying sediments. Prograding structures form a feature between the lowest marker and basement, and may be of sedimentary or hyaloclastic origin. The exploratory well drilled on the Kangamiut Structural High penetrated sediments of Paleocene age and younger, and reached Precambrian basement at 3700 m depth. Two main sedimentary environmments are recognized on the basis of the microfaunas and sediment types: a rapidly prograding deltaic environment and a prodelta environment. The offshore basin was possibly formed in Early Cretaceous time. Seismic facies analyses indicate that the sediments were mainly derived from the east. The strongly prograding character of the upper sedimentary section indicates an increased influx of coarse material, probably due to accelerated uplift of the crystalline shield in late Eocene-Oligocene time. A N-S trending fault system with downthrow to the east affects the lower sedimentary section in the northwestern parts of the basin.

Hydrocarbon potential can be assessed to some extent, from sediments from the onshore area, and from the Kangamiut 1 Well. The composition of the organic matter in these sediments, and the relatively low degree of thermal maturation, primarily indicates a potential for gas.