Stratigraphy, structure and petroleum potential of the Lady Franklin and Maniitsoq Basins, offshore southern West Greenland

The Lady Franklin Basin, which contains a thick succession of Cretaceous and Cenozoic sediments, constitutes the western part of the southern West Greenland offshore area. In the Davis Strait and Labrador Sea region rifting was initiated in the earliest Cretaceous and a number of basins formed. In time these basins deepened, although subsidence was interrupted by two main phases of uplift and erosion that took place in middle and late Cretaceous time, resulting in two hiatuses in the succession. Sediments with source or reservoir potential were deposited in the basins. Source rocks are known to occur in the marine Cretaceous successions of onshore northern Canada and central West Greenland and also offshore eastern Canada, and can therefore be expected to occur in the Lady Franklin and Maniitsoq basins. In the Lady Franklin area Paleocene volcanism associated with further tectonism caused the eruption of flood basalts and hyaloclastites on top of the Cretaceous mudstone and sandstone succession. A Lower Palaeogene sediment succession, which may contain both source and reservoir rocks, was then deposited on top of the basalts, as seen in the nearby Canadian Hekja O-71 well. Around the Ypresian to Lutetian transition a regression took place. The regression gave rise to an unconformity and a hiatus spanning a few million years throughout the entire West Greenland shelf. New deposition followed and, after a long period, major compression set in and a regression occurred across the whole shelf in Late Oligocene time. Erosion set in and was deep on the southern shelf, resulting in a hiatus spanning about 39 Ma. To the north the hiatus is only about 19 Ma. In early Middle Miocene time the tectonic regime in the Davis Strait area changed. Subsidence and deposition resumed offshore West Greenland. These events may have created conditions for generation of hydrocarbons in the potential source-rock sequences in the Cretaceous succession. Therefore, although hydrocarbon exploration has been limited in this region and had little success, it is thought that conditions are favourable for the discovery of significant oil and gas accumulations.