GEOLOGY OF THE NORTH FALKLAND BASIN

The North Falkland Basin comprises two main structural elements: a nor th-south trending graben, termed the North Falkland Graben; and a set of subsidiary basins to the west of this graben, also controlled by no rth-south trending extensional faults, but which have been constrained by NW-SE oriented, reactivated Palaeozoic thrust faults. The North Fa lkland Graben can be divided, in its northern part, into western and e astern depocentres, which are separated by a north-south trending intr a-graben high. Early syn-rift, late syn-rift, early post-rift and late past-rift successions have been identified within the North Falkland Graben. The subsidiary grabens to the west probably contain only early syn-rift deposits overlain by bate post-rift sediments: these basins were possibly uplifted along the shoulder of the main graben during it s main phase of extension in the Late Jurassic to Early Cretaceous. Al though predictions of sediment-infill type have only been made by regi onal correlations and seismic facies analysis in these undrilled basin s, two major deltaic units of early post-rift age are confidently infe rred to be present in the North Falkland Graben, and to pass laterally into possible anaerobic mudstones of source-rock quality. This petrol eum system will soon be tested by a number of oil companies sharing pr oduction licences for the entire axial area of the North Falkland Grab en.