The Falkland Islands lie at the western end of the Falkland Plateau, a relatively shallow water area of continental crust that extends out towards South Georgia.
The Islands comprise Pre-Cambrian to Permian rocks, with Jurassic dykes, and are surrounded by four major Mesozoic to Cenozoic sedimentary basins. These basins are set into the Falklands Plateau, which comprises probable Devonian and Permian age sedimentary rocks. The four basins are:
In essence, all four offshore basins contain more or less thick Mesozoic and thinner Cenozoic sediments, and each has considerable but under-explored petroleum potential.
The Falkland Plateau Basin, Malvinas Basin and South Falkland Basin together comprise the Southern Basins and lie to the east, west and south of the islands respectively. These basins are interconnected, and although their tectono-stratigraphic histories vary, regional correlation of major seismic reflectors between basins allow comparisons to be made.
The Falkland Plateau Basin to the east of the islands has a NE-SW trending faulted western margin, and terminates eastwards at the Maurice Ewing Bank, a bathymetric high some 250 km east of the islands. The Maurice Ewing Bank was drilled by the Deep Sea Drilling Project (Barker et al. 1976), and these boreholes provide an insight into the stratigraphy and petroleum potential of the Falkland Plateau Basin; see Southern Basins section for more details.
The Malvinas Basin to the west of the Falkland Islands [Regional basins map] appears to have a generally unfaulted eastern margin. It has been explored by about 17 commercial boreholes in Argentine waters, and data from these wells can be traced eastwards into Falklands waters; see Southern Basins section for more details.
The South Falkland Basin separates the Falkland Plateau and Malvinas basins [Regional basins map], and trends east-west along the northern side of the Scotia/South America plate boundary [3D map of bathymetry and designated area]. The basin plunges steeply to the south, into the plate boundary fault zone. The stratigraphy of the area has been interpreted by extrapolation of data from the Argentine wells to the west and from the DSDP boreholes to the east; see Southern Basins section for more details.
The North Falkland Basin is apparently structurally isolated within the Falkland Plateau north of the islands. This is the only one of the four offshore basins that has been drilled. However, there are only six wells, and they are all in one small area of the central part of the graben, and therefore provide only limited insight into the nature and petroleum potential of the basin.
The main phases of basin evolution common to all Falklands basins are tabulated below:
Possibly as early as Triassic, but maybe started in ?mid Jurassic
The regional geology and palaeogeographic evolution of the offshore Falkland Islands has been well documented by Richards and Fannin (1994), Richards (1995 and 1997), Lawrence and Johnson (1995), Platt and Philip (1995), Richards et al. (1996 a and b) and Richards and Fannin (1997).