Evidence for a volcanic rifted margin and oceanic crustal structure for the Falkland Plateau Basin

Marine geophysical data from the western Falkland Plateau show strongly lineated magnetic anomalies and a coincident linear gravity high that identify the southeastern margin of a Falkland Islands block as a volcanic rifted continental margin. Characteristics of onshore and offshore dykes suggest this margin is most probably slightly younger than 190 Ma. Together with these data, seismic reflection profiles and sonobuoy seismic refraction data from the basin province of the Falkland Plateau east of the islands indicate an elevated oceanic origin for the major part of the Falkland Plateau Basin, most probably within the Karoo hotspot province. These conclusions are compatible with, but do not directly indicate the independent rotation of a Falkland Islands block, and closely constrain models of southwest Gondwana evolution.