GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 165-1
Presentation Time: 8:05 AM


EGLINGTON, B.M., Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK S7N 5E2, Canada, EVANS, David, Geology and Geophysics, Yale University, 210 Whitney Ave, New Haven, CT 06511 and DALZIEL, Ian W.D., Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 10100 Burnet Road (R2200), Austin, TX 78758-4445

The Falklands Plateau, extending east into the Atlantic Ocean from South America comprises an exposed Mesoproterozoic crustal block in the Falklands Islands and a submerged Mesoproterozoic block in the Maurice Ewing bank, separated by the Falkland Basin. Since first suggested by Adie (1952), the Falklands Islands are often described as having rotated off of south eastern Africa during Gondwana breakup, based on various geological similarities, such as stratigraphic outcrop pattern. Available palaeomagnetic data for dolerite dykes. This rotated configuration is generally adopted by Precambrian geologists and plate reconstruction models. The preferred model for rotation from a Gondwana configuration to the present day involves a saloon-door type opening of the Falkland Islands block and the Ellsworth-Whitmore mountains block (now in Antarctica) as part of the separation of Antarctica-India-Madagascar from Africa before South America and Africa separated.

Following on from regional geophysical investigations of the Falklands Plateau as a consequence of oil exploration, most Mesozoic to Cenozoic geologists and plate reconstruction models favour the Falkland Islands being fixed in position relative to southern South America.

GIS-based compilation of geological and geophysical information from multiple sources provides context for the various components of the Falkland Plateau relative to South America and southern Africa. Modern sub-seafloor seismic studies of the Falkland Island area has extended the known spatial limits of Devonian and Permo-Carboniferous rocks which affects the rotated position of the block, while also defining fault and dyke patterns which can be correlated with Karoo/Ferrar and Parana/Etendeka volcanism and the opening of the Weddell Sea and Atlantic Ocean. Sediment deposition patterns in southern Africa and isopach distributions for a number of stratigraphic units provide additional constraints for the saloon door (drinking buddy) and in-situ (stay-at-home) scenarios. Some of the associations used to define the original rotated reconstruction are no longer supported butwith the exception of palaeomagnetic data, there are no unequivocal reasons to prefer either one of the model end members.