The tectono-stratigraphic architecture of the Falkland Plateau basin; implications for the evolution of the Falkland Islands Microplate

• Published in: Gondwana Research
• Main Authors: Stanca, Roxana M., McCarthy, Dave J., Paton, Douglas A., Hodgson, David M., Mortimer, Estelle J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2022
• Subjects: East Antarctica; Falkland Plateau; Antarc*; Antarctica
• Online Access: http://nora.nerc.ac.uk/id/eprint/531614/; https://nora.nerc.ac.uk/id/eprint/531614/1/1-s2.0-S1342937X2100277X-main.pdf; https://doi.org/10.1016/j.gr.2021.09.014

Commonly, intra-continental wrenching is associated with a high degree of crustal faulting and fragmentation. The resulting continental blocks can undergo vertical-axis rotations, which in turn can lead to the generation of intricate fault networks within and along their boundary regions. Investigations into these structural complexities can support understanding of when and how these continental blocks rotate, and what their position was prior to transform margin formation. In the case of the Falkland Islands Microplate (part of the Falkland Plateau transform margin), its position between South Africa, South America, and East Antarctica prior to the break-up of Gondwana is still debatable. This uncertainty affects the reliability of plate models for this region. Here we integrate gravity and 2D and 3D seismic reflection data from the eastern margin of the microplate (west side of the Falkland Plateau Basin) to provide insights into the tectono-stratigraphic architecture of this area from Jurassic onwards, and into the evolution of the Falkland Islands Microplate. Our findings show that the western part of the Falkland Plateau Basin is an integral part of the microplate, and it underwent deformation in a relatively fast-changing stress regime. Stress field configuration estimates across the Falkland Islands Microplate support an alternation between a NE-SW and NW-SE/WNW-ESE orientation of σ3 during the Jurassic and an ENE-WSW oriented σ3 during the Lower Cretaceous. Correlations of this local stress configuration with the regional support a Middle to Upper Jurassic rotation of the microplate in a predominantly extensional setting facilitated by the early fragmentation of south-western Gondwana.