The plate is separated from the Scotia plate by the East Scotia Rise, a back-arc spreading ridge formed by the subduction zone on its eastern margin.
The initiation of the South Sandwich subduction zone, a convergent plate margin, began around 66 million years ago in response to regional convergence of the Antarctic and South American tectonic plates.
The South Sandwich Microplate separated from the Scotia plate around 15 million years ago as a back arc basin formed with development of the East Scotia Rise.
Two primary mechanisms have been proposed, subducting slab roll back and absolute motion of the Scotia plate away from the trench.
A combination of these two mechanisms could also contribute to the current plate boundary configurations.