The significance of Antarctica for studies of global geodynamics

Antarctica has geometric significance for global plate kinematic studies, because it links seafloor spreading systems of
the African hemisphere (Indian and Atlantic Oceans) with
those of the Pacific. Inferences of plate motions back to 44
Ma, around the onset of rapid spreading south of Australia
and formation of a new boundary through New Zealand, are
consistent with Antarctic rifting and formation of the Adare
Basin during 44-26 Ma (i.e., no additional plate motions
are required in the South Pacific). The time period 52-44
Ma represents a profound global and South Pacific tectonic
change, and significant details remain unresolved. For 74 Ma
a significant nonclosure of the South Pacific plate-motion circuit is identified if Antarctic motion is not included. Alternate
inferences of motion through Antarctica during the interval
74-44 Ma imply significantly different subduction volumes
and directions around the Pacific, and imply different relative
motions between hotspots