High-resolution animated tectonic reconstruction of the South Pacific and West Antarctic margin
An animated reconstruction shows South Pacific plate kinematics between 90 and 45 Ma, using the satellite-derived gravity anomaly field, interpolated isochrons and plate rotation parameters from both published and new work on marine geophysical data. The Great South Basin and Bounty Trough, New Zealand, are shown as the earliest Pacific-Antarctic plate boundary that opened before 83 Ma. The earliest true Pacific-Antarctic seafloor formed within the eastern parts of this boundary, but later and farther west, seafloor formed within its Antarctic flank. After 80 Ma, the Bellingshausen plate converged with an oceanic part of the Antarctic plate to its east, while its motion simultaneously caused rifting in continental Antarctica to the south. The Pacific-Bellingshausen spreading center developed a set of long offset transform faults that the Pacific-Antarctic plate boundary inherited around chron C27 when the Bellingshausen plate ceased to move independently as part of a Pacific-wide plate tectonic reorganization event. Southwest of these transforms the Pacific-Antarctic Ridge saw an increase in transform-fault segmentation by similar to58 Ma. One of the long offset Pacific-Bellingshausen transforms, referred to as "V,'' was modified during the C27 reorganization event when a Pacific-Antarctic-Phoenix triple junction initiated on its southern edge. Eastern parts of "V'' started to operate in the Pacific-Phoenix spreading system, lengthening it even more, while its western parts operated in the Pacific-Antarctic system. This complicated feature was by-passed and deactivated by ridge axis propagation to its northwest at similar to47 Ma. We interpret our animation to highlight possible connections between these events.
Authors: Eagles, Graeme, Gohl, Karsten, Larter, Robert