Abstract
The kinematic evolution of the West Antarctic rift system has important consequences for regional and global geodynamics. However, due to the lack of Neogene seafloor spreading at the plate boundary and despite being poorly resolved, East-West Antarctic motion was assumed to have ended abruptly at 26 million years ago. Here we present marine magnetic data collected near the northern edge of the rift system showing that motion between East and West Antarctica lasted until the middle Neogene (~11 million years ago), long after the cessation of the known mid-Cenozoic pulse of motion. We calculate new rotation parameters for the early Neogene that provide the kinematic framework to understand the varied lithospheric settings of the Transantarctic Mountains and the tectono–volcanic activity within the rift. Incorporation of the Antarctic plate motion into the global plate circuit has major implications for the predicted Neogene motion of the Pacific Plate relative to the rest of the plates.
Highlights
The kinematic evolution of the West Antarctic rift system has important consequences for regional and global geodynamics
If the rift acted as a plate boundary during the Neogene, evidence of its motion should be documented in the oceanic crust younger than 26 million years (Myr) that formed along the two other arms of the triple junction (i.e., Australia-East Antarctica and Australia-West Antarctica spreading systems, Fig. 1)
If there was an active plate boundary in Antarctica during the Neogene, indications of East-West Antarctic motion should be apparent when rotating the Australian anomalies that are younger than anomaly 8o (26.0 Myr, anomaly ages are from Ogg29) back to East Antarctica by using the rotation parameters calculated based on data from west of the George V fracture zone (Fig. 1)
Summary
The kinematic evolution of the West Antarctic rift system has important consequences for regional and global geodynamics.
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