A sprawling network of low-elevation basins hidden beneath more than three kilometers of East Antarctic ice has been identified as a single geological province, formed when a vast slab of continental crust rotated and stretched apart over millions of years. The newly defined East Antarctic Fan-Shaped Basin Province, or EAFBP, radiates outward from a focal point near the South Pole and encompasses well-known features including the Wilkes and Aurora basins and the basin containing Lake Vostok. Researchers say the structure may represent one of the largest examples of rotational extension ever documented on Earth, rewriting assumptions about how the eastern and western halves of the continent moved relative to each other.
Why a continent-scale rotation changes Antarctic science now
The discovery matters because it connects features that geologists had long treated as separate. The Wilkes Basin, the Aurora Basin, and the trough holding Lake Vostok sit beneath ice exceeding roughly three kilometers thick in places, according to recent analyses. Until now, each basin had its own local explanation. The EAFBP framework groups them into a single fan-shaped unit whose V-shaped arms all point back toward one rotation axis. That reframing has direct consequences for how scientists model ice behavior, because the shape and depth of bedrock beneath ice sheets control where ice flows fastest and where it stalls.
The rotation that created the EAFBP did not act in isolation. It interacted with and overrode lithosphere belonging to the older West Antarctic Rift System, a continental-scale zone of thinned crust whose geometry and geophysical evidence base were established in earlier peer-reviewed work published in AGU research. The WARS stretches east of the Byrd Subglacial Basin, as documented in separate geophysical studies. The new study argues that the rotational extension of the EAFBP cut across and partly reshaped that older rift architecture, a claim that, if confirmed by independent datasets, would require geologists to revise plate-boundary reconstructions for the entire continent.
One practical consequence involves ice-sheet modeling. Present-day simulations of Antarctic ice flow rely on assumptions about basal friction, the resistance that bedrock exerts on the sliding ice above it. If the EAFBP rotation pole sits at a persistent zone of lithospheric weakness, the radial corridors fanning out from it would have systematically different rock properties than the ridges between them. Models that treat basal friction as uniform or that vary it only by local geology, without accounting for the large-scale rotational pattern, could under-predict ice flow speeds along those corridors. That gap would matter most for projections of sea-level rise, because faster-flowing ice delivers more mass to the ocean.
The fan-shaped geometry also offers a new way to think about how ice might respond to future warming. Basins aligned with the direction of past extension are likely to be deeper and smoother than surrounding terrain. If marine-based ice sheets thin and retreat inland, these corridors could act as expressways, guiding warm ocean water and subglacial melt farther beneath the ice. Conversely, the intervening ridges might serve as pinning points where grounded ice can stabilize temporarily. By tying these features to a single tectonic origin, the EAFBP concept gives modelers a clearer template for where to look for such vulnerabilities.
Bedmap3 and BedMachine data trace the fan-shaped province
The identification of the EAFBP rests on improved sub-ice topography compiled from two major datasets. Bedmap3, whose gridding products are maintained by the British Antarctic Survey, assembles radar and altimetry point observations into continent-wide elevation maps. BedMachine Antarctica v2, an independent bed model that applies mass-conservation techniques alongside radar and altimetry constraints, provides a cross-check on basin shapes and depths. Together, these datasets allowed researchers to see the low-elevation V-shaped basins as parts of a coherent, semi-continental-scale unit radiating from a single focal point near the South Pole.
In practice, the team traced the edges of individual basins in the gridded elevation models and extended their axes toward the interior of the continent. Where those axes converged, they inferred the approximate location of the rotation pole. The match between separate basins was not perfect, but the overall pattern was striking: a series of troughs, each several hundred kilometers long, splaying outward like the ribs of a fan. Statistical tests on the orientations suggested that the alignment was unlikely to be random.
The rotational extension mechanism also offers a new explanation for one of Antarctica’s most puzzling features. The Gamburtsev Subglacial Mountains, a range comparable in height to the Alps yet buried entirely beneath the ice sheet, have long defied easy explanation. Earlier peer-reviewed work in Nature linked East Antarctic rifting to uplift of the Gamburtsevs. The EAFBP study builds on that connection, proposing that the same rotation that stretched the fan-shaped basins apart also compressed and pushed up the mountain range at the edge of the rotating block. In this view, the Gamburtsevs are not an isolated anomaly but a tectonic response to the same forces that carved the surrounding basins.
No new radiometric ages tying the rotational phase directly to the Gamburtsev uplift event have been published, however, leaving the precise timing of the link unresolved. Some geodynamic models favor a Mesozoic age for the main phase of extension, while others allow for older or multi-stage histories. Without rock samples from beneath the ice, those scenarios remain difficult to distinguish. The topographic patterns alone cannot reveal when the deformation occurred, only that it left a consistent geometric imprint.
Open questions about the rotation’s age, rate, and ice-sheet effects
Several gaps in the evidence limit what can be concluded so far. The geometry of the EAFBP is inferred entirely from static topography models. No direct seismic or GPS measurements of ongoing or recent rotational motion have been cited in the published research. That means the rotation could be ancient and fully inactive, or it could have residual effects on present-day stress fields. Without geodetic data, the distinction remains unclear.
The location of the proposed Euler pole, the mathematical point around which the crustal block rotated, also lacks published error estimates specific to the Bedmap3 and BedMachine reconstructions. Small shifts in that pole would change the predicted amount of extension along each basin and the amount of compression where the rotating block abutted more rigid crust. Those differences could, in turn, alter interpretations of how much thinning occurred in the underlying lithosphere and how much uplift might be expected at basin margins.
Another open question is how far downward the rotational deformation extends. The current work focuses on the upper crust, where basin shapes are easiest to observe. But if the rotation involved the entire lithosphere, it would have influenced mantle flow patterns and heat transport beneath East Antarctica. Warmer mantle material rising beneath stretched regions could have promoted localized melting, weakening the crust and making it more susceptible to further extension. Cooler, thicker lithosphere beneath adjacent blocks would have responded differently, potentially sharpening contrasts in rock strength along the basin boundaries.
For ice-sheet scientists, the most immediate concern is how these deep structures translate into present-day sliding conditions. Basins formed in highly extended crust may be underlain by softer, more fractured rocks and thicker sedimentary fills than neighboring highs. Those materials tend to host more liquid water at the bed, which lubricates ice flow. Yet the available data on subglacial hydrology remain sparse, particularly in the interior of East Antarctica. Until radar surveys and seismic campaigns fill in those gaps, the link between tectonic history and modern ice dynamics will remain partly speculative.
Future work is likely to focus on three fronts. First, targeted seismic profiles across key basin margins could test whether crustal thickness variations match the amounts of extension implied by the fan-shaped geometry. Second, airborne and satellite-based gravity measurements could refine estimates of lithospheric density and help distinguish between shallow and deep sources of the observed basins. Third, ice-flow models that incorporate spatially variable basal friction tied to the EAFBP pattern could explore how sensitive sea-level projections are to the new tectonic framework.
Even with these uncertainties, the recognition of a continent-scale rotational province beneath East Antarctica underscores how much of the planet’s tectonic history remains hidden under ice. By tying together scattered basins into a single coherent structure, the EAFBP concept offers a unifying story for a region once seen as a patchwork of unrelated features. As better data arrive, that story will almost certainly be revised, but it has already shifted the way scientists think about the deep foundations of the Antarctic ice sheet and its long-term stability.
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*This article was researched with the help of AI, with human editors creating the final content.
