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| Wilkes Land crater | |
|---|---|
| Name | Wilkes Land crater |
| Location | Wilkes Land, East Antarctica |
| Diameter | ~500 km (gravity anomaly) |
| Age | Late Permian? Cretaceous? (disputed) |
| Discovered | 2006 (gravity anomaly studies) |
| Country | Antarctica |
Wilkes Land crater is a hypothesized large impact structure beneath the ice of Wilkes Land in East Antarctica. First proposed after geophysical surveys revealed a pronounced subsurface gravity anomaly, it has been linked in some studies to large impacts and debated connections with global events such as the Permian–Triassic extinction event and the Cretaceous–Paleogene extinction event. The feature remains controversial because direct geological exposure is precluded by the Antarctic ice sheet and because alternative explanations invoke tectonic processes described in studies from institutions such as the United States Geological Survey and the British Antarctic Survey.
Initial evidence for a large subsurface anomaly in Wilkes Land emerged from reanalysis of satellite-derived gravity data and airborne magnetics, including datasets produced by the Gravity Recovery and Climate Experiment and mission-calibrated maps used by the National Aeronautics and Space Administration. Geophysicists reported a roughly circular positive gravity anomaly that suggested a dense mascon-like concentration beneath the ice, resembling structures like the Chicxulub crater and mascon features seen on the Moon. Early proponents compared the anomaly to known impact structures catalogued by the International Association of Seismology and Physics of the Earth's Interior and linked it to gravity anomalies documented in surveys by the Lamont–Doherty Earth Observatory.
The anomaly beneath Wilkes Land exhibits a roughly circular shape, an amplitude and wavelength consistent with a buried central uplift or denser mantle material, and spatial correlation with magnetic anomalies recorded by the British Antarctic Survey and the Australian Antarctic Division. Gravity inversion models inferred a concentration some hundreds of kilometers across, with spectra analogous to the Vredefort crater and Sudbury Basin at smaller scales. Seismic reflection and wide-angle seismic profiles acquired during Antarctic campaigns by teams from the Scripps Institution of Oceanography and the Institut polaire français Paul-Émile Victor have been used to constrain crustal thickness and subsurface structure, though ice-penetrating radar results from the European Space Agency and the Polar Geospatial Center complicate interpretations because of isostatic adjustments associated with the Antarctic Ice Sheet.
Age estimates for the hypothesized structure are highly uncertain. Some geoscientists suggested a Late Permian age potentially linking it to the Permian–Triassic extinction event, while others proposed a younger Cretaceous age that would be temporally nearer to the Cretaceous–Paleogene extinction event. These hypotheses invoked stratigraphic correlations with radiometric dates established by laboratories associated with the Geological Survey of Western Australia and the Geological Survey of Canada. Alternative formation scenarios include rift-related magmatism connected to the breakup of Gondwana and plume activity associated with the Kerguelen hotspot, invoking comparisons with the Deccan Traps and flood basalt provinces documented by researchers at the Geological Society of America.
Because of the potential size of the anomaly, several papers speculated about causal links between the feature and mass extinctions such as the Permian–Triassic extinction event and the Cretaceous–Paleogene extinction event. Proponents argued that an impact of sufficient magnitude could generate global environmental effects similar to models developed for Chicxulub that involve ejecta, atmospheric dust, and wildfires discussed in publications by the National Academy of Sciences. Critics countered that temporal correlation is unproven and that geochemical signatures—such as global iridium anomalies, shocked minerals, or isotopic excursions recorded in cores curated by the Lamont–Doherty Earth Observatory and the International Ocean Discovery Program—have not been definitively linked to this Antarctic anomaly. The debate reflects broader discussions about the role of impacts versus volcanism in mass extinctions informed by work from the Royal Society and the American Geophysical Union.
After the initial reports, teams from institutions including the Australian Antarctic Division, the British Antarctic Survey, and several universities conducted follow-up gravity, magnetic, seismic, and ice-penetrating radar studies. Some publications supported an impact origin citing similarity to known craters, while others argued for tectono-thermal origins related to Gondwana breakup and intraplate magmatism linked to research from the Centre National de la Recherche Scientifique. Controversies center on data resolution limits, modeling assumptions in gravity inversion, and the absence of drill cores or exposed ejecta comparable to those recovered by the US Antarctic Program and the Kola Superdeep Borehole projects. Conferences held under the aegis of the European Geosciences Union and special issues in journals from the Geological Society of London have hosted much of the technical debate.
Wilkes Land hosts other geologic and geophysical features studied by the Antarctic Treaty Secretariat and national programs, including rifted margins associated with the breakup of Gondwana, flood basalt provinces correlated with the Kerguelen Plateau, and crustal blocks whose architectures resemble parts of the East African Rift and the Siberian Traps provinces. Ice-sheet dynamics over these substrates have been imaged by radar campaigns from the European Space Agency and the National Science Foundation, revealing subglacial basins, subglacial lakes akin to Lake Vostok, and tectonic boundaries mapped in surveys by the Geological Survey of Norway.
Category:Impact craters Category:Antarctica geology