PATERSON CRATER*

*The earliest known ground-based investigation of this region is the 1953–1954 British North Greenland Expedition, which included eminent glaciologist W. S. B. (Stan) Paterson (Paterson, 1955). Should the impact origin of this structure be established definitively, we suggest respectfully that it be named the Paterson crater. (MacGregor et al Feb 2019)

by: Charles O’Dale

Data references from:  Geophysical Research Letters   11 February 2019

• Type: Complex
• Age:  >10⁵  to >10⁸ years (Geological dating)^a
• Diameter: 36.5 ± 0.2 km
• Location: N 78.27°  W 58.41°

^aThe period necessary to erode a putative crater to its present morphology also loosely constrains its age (Kjær et al., 2018). Assuming that the structure’s original morphology had a rim-to-floor depth of >1 km, which is consistent with that expected for a crater of this size (Collins et al., 2005) but an order of magnitude greater than its present value (~160 m), then >10⁵ years is required to erode into the present morphology beneath a thawed ice sheet bed and >10⁸ years for a frozen bed. This simple calculation ignores likely subglacial sediment deposition on the crater floor, which would occur at a rate comparable to erosion and decrease the burial period. (MacGregor et al Feb 2019)

A Possible Second Large Subglacial Impact Crater in Northwest Greenland

Joseph A. MacGregor, William F. Bottke Jr., Mark A. Fahnestock, Jeremy P. Harbeck, Kurt H. Kjær, John D. Paden, David E. Stillman, Michael Studinger

Geophysical Research Letters, February 2019

Abstract

Following the discovery of the Hiawatha impact crater beneath the northwest margin of the Greenland Ice Sheet, we explored satellite and aerogeophysical data in search of additional such craters. Here we report the discovery of a possible second subglacial impact crater that is 36.5-km wide and 183 km southeast of the Hiawatha impact crater. Although buried by 2 km of ice, the structure’s rim induces a conspicuously circular surface expression, it possesses a central uplift, and it causes a negative gravity anomaly. The existence of two closely spaced and similarly sized complex craters raises the possibility that they formed during related impact events. However, the second structure’s morphology is shallower, its overlying ice is conformal and older, and such an event can be explained by chance. We conclude that the identified structure is very likely an impact crater, but it is unlikely to be a twin of the Hiawatha impact crater.

 

Plain Language Summary

It is increasingly rare to find new large impact craters on Earth, let alone such craters buried beneath ice. We describe a possible impact crater buried beneath 2 kilometers of ice in northwest Greenland. The circular structure is more than 36 kilometers wide, and both its shape and other geophysical properties are consistent with an impact origin. If eventually confirmed as an impact crater, it would be only the second found beneath either of Earth’s ice sheets. The first was the Hiawatha impact crater, which is also in northwest Greenland and only 183 kilometers away from this new structure, so we also evaluated whether these two craters could be related. They are similarly sized, but the candidate second crater appears more eroded and ice above it is much less disturbed than above the Hiawatha impact crater. Statistical analysis of the frequency of two unrelated but nearby large impacts indicates that it is improbable but not impossible that this pair is unrelated. Our study expands knowledge of the impact history of the Earth and raises the question as to how many other impact craters buried beneath ice have yet to be found.

 

Following the discovery of the Hiawatha impact crater beneath the northwest margin of the Greenland Ice Sheet, we explored satellite and aerogeophysical data in search of additional such craters. Here we report the discovery of a possible second subglacial impact crater that is 36.5‐km wide and 183 km southeast of the Hiawatha impact crater. Although buried by 2 km of ice, the structure’s rim induces a conspicuously circular surface expression, it possesses a central uplift, and it causes a negative gravity anomaly. The existence of two closely spaced and similarly sized complex craters raises the possibility that they formed during related impact events. However, the second structure’s morphology is shallower, its overlying ice is conformal and older, and such an event can be explained by chance. We conclude that the identified structure is very likely an impact crater, but it is unlikely to be a twin of the Hiawatha impact crater.

Reference:

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Collins, G. S., Melosh, H. J., & Marcus, R. A. (2005). Earth impact effects program: A web-based computer program for calculating the regional environmental consequences of a meteoroid impact on Earth. Meteoritics and Planetary Science, 40(6), 817– 840.

Howat, I. M., Negrete, A., & Smith, B. E. (2014). The Greenland Ice Mapping Project (GIMP) land classification and surface elevation data sets. The Cryosphere, 8(4), 1509– 1518.

Kjær, K. H., Larsen, N. K., Binder, T., Bjørk, A. A., Eisen, O., Fahnestock, M. A., et al. (2018). A large impact crater beneath Hiawatha Glacier in northwest Greenland. Science Advances, 4(11), eaar8173-12.

Mosley-Thompson, E., McConnell, J. R., Bales, R. C., Li, Z., Lin, P., Steffen, K., et al. (2001). Local to regional-scale variability of annual net accumulation on the Greenland ice sheet from PARCA cores. Journal of Geophysical Research, 106(D24), 33,839– 33,851.

Paterson, W. S. B. (1955). Altitudes on the inland ice of north Greenland. Meddelelser om Grønland, 137(1), 1– 12.

Zwally, H. J., Giovinetto, M. B., Beckley M. A., & Saba, J. L. (2012). Antarctic and Greenland drainage systems.