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The Wilkes Land Anomaly revisited
- John G. Weihaupt, Frans G. Van Der Hoeven, Frederick B. Chambers, Claude Lorius, John W. Wyckoff, Devin Castendyk
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- Journal:
- Antarctic Science / Volume 27 / Issue 3 / June 2015
- Published online by Cambridge University Press:
- 14 January 2015, pp. 291-305
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The Wilkes Land Gravity Anomaly, first reported in 1959–60, is located in northern Victoria Land in the Pacific Ocean sector of East Antarctica, 1400 km west of the Ross Sea and centred at 70°00'S-140°00'E. Initially described on the basis of ground-based seismic and gravity survey, and estimated at the time to have a diameter of 243 km, the original data are now supplemented by data from airborne radiosound survey, airborne gravity survey, airborne magnetic survey and satellite remote sensing. These new data enable us to expand upon the original data, and reveal that the structure has a diameter of some 510 km, is accompanied by ice streams and a chaotically disturbed region of the continental ice sheet, has a subglacial topographical relief of ≥1500 m, and exhibits a negative free air gravity anomaly associated with a larger central positive free air gravity anomaly. The feature has been described as a volcanic structure, an igneous intrusion, an ancient igneous diapir, a subglacial sedimentary basin, a glacially eroded subglacial valley, a tectonic feature and a meteorite impact crater. We re-examine the feature on the basis of these collective data, with emphasis on the free air gravity anomaly signs, magnitudes and patterns, magnetic signature magnitudes and patterns, and the size, shape, dimensions and morphology of the structure. This enhanced view adds substantially to the original description provided at the time of discovery, and suggests several explanations for the origin of the Wilkes Land Anomaly. However, the importance of this feature lies not only in determining its origin but by the fact that this part of the Wilkes Subglacial Basin is one of the most prominent regional negative geoid and associated gravity anomalies of the Antarctic continent.
Origin(s) of Antarctica's Wilkes Subglacial Basin
- John G. Weihaupt, Frans G. Van Der Hoeven, Claude Lorius, Frederick B. Chambers
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- Journal:
- Antarctic Science / Volume 26 / Issue 4 / August 2014
- Published online by Cambridge University Press:
- 16 December 2013, pp. 377-383
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The Wilkes Subglacial Basin (WSB), the largest subglacial basin in East Antarctica, is a topographic depression of continental proportions that lies beneath the East Antarctic continental ice sheet. Discovered by the US Victoria Land Traverse 1959–60, the origin of the WSB and the influence of palaeoclimate on its overlying continental ice sheet have remained uncertain since the time of its discovery. Most explanations of origin favour lithospheric structural control as a function of tectonic activity. Lithospheric flexure due to thermally or isostatically induced uplift of the Transantarctic Mountains was suggested in the 1980s. Lithospheric extension and rifting was proposed in the 1990s. More recent investigations have revealed the presence of fold and thrust belts, casting doubt on flexural and extensional hypotheses as the primary mechanisms, suggesting instead a compressional scenario. While remaining inconclusive, these tectonic mechanisms in one form or another, or in combination, are now believed to have provided the structural control for the origin of the WSB. Not yet comprehensively examined, however, is the role of non-tectonic processes in the formation of the WSB, as they may have influenced the size, configuration, subglacial sedimentation and subglacial topography of the WSB. In this paper we review the tectonic hypotheses and examine post-tectonic climate change along with glacial and marine processes as potentially significant factors in the present condition and configuration of the WSB. In the process, we find that there are a number of features not included in previous investigations that may have been major factors in the modification of the subglacial basin.
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