Potential Meteorite Impact Area Found in Argentina
15 May 2002
(Source: Planetary and Space Sciences Research Center)
Media Relations Office
The Open University
Milton Keynes, U.K.
Phil Bland, Planetary and Space Sciences Research Institute
Neil Coaten, Open University Media Relations
A new area of glass fragments thought to date from a meteorite impact almost half a million years ago has been discovered by an international team led by a scientist at the Open University.
The glass is found in an area of the Pampas region of Argentina, a site that became famous in 1992 when a US-led team identified ten elongate shallow depressions -- each kilometres long. They suggested they had been formed by the low-angle impact of an asteroid that had hit the Earth like a bouncing bomb. Meteorite glass was found in several of these depressions.
The new study of part of the Pampas region revealed more than 400 depressions, spread over an area that is too large to be the result of the low-angle impact that the scientists of the early 90s suggested. Instead, the team believes the depressions in the area around the city of Rio Cuarto were the result of wind action.
The Open University's Phil Bland, a Royal Society university research fellow, and Dr Simon Kelley, also from the OU, were joined by researchers from Brazil, the USA, Australia, Russia and Argentina for their work. They initially assessed satellite images of the area before undertaking field visits to 52 of the features.
The team believes that the fragments of glass it dated at the Rio Cuarto depressions are of a similar age to that of glass recovered 800km away, indicating that glass is found over a huge region and is not confined to shallow depressions. The material may be tektite glass -- pieces of fused rock and soil formed when a large meteorite strikes the Earth -- from an impact event about half a million years ago.
Glass would have splashed out of the impact, showering down over the surrounding area, and is found today in places where the wind has blown soil away -- the original shallow depressions.
Phil Bland said: "It seems plausible that the material we found is representative of a widespread tektite-strewn field in Argentina that is about 480,000 years old. We suggest that a recent, possibly well-preserved, complex crater remains to be discovered beneath the Pampean Plain of Argentina."
The team's paper A Possible Tektite-Strewn Field in the Argentinian Pampa is published in the 10 May 2002 issue of Science.
Phil Bland is a research fellow working in the Open University's Planetary and Space Sciences Research Institute; Dr Simon Kelley works in the university's Department of Earth Sciences. The team was also helped by Vanessa Evers, of the university's Institute of Educational Technology.