December 10, 2013
Mapping The Dinosaur-Killing Yucatan Peninsula Asteroid Impact Site
April Flowers for redOrbit.com - Your Universe Online
An asteroid or comet crashed into a shallow sea near what is now the Yucatan Peninsula of Mexico approximately 65 million years ago. A firestorm and global dust cloud resulted, causing the extinction of many land plants and large animals, including most of the dinosaurs.
Researchers from the Monterey Bay Aquarium Research Institute (MBARI) presented evidence this week at a meeting of the American Geophysical Union (AGU) that remnants from this devastating impact are exposed along the Campeche Escarpment—an immense underwater cliff in the southern Gulf of Mexico.
The impact from this ancient meteorite created a crater over 99 miles across. The crater is buried beneath hundreds of feet of debris and at least half a mile of marine sediments, making it nearly invisible for modern geologists, however. The fallout from the impact has been found in rocks around the globe, although there has been surprisingly little research done on the rocks close to the impact site, partially because they are so deeply buried. Currently existing samples of impact deposits close to the crater have come from deep boreholes drilled on the Yucatan Peninsula.
Led by MBARI scientist Charlie Paull, an international team of scientists created the first detailed map of the Campeche Escarpment in March 2013 using multi-beam sonars on the research vessel Falkor, operated by the Schmidt Ocean Institute. Google Maps and Google Earth have recently incorporated the new maps for viewing by researchers and the general public.
Just northwest of the Yucatan Peninsula is the Campeche Escarpment, a 372-mile long underwater cliff. Paull has long suspected that rocks associated with the impact crater might be exposed along this nearly 13,000-foot tall cliff, which is one of the steepest and tallest underwater features on Earth. Except that the Escarpment is thousands of feet below the sea, it is comparable to one wall of the Grand Canyon.
Sedimentary rock layers are exposed on the face of the Campeche Escarpment, much like on the walls of the Grand Canyon. These layers provide a sequential record of the events that have occurred over millions of years. The new maps suggest that rocks formed before, during and after the impact are all exposed along different areas of the cliff face.
Paull hopes that one day, geologists will be able to perform geologic fieldwork -- such as collecting samples along the Escarpment -- just as they can map layers of rock walking the Grand Canyon. Performing large-scale geological surveys thousands of feet below the ocean surface would have seemed a distant fantasy just a few decades ago. Such mapping has become almost routine for MBARI geologists in the last eight years, with the use of underwater robots.
A new chapter in research about one of the largest extinction events in the history of our planet could be opened up by the new maps and the data they represent. Researchers from MBARI and other institutions are already using these maps to plan further studies in this little-known area. Fascinating new clues about what happened during the massive impact event that ended the reign of the dinosaurs will be revealed through detailed analysis of the bathymetric data and eventual fieldwork on the escarpment – clues that have been hidden beneath the ocean for 65 million years.