Geology Field Report by Gordon Osinski and Colleen Lenahan
Impact craters are produced by the intense shock waves that are generated at, and which radiate out from the point of impact. As these shock waves expand outwards, they set the target rocks in motion, forcing debris outwards and upwards, thus excavating a crater. In large structures (> 2 to 4 km diameter), the initially steep crater walls undergo gravitational collapse along a series of interconnected faults. A major part of this years impact geology program has focussed on the characterization of these faults, in connection with ongoing structural and hydrothermal studies.
Many of the faults formed during the impact event have been exposed in a series of remote and virtually untouched canyon systems in the south of the Haughton impact structure. Because of the location of base camp on the northwest crater rim and the inaccessibility of the canyons, two intrepid geologists, Gordon "Oz" Osinski and Colleen Lenahan, set off on July 17th for a five day remote camp:
"We set off with packed ATV's on an overcast day with the Discovery film crew... the rain soon followed. After filming in the west of the crater, we left the film crew for what we hoped would be the sunnier southeast. Unfortunately, it was not to be, but we found a great campsite nestled, rather appropriately, between several large boulders. We set up camp very quickly during a lull in the rain and then settled in for supper and sleep... We awoke to a slightly nicer day, however, we were still wearing an average of nine layers of clothing each! We were eager to start the day's traverse into the Alan Shepard Canyon, named for the Apollo astronaut who passed away two summers earlier.
On entering the main canyon, our jaws dropped. The sight in front of us was sheer splendour. Steep canyon walls, rock pinnacles, turquoise waters... Over the next few days we explored the area in detail, making observations in our notebooks, taking photographs and collecting samples to take back to New Brunswick for further study. As the weather improved we soon found what we came looking for: several exposed fault planes, usually associated with large volumes of broken and ground up rock called breccia. Detailed study of these fault systems will hopefully give us a better understanding of how impact craters form on Earth, Mars and other planetary bodies. We also hope to learn how the structure of an impact crater governs any post-impact hydrothermal system, with its important astrobiological implications".
