Recent Advances in Meteorite Crater Research at the Dominion Observatory, Ottawa, Canada

Abstract

AbstractThe Dominion Observatory's meteorite crater research program is reviewed, with brief outlines of the methods of investigation, the progress to date, and plans for the future. The results and implications of recent investigations at the Deep Bay crater, the New Quebec crater and the Carswell Lake structure are presented.At Deep Bay diamond drilling near its center has confirmed that Cretaceous sedimentary rock lies within the crater, indicating a minimum crater age of 140 million years. Analysis of deformed rock and gneiss breccia encountered in a drill hole one mile from shore suggests that the original crater diameter is about 31,000 feet, considerably less than first estimated.Preliminary results of a gravity survey and a new shaded topographical map of the New Quebec Crater are presented. After correcting for terrain and regional effects a residual negative gravity anomaly of 6 milligals is indicated. Integration of topographical irregularities shows that the volume of the rim of the New Quebec Crater is about double the volume of the crater below the surrounding plain.Gravity and magnetic results over the Carswell Lake structure are consistent with an impact crater some 19 miles in diameter, taking into consideration that its original deformed floor has been uplifted in response to isostatic forces. Fragments of gneiss having radiating strations characteristic of shatter cones, discovered in the area of central uplift, support the meteoritic hypothesis of origin for this structure.