CONFIRMED IMPACT CRATERS
Combined results of two magnetic surveys performed using the GEM Systems GSM 19-TW. This represents the diurnally corrected data. Dense vegetation along the southern half of the grid made surveying slightly more difficult. A large magnet was found at the large positive anomaly on the NW crater rim (one of three found to date, likely left behind by meteorite hunters). With the exception of the magnet, large meteorites, about several hundred grams each, were found at all the major anomalies. Several other meteorites of similar scale were recovered from additional localized anomalies evident only in the raw data.
SUSPECTED IMPACT CRATERS
CAN-AM (PROBABLE) IMPACT STRUCTURE
Regional shaded relief map of residual magnetic anomaly field of the Can-Am structure located within Lake Huron.
Can-Am vertical derivative of residual magnetic anomaly field. G.F. = Grenville front.
A strongly negative magnetic anomaly coincides with Charron Lake, Manitoba. D. H. Hall (University of Manitoba) calculated that the removal of a block of the slightly magnetic country rock granite would produce the negative anomaly over the lake.
Lake Charron, top centre, contains a very strong magnetic anomaly (Natural Resources Canada).
HIGH ROCK LAKE
Location of coreholes in the High Rock Lake structure magnetic map and of cross-section A-A’ (after McCabe, 1982).
Magnetic contour map of vicinity of Merewether (J. Vise and L.I. Cowan).
The type of magnetic field change, a negative magnetic anomaly of ~80nT centered over the crater, is consistent with that found at other impact sites. The model suggests it is 3.4 km wide and the undisturbed bedrock is at ~750 m (Unpublished geomagnetic and electrical survey report Energy Mines and Resources, Earth Physics Branch (GSC) by J.F. Clark). Courtesy of Dr. James Whitehead, Planetary and Space Science Centre, University of New Brunswick. http://www.unb.ca/passc/ImpactDatabase/This Aeromagnetic Chart was researched and forwarded to me by fellow RASC member Eric Briggs.
MANITOU ISLAND COMPLEX
Abstract, (Rowe 1954) Two concentric fenitic zones comprise the outer part of the complex : 1 ) an outer zone of quartz fenite as much as 400 feet wide ; and 2 ) an inner zone of aegirine-potassic feldspar fenite as much as 1,500 fee t wide .