DETAILED GRAVITY AND MAGNETIC SURVEYS AS AN AID TO SEARCHING FOR NATURAL GAS IN THE LAKE CHAMPLAIN VALLEY, NEW YORK

In southwestern Quebec, several blocks of land have been leased for natural gas exploration, one of which is just north of the Canadian-American border in the Lake Champlain Valley. These rocks continue southward into the Lake Champlain Valley in Clinton and Essex Counties in New York. Also there is natural gas in the Champlain Valley which is marked by several major faults. No detailed geophysical investigations in search of natural gas have been undertaken in this part of New York State although Columbia Gas ran five seismic lines. The occurrence of natural gas elsewhere in the same kinds of rocks (limestone and sandstone) that dominate the survey area make the Lake Champlain Valley attractive for a regional geophysical investigation relevant to natural gas exploration.

Gravity and magnetic investigations are important in searching for natural gas and oil because they detect linear patterns which often signify faults. The faults can serve as conduits for upward migration of gas and oil and also trap the gas. Three hundred and eight new magnetic measurements and three hundred forty three gravity measurements were made in the Lake Champlain Valley between 44.70 and 45.00 degrees North Latitude and 73.40 and 73.65 West Longitude. The gravity and magnetic maps show anomalies that originate in the Precambrian basement and correlate with surface faults in the overlying Cambro-Ordovician sedimentary rocks. This indicates that the faulting in the sedimentary rocks is controlled by faulting in the Precambrian basement. The gravity and magnetic maps are similar indicating the rock types producing the gravity highs and lows are also producing magnetic highs and lows and could indicate basement relief that could play a role in trapping gas.