REGIONAL GEOLOGICAL FRAMEWORK FOR EXPLORATION OF NATURAL GAS IN THE ST. LAWRENCE LOWLANDS AND THE CHAMPLAIN VALLEY OF NORTHEASTERN NEW YORK AND QUEBEC

摘要

A multidisciplinary investigation involving remote sensing, GIS and field geology was conducted in order to characterize the study area with the ultimate objective being to assess the potential for natural gas reserves. Results show that current drainage features, developed over flat agricultural areas, are associated with geomorphic depressions on top of the bedrock, which are probably basement-controlled fault zones as suggested by the geological and geophysical data. Along the western border of Lake Champlain and the northward continuation into southern Quebec those linear features trend predominantly N-S to NNE, although there are other trends as well. They and many other lineaments throughout the entire study area are clearly expressed as ridges and streams and many seem to correlate well with geophysically expressed lineaments which pass from the Precambrian basement upward at least to the top of the Trenton Group. From the field geological investigations and available seismic data, the N-S to NNE lineaments are interpreted as east-dipping normal or thrust faults zones, any of which may represent potential pathways for the migration and trapping of natural gas. On the northern rim of the Adirondacks, NNW drainage features correlate very well with NNW magnetic discontinuities. NW- and NE-trending fractures occur along the border of a major sub-circular magnetic anomaly, more than 70 km in diameter, which is located in the basement of southern Quebec. That regional geophysical anomaly is inferred to be associated with a major intrusion, the emplacement of which may have favoured the development of normal fault zones on its border. Furthermore, that anomaly is bounded and cut by several NE and NW magnetic discontinuities along, or parallel to, which clusters of earthquakes have been recorded. Those earthquakes are clear indicators that those faults are presently active and they may also represent conduits for hydrocarbon fluid flow.