DIGITAL MAGNETIC, GRAVITY, AND HEAT FLOW DATA FOR MAINE AND CANADA INTEGRATED WITH OTHER DIGITAL DATA IN AN OBJECT ORIENTED GEOGRAPHICAL INFORMATION SYSTEM

Digital data for the Earth’s magnetic field, gravity field and heat flow of the region straddling the St. Lawrence River valley for all of Maine and adjacent Quebec and Ontario in Canada have been assembled into an Object-Oriented Geographical Information System. These data have been combined with a previously acquired Digital Elevation Model, the Canadian and Maine digital geologic maps, seismicity data, World Stress Map stress vectors, and Global Positioning System data. A mosaic of four digital images derived from Landsat 5-TM satellite data of western Maine and adjacent Canada was used as a base for considering regional geology and tectonics in an intra-plate locale.

The heat flow, magnetic, and gravity contours were generated from 87, from 65,536 and from 82,544 data values, respectively. For the geophysical data analyzed, we found that earthquake epicenters are generally correlated with zones of high aeromagnetic anomalies, zones of low Bouguer gravity anomalies, and with values of low to intermediate heat flow. Magnetic values showed the highest correlation with bedrock geology. As expected, earthquakes are highly correlated with fault patterns in the St. Lawrence River valley. Data-resolution and recent regional de-glaciation are concerns in interpreting the regional geology and crustal dynamics.

The result of this investigation is a new and integrated view of the region for the purpose of geologic interpretation.