METHODS OF EXPLORATION FOR STRATA-BOUND MINERAL DEPOSITS IN THE APPALACHIAN-CALEDONIAN OROGEN.

In response to a questionnaire on the topic of strata-bound mineral deposits in the Caledonian-Appalachian orogen circulated in 1980-1981, 82 contributions were received: United States (20), Canada (17), Denmark - for Greenland (3), Ireland (3), United Kingdom (10), Norway (6), and Sweden (23). On the basis of 68 strata-bound mineral deposits found in the past, the most successful methods of exploration have been geologic mapping and ground electromagnetic surveys, followed by geologic interpretation and prospecting. Boulder tracing found Laisvall and many other deposits in Sweden. The Brunswick 12 deposit in Canada was discovered by airborne magnetic and ground electromagnetic methods. Reports from 58 districts illustrate that a wider range of methods is currently being used for strata-bound mineral exploration in the Appalachian-Caledonian orogen than in the past. Geologic interpretation and ground electromagnetic techniques are proving to be most effective, followed by mapping and soil and till sampling. Photogeology, general prospecting, boulder tracing, drainage geochemistry, and airborne techniques are also achieving considerable success. Outstanding results are being obtained from magnetic and gravity surveys in the Bathurst area of Canada.