Mineral-resource map of the Petersburg quadrangle and parts of the Port Alexander, Sitka, and Sumdum quadrangles, southeastern Alaska

Abstract

The Petersburg project region covers about 16,300 km and includes all of the Petersburg, about one-third of the Port Alexander, a small part of the Sitka, and about one-tenth of the Sumdum l:250,000-scale quadrangles. The region is located in south-central southeastern Alaska and includes parts of the (from west to east) Chatham Trough, Prince of Wales Mountains, Kupreanof Lowland, Coastal Foothills, and Boundary Ranges physiographic divisions of Wahrhaftig (1965). Two towns, Petersburg and Wrangell, and two villages, Kake and Point Baker, are in the region. The region contains three mines and a wide variety of metallic mineral occurrences (Grybeck and others, 1984). One mine produced barite, one gold, and the other garnet. The region has long attracted the attention of prospectors and mineral exploration companies. This map and text report the results of a mineralresource-assessment study done during the period 1978 to 1982. The resource terminology used here is that of the U.S. Bureau of Mines and U.S. Geological Survey (1980; see Appendix A). As described below, a multidisciplinary team working in the field and office identified five mineral-resource tracts containing identified resources and other attributes that indicate a high probability for the occurrence of economic mineral deposits. The team also identified eight other tracts that have quantified undiscovered resources and other attributes that indicate a lesser probability for economic deposits. Unqualified undiscovered resources are believed to be present in 15 other tracts; three tracts have only geophysical anomalies that may have mineral-resource significance. Altogether, 31 tracts are shown on the map and described below. Several of the tracts overlap because they are defined by separate criteria or because different types of deposits are interpreted to be present.