Gold mineralization in northeastern Minnesota occurs in numerous prospects east of Lake Vermilion in rocks of the Bass Lake sequence (Peterson and Jirsa, 1999) of the Neoarchean Wawa Subprovince of the Canadian Shield. This zone of abundant gold mineralization is bounded to the south by the Mud Creek shear zone and to the north by the Vermilion fault (Fig. 1). The main access to these prospects is along the Mud Creek road (County Road 38).
A brief period of mineral exploration for lode-gold deposits in this immediate area of the Vermilion district occurred in the mid 1980s to early 1990s. These programs typically consisted of grid-based geologic mapping, bedrock sampling, ground geophysics, and the completion of soil geochemical surveys. Personal conversations with many of the people involved in gold exploration programs in the area, and compilation of all exploration data from the district as a whole by Peterson (2001), has led to the conclusion that interpretation of linear structural elements exposed in outcrops were typically not used in designing exploratory drilling plans in the map area. Therefore, many of the prospects discovered on the surface as a result of these exploration programs remain untested by drilling. The goal of this project was to try to determine the downdip orientation of specific gold mineralized zones discovered in these previous exploration programs, and therefore, encourage new gold exploration in the area. Brief descriptions of the techniques used in the project are described below.
Detailed geologic outcrop maps (at scales ranging from 1:1,000 to 1:3,000) were completed for a number of the gold prospects located in the field area. The mapping was focused on structural (shear zones, lineations, intersecting foliations and small-scale folds), geological (contact relationships, competence contrasts), geochemical (gold assays, trace element characteristics), and alteration (Fe-bearing carbonate, sericite, pyrite, silicification) features within and around areas of gold mineralized exposures.
NRRI Economic Geology Group Map Series;
Peterson, Dean M; Patelke, Richard L.
Bedrock Geology and Lode Gold Prospect Data Map of the Mud Creek Road Area, Northern St. Louis County, Minnesota.
University of Minnesota Duluth.
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