PREFACE The Division of Minerals is responsible for managing state and local government mineral interests on more than 10,000,000 acres of land. The geologic drilling program is one of a number of projects carried out to improve the mineral potential data base to aid in managing these interests, particularly in those areas where greater mineral potential is suspected but data is lacking and there is no industry leasing of state mineral ownership. The current program is a continuation of one begun in 1980 as a result of funding by the Legislative Commission on Minnesota Resources. The information gained serves to aid managers in making land use decisions, establishing mineral leasing priorities, and encouraging mineral diversification activities in Minnesota.
A variety of factors are taken into account when choosing or determining regions worthy of further investigation. These include the character of the geology of the regions, the type of mineralization that might be expected, the commodity(s) of greatest current economic interest as well as those having potential future interest, the mode of occurrence of potential mineralization, and the current level of knowledge with respect to these regions. As part of this process, a variety of data sources are used including available geologic maps and literature, Minnesota Geological Survey aeromagnetic and gravity data, existing geocheMical information, and discussions with people from industry and academia. The Minnesota Geological Survey personnel were particularly helpful, especially Dr. D. Southwick, Dr. G. Morey, and Dr. V. Chandler. Geological, geochemical, and geophysical investigations were also used, when applicable, to further evaluate areas of interest. The DNR Division of Waters contributed both personnel and equipment for the conduct of refraction seismic surveys. Pat Bloomgren, Andrew Streitz and Joe Julik were particularly helpful. Finally, a diamond drill hole might be cored to determine whether or not the lithologic, structural, or economic indicators suggested by this investigation are indeed present.
Lithologic units covered in this report are all Proterozoic in age and include the Thompson Formation in St. Louis County, the Glen Township Formation in Aitkin County, the Larson Lake area in Crow Wing County, and several locations within the Duluth Complex in St. Louis and Lake counties. Each location is treated separately in the report as a self-contained section consisting of all information derived for that location. This includes the geophysical data, geologic log and analytical data for the drill hole.
Report 251: 1986-1987 Geodrilling Report; DNR Drill Core from T46N R25W, T46N R28W, T52N R15W, T59N R12W, T56N R14W, T57N R12W
(190 pages, 8.5 x 11 inches, 5.91 MB)
Authors: E.H. Dahlberg, B.A. Frey, L.W. Gladen, T.L. Lawler, K.L. Malmquist, and M.P. McKenna
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