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    Information Circular 4. Directory of Minnesota Mineral Producers 1964
    (Minnesota Geological Survey, 1966) Hogberg, R.K.
    This Information Circular is published by the Minnesota Geological Survey to fulfill a part of its responsibility for providing information on the State's mineral resources. In this directory a mineral producer is defined as one who removed or mined mineral-bearing materials or substances other than water from their natural setting. Generally the producer processed the mineral raw materials into a form more suitable for marketing. The business addresses, locations of the sites of exploitation and associated plants are listed.
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    Information Circular 47. Compositions of Rift-Related Volcanic Rocks of the Keweenawan Supergroup Atop the St. Croix Horst, Southeastern Minnesota
    (Minnesota Geological Survey, 2001) Morey, G.B.
    This information circular summarizes stratigraphic and geochemical information obtained in the 1980s and early 1990s from Mesoproterozoic volcanic rocks associated with the Midcontinent rift system. These rift-related rocks comprise the St. Croix horst, a major structural feature now mostly buried by a thin cover of generally flat-lying sedimentary rocks of Paleozoic age. Although the studies described herein were completed 10 to 15 years ago, the results have never been published. This report is intended to correct that omission.
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    Information Circular 46. Aggregate Resources Inventory of the Seven-County Metropolitan Area, Minnesota
    (Minnesota Geological Survey, 2000) Southwick, D.L.; Jouseau, M.; Meyer, G.N.; Mossler, J.H.; Wahl, T.E.
    Construction aggregates are sand, gravel, and crushed rock-bulk granular materials that are used in building and landscaping projects of all sizes and kinds. Most of the highest quality aggregate is used in the manufacture of concrete and top-grade asphalt paving. Aggregates of lower quality are used as fill, base-course for roads, and for a myriad of other purposes. Aggregate quality is determined by the mechanical and chemical properties of the constituent rock particles. In very general terms, the best aggregates for high-end uses contain particles that are strong (resist abrasion and fracturing), chemically inert (do not decompose, swell, or shrink on exposure to air, moisture, or road chemicals; do not react adversely with cement materials), and are of optimum size and shape for the specific engineering requirements. High-strength concrete for heavy-duty use such as highways and airport runways requires aggregate composed of particles that are strong and inert, and also have broken faces; i.e. they are not round and smooth. This broken shape enables the particles to lock up mechanically with one another rather than roll under stress, and improves the durability of the paving. Construction aggregate producers and their largest customers in the construction sector have recognized for many years that the aggregate resources available for mining within the seven- county metropolitan area are rapidly diminishing. The ultimate reason for this is urbanization, which on the one hand increases the demand for construction aggregates, and on the other, tends to remove aggregate-bearing lands from production through land development and zoning decisions that preclude mining. When sources of aggregate are eliminated locally, and become more remote from places of need, the costs of construction rise significantly. This is mainly because of the increased cost associated with aggregate transportation. Cost increases are felt most acutely in large projects such as freeway or airport runway construction that require huge volumes of high-quality aggregate for concrete. Local decision-makers have become increasingly aware of aggregate-resource issues over the past few decades. Most counties and townships are substantial purchasers of aggregate materials for road building and other purposes, and are therefore sensitive to aggregate costs. Many are also involved in the controversies between neighbors and aggregate producers over the noise, dust, truck traffic, and other environmental impacts (real or perceived) associated with aggregate- mining operations. In Minnesota, including the seven-county metropolitan area, the powers to regulate aggregate mining and associated industrial operations reside largely at the county, city, and township level. Issues of land-use planning and regulation that apply to the construction aggregates industry need to be resolved. Government entities, the aggregate industry, and citizens of the seven-county metropolitan area all require dependable information on the physical distribution of aggregate resources and the probable economic lifespan of the local resource base. This report and the companion geological maps on which it is based (Meyer and MossIer, 1999) were prepared to meet that need.
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    Information Circular 45. Utility of Elemental Geochemical Data in Correlation and provenance Studies of Pleistocene Materials: A Case Study in Stearns county, Central Minnesota
    (Minnesota Geological Survey, 2000) Morey, G.B.; Lively, R.S.; Meyer, Gary N.
    Geochemical attributes, especially minor, trace, and rare-earth elements, are commonly used to characterize various kinds of sedimentary rocks and to elucidate their provenance. Similar techniques have been applied to glacial materials with varying degrees of success. In Minnesota, for example, Martin and others (1989, 1991) concluded that few if any geochemical elements were useful for correlating tills across large areas. In contrast, Gowan (1998), in a study of six till units from central Minnesota, concluded that geochemical attributes were useful in delineating stratigraphic units and their provenance. Results of a similar study in southwestern Minnesota (Patterson and others, 1995) were inconclusive. The geochemical studies undertaken to date in Minnesota have utilized the silt and clay-size fraction as a sample medium and Atomic Adsorption spectrometry or Inductively Coupled Plasma emission spectrometry as the principal analytical technique. Unfortunately, both techniques require that the sample medium be dissolved prior to analysis, which can limit the value of the resulting data. For example, relative to the composition of the sample matrix and the particulates, certain minerals and elements may be selectively leached or incompletely dissolved, or spectral signals from some concentrated elements may interfere with weaker signals from less abundant elements. Such problems are best addressed by the use of replicates and standards developed from materials similar to those being analyzed. To our knowledge, sets of material standards that could be used to calibrate the various analytical methods have not been developed for Pleistocene sediments in Minnesota. In this study we avoided problems associated with partial dissolution and interference by using Instrumental Neutron Activation Analysis (INAA) techniques (XRAL Activation Services Inc., Ann Arbor, Michigan). We analyzed 123 subsurface samples from five drill sites in Stearns County, east-central Minnesota, for 32 elements. The results in this report are not directly comparable with those of Martin and others (1988), Gowan (1998), and Patterson and others (1995), because they were obtained on whole-rock samples from which only clasts of pebble or larger size had been removed. Nonetheless, the data provide insight into the utility of geochemical techniques to investigate provenance and transport patterns of glacial materials. The complete file of analytical data is summarized in the Appendix.
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    Information Circular 44. Geochemical Evaluation of Platinum Group Element (PGE) Mineralization in the Sonju Lake Intrusion, Finland, Minnesota
    (Minnesota Geological Survey, 1999) Miller, James D., Jr.
    This study was undertaken to evaluate the potential for stratiform platinum group element (PGE) mineralization in the Sonju Lake intrusion (SLI). The SLI is a well differentiated, tholeiitic, mafic layered intrusion that is part of the multiple intrusive Beaver Bay Complex, and is exposed near Finland, Minnesota. Geochemical analyses of outcrop and drill-core samples that span the 1200-m-thick SLI were interpreted in the context of (1) data from PGE reefs in other tholeiitic layered intrusions (most notably the Skaergaard intrusion of East Greenland), and (2) models of PGE and sulfide mineralization in tholeiitic intrusions. The geochemical data show that a PGE-mineralized horizon is present approximately two-thirds of the way up from the base of the moderately south-dipping, sheet-like SLI. PGE mineralization was apparently related to initial sulfide saturation and subsequent exsolution of sulfide melt from the SLI magma. The data also indicate that as it settled, the sulfide melt efficiently scavenged PGEs from the SLI magma, and concentrated them into a relatively narrow interval of gabbroic cumulates. The geochemical signature of the SLI is remarkably similar to that of the PGE-bearing Platinova reef in the Skaergaard intrusion. The highest Pd, Pt and Au concentrations in SLI outcrop samples are far from economic grade (360, 66, and 85 ppb respectively); but a more precise evaluation of peak grade, thickness, and lateral continuity requires drilling and analysis of the entire interval. When the results of the study reported here are combined with evidence for similar mineralization in the Layered Series at Duluth, they indicate that tholeiitic layered intrusions of the Duluth and Beaver Bay complexes are favorable exploration targets for reef-type PGE mineralization.
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    Information Circular 43. Background Levels of Mercury and Arsenic in Paleoproterozoic Rocks of the Mesabi Iron Range, Northern Minnesota
    (Minnesota Geological Survey, 1999) Morey, G.B.; Lively, R.S.
    This study was primarily designed to calculate background levels of mercury and arsenic in the Biwabik Iron Formation of the Mesabi range. A second objective was to evaluate the ability of various laboratories to provide analytical data for mercury and arsenic that is reasonably priced yet sufficiently reliable for the purpose of environmental screening. Mercury and arsenic where present in sufficient concentrations are considered to be hazardous substances. They may be naturally occurring, of anthropogenic origin, or some combination thereof. To establish natural background levels and to reduce the possibility of anthropogenic sources, 191 samples of the Biwabik Iron Formation were collected from drill-core sites located south of the Mesabi range (Fig. 1). Ten samples of the overlying Virginia Formation were also analyzed for comparison. Four of the selected sites were jointly drilled by the Minnesota Geological Survey and the Iron Range Resources and Rehabilitation Board (IRRRB) in 1966 and 1967; principal facts for these holes are summarized in Pfleider and others (1968). The fifth site, U.S. Steel 17,700 was drilled sometime in the 1950s, and the core was donated to the Minnesota Geological Survey in the late 1960s; principal facts for it are summarized in Morey and others (1972).
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    Information Circular 42. Scientific Test Drilling and Mapping in East-Central Minnesota, 1994-1995: Summary of Lithologic Results
    (Minnesota Geological Survey, 1997) Jirsa, Mark A.; Chandler, V.W.
    This report summarizes the results of test drilling, outcrop mapping, and geophysical analyses conducted by the Minnesota Geological Survey (MGS) in east-central Minnesota (Fig. 1). It is a companion to MGS Open-File Report 95-1 Jirsa, and others, 1995a). The results reported here, along with information from water-well records; exploration, engineering, and scientific test drilling; and existing geophysical maps, were used to construct the open-file map and the geological description in the following section. The western part of the map relies heavily on the interpretations of Boerboom and others (1995). Because geophysical data and interpretations played an essential role in targeting drill-hole locations and creating the geologic map, they are presented in a separate publication (Chandler and Jirsa, in preparation). This study focused on the Archean and Early Proterozoic geology of east-central Minnesota, which was some of the least understood in Minnesota. Previous interpretations depicted the area as largely Penokean granitoid intrusions. This work indicates that much of the area is indeed granitic; however, gravity and aeromagnetic data, and results given here, provide new insight about diverse rock types and complex structures that are also present. In addition, the study provided valuable stratigraphic information about the Middle Proterozoic (Keweenawan), Paleozoic, and Cretaceous bedrock, Quaternary glacial sediments, and the nature of boundaries between these strata.
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    Information Circular 41. Geochemical Investigation of Minor and Trace Elements in the Acid-Insoluble Residues of Lower Paleozoic Carbonate and Related Strata, Southeastern Minnesota-The Data Base
    (Minnesota Geological Survey, 1994) Morey, G.B.; Lively, R.S.; Mossler, John H.; Hauck, S.A.
    The Upper Mississippi Valley mining district in Iowa, Wisconsin, and Illinois is one of several world-class lead-zinc mineral districts in developed Paleozoic strata of the northern Midcontinent. Although Mississippi Valley-type deposits vary considerably from district to district, they are defined as being predominantly sphalerite-galena replacement and vein deposits-including vug and breccia fillings-in carbonate host rocks. In general, they are restricted to certain formations; as such they are peneconformable but clearly crosscutting. Therefore, Mississippi Valley-type mineral deposits are epigenetic and stratabound, but not stratiform. Minor occurrences of base-metal sulfides also are present in calcareous and, to a lesser extent, in shaly and sandy rocks in a broad zone surrounding the main Upper Mississippi Valley lead-zinc district. These outlying occurrences are of special interest because similarities in form, distinctive mineral paragenesis, and sulfur and lead isotope systematics imply that they were cogenetic with mineralization in the main district. The outlying occurrences may represent remnants of fluid pathways associated with mineralization in the main district. To evaluate the extent of mineralization in southeastern Minnesota, we initiated a geochemical study that focused on the minor-and trace-element content of insoluble residues in carbonate rocks, using samples from drill holes and operating quarries throughout southeastern Minnesota (Fig. 2; Tables 4-52 in appendix). Regional geochemical studies of this kind have revealed, even in rocks that appear to be barren of sulfide ores, a suite of metals characteristic of Mississippi Valley-type mineral deposits. In particular, this suite includes Pb, Zn, As, Cu, Ni, Ca, Ag, and Mo. Geochemical analysis of insoluble residues from Paleozoic carbonate rocks has become an integral part of the assessment of mineral resources in the northern Midcontinent (Erickson and others, 1981, 1983; Mosier and Motooka, 1983; Viets and others, 1983). Insoluble residues are the materials remaining after calcium carbonate has been dissolved in a aqueous solution of 5:1 hydrochloric acid. Measurements of the minor-and trace- element composition of the residues provide a rapid, yet sensitive means of identifying regional ground-water flow patterns of metal-bearing brines. The method also appears to have some applicability in identifying previously unrecognized areas with Mississippi Valley-type lead- zinc deposits and, by extension, providing clues to possible locations of mineral deposits in southeastern Minnesota.
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    Information Circular 40. Scientific and Exploration Drilling in Northwestern Minnesota
    (Minnesota Geological Survey, 1993) Jirsa, Mark A.; Boerboom, Terrence J.
    Scientific test drilling in northwestern Minnesota was undertaken by the Minnesota Geological Survey (MGS) primarily to elucidate the geology of Precambrian and Phanerozoic bedrock in this area where the bedrock is buried beneath several hundred feet of Quaternary glacial sediment. The results of this drilling of 23 holes, and of selected logging, and analyses of the approximately 80 archived records and core from previous drilling, are presented in this report. These data, in conjunction with various geophysical maps, were utilized by the authors and others to construct a series of new geologic maps of northwestern Minnesota that are part of MGS Open-File Report 93- lA (Jirsa and others, 1993). Parts of that report will soon be published in the MGS Miscellaneous Map Series. An important secondary objective of this project is to describe the Quaternary deposits that overlie bedrock, though no systematic regional interpretation of those deposits has been undertaken to date. This is the seventh information circular since 1980 to report the results of test drilling by the Minnesota Geological Survey. Figure 1 shows the areas covered by those earlier studies in relation to this study area in northwestern Minnesota.
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    Information Circular 39. Scientific Test Drilling, 1989-1992: Descriptions and Interpretations Pertinent to the Bedrock Geology and Quaternary Hydrogeology of Southwestern Minnesota
    (Minnesota Geological Survey, 1993) Southwick, D.L.; Setterholm, Dale R.; Runkel, Anthony J.; Patterson, Carrie J.; Chandler, V.W.
    In 1980 the Minnesota Geological Survey (MGS) started a program of scientific test drilling designed to acquire a better understanding of the complex Precambrian bedrock of Minnesota. A research approach that combined selective test drilling with geophysical surveying of the Precambrian terrane was dictated by the fact that the Precambrian rocks are covered by substantial thicknesses of quaternary glaciogenic sediment in most places and therefore are not amenable to standard outcrop mapping techniques. This circular is the seventh to report basic results from the drilling program. It contains data from 20 holes drilled for three separate studies undertaken in southwestern Minnesota in 1989-92. The drilling for two of the three projects reported here was closely coordinated with geophysical surveys, and the selection of drilling targets was guided by geophysics to the maximum extent practicable. The third study, consisting of the single hole PR-90-1, was somewhat abnormal in that drilling was targeted on a topographic rather than a geophysical feature (see discussion below for details). Apart from this one exception, our standard procedure was to formulate regional interpretations of the buried Precambrian geology from the geophysical data and then drill to verify, modify, or otherwise constrain the geophysical interpretation. Earlier applications of this approach have contributed to regional-scale geologic maps of the Penokean orogen (Early Proterozoic) in east-central Minnesota (Southwick and others, 1988) and an Archean greenstone belt in north-central Minnesota (Jirsa and Boerboom, 1990; Jirsa, 1990; Jirsa and others, 1991). The data tabulated in this circular will eventually contribute to a new geologic map for southwestern Minnesota.
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    Information Circular 38. Analytical Results of the Public Geologic Sample Program, 1989-1991 Biennium
    (Minnesota Geological Survey, 1992) Morey, G.B.; Day, L.S.
    In 1983 the Minnesota Geological Survey, in conjunction with the Minnesota Department of Natural Resources, Division of Minerals, began a geologic sample program involving the chemical analysis of geologic materials, in part submitted by the general public. This Information Circular summarizes the results of that program during the 1989-1991 biennium. In all, 106 samples were evaluated by Survey geologists as potential candidates. In addition we received 115 written and phone requests for information about the program. In the end, only one public sample (Table 1 and 7) was analyzed for a variety of constituents. Also, 308 samples of Archean to Quaternary age submitted by Survey geologists were analyzed for a variety of major, minor, and trace constituents. Tables within those categories are organized by the geologic age of the material analyzed. In addition, 39 samples of water derived from the Hinckley-Mt. Simon aquifer of southeastern Minnesota were analyzed for their trace-element contents (Table 13), as were 33 samples for the del S34 content (Table 14). Effective July 1.1989, the program was discontinued; this is the last report in this series.
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    Information Circular 37. Scientific Core Drilling in Parts of Itasca, St. Louis, and Lake Counties, Northeastern Minnesota, 1989-1991
    (Minnesota Geological Survey, 1993) Meints, Joyce P.; Jirsa, Mark A.; Chandler, V.W.; Miller, James D., Jr.
    This information circular is the fifth since 1980 to report on the basic results of test drilling (Fig. 1) by the Minnesota Geological Survey (MGS). As with the previous projects, this test drilling was conducted primarily to provide a better understanding of the Precambrian geology in areas of Minnesota where bedrock is covered by variable thicknesses of glaciogenic sediment, and thus could not be thoroughly mapped by standard outcrop mapping and sampling procedures. The drilling summarized here was conducted during 1989-1991 in areas where the bedrock is locally well exposed, but where exposures are separated by covered terrane. Thus, the selection of drill targets was constrained largely by the interpretation of geophysical surveys (Chandler, 1983a, b). Our procedure is to formulate a regional geologic interpretation based on geophysical maps, new and existing outcrop data and the archived records of previous drilling, and then to constrain and test the interpretation by selective drilling. The results have been incorporated into new geologic maps of the region including Jirsa and others (1991) and Southwick (in prep.). An important secondary objective of this project is to describe the Quaternary deposits that overlie bedrock, though no systematic regional interpretation of those deposits has been undertaken to date. This report summarizes the results of studies in two areas of vastly different geology: 1) Archean and Early Proterozoic rocks of the Cook area in west-central St. Louis and eastern Itasca Counties, and 2) Middle Proterozoic rocks of the central Duluth Complex in parts of St. Louis and Lake Counties. The geology of each area is summarized in the "results" section of this report.
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    Information Circular 36. Radium in the Mt. Simon-Hinckley Aquifer, East-Central and Southeastern Minnesota
    (Minnesota Geological Survey, 1992) Lively, R.S.; Jameson, Roy; Alexander, E. Calvin, Jr.; Morey, G.B.
    Studies conducted in the 1960s showed that radium was a fairly common constituent in ground water throughout much of the Midwest. Concentrations of 226Ra ranging from 1 to 80 pCi/L (picoCuries per liter) were found in northern illinois, Iowa, and eastern Wisconsin (Rowland and others, 1977). The high radium values were associated with water from deep sandstone aquifers of Cambro-Ordovician age, but not with aquifers above or below. Additional studies and reports of radium in the Cambro-Ordovician aquifers by Gilkeson and Cowart (1982, 1987), Hahn (1984), and Weaver and Bahr (1991) further delineated distribution patterns and have suggested sources for the observed concentrations. Radium is a naturally occurring radioactive element, formed by radioactive decay of uranium and thorium. The most abundant radium isotope, 226Ra, has a half-life of 1600 years and is part of the 238U decay series. Two other isotopes, 228Ra (half-life = 5.76 years) and 224Ra (half-life = 3.7 days), are part of the 232Th decay series. In 1976, the U.S. Environmental Protection Agency published regulations that established contaminant levels for radioactivity and radioactive nuclides in public water systems. The maximum contaminant level (MCL) for gross alpha activity was not to exceed 15 pCi/L and the combined 226Ra and 228Ra activity in the water was not to exceed 5 pCi/L (Federal Register, 1976). The U.S. Environmental Protection Agency is reviewing the contaminant levels for radioactive nuclides in drinking water. Testing of public water supplies by the Minnesota Department of Health showed that many communities in the southern half of Minnesota were not in compliance with the drinking water standards for radium. Sampling of some municipal wells indicated that high radium levels were chiefly associated with water from the Mt. Simon-Hinckley aquifer, a sandstone aquifer of Late Cambrian/Middle Proterozoic age. A few wells in the Jordan Sandstone of Late Cambrian age also showed elevated radium levels. Because these data were obtained from municipal wells in communities with known radium problems, it was difficult to detect a pattern or to isolate specific radium-producing horizons within the aquifer(s). Therefore, the Minnesota Geological Survey sampled water from sole-source Mt. Simon-Hinckley wells to identify the distribution of radium within the regional geologic framework. Base-level data were also acquired on other radionuclides, the age of the water, and the water chemistry. Sole-source Mt. Simon-Hinckley wells were selected for sampling based on existing water-well information, and included wells previously monitored by the Minnesota Department of Health. The study area extended north to south from the town of Hinckley to the Root River basin, and west to east from the Mankato area to the Mississippi River. Complete coverage could not be obtained because of a lack of sole-source Mt. Simon-Hinckley wells in the south-central part of the aquifer. Several Jordan aquifer wells were also selected for sampling. The data accumulated in this study provide a starting point for selecting mitigation strategies or for choosing appropriate sites for future wells.
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    Information Circular 35. Geophysical Solutions to Geologic Problems of Continental Interiors: A Minnesota Workshop
    (Minnesota Geological Survey, 1991) Chandler, V.W.
    Geophysics has long been a companion to geologic studies in Minnesota, where most of the bedrock lies beneath a thick cover of glacial drift. In 1979 the Minnesota Geological Survey (MGS), through funding by the Legislative Commission on Minnesota Resources (LCMR), began an ambitious geophysical project-a state-wide program of high-resolution aeromagnetic surveying. On the occasion of the completion of this highly successful program, the MGS through LCMR support hosted an international geophysics workshop during March 3-6,1991. The main objective of the workshop was to determine how the LCMR data and other geophysical information can most effectively be used, and what sorts of new geophysical investigations are desirable for Minnesota. Such an assessment must address private, academic, and governmental needs and must consider a diversity of topics, including mineral exploration, environmental and ground-water studies, geologic mapping, and crustal studies. The recommended tasks must also be consistent with the MGS mission of geologic mapping and framework studies. Sessions were centered on near-surface studies, geologic mapping, mineral exploration, and crustal studies. Speakers were selected from diverse perspectives and included individuals from the United States, Canada, Australia, and Finland. Posters included presentations by some of the speakers, as well as other geophysicists working in the region. The workshop attracted over 100 earth scientists, representing 10 states and 4 countries, and the sessions stimulated many useful discussions and ideas. This report summarizes the workshop, and discusses some of its most important recommendations. These recommendations will help set the course for Minnesota geophysics into the 21st century.
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    Information Circular 34. Precambrian Geology of the Southern Canadian Shield and the Eastern Baltic Shield
    (Minnesota Geological Survey, 1991) Ojakangas, Richard W.
    The geologic histories of the Canadian and Baltic Shields in North America and Europe, respectively, are broadly similar, and the topic was discussed during a conference and field trip involving North American and Russian participants in the late summer of 1990. During a two-day meeting prior to the field trip, twelve North American and eleven Soviet geologists presented papers, and participants discussed a variety of problems and ideas in Precambrian stratigraphy, sedimentology, tectonics, magmatism, industrial minerals, and metallogeny. Special emphasis was placed on problems of correlation. All papers were simultaneously interpreted by Senior Translator and Interpreter Grigori Sokolov of the Institute of Geology, Karelian Branch, U.S.S.R. Academy of Sciences, who accompanied the Russian delegation. His ability contributed greatly to the meeting's success. In addition to the speakers, thirty-eight geologists attended the conference: four Canadians, two Finns, and thirty-two Americans, including eight graduate students. As a result of the seminar and field trip, exciting and promising opportunities for continued cooperation were identified. Specific proposed activities include meetings, field excursions, short courses, joint publications, individual research-oriented exchanges, and joint projects. Involvement of young geologists was especially encouraged to promote long-term cooperative relationships. Opportunities also were identified for cooperation with other international projects, such as existing bilateral programs and the International Geological Correlation Program. It was mutually agreed that in 1991-1992, the Institute of Geology, Karelian Research Center, and the Kola Research Center of the USSR Academy of Sciences will host conferences and field trips on Proterozoic and Archean geology and metallogeny in the eastern Baltic shield. In 1991, the field program will emphasize Proterozoic geology, and in 1992, Archean geology. Other joint activities in the future will depend on the outcome of the 1991 and 1992 meetings. It was the intent of the organizers to bring this joint activity to the attention of officials involved in relevant international programs. Toward that end this proceedings volume has been published by the Minnesota Geological Survey. The body of this report consists of two parts; the first is a series of short papers that provide an overview of the Precambrian geology in the Great Lakes Region; the second part consists of a similar overview of the eastern part of the Baltic Shield.
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    Information Circular 33. Catalog of Paleontological Type Specimens in the Geological Museum, University of Minnesota
    (Minnesota Geological Survey, 1990) Rice, William F.
    This paper contains reference information for 1712 published paleontological primary type specimens housed in the geological/paleontological collection of the Newton Horace Winchell School of Earth Sciences at the University of Minnesota. This outstanding collection contains specimens from Minnesota and throughout the world. The geographic, chronologic, and taxonomic diversity of the collection reflects the diverse paleontological interests of past and present faculty, staff, and students in the earth sciences discipline at the University of Minnesota. The collection started in 1872 when the Minnesota Legislature authorized the University of Minnesota to organize the Geological and Natural History Survey of Minnesota. Section 6 of the enabling legislation for the Survey also authorized the establishment of a museum to house "specimens, skillfully prepared, secured and labeled, of all rocks, soils, ores, coals, fossils, cements, building stones, plants, woods, skins, and skeletons of animals, birds, insects and fishes, and other mineral, vegetable and animal substances and organisms discovered or examined in the course of said surveys" (Winchell, 1889, p. 6). The collections of the museum grew rapidly, and in 1890 the museum was separated into three divisions: geological (including paleontology), zoological, and botanical; all three were housed in Pillsbury Hall on the Minneapolis campus of the University. The zoological and botanical collections were later moved from Pillsbury Hall, but the geological/paleontological collection remains there to this day, providing a valuable source for reference and research. Contributors to the collection have included some of the most prominent paleontologists of their times. From 1872 to 1900, Professor Newton H. Winchell, assisted by Edward O. Ulrich, Charles Schuchert, Wilbur H. Scofield, and others, amassed a large collection of Ordovician fossils from Minnesota, Iowa, and Wisconsin. Frederick W. Sardeson, as a student, instructor, and professor at the University, collected Ordovician fossils in Minnesota, Iowa, and Wisconsin from about 1890 to 1914. Sardeson continued to collect after his departure from the University, and in 1947 the Department of Geology and Mineralogy acquired his large private collection. From the 1920s through the 1940s, Professor Clinton R. Stauffer added thousands of specimens, especially conodonts and scolecodonts from the Ordovician of Minnesota and the Devonian of Minnesota, Ohio, and Ontario. In the late 1940s, Professor William C. Bell and his students collected many important Cambrian trilobites from Minnesota and Wisconsin. For the past forty years Professor Frederick M. Swain has added to the collection countless ostracods from all over the world. Most recently, Professor Robert E. Sloan's work in the western United States has produced numerous Late Cretaceous and Paleocene vertebrates.
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    Information Circular 32. Geology and Manganese Resources of the Cuyuna Iron Range, East-Central Minnesota
    (Minnesota Geological Survey, 1990) Morey, G.B.
    Ever since their discovery in 1904, it has been recognized that the iron-formations and associated ore deposits of the Cuyuna iron range in east-central Minnesota contained appreciable quantities of manganese which was extracted as ferromanganese ores from several mines on the North range from 1911 to 1984. The presence of this manganese resource sets the Cuyuna range apart from other iron-mining districts of the Lake Superior region. The emphasis of this report is on the geologic factors that seem to control how the manganese is distributed on the Cuyuna range. However because the range was exploited principally for its iron ores, much of the available information is fragmentary. Although the manganese is closely associated with the iron ores, it was carefully evaluated by only a few of the companies operating on the range. Other companies examined the manganese-bearing material in only a cursory manner, and therefore in spite of what appears to be an extensive data base, our knowledge of the geology of the manganese resources is fragmentary and in part confusing. It is not yet possible to construct a coherent, detailed picture of the primary origin of the manganese-bearing strata, the structure and stratigraphic positions of these strata, and the precise tenor, extent, and localization of the several different kinds of manganese-bearing material that have been recognized. The ultimate utilization of the Cuyuna manganese deposits will require new metallurgical and beneficiation techniques that must be designed specifically for the different kinds of ores, and this report, if nothing else, should call attention to the deficiencies of the present geological data base.
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    Information Circular 31. Scientific Test Drilling in West-Central Minnesota Summary of Lithologic and Stratigraphic Results, 1987-1988, and Some Preliminary Geological Conclusions
    (Minnesota Geological Survey, 1990) Southwick, D.L.; Setterholm, Dale R.; Boerboom, Terrence J.
    In 1980 the Minnesota Geological Survey (MGS) began a program of scientific test drilling designed to acquire a better understanding of the complex Precambrian bedrock of Minnesota. A research approach that combined selective test drilling with geophysical surveying of the Precambrian terrane was dictated by the fact that the Precambrian rocks are covered by substantial thicknesses of Quaternary glaciogenic sediment in most places and therefore are not amenable to standard mapping and sampling techniques. This circular is the fourth to report basic results from the drilling program. It contains data from four separate studies that were undertaken in central and western Minnesota in 1987-1988 (Fig. 1). The drilling summarized here, like that in previous projects (Southwick and others, 1986; Mills and others, 1987; Boerboom and others, 1989), was closely coordinated with geophysical surveys, and the selection of drilling targets was guided by geophysics to the maximum extent practicable. Our standard procedure was to formulate regional interpretations of the buried Precambrian geology from the geophysical data and then drill to verify, modify, or otherwise constrain the geophysical interpretation. Earlier applications of this approach have contributed to regional-scale geologic maps of the Penokean orogen (Early Proterozoic) in east-central Minnesota (Southwick and others, 1988) and an Archean greenstone belt in north-central Minnesota (Jirsa and Boerboom, 1990); the data tabulated in this circular will eventually contribute to new geologic maps for west-central Minnesota.
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    Information Circular 30. Workshop on the Applicability of Gold and Platinum-Group-Element Models in Minnesota
    (Minnesota Geological Survey, 1989) Morey, G.B.
    The geology of Minnesota is highly varied and contains combinations of lithologic and structural factors that are known to be associated with important deposits of metallic minerals elsewhere in the world. Despite this broadly favorable potential for a diverse array of deposit types, however, only the world-class deposits of iron ore have yet been discovered. This suggests that we know too little about the geology, too little about the criteria for recognizing nonferrous mineral deposits, or, as is probably the case, too little about both. As a step toward remedying these deficiencies, a mineral deposit workshop was convened in April 1989 with support from the Minnesota Legislature through the Mineral Diversification Program, as administered by the Minnesota Minerals Coordinating Committee (W.C. Brice, Minnesota Department of Natural Resources, Division of Minerals; P.C. Grew, Minnesota Geological Survey; K.J. Reid, Mineral Resources Research Center; T.B. Johnson, Natural Resources Research Institute). The topic of the workshop was a discussion of mineral deposit models applicable to gold and the platinum group of elements (PGE) in Minnesota. Co-convenors of the workshop were Priscilla C. Grew (Minnesota Geological Survey), Michael P. Foose (U.S. Geological Survey), and Steven A. Hauck (Natural Resources Research Institute, University of Minnesota, Duluth). Professor Samuel S. Adams (Colorado School of Mines) provided special assistance in planning the workshop program. Industry participation was coordinated by Keith Laskowski (Newmont Exploration, Ltd.) and William C. Ulland (American Shield), both of the Minnesota Exploration Association. The body of this report consists of two parts-an overview of Minnesota's geologic framework, by D.L. Southwick, and a summary of the workshop discussions.
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    Information Circular 29. Analytical Results of the Public Geologic Sample Program, 1987-1989 Biennium
    (Minnesota Geological Survey, 1989) Morey, G.B.; McDonald, Linda L.
    In 1983 the Minnesota Geological Survey, in conjunction with the Minnesota Department of Natural Resources, Division of Minerals, began a geologic sample program involving the chemical analysis of geological materials, in part submitted by the general public. This Information Circular summarizes the results of that program during the 1987-1989 biennium. In all, 166 samples were evaluated by Survey geologists as potential candidates. Of that total, 129 samples were rejected because they were not deemed suitable for analysis and 25 samples were rejected because the submitters were unwilling or unable to provide locations as required by the program. In the end, 4 public samples (Tables 1, 4, and 9) were analyzed for a variety of constituents. Additionally, 326 samples submitted by Survey geologists were analyzed for a variety of major, minor, and trace constituents. The analytical results from 10 other miscellaneous samples were also donated to the Survey during the biennium and are included in this report. Tables within those categories are organized by the geological age of the material analyzed.