Open-File Reports

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Bedrock geologic map of Carver County, Minnesota
(Minnesota Geological Survey, 1993) Runkel, A.C.
Bedrock geologic map of Carver County with bedrock topography contours.
Bedrock geologic maps, eastern half of Houston County, Minnesota
(Minnesota Geological Survey, 1995) Runkel, A.C.
Preliminary bedrock geologic map of the eastern part of Houston County, scale 1:100,000
Compilation Geologic Model for Cannon River Watershed: A Pilot Project
(Minnesota Geological Survey, 2022-07) Steenberg, Julia R; Retzler, Andrew J; Hamilton, Jacqueline D; Francis, Sarah W
This report is a summary of year one of a two-year pilot project conducted by the Minnesota Geological Survey for the Minnesota Department of Health Groundwater Restoration and Protection Strategies (GRAPS) program designed to support watershed planning efforts in the Cannon River Watershed. Our goal was to provide a compilation of both surface and subsurface geologic data within selected Board of Water and Soil Resources One Watershed One Plan boundaries in a format suitable for both modelers and the general public. Seamless geologic products provided within the watershed are based on a compilation of previously published MGS maps along with new mapping where necessary. Compilation methods and limitations associated with the subsurface modeling processes are described in the report. These products were transferred into web-based 3D models so they could be readily visualized and used outside of a GIS environment by water planners, other state agencies involved in the GRAPS process, and the public. The 3D model is available online at https://arcg.is/09OS1L0.
Compilation Geologic Model for Missouri River Watershed: A Pilot Project
(Minnesota Geological Survey, 2022-07) Steenberg, Julia R; Retzler, Andrew J; Hamilton, Jacqueline D; Francis, Sarah W
This report is a summary of year one of a two-year pilot project conducted by the Minnesota Geological Survey for the Minnesota Department of Health Groundwater Restoration and Protection Strategies (GRAPS) program designed to support watershed planning efforts in the Missouri River Watershed. Our goal was to provide a compilation of both surface and subsurface geologic data within selected Board of Water and Soil Resources One Watershed One Plan boundaries in a format suitable for both modelers and the general public. Seamless geologic products provided within the watershed are based on a compilation of previously published MGS maps along with new mapping where necessary. Compilation methods and limitations associated with the subsurface modeling processes are described in the report. These products were transferred into web-based 3D models so they could be readily visualized and used outside of a GIS environment by water planners, other state agencies involved in the GRAPS process, and the public. The 3D model is available online at https://arcg.is/1iimH50.
Compilation Geologic Model for Redeye River Watershed: A Pilot Project
(Minnesota Geological Survey, 2022-07) Steenberg, Julia R; Retzler, Andrew J; Hamilton, Jacqueline D; Francis, Sarah W
This report is a summary of year one of a two-year pilot project conducted by the Minnesota Geological Survey for the Minnesota Department of Health Groundwater Restoration and Protection Strategies (GRAPS) program designed to support watershed planning efforts in the Redeye River Watershed. Our goal was to provide a compilation of both surface and subsurface geologic data within selected Board of Water and Soil Resources One Watershed One Plan boundaries in a format suitable for both modelers and the general public. Seamless geologic products provided within the watershed are based on a compilation of previously published MGS maps along with new mapping where necessary. Compilation methods and limitations associated with the subsurface modeling processes are described in the report. These products were transferred into web-based 3D models so they could be readily visualized and used outside of a GIS environment by water planners, other state agencies involved in the GRAPS process, and the public. The 3D model is available online at https://arcg.is/15Gnz02.
From Compass to Drone: The Evolving Role of Magnetics in Mapping the Geology and Ore Deposits Of the Lake Superior Region: 1830-2022
(Minnesota Geological Survey, 2022) Hinze, William J
The Lake Superior region, the “Birthplace of North American Precambrian Geology,” is noted for its world-class mineral resources, especially its native copper and iron ore deposits, and its classic bedrock of Archean and Proterozoic orogenic belts and the exposures of rocks of the Midcontinent Rift System. The magnetic method of mapping the region’s ore deposits and bedrock geology has been used for nearly two centuries because of limitations in the exposure of the Precambrian bedrock in the region. For the first century magnetic mapping was directed primarily at the identification of regions favorable for iron and copper ore deposits using simple magnetic needle instrumentation. Initially instrumentation was limited to the use of the dial (sun) compass and used mainly for exploration of hard, magnetite-rich iron ore deposits. With the introduction of the dip needle, a counterbalanced magnetic needle oscillating vertically in the magnetic meridian, to the Lake Superior region likely in 1865 by T.B. Brooks, magnetic mapping was no longer restricted to the difficult to interpret magnetic field angular variations.
Gravity and Magnetic Studies in Carver County and Adjacent Areas, Southeastern Minnesota
(Minnesota Geological Survey, 2009) Chandler, V.W.
This report summarizes the gravity and magnetic studies that were done as part of the Carver County Geologic Atlas (CGA) study. This work compliments the bedrock geology component of the project, and it has three objectives, as described below: 1. The first objective is to create gravity and magnetic grid images to assist in compiling the bedrock map sheet for the CGA. 2. The second objective was to use gravity and magnetic model studies to help create geologic cross sections that are to accompany the bedrock geology map sheet. 3. The third objective was to apply a semi-automated magnetic interpretation scheme called Euler Deconvolution (Reid and others, 1990), which estimates the location and depth of magnetic anomaly sources.
OFR 07-07, Bedrock geology, topography, and karst feature inventory of Steele, Dodge, Olmsted and Winona Counties
(Minnesota Geological Survey, 2007) Tipping, R.G.; Mossler, J.H.; Alexander, E. Calvin, Jr.; Gao, Y.; Green, Jeffrey A.; Alexander, S.C.
Final Project Report Regulating contaminant sources and addressing remediation of contaminated sites is difficult in sensitive karst areas because of the unpredictable nature of groundwater movement in solution-weathered bedrock. In this project, the Minnesota Departments of Health, Natural Resources and the Minnesota Pollution Control Agency partnered with the Minnesota Geological Survey and the Department of Geology and Geophysics – University of Minnesota, to develop better tools to understand and manage point and non-point sources on contamination in karst terrains. Contaminant Management in the Karst Region Contract with MGS, also includes summary information for 319 Karst Demonstration Project
OFR07-06, Upgrade of Aeromagnetic Databases and Processing Systems at the Minnesota Geological Survey
(Minnesota Geological Survey, 2007) Chandler, Val W
During 2005-2007 a program to upgrade the aeromagnetic database for Minnesota was conducted by the Minnesota Geological Survey (MGS). Most of the Minnesota aeromagnetic data were acquired during a 1979-1991 state-wide survey program, and compilation and processing were limited to the computer capabilities of the time. Since that time significant improvements have been made in the development of computers and software that can efficiently handle massive database operations, such as line leveling and gridding. This project was consequently initiated to upgrade the MGS database using up-to-date software and hardware. Access to the data was also to be improved by making all upgraded data available via the web.
OFR10-02, Preliminary Bedrock Geologic Map of Minnesota
(Minnesota Geological Survey, 2010) Jirsa, M.A.; Bauer, E.J.; Boerboom, T.J.; Chandler, V.W.; Lively, R.S.; Mossler, J.H.; Runkel, A.C.; Setterholm, D.R.
The geologic map and some associated digital map files that are part of this Open File Report have been superseded by the map and digital data that comprise S-21 in the State Map Series.
OFR12-01, Geologic Atlas User's Guide: Using Geologic Maps and Databases for Resource Management and Planning
(Minnesota Geological Survey, 2019) Setterholm, Dale, R.
A geologic atlas is intended to describe the geologic framework of our home and how the subsurface environment provides the resources we need. It describes the materials and features that begin just beneath the soil and it continues down to the bedrock surface and beyond. This User’s Guide is intended for people that don’t have training in geology or hydrology- most people. Every Minnesotan uses water, and every Minnesotan has an effect on water, so we all have a role and a stake in how that resource is distributed, how it is used, and how we affect its quality and availability. The purpose of the Guide is to explain in simple terms where our water comes from, how geology and climate control its distribution, and how we can manage water to maximize the availability of high quality water for ourselves and the habitat we live in. The atlases can provide very practical information such as what aquifers are available to a homeowner that needs to drill a well. The atlases also work at larger scales answering questions such as “where is the largest or most productive aquifer in this county”, or conversely, “where is the best place in this county to isolate potential contaminants from our water system?”. The atlases document existing hydrologic conditions, such as water levels in aquifers, so that we can recognize and respond to changes in those levels if necessary.
OFR14-01, Evaluation of the horizontal-to-vertical spectral ratio (HVSR) passive seismic method for estimating the thickness of Quaternary deposits in Minnesota and adjacent parts of Wisconsin
(Minnesota Geological Survey, 2014) Chandler, V.W.; Lively, R.S.
Horizontal to vertical spectral ratios (HVSR) of ambient seismic noise may be used to estimate the thickness of sediment over bedrock, based on empirically-derived, power-curve relationships between sediment thickness and primary resonant frequency of shear-waves. The primary resonant frequency can be deduced from prominent peaks or troughs in the HVSR spectra, provided that the sediment-bedrock interface is reasonably flat, and is associated with a strong acoustic impedance contrast. Several recent geologic investigations in southern Minnesota have provided an opportunity to evaluate the HVSR method as a way to estimate the thickness of Quaternary sediments for a variety of bedrock and sediment conditions. Wherever Quaternary sediments cover the bedrock in Minnesota and adjacent areas, the HVSR method will be a useful supplement to geological and other geophysical investigations, provided that appropriate cautions are heeded. Although, the HVSR method does not match conventional seismic studies in the level of interpretive detail such as modeling a surface, it offers distinct advantages of rapid data collection, much lower equipment and staff costs, ease of data analysis and the large number of samples that can be collected within an area. The HVSR method can also be readily applied in areas of significant cultural noise, where conventional seismic data is difficult or impossible to obtain.
OFR14-02, Geologic controls on groundwater and surface water flow in southeastern Minnesota and its impact on nitrate concentrations in streams
(Minnesota Geological Survey, 2014) Runkel, Anthony C.; Steenberg, Julia R.; Tipping, Robert G.; Retzler, Andrew J.
This report summarizes the results of a Minnesota Geological Survey (MGS) investigation conducted for the Minnesota Pollution Control Agency (MPCA) designed to support watershed planning efforts in southeast Minnesota. Specifically it provides better understanding of the geologic controls on nitrate transport in the region, including nitrate in groundwater that is the source of baseflow to streams. Nitrate contamination of surface water and groundwater is a long- standing issue in southeastern Minnesota. We focused much of our investigation on an evaluation of nitrate (NO3 ion) transport in the Root River watershed because of the relatively advanced understanding of the karstic conditions in that area. However, the overall scope of the project includes the entire bedrock-dominated landscape of southeast Minnesota. Our results therefore support a broader MPCA watershed planning effort that directly pertains to the Root River, as well as to other watersheds within the Lower Mississippi River Basin in Minnesota.
OFR14-03, Geologic Controls on Groundwater and Surface Water Flow in Southeastern Minnesota and its Impact on Nitrate Concentrations in Streams: Local Project Area Report
(Minnesota Geological Survey, 2014) Steenberg, Julia R.; Tipping, Robert G.; Runkel, Anthony C.
This report summarizes the results of part of a Minnesota Geological Survey (MGS) investigation conducted for the Minnesota Pollution Control Agency (MPCA) designed to support watershed planning efforts in southeast Minnesota. The broader project provides better understanding of the geologic controls on nitrate transport in the region, including nitrate in groundwater that is the source of baseflow to streams. This report describes a local scale subproject focused on a relatively small part of the Root River watershed in Fillmore County. We conducted new mapping that provides a more detailed depiction of the geologic conditions in a three dimensional electronic format suitable for groundwater-surface water modeling. In addition, we used existing maps and reports along with new field data collected during the course of this project to improve the hydrostratigraphic characterization of the bedrock. This led to a more comprehensive understanding of the hydrostratigraphic attributes of bedrock that forms the Upper Carbonate Plateau, which dominates the landscape in the local project area. Cross sections within the local project area are used to illustrate how nitrate is transported in the ground and surface water system.
OFR14-04, Hydrogeologic Properties of the St. Lawrence Aquitard, Southeastern Minnesota
(Minnesota Geological Survey, 2014) Runkel, Anthony C.; Tipping, Robert R.; Green, J.A.; Jones, Perry M.; Meyer, Jessica R.; Parker, Beth L.; Steenberg, Julia R.; Retzler, Andrew J.
To better understand the properties of bedrock aquitards, we initiated a project that utilizes widely ranging methods to gain insights into the properties of the St Lawrence Formation and adjacent strata of the upper Tunnel City Group (Mazomanie and Lone Rock Formations) and lower Jordan Sandstone. The St Lawrence Formation has been traditionally regarded as an aquitard in the Paleozoic bedrock hydrogeologic system.Our investigation addresses hydraulic properties at site-specific as well as sub-regional (square miles) scales. Specific activities included drilling, testing and instrumentation of a borehole in the eastern Twin Cities Metro area (TCMA), the Afton multilevel system (MLS) hole, that has provided us with detailed multi-level measurements of hydraulic characteristics above, below and within the St. Lawrence Formation. We also analyzed the distribution of fractures in bedrock outcrops, in an effort to understand the controls these fractures might have on borehole hydraulic conditions. Borehole and outcrop scale data are augmented with ground-water tracer experiments that provide horizontal and vertical travel times at the sub-regional scale. Compilation of existing published and unpublished hydraulic and water chemistry data provide additional insights into the properties of the St Lawrence Formation and adjacent units across a wider extent of southeastern Minnesota.
OFR14-05, A HYDROCHEMICAL SURVEY OF GROUNDWATER FLOW IN THE ROCHESTER METROPOLITAN AREA, MINNESOTA
(Minnesota Geological Survey, 2014) Tipping, Robert G.
Historical chemical and isotopic data from Olmsted County, Minnesota were used to distinguish groundwater types based on similar chemical and isotopic composition. The extent of recent waters, identified by detectible tritium, chloride, nitrate or sulfate concentrations above background levels, along with groundwaters having elevated calcium to magnesium molar ratios were mapped in three dimensions. The distribution of these waters can be explained, in part, by the permeability of unconsolidated sediments overlying bedrock, bedrock hydrostratigraphy, and vertical hydraulic gradients within the Rochester Central Metropolitan Area (RCMA) dueto high capacity pumping. The spatial distribution of groundwater chemical types is also a function of changes in vertical hydraulic gradients with time. Within the last 20 years, the extent of recent waters within the RCMA has expanded both horizontally and vertically. Groundwater calcium to magnesium ratios in the Prairie du Chien Group (Shakopee aquifer) and the Jordan Sandstone (Jordan aquifer) within the RCMA have also increased and show greater variability through time, indicating a greater percentage of recharge to these aquifers moving vertically within the RCMA and from the Decorah edge than before high-capacity pumping began.
OFR16-4, Preliminary geologic maps of Lake and St. Louis Counties, northeastern Minnesota
(Minnesota Geological Survey, 2016--2018) Jirsa, Mark A, Project Manager
This Open-File Report (OFR) is a repository for on-going mapping in Lake and St. Louis counties that began in 2015 and will be largely completed by 2020. It contains preliminary bedrock and surficial geologic maps and associated products covering parts, and eventually all of the two counties. Because the counties are large, they have been divided for mapping purposes into subareas, each containing the name Arrowhead. Surficial, Bedrock Topography, and Depth to Bedrock maps are divided into 4 subareas referred to here as the Central (content prefixed “CA,” 2016, 2017); Southeastern (SeA, 2017, 2018); Southwestern (SwA, 2018), and Northern Arrowhead (NA) areas. Bedrock maps and associated files cover 3 subareas referred to as Central (CA, 2016); Southern (SA, 2017); and Northern Arrowhead (NA, 2018). Note that the boundaries of subareas differ somewhat between the surficial and bedrock maps. Products within this Open File Report include bedrock geologic maps, surficial geologic maps, bedrock topography and depth to bedrock maps, Quaternary stratigraphy, sand distribution models, corresponding GIS files, and other digital content. Ancillary files such as technical reports, geophysical imagery and models, and geochronologic data are included for bedrock mapping in the 3 bedrock subareas. Once these preliminary products are complete, the data and interpretations will be recombined into County Geologic Atlases that will supersede this OFR. Authors of individual maps and reports within the OFR include: Boerboom, T.J., Chandler, V.W., Dengler, E.L., Hamilton, J.D., Horton, J.M., Jirsa, M.A., Lively, R.S., Meyer, G.N., Peterson, D.M., Radakovich, A.L., Schmitz, M.D., Setterholm, D.R., Wagner, K.G., and Wall, C.
OFR18-02, Stratigraphic Positions of Springs in Southeast Minnesota
(Minnesota Geological Survey, 2018) Steenberg, Julia R; Runkel, Anthony C
Springs are places where groundwater is returned naturally to the surface and are a place to study the state of the groundwater in the aquifer system. In southeast Minnesota, springs are outlets in a conduit flow system in both carbonate and siliciclastic bedrock formations. They provide baseflow for streams and are a critical source of cold, relatively constant temperature water for trout. This report and associated database summarizes the results of various projects, inquiries, and studies over the years during which MGS staff investigated the location and stratigraphic position of southeastern Minnesota springs. It was produced as part of a contract between MDNR and MGS. The primary contract deliverable is a GIS feature class that contains the essential data from our hydrostratigraphic work. We have also placed notes associated with many of our interpretations into Appendix A of this report.
OFR20-01, Minnesota Data Preservation Report for 2019/2020: Updated Data Inventory, Preservation of Pillsbury Hall Rock Collections and Documentation, Assembly of Mineral Potential Related Information
(Minnesota Geological Survey, 2020) Thorleifson, L Harvey
Minnesota Geological Survey (MGS) activity is focused primarily on recommendations of Legislative panels that indicate that statewide coverage of layered County Geologic Atlases will be needed to support management of water resources, while concurrently being needed for applications such as mineral resources, engineering, hazards, and research. All MGS activity is reliant on geological specimens, as well as geological, geophysical, and geochemical data. The MGS long-term data preservation plan prepared in 2009 identified the highest priorities in relation to applications such as groundwater management and mineral resource assessment. Included were: 1) reprocessing of the aeromagnetic database; 2) enhancement of location precision for gravity stations; 3) vertical georeferencing of the rock property database; 4) cataloging and georeferencing of rocks and thin sections stored at the building MGS occupied from 1983 to 2015; 5) standardized formats for existing databases; and 6) scan and web enable all publications. More recently, a need was recognized for: 7) scanning, digitizing, and enhanced cataloging of borehole geophysical records, 8) comprehensive regional geophysical survey rescue, 9) enhancements to the cuttings collection and database. Objectives 1, 2, and 3 were completed with State of Minnesota support. Objective 4 was completed with multiple years of NGGDPP support. Objective 5 is ongoing. Objective 6 was completed with University of Minnesota Library support. Objective 7 was completed for gamma logs with our 2015 NGGDPP grant, and was completed for all borehole geophysical logs due to 2017 NGGDPP support. Geophysical survey rescue will remain unfulfilled due to staff availability constraints. Work on cuttings will be carried out due to NGGDPP support during 2020/2021.
OFR21-03, Compilation Geologic Model for Zumbro River Watershed: A Pilot Project
(Minnesota Geological Survey, 2021-06) Steenberg, Julia; McDonald, Jennifer; Retzler, Andrew; Hamilton, Jacqueline
This report is a summary of year one of a two-year pilot project between the Minnesota Geological Survey and the Minnesota Department of Health Groundwater Restoration and Protection Strategies (GRAPS) program designed to support watershed planning efforts in the Zumbro River Watershed. Our goal was to provide a compilation of both surface and subsurface geologic data within selected Board of Water and Soil Resources One Watershed One Plan boundaries in a format suitable for both modelers and the general public. Seamless geologic products provided within the watershed are based on a compilation of previously published MGS maps along with new mapping where necessary. Compilation methods and limitations associated with the subsurface modeling processes are described in the report. These products were transferred into web-based 3D models so they could be readily visualized and used outside of a GIS environment by water planners, other state agencies involved in the GRAPS process, and the public. The 3D model is available online at https://arcg.is/fevGS.