Browsing by Subject "Paleozoic"

Now showing 1 - 12 of 12

Bulletin No. 29. The Paleozoic and Related Rocks of Southeastern Minnnesota
(Minnesota Geological Survey, 1941) Stauffer, Clinton R.; Thiel, George A.
The area covered by this report is mainly the southeastern part of Minnesota. It includes that portion of the state lying along or bounded by the St. Croix, the Minnesota, and the Mississippi rivers from Pine County southward to the Iowa state line and from Brown County eastward to the Wisconsin state line. Adjoining areas are referred to at various points in the text, chiefly for correlative purposes or in order to clarify the discussion. This area lies mostly within the hardwood timber section. Numerous towns and villages dot the region, which is part of the more thickly populated area of Minnesota, settled for over seventy-five years and first pioneered over one hundred years ago. Many of the old traders and missionaries traveled its navigable waters early in the seventeenth century; and for untold centuries before that it was an important part of the great hunting ground of the American Indian. The state of Minnesota lies on the southern border of the great Canadian Shield, so that much of its surface is covered by the preCambrian rocks characteristic of that ancient land mass. There more recent sediments overlie these older rocks, they vary in age from Cambrian to Cretaceous and later, for the glacial drift and the recent non-marine sediments may lie directly on the preCambrian. The strand line of Paleozoic and late Mesozoic time often passed through Minnesota; and the position of the ancient shore, varying from time to time, left many unconformities. The significance of some of these unconformities may not yet be fully appreciated, but they range from short breaks (diastems) in sedimentation, like those in the St. Croixian series, to great erosion intervals (disconformities) like that between the Maquoketa formation and the Cedar Valley limestone, where a whole system and fully half of another are wanting. It is evident, therefore, that during these long intervals diastrophism caused the land mass to the north to be extended beyond the boundaries of the state and that during such periods profound erosion must have affected this area, removing an unknown amount of the surface, probably base-leveling it several times.
C-34, Geologic Atlas of Winona County, Minnesota
(2014) Setterholm, Dale, R.
Surface and bedrock geology of Winona County, Mn., also includes data-base information, bedrock topography, depth-to-bedrock and structural tops of bedrock strata.
Guidebook 4. Field Trip Guide Book for Paleozoic and Mesozoic Rocks of Southeastern Minnesota
(Minnesota Geological Survey, 1972) Webers, G.F.; Austin, G.S.
The Paleozoic rocks of southeastern Minnesota (fig. 1) were deposited from a marine sea which occupied the Hollandale Embayment (fig. 2), a shallow depression that extended northward from the Ancestral Forest City Basin (Iowa Basin) onto the cratonic shelf and into Minnesota and Wisconsin in Early and Middle Paleozoic time. The rocks that now remain within the embayment in Minnesota are bordered to the east by nearshore-facies Paleozoic rocks on the Wisconsin Arch, to the northeast by Precambrian rocks that constitute the Wisconsin Dome, and to the north and west by nearshore-facies Paleozoic rocks lying near the margins of the Hollandale Embayment and the Precambrian rocks of the Transcontinental Arch. The embayment overlies older basins and horsts that are bounded by largescale Precambrian faults (Sims and Zietz, 1967). Many smaller Paleozoic basins, depositional barriers, and faults within the embayment probably have resulted from relatively minor recurrent movements along Precambrian faults during Paleozoic time (Craddock and others, 1963).
Guidebook 8. Field Trip Guide Book for Hydrogeology of the Twin Cities Artesian Basin
(Minnesota Geological Survey, 1972) Winter, T.C.; Norvitch, R.F.
This field trip focuses on several of the more significant aspects of the hydrogeology of the Minneapolis-St. Paul (Twin Cities) area. Emphasis is placed on the principal bedrock aquifer and the role of glacial drift in the hydrology. Stops (fig. 1) include field examination of the Jordan-Prairie du Chien aquifer, a well-screen manufacturing plant and its research well field, views of surface expression of partly buried bedrock valleys, an artificial-recharge site where experiments were run on deep-well water injection into the Prairie du Chien Group (carbonate rock), and a site where ground water discharges as a large spring from the Prairie du Chien Group. Although much glacial geology is seen along the trip route, emphasis is placed on the drift-filled bedrock valleys. An understanding of the hydrogeology of the Twin Cities area is becoming more critical as urbanization progresses. The population of the metropolitan area is 1,874,000 (1970), an increase of 350,000 since 1960. Predictions of population for the year 2000 are in the neighborhood of 3,000,000. Accompanying the population increase are questions concerning the adequacy of water supply; the effect of surface and subsurface waste disposal, paving, sewering, and other land-use practices on the hydrologic system; and the reasons for lake-level declines and accelerated eutrophication. The Twin Cities supply themselves and 13 surrounding municipalities with water from the Mississippi River. Water from a large number of wells within the cities is used mainly for industry and air conditioning. In addition, most suburban communities use ground water to the extent that ground water now exceeds surface water as a source of supply. Total ground water use in 1970 in the metropolitan area was 194 mgd (million gallons per day); 48 mgd was for domestic purposes, 75 mgd for air conditioning (based on 137 days), 100 mgd for industrial and commercial purposes, and 38 mgd for irrigation (based on 90 days). According to Norvitch (unpublished data), the amount of ground water that can be developed in the metropolitan area on a sustained basis is about 845 mgd. Optimum development of the ground-water resources will be possible only through proper management based on a thorough understanding of the hydrologic system.
Information Circular 6. Paleozoic Lithostratigraphic Nomenclature for Southeastern Minnesota
(Minnesota Geological Survey, 1969) Austin, G.S.
The Paleozoic lithostratigraphic nomenclature shown in the column was compiled from information obtained from several sources-outcrops, deep cores, and theses on the geology of southeastern Minnesota. It is a revision of the Paleozoic stratigraphic column published in 1956 (Schwartz, 1956). The purpose of this discussion is to describe the Paleozoic strata of southeastern Minnesota in terms of the revised nomenclature and to call attention to related post-1956 publications and other source materials.
M-194 Bedrock Geology of the Twin Cities Ten-County Metropolitan Area, Minnesota
(2013-08-01) Mossler, John H.
This regional map is partly a compilation of existing maps of bedrock geology in the metropolitan area and partly a remapping of bedrock in areas where the existing maps were out of date because of the acquisition of new subsurface data.
Minnesota at a Glance Paleozoic History of Southeastern Minnesota-Ancient Tropical Seas
(Minnesota Geological Survey, 2020; 2002; 2000) Runkel, A.C.
Imagine a sandy, tropical seashore extending across southern Minnesota—part of a vast, shallow sea that covers much of North America. The sandstone, shale, and limestone rock layers exposed across much of southeast Minnesota (Figs. 1 and 2) are a geologic record of such conditions that existed hundreds of millions of years ago, during the early Paleozoic Era. Although many people are not aware of the geologic history of the Paleozoic bedrock in Minnesota, the rocks are familiar to anyone who has visited southeastern Minnesota. The bluffs along the St. Croix, Minnesota, and Mississippi Rivers, and their tributaries, are composed of layers of Paleozoic-aged rock such as the St. Peter Sandstone and the Prairie du Chien Group (Fig. 2). Paleozoic rocks lie beneath glacial sediments across much of southeast Minnesota, from as far north as Taylors Falls, southwest to Mankato (Fig. 1). They extend south into Iowa and east into Wisconsin. To understand the detailed history of the rock in southeastern Minnesota, you need only be familiar with the processes of deposition and erosion. These Paleozoic rock layers are sedimentary in origin. They are composed of particles of pre-existing rocks or minerals, or are precipitated by biological or chemical processes. Deposition is the accumulation of particles into layers, or beds. Small grains are dropped by wind or settle in water to form sandstone and shale. Elements, such as calcium, magnesium, carbon, and oxygen precipitate from seawater or are left as biological remains, such as shells, to form what we call calcareous, or carbonate sediments and later rocks —either calcium-rich limestone largely consisting of the mineral calcite, or more magnesium-rich dolostone largely consisting of the mineral dolomite—with much of the magnesium commonly added later by percolating water
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.
S-21 Geologic Map of Minnesota-Bedrock Geology
(Minnesota Geological Survey, 2011) Jirsa, Mark A.; Boerboom, Terrence J.; Chandler, V.W.; Mossler, John H.; Runkel, Anthony C.; Setterholm, Dale R.
This map is a new construct that incorporates existing geologic maps where prior mappers had adequate ground control, and new interpretations based on drill hole, geophysical, and unpublished data where they did not. The interpretation differs significantly from previous maps to reflect new data and accommodate scale. It portrays our current geologic understanding of the temporal and geographic distribution of units within major Precambrian terranes and of the Phanerozoic strata. The western part of the mapped Precambrian terrane is inferred largely from geophysical maps, anchored locally by drilling. In many places, contacts are drawn between units of the same or similar apparent rock type (and same unit label); these are recognized as geometrically distinct, though geophysically or lithologically similar. Digital files corresponding to this map allow removal of Cretaceous, Paleozoic, and some parts of Mesoproterozoic strata to reveal an interpretation of the underlying Precambrian bedrock. For additional data see: (http://hdl.handle.net/11299/98043 [select, copy and paste into browser]) which contains files associated with Bedrock Topography, Depth to Bedrock, and locations of Outcrop and Geochronologic analyses.

University Digital Conservancy

Browse by Subject

Browsing by Subject "Paleozoic"